The association between behavioural and emotional problems and age in adults with Down syndrome without dementia: Examining a wide spectrum of behavioural and emotional problems.

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Contents lists available at ScienceDirect

Research in Developmental Disabilities

The association between behavioural and emotional problems and age in adults with Down syndrome without dementia: Examining a wide spectrum of behavioural and emotional problems Anna T. Makary a, Renee Testa a,b, Stewart L. Einfeld c, Bruce J. Tonge a, Caroline Mohr a, Kylie M. Gray a,1,* a

Centre for Developmental Psychiatry and Psychology, Department of Psychiatry, Southern Clinical School, Monash University, Early in Life Mental Health Service, Monash Medical Centre b Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Parkville, P.O Box 294, St Albans, VIC, 3021, Australia c Faculty of Health Sciences and Brain and Mind Research Institute, University of Sydney, 100 Mallet Street, Camperdown, NSW 2006, Australia

A R T I C L E I N F O

A B S T R A C T

Article history: Received 30 September 2013 Received in revised form 7 April 2014 Accepted 8 April 2014 Available online xxx

The literature on the association between behavioural and emotional problems and ageing in adults with Down syndrome (DS) without dementia is limited and has generally not reported on a wide range of behavioural and emotional problems. This research aimed to extend the field by examining the associations between age and a wide spectrum of behavioural and emotional problems in adults with DS without dementia. A preliminary analysis of the association between potential covariates and behavioural and emotional problems was also undertaken. Parents and caregivers completed a questionnaire on behavioural and emotional problems for 53 adults with DS aged between 16 and 56 years. Twenty-eight adults with DS and their caregivers were part of a longitudinal sample, which provided two time points of data approximately four years apart. Additionally, 25 participants with DS and their caregivers were from a cross sectional sample, which provided one time point of data. Random effects regression analyses were used to examine the patterns in item scores for behavioural and emotional problems associated with age. No significant associations between age and the range or severity of any behavioural and emotional items were found. This suggested a more positive pattern for ageing adults with DS than has been previously described. Given that behavioural and emotional problems were not associated with age, investigation into other factors that may be associated with the behavioural and emotional difficulties for adults with DS is discussed. ß 2014 Elsevier Ltd. All rights reserved.

Keywords: Down syndrome Age Emotional problems Behavioural problems Intellectual disability

* Corresponding author. Tel.: +61 03 9902 4563. E-mail addresses: [email protected] (A.T. Makary), [email protected] (R. Testa), [email protected] (S.L. Einfeld), [email protected] (B.J. Tonge), [email protected] (C. Mohr), [email protected] (K.M. Gray). 1 Mailing address: Centre for Developmental Psychiatry and Psychology, Department of Psychiatry, Southern Clinical School, Monash University, Early In Life Mental Health Service, Monash Medical Centre, 246 Clayton Road, Clayton, VIC, 3168. http://dx.doi.org/10.1016/j.ridd.2014.04.010 0891-4222/ß 2014 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Makary, A. T., et al. The association between behavioural and emotional problems and age in adults with Down syndrome without dementia: Examining a wide spectrum of behavioural and emotional problems. Research in Developmental Disabilities (2014), http://dx.doi.org/10.1016/j.ridd.2014.04.010

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1. Introduction Down syndrome (DS) is one of the most common genetic disorders associated with intellectual disability (ID; Fidler & Nadel, 2007; Nadel, 2003; Silverman, 2007), and has a complex cognitive, adaptive, neurobiological and behavioural phenotype (AAIDD, 2010; Di Nuovo & Buono, 2011; Rachidi & Lopes, 2007). It is suggested in the contemporary literature that the DS phenotype is generally not stable across the lifespan, but rather it changes with ongoing development and ageing (Couzens, Cuskelly, & Haynes, 2011; Dykens, Hodapp, & Evans, 2006). Given these possible developmental phenotypic changes, research on trajectories is generally considered more fruitful for understanding genetic syndromes than are studies that focus only on a particular age group (Cornish, Bertone, & Scerif, 2012; Elsabbagh & Karmiloff-Smith, 2012). Cognitive (Burt et al., 1995; Cornish, Scerif, & Karmiloff-Smith, 2007), biological (Berger-Sweeney, 2003; Pietrini et al., 1997) and adaptive behaviours (Esbensen, Seltzer, & Krauss, 2008; Hawkins, Eklund, James, & Foose, 2003) in people with DS are often studied within a developmental trajectory framework. Less research focus has, however, been placed on the trajectory of behavioural and emotional problems in individuals with DS. This is surprising given the growing literature on such trajectories of people with ID syndromes in general (e.g. Day & Jancar, 1994; Deb, Thomas, & Bright, 2001; Einfeld & Tonge, 1996). For ID syndromes in general, while some populationbased studies suggest no associations (Cooper, Smiley, Finlayson, et al., 2007; Cooper, Smiley, Morrison, Williamson, & Allan, 2007a; Cooper, Smiley, Morrison, Williamson, & Allan, 2007b; Einfeld & Tonge, 1996) or positive associations (Deb et al., 2001) between behavioural and emotional problems (and psychiatric diagnoses) and age, a number of papers also report decreases in such symptomology from adolescence to older age. Specifically, population-based studies have generally described significant decreases in the levels of behavioural and emotional problems associated with ageing for people with ID from adolescence into early (e.g. until 23 years of age; Einfeld et al., 2006) and then later adulthood (e.g. until 86 years of age; Day & Jancar, 1994; Mohr, Tonge, Einfeld, & Taffe, 2011; Pennington, 2010; Taylor, Hatton, Dixon, & Douglas, 2004). The paucity of behavioural and emotional research focusing specifically on trajectories of people with DS may in part be due to the mistaken view that individuals with DS mostly enjoy positive behavioural outcomes. While it is true that DS is associated with lower rates of behavioural and emotional problems (i.e. a prevalence of 0.6%; Mantry et al., 2008) when compared to other intellectual disability syndromes (Haveman, Maaskant, Van Schrojenstein Lantman, Urlings, & Kessels, 1994; Jones et al., 2008), the DS prevalence of such problems (point prevalence estimated at 23.7%; Mantry et al., 2008) still remains significantly higher than that of the typically developing population (Coe et al., 1999; Dykens, 2007; Einfeld, Tonge, Gray, & Taffe, 2007). Moreover, given the significant impact that these behavioural and emotional problems can have for people with DS including: distress, higher caregiver burden (McIntyre, Blacher, & Baker, 2002), lower quality of life (Esbensen et al., 2008), and reduced cognitive, educational and adaptive behavioural outcomes (Ball, Holland, Watson & Huppert 2010; Burt et al., 2005; Myers & Pueschel, 1995), further research and clinical attention is warranted. Depression is generally the most common symptomology (5.2% incidence; Mantry et al., 2008) reported for people with DS (Collacott Cooper, & McGrother, 1992; Myers & Pueschel, 1991). Despite earlier reports of higher levels of depression for people with DS when compared to other ID syndromes, recent analyses suggest that depression rates for those with DS are actually lower than in other ID disorders (Walker, Dosen, Buitelaar, & Janzing, 2011). Problem behaviours (3.7% incidence), notably non-compliance and stubbornness, as well as anxiety (1.5% incidence) are also common symptomology noted in both clinical and epidemiological studies for DS (Mantry et al., 2008). These studies (e.g. Collacott, et al., 1992; Mantry et al., 2008; Myers & Pueschel, 1991) are limited, however, in that they have not specifically evaluated the trajectories (or age associations) of behavioural and emotional problems for any developmental period in people with DS. Indeed, such developmental trajectory research is necessary if people with DS are to be provided with appropriate behavioural and emotional supports specific to their needs across all stages of the lifespan. The handful of studies that have examined behavioural and emotional problems and trajectories (or age associations) of young people with DS mostly depict the transitions from childhood to adolescence and young adulthood (e.g. until 18–20 years of age) and are broadly consistent with the findings for young people with ID in general (e.g. Einfeld et al., 2006). Specifically, these paediatric developmental studies indicated higher levels of externalising symptoms (Coe et al., 1999; Dykens, Shah, Sagun, Beck, & King, 2002; Einfeld et al., 2007; Myers & Pueschel, 1991), anxiety (Coe et al., 1999; Einfeld et al., 2007; Myers & Pueschel, 1991), and repetitive behaviours during the childhood years (Coe et al., 1999; Myers & Pueschel, 1991). Throughout adolescence the levels of externalising symptoms and anxiety have been noted to decrease (Dykens, 2007; Einfeld et al., 2007; Myers & Pueschel, 1991). The adolescent trajectory of depression is unclear, with some studies reporting unchanged levels over time (Einfeld et al., 2007), while others describe increases in symptomology (Dykens et al., 2002; Myers & Pueschel, 1991). More recently, research focusing on the trajectories of behavioural and emotional problems throughout adulthood for people with DS has appeared in the literature. Impetus for this research is likely a result of the significantly increased life expectancy (from 12 to 60 years of age) for people with DS over the last two generations (Bittles, Bower, Hussain, & Glasson, 2007) and the need to care for and support older adults with DS. At present, a particularly popular area of adult DS research relates to the pathological ageing trajectory, where investigation into the behavioural and emotional features associated with early stages of dementia and then subsequent progression are conducted (Adams et al., 2008; Ball et al., 2006; Ball, Holland, Treppner, Watson, & Huppert, 2008; Gregory & Hodges, 1993; Nelson, Orme, Osann, & Lott, 2001; Urv, Zigman, & Silverman, 2003). Given evidence that now refutes the inevitability of dementia in people with DS (Contestabile, Benfenati, & Gasparini, 2010; Head, Lott, Patterson, Doran, & Haier, 2007; Holland, Hon, Huppert, Stevens, & Watson, 1998; Zigman, Silverman, & Wisniewski, 1996), the study of the healthy ageing trajectory of adults with DS (assumed if the individual fails


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to meet the diagnostic criteria for dementia; Burt et al., 2005; Bush & Beail, 2004) as a sequelae unique from pathological ageing is now best practice in the field (Burt et al., 1995; Devenny et al., 1996). Much less research focus has been placed on monitoring this healthy ageing trajectory of behavioural and emotional problems in adults with DS (Dykens, 2007; Thorpe, Davisdson, & Janicki, 2001). An understanding of such ageing is necessary if we are to ensure that older healthy adults with DS continue to be productive and engaged members of the community. To date, the limited studies on behavioural and emotional problems and healthy adult ageing for individuals with DS have produced diverse findings. Longitudinal (three year follow up timeframe; Dalton, Mehta, Fedor, & Patti, 1999) and cross sectional investigations (Collacott, Cooper, Branford, & McGrother, 1998; Fenner, Hewitt, & Torpy, 1987; Patti & Tsiouris, 2006; Prasher & Chung, 1996) have reported no significant association between age and a range of behavioural and emotional problems (e.g. depression, irritability, withdrawal, aggression, antisocial, uncooperativeness and untruthfulness) for adults aged 17–58 years. Others have conversely noted significant associations between behavioural and emotional problems and ageing, although the direction and nature of these associations are generally not consistent across studies. A decrease in externalising behaviours (e.g. disruptive, aggressive and conduct) with advanced age is perhaps one of the most consistent findings (Esbensen et al., 2008; Myers & Pueschel, 1991; Patti & Tsiouris, 2006). The age at which decreases begin is yet to be established and varies significantly across reports (e.g. >20, >30 or >50 years; Esbensen et al., 2008; Myers & Pueschel, 1991; Patti & Tsiouris, 2006). The trajectory of depressive symptomology is more controversial. Some authors have reported increases in depression for those over 20 years of age when compared to children and adolescents (Myers & Pueschel, 1991). Conversely, using a multiple measurement longitudinal design (seven time points over nine years), Esbensen et al. (2008) noted decreases in depression (and overall internalising behaviours) for adults with DS during their thirties and early forties. This limited literature on healthy adult ageing for people with DS for behavioural and emotional problems is further constrained by: (1) inadequate methodological design within investigations that would permit the evaluation of behavioural and emotional problems and ageing (e.g. Dalton et al., 1999; Fenner et al., 1987; Prasher & Chung, 1996; where the primary focus was not on such evaluations), and (2) the restricted range of behavioural and emotional problems analysed by the majority of papers (generally only 34–40 questionnaire items; Dalton et al., 1999; Fenner et al., 1987; Myers & Pueschel, 1991). Generally, only total behaviour scores are reported (Prasher & Chung, 1996) or dichotomously recoded responses (Collacott et al., 1998). The clinical importance of understanding changes in a wide spectrum of behavioural and emotional problems, rather than just specific behaviours or emotions, has been demonstrated in the paediatric DS and general ID literature (Coe et al., 1999; Deb et al., 2001; Dykens et al., 2002; Einfeld et al., 2007; Myers & Pueschel, 1991). The primary aim of this study was to examine associations between age and a wide spectrum of behavioural and emotional problems in healthy ageing adults with DS. Secondary to this aim, a preliminary analysis of the association between potential covariates (i.e. level of ID, gender, mutation, and medical conditions) and behavioural and emotional problems was also undertaken. 2. Method 2.1. Participants This study consisted of both a longitudinal (n = 28, with two time points of data) and a cross sectional (n = 25) sample of adults with DS aged between 16 and 56 years (participant demographics in Table 1). Participants in the longitudinal sample were involved in previous Centre for Developmental Psychiatry and Psychology (CDPP) studies that collected a range of behavioural information for adults with intellectual disabilities from 2006 to 2008 (time point one data; T1). These sample are described in detail elsewhere (Einfeld et al., 2006, 2007; Mohr, Tonge, Einfeld, et al., 2011; Mohr, Tonge, Taffe, et al., 2011). From these studies, 152 eligible individuals were invited to participate in the current study, which was conducted from 2010 to 2012 (time point two data; T2), approximately 4.53 (SD = .54) years following the T1 data collection. Eight of the invited individuals could not be located, six were deceased and 28 responded, which gave a participation response rate of 20.28% (after excluding the deceased and un-contactable individuals). The cross sectional sample (n = 25) provided only one data point collected between 2010 and 2012 and were recruited from Down syndrome Associations, in Victoria and South Australia, Australia. The diagnosis of DS and the human chromosome 21 (Hsa21) mutation (for example, trisomy, mosaic or translocation) was confirmed, where possible, via parent/caregiver reports of karyotype testing (n = 44). Given the high frequency (90–95%) of the trisomy karyotype in the population with DS (Capone, 2001; Carter, Hamerton, Polani, Gunalp, & Weller, 1960; Clarke, Edwards, & Smallpeice, 1961; Nadel, 2003), in situations where karyotype information could not be sourced (n = 9) these individuals are described and analysed as a part of the trisomy group. Participant degree of ID (mild, moderate, severe or profound) was determined for the longitudinal sample at T1 based on psychologist’s estimates from full case file reviews (including assessment of adaptive functioning) and/or parent/ caregiver report. Two senior psychologists (PhD) with extensive clinical and research experience in working with people with intellectual disabilities were responsible for these estimates. For the longitudinal sample at T2 and for the cross sectional sample intellectual functioning was assessed by one of these senior psychologist’s using the Peabody Picture Vocabulary Test 4th Edition (PPVT-4) standard score (Dunn & Dunn, 2007). Given the reported high correlations between


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Table 1 Participant demographics for the longitudinal and cross sectional samples. Longitudinal sample

Cross sectional sample (n = 25)

Time 1 (n = 28)

Time 2 (n = 28)

Age in years M (SD) Range in years

33.34 (10.84) 20.33–52.75

37.7 (10.48) 24.83–56.41

26.67 (7.62) 16.67–42.33

Gender (n) Male Female

15 (53.57%) 13 (46.43%)

15 (53.57%) 13 (46.43%)

17 (68%) 8 (32%)

Degree of ID (n)b Mild/moderate Severe/profound

20 (71.43%) 8 (28.57%)

20 (71.43%) 8 (28.57%)

18 (72%) 7 (28%)

Karyotype (n) Trisomy Moasic

28 (100%) 0 (0%)

28 (100%) 0 (0%)

23 (92%) 2 (8%)

NA

36.61 (15.71) 0–65 0

35.48 (9.24) 5–52 0

Accommodation (n) Family Small groupc Care facilityd

19 (67.9%) 8 (28.6%) 1 (3.6%)

10 (35.7%) 16 (57.1%) 2 (7.1%)

25 (100%) 0 (0%) 0 (0%)

Main daytime activity (n) No structured activity Student Supported day programme Other employment

3 (10.7%) 1 (3.6%) 21 (75%) 3 (10.7%)

9 (32.1%) 1 (3.6%) 14 (50%) 4 (4.13%)

8 (32%) 5 (20%) 10 (40%) 2 (8%)

ABDQ totala M (SD) Range Dementia threshold (n)

a

ABDQ = Adaptive Behaviour Dementia Questionnaire; ID = intellectual disability. b Degree of ID according to DSM-IV-TR criteria (mild/moderate = PPVT-4 standard score > 35 or severe/profound = PPVT-4 standard < 35; APA, 2000) or previous file/parent reports. c Participant living in a small group home (4 people) with supervision. d Participant living in a care facility with 24 h/day care and supervision.

the PPVT-4 standard score (including previous PPVT-3 and PPVT-R Editions) and the full scale intelligence score in both typically developing (Bell, Lassiter, Matthews, & Hutchinson, 2001; Dunn & Dunn, 1997; Strauss, Sherman, & Spreen, 2006) and clinical populations (Naglieri, 1982; Powell, Plamondon, & Retzlaff, 2002), PPVT-4 standard scores were used to estimate degree of ID according to the Diagnostic and Statistic Manual of Mental Disorders Fourth Edition – Text Revised (DSM-IV-TR) criteria (mild/moderate = standard score > 35 or severe/profound = standard < 35; American Psychiatric Association [APA], 2000). PPVT-4 scores were not available for five participants (longitudinal sample at T2 n = 4; cross sectional sample n = 1), as consent to conduct individual testing was not provided (n = 3) or the participants were unable to attend testing sessions (n = 2). In situations where PPVT-4 scores were not available the same psychologists’ again estimated level of ID based on case file reviews and/or parent/caregiver reports. For participants in the longitudinal sample, the degree of ID determined from the PPVT-4 at T2 was consistent with the psychologist’s estimate made at T1 in all cases. Parents/caregivers provided information on current medical morbidities, assistance required for behavioural and emotional problems, and formal psychiatric diagnoses (including dementia) for both samples (see Table 2). Parents/ caregivers reported that appropriate professionals had diagnosed all medical and psychiatric conditions however, information on these professionals was not available and independent clinical assessment to confirm diagnoses was not within the scope of this study. Participants with a diagnosis of dementia or suspected dementia (n = 0) were not eligible for this study of healthy ageing, as by definition they were experiencing a pattern of decline not defined as healthy (Aylward, Burt, Thorpe, Lai, & Dalton, 1997; Bush & Beail, 2004; WHO, 1992). Given the high co-morbidity of DS with psychiatric and medical conditions, no psychiatric (other than dementia) or medical exclusion criteria were set (Coe et al., 1999; Dykens, 2007; Galdzicki & Siarey, 2003; Gibson et al., 2005; Greene et al., 2008; Prasher, 1999; Ravindranath, 2005). All conditions/problems were reported by the parent/caregiver as stable and under professional management at the time of assessment. Adults were also screened for possible unreported/undiagnosed dementias by the researchers (only at T2 for the longitudinal sample) using the Adaptive Behaviour Dementia Questionnaire; ABDQ (Prasher, Farooq, & Holder, 2004). No participant met the ABDQ dementia-screening threshold for the cross sectional sample or for the longitudinal sample at T2. Thus, it was inferred that all participants were dementia free in the longitudinal sample at T1,


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Table 2 Medical conditions, psychiatric conditions and professional assistance received for behavioural and emotional problems for the longitudinal and cross sectional samples. Longitudinal sample

Cross sectional sample (n = 25)

Time 1 (n = 28)

Time 2 (n = 28)

Medical conditions (n)a No conditions Condition/s Allergies Congenital heart Cardiovascular Thyroid Diabetes Asthma Respiratory Sleep apnea Other

9 19 1 5 4 5 2 3 2 2 3

(32.14%) (67.86%) (3.57%) (17.86%) (14.29%) (17.86%) (7.14%) (10.71%) (7.14%) (7.14%) (10.71%)

5 23 2 5 8 7 2 3 2 5 5

(17.86%) (82.14%) (7.14%) (17.86%) (28.57%) (25%) (7.14%) (10.71%) (7.14%) (17.86%) (17.86%)

17 8 0 1 0 3 0 0 0 1 5

(68%) (32%) (0%) (4%) (0%) (12%) (0%) (0%) (0%) (4%) (20%)

Psychiatric diagnoses (n)a No diagnosis Diagnosis/ses Depression OCDb Psychotic Other

22 6 4 0 2 1

(78.57%) (21.43%) (14.29%) (0%) (7.14%) (3.57%)

22 6 4 0 2 1

(78.57%) (21.43%) (14.29%) (0%) (7.14%) (3.57%)

24 1 0 1 0 0

(96%) (4%) (0%) (4%) (0%) (0%)

Behavioural/emotional problems (n) a b

6 (21.43%)

12 (42.86%)

11 (44%)

Some participants have more than one medical condition or psychiatric diagnosis. OCD = obsessive–compulsive disorder.

although this could only be confirmed by a detailed clinical assessment of each of the participants, which was not feasible in this study. 2.2. Measures 2.2.1. Peabody Picture Vocabulary Test 4th Edition; PPVT-4 (Dunn & Dunn, 2007) The Peabody Picture Vocabulary Test 4th Edition; PPVT-4 (Dunn & Dunn, 2007), provides a measure of an individual’s receptive vocabulary and has been previously used as a measure of intelligence in research in people with DS (Ball et al., 2008; Cornish et al., 2007; Iacono, Torr, & Wong, 2010). The PPVT-4 has good psychometric properties (test-retest reliability: r = .93; split half reliability r = .94–.95; convergent validity r = .80–.84) and validity for use in populations with mild to moderate ID (Dunn & Dunn, 2007). 2.2.2. Adaptive Behaviour Dementia Questionnaire; ABDQ (Prasher et al., 2004) The Adaptive Behaviour Dementia Questionnaire (ABDQ) is a screening tool designed to detect changes in daily functioning associated with dementia in DS (Prasher et al., 2004). The ABDQ is a 15-item checklist administered using a proxy interview, with items focusing on changes in adaptive skills from an individual’s previous ‘normal’ functioning. The ABDQ was selected in preference to other commonly used measures of dementia in DS (e.g. the CAMDEX-DS by Ball et al., 2004; and the DMR by Evenhuis, 1996) as it does not rely on repeated assessments over time but rather, it provides a single time point measure of decline associated with dementia. Higher ABDQ scores indicate greater levels of decline and a total score of 78 signifies the presence of dementia. The ABDQ has good inter-rater reliability (r = .95), sensitivity (89%), specificity (89%) and an overall accuracy of 92% (Prasher et al., 2004). 2.2.3. The Developmental Behaviour Checklist-Adult; DBC-A (Mohr, Tonge, Einfeld, et al., 2011) The Developmental Behaviour Checklist-Adult; DBC-A (Mohr, Tonge, Einfeld, et al., 2011), is a 107 item-checklist that provides an indication of behavioural and emotional disturbances experienced by adults (aged 16+ years) with ID over the last six months (Mohr, Tonge, & Einfeld, 2005; Mohr, Tonge, Einfeld, et al., 2011). Each item is rated by a parent/caregiver on a Likert scale, ‘00 – not true as far as you know, ‘10 – somewhat or sometimes true, or ‘20 – very true or often true. The DBC-A provides six subscale scores (disruptive behaviours, communication and anxiety disturbance, self absorbed behaviours, antisocial behaviours, depressive symptoms and social relating) and an overall measure of behaviour disturbance, which is called the Total Behaviour Problem Score (TBPS). Scores can be interpreted at the item, subscale or the total scale level (TBPS). Test-retest reliability (r = .75–.85), inter-rater reliability (r = .69–.72) and internal consistency (Cronbach a .95) are good (Mohr, Tonge, Einfeld, et al., 2011). The concurrent validity with other behavioural checklists is also good and ranges from r = .52–.63 (Mohr, Tonge, Einfeld, et al., 2011).


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Rather than calculating the sum of item scores for the DBC-A, mean item scores (MIS) were derived. This is advantageous as the component scores of the MIS provide additional information in terms of how scores may be differentially accounted for by either number of items observed (e.g. the proportion of items positively check [PIC] or the range) or the severity of behaviour (e.g. the intensity index [II], which is the proportion of positively checked items that are scored 2; Taffe, Tonge, Gray, & Einfeld, 2008). For example, a high total DBC-A MIS score could either be attributed to a large number of low severity items (e.g. 1), or a smaller number of items with higher severity (e.g. 2). Higher DBC-A MIS indicated greater levels of behavioural and emotional disturbance (range 0–2). 2.3. Procedures Participants and their families (for both samples) were invited to participate in this research via a mail out of explanatory statements and consent forms. Written consent to access the 2006–2008 T1 behavioural data for the longitudinal sample from the CDPP was obtained from a legal guardian at the time that they consented to be involved in the current study. T1 longitudinal data used in this study included demographics and the DBC-A scores. A parent/caregiver who had regular contact with the participant and was considered to know them best completed the DBC-A and the ABDQ for both samples, following the procedures outlined in the respective test manuals. For the cross sectional sample and the longitudinal sample at T2 the PPVT-4 was administered in accordance with standardised test manual procedures. Relevant ethics clearances were obtained from Monash University’s Human Research Ethics Committee and organisations associated with the recruitment process at all phases of data collection. 3. Data analysis Information from the two samples (cross sectional and longitudinal) was combined and analysed via random effects regression, with the cross sectional sample providing one and the longitudinal sample providing two time points. DBC-A outcome variables were modelled as a function of age, while level of ID (mild/moderate reference group), gender (male reference group), ABDQ score, total number of comorbid medical conditions and Hsa21 mutation (trisomy reference group) were entered as co-variates. The coefficients of age and medical conditions, which, like the outcomes, vary with time for some in the combined sample but not for others, are assumed to be appropriate for describing both between person and within person aspects of these explanatory variables. Whereas those for the other explanatory variables are simply measures of between person effects. 4. Results The results presented in Tables 3 and 4 show the patterns in item scoring for behavioural and emotional problems (DBC-A scores) and age (and the other co-variates) in adults with DS. For the regression analyses, the only significant model produced was for the proportion of item positively checked on the DBC-A self-absorbed subscale (p = .02). Here, however, severe/profound ID and mosaic mutation were the only variables significantly associated with the self-absorbed proportion of items positively checked. Specifically, the self-absorbed proportion of items positively checked was associated with higher values for those with severe/profound ID and mosaic mutation when compared to the respective mild/moderate ID and trisomy reference groups. No regression model for the mean item score, proportion of item positively checked or intensity of any other DBC-A variable was significant at the p < .05 level. This indicated that the model variables, including age, were generally not associated with the DBC-A outcome variables. While some co-variates for the non-significant models were significant (e.g. mosaic mutation and medical conditions), they typically had small effect sizes (see Table 4).

Table 3 DBC-A TBPS and subscale score means (standard deviations) for MIS, PIC and II. Sample

TBPS MIS

PIC

II

MIS

PIC

II

MIS

PIC

II

MIS

PIC

II

1 (n = 25) 2 (n = 28)

.25 (.18) .18 (.11) .28 (.21)

.21 (.14) .15 (.09) .23 (.20)

.14 (.14) .12 (.15) .17 (.24)

.28 (.27) .20 (.15) .29 (.29)

.25 (.20) .19 (.13) .23 (.20)

.07 (.13) .04 (.11) .17 (.24)

.36 (.27) .23 (.16) .38 (.28)

.29 (.20) .20 (.14) .28 (.19)

.21 (.21) .14 (.22) .31 (.26)

.13 (.12) .10 (.14) .18 (.24)

.12 (.10) .08 (.10) .15 (.17)

.15 (.29) .13 (.24) .14 (.22)

Time 1 Time 2

Disruptive

Antisocial

1 (n = 25) 2 (n = 28)

Time 1 Time 2

Comm/anx

Self absorbed

Depressed

Social relating

MIS

PIC

II

MIS

PIC

II

MIS

PIC

II

.24 (.22) .16 (.12) .26 (.29)

.21 (.18) .15 (.11) .20 (.19)

.09 (.18) .09 (.23) .21 (.31)

.23 (.22) .25 (.36) .36 (.35)

.20 (.17) .20 (.23) .31 (.25)

.08 (.21) .14 (.29) .09 (.17)

.49 (.39) .29 (.24) .45 (.36)

.38 (.23) .25 (.20) .36 (.26)

.20 (.29) .14 (.26) .21 (.24)

Notes: DBC-A = Developmental Behaviour Checklist – Adult; TBPS = Total Behaviour Problem Score; Sample 1 = cross sectional sample; Sample 2 = longitudinal sample; MIS = mean item score; PIC = proportion of items positively checked; II = intensity index; Comm/Anx = communication and anxiety.


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Table 4 Regression B Coefficients for Random Effects Models Based on 81 Observations From 53 Participants.

MIS Age Severe/profound ID Female gender Medical ABDQ total Mosaic mutation PIC Age Severe/profound ID Female gender Medical ABDQ total Mosaic mutation II Age Severe/profound ID Female gender Medical ABDQ total Mosaic mutation

TBPS

Disruptive

Comm/Anx

Self-absorbed

Antisocial

Depressed

Social relating

.001 .067 .001 .018 .000 .282*

.003 .067 .045 .013 .000 .475**

.002 .085 .009 .030 .001 .267

.001 .126 .047 .006 .000 .177

.005 .058 .020 .014 .000 .406**

.004 .022 .039 .007 .000 .170

.002 .123 .042 .044 .004 .230

.000 .050 .013 .012 .001 .225**

.001 .041 .051 .006 .000 .299*

.001 .062 .028 .014 .001 .217

.001 .098** .024 .004 .001 .199*

.002 .037 .007 .015 .001 .311**

.003 .015 .049 .007 .001 .120

.003 .110 .011 .025 .003 .182

.001 .001 .047 .059** .002 .040

.004* .020 .043 .037 .003 .227

.001 .012 .043 .066* .000 .007

.005 .059 .096 .079** .001 .171

.004 .080 .067 .007 .004 .111

.002 .028 .049 .004 .004 .052

.003 .002 .056 .041 .000 .119

Notes: ID = intellectual disability; TBPS = Total Behaviour Problem Score; Comm/Anx = communication and anxiety; ABDQ = Adaptive Behaviour Dementia Questionnaire; MIS = mean item score; PIC = proportion of items positively checked; II = intensity index. * p < .05. ** p < .01.

5. Discussion This study primarily considered the association between age and behavioural and emotional problems in healthy ageing adults with DS. A statistically combined cross sectional and longitudinal sample was utilised for analyses. Participant characteristics previously suggested as relevant to behavioural and emotional problems and age such as level of ID, gender, mutation, and medical conditions (Cooper, Smiley, Finlayson, et al., 2007; Dykens, 2007; Einfeld et al., 2007; Forster, Gray, Taffe, Einfeld, & Tonge, 2011; Holden & Gitlesen, 2004; Nelson et al., 2001; Prasher, 1995) were also controlled for and considered at a preliminary level. This study contributed to the existing literature by using the DBC-A to comprehensively assess a wide spectrum of behavioural and emotional problems. Further, age (and covariate) associations were able to be analysed using methods developed to extract more information from behavioural checklists introduced by Taffe et al. (2008). Overall, this study observed that age, in combination with the relevant participant covariates, was not associated with the mean item score, proportion of items positively endorsed or intensity for any DBC-A variable. The current findings are consistent with those of other studies that have reported no age associations for adults with DS in regards to depression, withdrawal, irritability, aggression, antisocial, uncooperative, and untruthful behaviours and emotions (Collacott et al., 1998; Dalton et al., 1999; Fenner et al., 1987; Patti & Tsiouris, 2006; Prasher & Chung, 1996). Conversely, this paper’s findings do not support the studies that have noted improvements and/or deteriorations in behavioural and emotional problems associated with ageing (e.g. aggression, disruptive, conduct, depression and internalising symptoms more generally; Esbensen et al., 2008; Myers & Pueschel, 1991; Patti & Tsiouris, 2006). This discrepancy between these findings and those of the present study may be attributed to a number of issues, although differences in methodology are likely to be the principal cause. Myers and Pueschel (1991) advised that they could not rule out the possibility that the elevated depressive symptomology levels of their participants during adulthood may have been associated with early stage dementia rather than a characteristic of healthy ageing. Thus, it is possible that the significant increase in depression reported by Myers and Pueschel (1991) was not replicated in the present study due to more stringent screening processes for possible dementia within the current study’s sample. Similarly, the declines previously described in externalising (Esbensen et al., 2008; Patti & Tsiouris, 2006) and internalising (Esbensen et al., 2008) behaviours are possibly a product of: (1) the clinical (rather than population based) sample analysed by Patti and Tsiouris (2006), and (2) that the longitudinal multi-time point design of Esbensen et al. (2008) had greater sensitivity to subtle age differences than the present study. More broadly, while this study lacked a non-DS control group, comparison to the ageing patterns noted for adults with ID in the Australian DBC-A development study (C. Mohr, personal communication, May 2009) and the Australian DBC-A normative sample (Mohr, Tonge, Einfeld, et al., 2011) can be applied in a descriptive manner. Utilising such comparisons, this study’s finding that age was not associated with any of the DBC-A variables for adults with DS are distinct from those from the Australian development study and normative sample. Overall, the development study revealed that significant decreases in behavioural and emotional problems, as measured by the DBC-A, were associated with advancing age in adults with ID (C. Mohr, personal communication, May 2009). Although significance testing was not reported, the age (and degree of ID) based norms provided for the DBC-A Australian normative sample similarly indicated that decreases in the mean item score, range


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and intensity for all the subscales were observed in the older age groups (e.g. ranges: 18–34, 35–49 and 50+ years). These descriptive comparisons suggest, even if only at a preliminary level, that adults with DS may experience different ageing patterns for behavioural and emotional problems when compared to the adults with ID from the development and normative studies. The underlying basis for the different ageing patterns for behavioural and emotional problems for adults with DS when compared descriptively to those previously reported for adults with ID are unclear. It is postulated that the lower overall prevalence of behavioural and emotional problems for adults with DS when contrasted to adults with other IDs (Einfeld & Tonge, 1996; Haveman et al., 1994; Jones et al., 2008; Mantry et al., 2008) may be associated with this ageing finding. Others, particularly in the cognitive field (e.g. Das, Divis, Alexander, Parrila, & Naglieri, 1995; Margallo-Lana et al., 2004), have highlighted the problems surrounding quantitatively identifying decline on measures where very low scores are originally endorsed. Such a difference is important as it suggests that applying the findings from general ID behavioural research for interventions with adults with DS may not be appropriate. Such contrasts between the current findings and those of the other DBC-A studies reinforce the importance of dealing with ageing in adults with DS separately. 5.1. Limitations and future directions This study was limited by the small sample size, the lack of a non-DS group, which ruled out direct comparison, and an inability to analyse the longitudinal data separately by time point due to the wide age range at time one. Given these limitations and the importance of managing behavioural and emotional problems in adults with DS over the lifespan, continued ageing research in this field is necessary. However, in the context of the non-significant ageing findings from the present study and others (e.g. Collacott et al., 1998; Dalton et al., 1999; Prasher & Chung, 1996), consideration of other factors that may be associated with behavioural and emotional problems in adults with DS could prove a worthwhile future research avenue. Factors that have previously been suggested as relevant to behavioural and emotional problems in ID research (i.e. degree of ID, mutation type, gender and health status) were included as covariates in this study, and preliminary analysis of their impact on behavioural and emotional problems was a secondary aim. While regression coefficients for these covariates were presented (see Table 4), the small cell sizes for some covariates (e.g. mosaic mutation n = 2) restricted the interpretation of this data. Despite this, significant associations were noted for degree of ID and mutation type for the proportion of items positively checked on the self-absorbed subscale. Other covariates (e.g. medical conditions) were also significantly associated with various DBC-A outcome variables, albeit in non-significant overall models. Given preliminary evidence for such associations, larger research projects with the ability to support such analyses may reveal that behavioural and emotional problems in adults with DS can be better supported by targeting factors such as degree of ID, mutation type or health status, for example, rather than, or in addition to, having age based interventions. 5.2. Conclusions This study did not find any significant associations between a wide spectrum of behavioural and emotional problems, as measured by the DBC-A, and age for healthy ageing adults with DS. Descriptive comparisons to other DBC-A ID ageing data suggested that this lack of age association might be a feature specific to adults with DS. Therefore, clinicians and researchers should exercise caution when combining adults with DS and adults with other ID syndromes as they likely present with different age related behavioural and emotional needs. The finding that behavioural and emotional problems for adults with DS were not associated with age suggested a more positive pattern for ageing adults with DS than has been described by some earlier studies. Investigation of other factors, for example mutation type and level of ID, that may be more strongly associated with behavioural and emotional problems for adults with DS is also necessary. Conflict of interest There are no conflicts of interest. Acknowledgements We would like to acknowledge the statistical support provided by Dr. John Taffe. The data used from the previous Monash University, Centre for Developmental Psychiatry and Psychology studies were funded by: the National Health and Medical Research Council (grants 912579, 954614, 113844 to Stewart Einfeld and Bruce Tonge); the Australian Research Council Linkage Grant (Number LP0561542), with Disability Services South Australia, Minda Inc., and the South Australian Department of Education. References Adams, D., Oliver, C., Kalsy, S., Peters, S., Broquard, M., Basra, T., et al. (2008). Behavioural characteristics associated with dementia assessment referrals in adults with Down syndrome. Journal of Intellectual Disability Research, 52, 358–368.


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American Association on Intellectual and Developmental Disabilities (AAIDD). (2010). Intellectual disability: Definition, classification, and systems of support (11th ed.). Washington, DC: American Association on Intellectual and Developmental Disabilities. American Psychiatric Association (APA). (2000). Diagnostic and statistical manual of mental disorders (4th ed., text revision). Arlington, VA: American Psychological Association. Aylward, E. H., Burt, D. B., Thorpe, L., Lai, F., & Dalton, A. J. (1997). Diagnosis of dementia in individuals with intellectual disability. Journal of Intellectual Disability Research, 41, 152–164. Ball, S. L., Holland, A. J., Watson, P. C., & Huppert, F. A. (2010). Theoretical exploration of the neural bases of behavioural disinhibition, apathy and executive dysfunction in preclinical Alzheimer’s disease in people with Down syndrome: Potential involvement of multiple frontal-subcortical neuronal circuits. Journal of Intellectual Disability Research, 54(4), 320–336. Ball, S. L., Holland, A. J., Hon, J., Huppert, F. A., Treppner, P., & Watson, P. C. (2006). Personality and behaviour changes mark the early stages of Alzheimer’s disease in adults with Down’s syndrome: Findings from a prospective population-based study. International Journal of Geriatric Psychiatry, 21, 661–673. Ball, S. L., Holland, A. J., Huppert, F. A., Treppner, P., Watson, P., & Hon, J. (2004). The modified CAMDEX informant interview is a valid and reliable tool for use in the diagnosis of dementia in adults with Down’s syndrome. Journal of Intellectual Disability Research, 48, 611–620. Ball, S. L., Holland, A. J., Treppner, P., Watson, P. C., & Huppert, F. A. (2008). Executive dysfunction and its association with personality and behaviour changes in the development of Alzheimer’s disease in adults with Down syndrome and mild to moderate learning disabilities. British Journal of Clinical Psychology, 47, 1–29. Bell, N. L., Lassiter, K. S., Matthews, T. D., & Hutchinson, M. B. (2001). Comparison of the Peabody Picture Vocabulary Test-Third Edition and Wechsler Adult Intelligence Scale-Thrid Edition with university students. Journal of Clinical Psychology, 57, 417–422. Berger-Sweeney, J. (2003). The cholinergic basal forebrain system during development and its influence on cognitive processes: Important questions and potential answers. Neuroscience and Biobehavioral Reviews, 27, 401–411. Bittles, A. H., Bower, C., Hussain, R., & Glasson, E. J. (2007). The four ages of Down syndrome. European Journal of Public Health, 17, 221–225. Burt, D. B., Loveland, K. A., Chen, Y., Chuang, A., Lewis, K. R., & Cherry, L. (1995). Aging in adults with Down syndrome: Report from a longitudinal study. American Journal on Mental Retardation, 100, 262–270. Burt, D. B., Primeaux-Hart, S., Loveland, K. A., Cleveland, L. A., Lewis, K. R., Lesser, J., et al. (2005). Aging in adults with intellectual disabilities. American Journal on Mental Retardation, 110, 268–284. Bush, A., & Beail, N. (2004). Risk factors for dementia in people with Down syndrome: Issues in assessment and diagnosis. American Journal on Mental Retardation, 109, 83–97. Capone, G. T. (2001). Down syndrome: Advances in molecular biology and the neurosciences. Developmental and Behavioral Pediatrics, 22, 40–59. Carter, C. O., Hamerton, J. L., Polani, P. E., Gunalp, A., & Weller, S. D. V. (1960). Chromosome translocation as a cause of familial mongolism. The Lancet, 2, 678–680. Clarke, C. M., Edwards, J. H., & Smallpeice, V. (1961). 21-Trisomy/normal mosaicism in an intelligent child with some mongoloid characters. The Lancet, 1, 1028– 1030. Coe, D. A., Matson, J. L., Russell, D., Slifer, K. J., Capone, G. T., Baglio, C., et al. (1999). Behavior problems of children with Down syndrome and life events. Journal of Autism and Developmental Disorders, 29, 149–156. Collacott, R. A., Cooper, S. A., Branford, D., & McGrother, C. W. (1998). Behaviour phenotype for Down’s syndrome. British Journal of Psychiatry, 172, 85–89. Collacott, R. A., Cooper, S. A., & McGrother, C. W. (1992). Differential rates of psychiatric disorders in adults with Down’s syndrome compared with other mentally handicapped adults. British Journal of Psychiatry, 161, 671–674. Contestabile, A., Benfenati, F., & Gasparini, L. (2010). Communication breaks-down: From neurodevelopment deficits to cognitive disabilities in Down syndrome. Progress in Neurobiology, 91, 1–22. Cooper, S., Smiley, E., Finlayson, J., Jackson, A., Allan, L., Williamson, A., et al. (2007). The prevalence, incidence, and factors predictive of mental ill-health in adults with profound intellectual disabilities. Journal of Applied Research in Intellectual Disabilities, 20, 493–501. Cooper, S., Smiley, E., Morrison, J., Williamson, A., & Allan, L. (2007a). An epidemiological investigation of affective disorders with a population-based cohort of 1023 adults with intellectual disabilities. Psychological Medicine, 37, 873–882. Cooper, S., Smiley, E., Morrison, J., Williamson, A., & Allan, L. (2007b). Mental ill-health in adults with intellectual disabilities: Prevalence and associated factors. British Journal of Psychiatry, 190, 27–35. Cornish, K., Bertone, A., & Scerif, G. (2012). Linking genes to cognition: The case of Fragile X syndrome. In J. A. Burack, R. Hodapp, G. Iarocci, & E. Zigler (Eds.), The Oxford handbook of intellectual disability and development (pp. 42–60). New York: Oxford University Press. Cornish, K., Scerif, G., & Karmiloff-Smith, A. (2007). Tracing syndrome-specific trajectories of attention across the lifespan. Cortex, 43, 672–685. Couzens, D., Cuskelly, M., & Haynes, M. (2011). Cognitive development in Down syndrome: Age-related change on the Stanford-Binet Test (fourth edition). American Journal of Intellectual and Developmental Disabilities, 116, 181–204. Dalton, A. J., Mehta, P. D., Fedor, B. L., & Patti, P. J. (1999). Cognitive changes in memory precede those in praxis in aging persons with Down syndrome. Journal of Intellectual & Developmental Disability, 24, 169–187. Das, J. P., Divis, B., Alexander, J., Parrila, R. K., & Naglieri, J. A. (1995). Cognitive decline due to aging among persons with Down syndrome. Research in Developmental Disabilities, 16, 461–478. Day, K., & Jancar, J. (1994). Mental and physical health and ageing in mental handicap: A review. Journal of Intellectual Disability Research, 38, 241–256. Deb, S., Thomas, M., & Bright, C. (2001). Mental disorder in adults with intellectual disability. 1: Prevalence of functional psychiatric illness among a communitybased population aged between 16 and 64 years. Journal of Intellectual Disability Research, 45, 495–505. Devenny, D. A., Silverman, W., Hill, A. L., Jenkins, E., Sersen, E. A., & Wisniewski, K. E. (1996). Normal ageing in adults with Down’s syndrome: A longitudinal study. Journal of Intellectual Disability Research, 40, 208–221. Di Nuovo, S., & Buono, S. (2011). Behavioral phenotypes of genetic syndromes with intellectual disability: Comparison of adaptive profiles. Psychiatry Research, 189, 440–445. Dunn, L. M., & Dunn, D. M. (2007). PPVT-4, Peabody Picture Vocabulary Test, Fourth Edition, Manual. Minneapolis, MN: Pearson Education. Dunn, L. M., & Dunn, L. M. (1997). Examiner’s Manual for the Peabody Picture Vocabulary Test, Third Edition. Circle Pines, MN: American Guidance Service. Dykens, E. M. (2007). Psychiatric and behavioral disorders in persons with Down syndrome. Mental Retardation and Developmental Disabilities Research Reviews, 13, 272–278. Dykens, E. M., Hodapp, R., & Evans, D. (2006). Profiles and development of adaptive behavior in children with Down syndrome. Down Syndrome Research and Practice, 9, 45–50. Dykens, E. M., Shah, B., Sagun, J., Beck, T., & King, B. H. (2002). Maladaptive behaviour in children and adolescents with Down’s syndrome. Journal of Intellectual Disability Research, 46, 484–492. Einfeld, S. L., Piccinin, A. M., Mackinnon, A., Hofer, S. M., Taffe, J., Gray, K. M., et al. (2006). Psychopathology in young people with intellectual disability. Journal of the American Medical Association, 296, 1981–1989. Einfeld, S. L., & Tonge, B. J. (1996). Population prevalence of psychopathology in children and adolescents with intellectual disability: II. Epidemiological findings. Journal of Intellectual Disability Research, 40, 99–109. Einfeld, S. L., Tonge, B. J., Gray, K. M., & Taffe, J. (2007). Evolution of symptoms and syndromes of psychopathology in young people with mental retardation. International Review of Research In Mental Retardation, 33, 247–265. Elsabbagh, M., & Karmiloff-Smith, A. (2012). The contribution of developmental models towards understanding gene-to-behavior mapping: The case of Williams syndrome. In J. A. Burack, R. Hodapp, G. Iarocci, & E. Zigler (Eds.), The Oxford handbook of intellectual disability and development (pp. 30–41). New York: Oxford University Press. Esbensen, A., Seltzer, M., & Krauss, M. (2008). Stability and change in health, functional abilities, and behavioural problems among adults with and without Down syndrome. American Journal on Mental Retardation, 113, 263–277. Evenhuis, H. M. (1996). Further evaluation of the Dementia Questionnaire for the Persons with Mental Retardation (DMR). Journal of Intellectual Disability Research, 40, 369–373.


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Fenner, M. E., Hewitt, K. E., & Torpy, D. M. (1987). Down’s syndrome: Intellectual and behavioural functioning during adulthood. Journal of Mental Deficiency Research, 31, 241–249. Fidler, D. J., & Nadel, L. (2007). Education and children with Down syndrome: Neuroscience, development, and intervention. Mental Retardation and Developmental Disabilities Research Reviews, 13, 262–271. Forster, S., Gray, K. M., Taffe, J., Einfeld, S. L., & Tonge, B. J. (2011). Behavioural and emotional problems in people with severe and profound intellectual disability. Journal of Intellectual Disability Research, 55, 190–198. Galdzicki, Z., & Siarey, R. J. (2003). Understanding mental retardation in Down’s syndrome using trisomy 16 mouse models. Genes, Brain and Behavior, 2, 167–178. Gibson, P. A., Newton, R. W., Selby, K., Price, D. A., Leyland, K., & Addison, G. M. (2005). Longitudinal study of thyroid function in Down’s syndrome in the first two decades. Archives of Disease in Childhood, 90, 574–578. Greene, A. K., Kim, S., Rogers, G. F., Fishman, S. J., Olsen, B. R., & Mulliken, J. B. (2008). Risk of vascular anomalies with Down syndrome. Pediatrics, 121, 135–140. Gregory, C. A., & Hodges, J. R. (1993). Dementia of the frontal type and the focal lobar atrophies. International Review of Psychiatry, 5, 397–406. Haveman, M. J., Maaskant, M. A., Van Schrojenstein Lantman, H. M., Urlings, H. F. J., & Kessels, A. G. H. (1994). Mental health problems in elderly people with and without Down’s syndrome. Journal of Intellectual Disability Research, 38, 341–355. Hawkins, B. A., Eklund, S. J., James, D. R., & Foose, A. K. (2003). Adaptive behaviour and cognitive function of adults with Down syndrome: Modeling change with age. Mental Retardation, 41, 7–28. Head, E., Lott, I. T., Patterson, D., Doran, E., & Haier, R. J. (2007). Possible compensatory events in adult Down syndrome brain prior to the development of Alzheimer disease neuropathology: Targets for nonpharmacological intervention. Journal of Alzheimer’s Disease, 11, 61–76. Holden, B., & Gitlesen, J. P. (2004). The association between severity of intellectual disability and psychiatric symptomatology. Journal of Intellectual Disability Research, 48, 556–562. Holland, A. J., Hon, J., Huppert, F. A., Stevens, F., & Watson, P. (1998). Population-based study of the prevalence and presentation of dementia in adults with Down’s syndrome. British Journal of Psychiatry, 172, 493–498. Iacono, T., Torr, J., & Wong, H. (2010). Relationships amongst age, language and related skills in adults with Down syndrome. Research in Developmental Disabilities, 31, 568–576. Jones, S., Cooper, S., Smiley, E., Allan, L., Williamson, A., & Morrison, J. (2008). Prevalence of, and factors associated with, problem behaviors in adults with intellectual disabilities. The Journal of Nervous and Mental Disease, 196, 678–686. Mantry, D., Cooper, S. A., Smiley, E., Morrison, J., Allan, J., Williamson, A., et al. (2008). The prevalence and incidence of mental ill-health in adults with Down syndrome. Journal of Intellectual Disability Research, 52, 141–155. Margallo-Lana, M., Morris, C. M., Gibson, A. M., Tan, A. L., Kay, D. W. K., Tyrer, S. P., et al. (2004). Influence of the amyloid precursor protein locus on dementia in Down syndrome. Neurology, 62, 1996–1998. McIntyre, L. L., Blacher, J., & Baker, B. L. (2002). Behaviour/mental health problems in young adults with intellectual disability: The impact on families. Journal of Intellectual Disability Research, 46, 239–249. Mohr, C., Tonge, B. J., & Einfeld, S. L. (2005). The development of a new measure for the assessment of psychopathology in adults with intellectual disability. Journal of Intellectual Disability Research, 49, 469–480. Mohr, C., Tonge, B. J., Einfeld, S. L., & Taffe, J. (2011). Manual for the Developmental Behaviour Checklist for Adults (DBC-A): Supplement to the Manual for the Developmental Behaviour Checklist-DBC-P and DBC-T. Melbourne, Australia: University of Sydney and Monash University. Mohr, C., Tonge, B. J., Taffe, J., Rymill, A., Collins, D., Keating, C., et al. (2011). Inter-rater reliability of the Developmental Behaviour Checklist for Adults in community accomodation settings. Journal of Intellectual Disability Research, 55, 710–713. Myers, B. A., & Pueschel, S. M. (1991). Psychiatric disorders in persons with Down syndrome. The Journal of Nervous and Mental Disease, 179, 609–613. Myers, B. A., & Pueschel, S. M. (1995). Major depression in a small group of adults with Down syndrome. Research in Developmental Disabilities, 16(4), 285–299. Nadel, L. (2003). Down’s syndrome: A genetic disorder in biobehavioral perspective. Genes, Brain and Behavior, 2, 156–166. Naglieri, J. A. (1982). Use of the WISC-R and PPVT-R with mentally retarded children. Journal of Clinical Psychology, 38, 635–637. Nelson, L. D., Orme, D., Osann, K., & Lott, I. T. (2001). Neurological changes and emotional functioning in adults with Down syndrome. Journal of Intellectual Disability Research, 45, 450–456. Patti, P. J., & Tsiouris, J. A. (2006). Psychopathology in adults with Down syndrome: Clinical findings from an outpatient clinic. International Journal on Disability and Human Development, 5, 357–364. Pennington, B. (2010). Investigating the mental health of older people with an intellectual disability (unpublished doctoral dissertation) Melbourne, Australia: Monash University. Pietrini, P., Dani, A., Furey, M. L., Alexander, G. E., Freo, U., Grady, C. L., et al. (1997). Low glucose metabolism during brain stimulation in older Down’s syndrome subjects at risk for Alzheimer’s disease prior to dementia. American Journal of Psychiatry, 154, 1063–1069. Powell, S., Plamondon, R., & Retzlaff, P. (2002). Screening cognitive abilities in adults with developmental disabilities: Correlations of the K-BIT, PPVT-3, and CVLT. Journal of Developmental and Physical Disabilities, 14, 239–246. Prasher, V. (1995). Age-specific prevalence, thyroid dysfunction and depressive symptomatology in adults with Down syndrome and dementia. International Journal of Geriatric Psychiatry, 10, 25–31. Prasher, V. (1999). Down syndrome and thyroid disorders: A review. Down Syndrome Research and Practice, 6, 25–42. Prasher, V., & Chung, M. C. (1996). Causes of age-related decline in adaptive behavior of adults with Down syndrome: Differential diagnosis of dementia. American Journal on Mental Retardation, 101, 175–183. Prasher, V., Farooq, A., & Holder, R. (2004). The Adaptive Behaviour Dementia Questionnaire (ABDQ): Screening questionnaire for dementia in Alzheimer’s disease in adults with Down syndrome. Research in Developmental Disabilities, 25, 385–397. Rachidi, M., & Lopes, C. (2007). Mental retardation in Down syndrome: From gene dosage imbalance to molecular and cellular mechanisms. Neuroscience Research, 59, 349–369. Ravindranath, Y. (2005). Down syndrome and leukemia: New insights into the epidemiology, pathogenesis, and treatment. Pediatric Blood Cancer, 44, 1–7. Silverman, W. (2007). Down syndrome: Cognitive phenotype. Mental Retardation and Developmental Disabilities Research Reviews, 13, 228–236. Strauss, E., Sherman, E. M. S., & Spreen, O. (2006). A compendium of neuropsychological tests. New York: Oxford University Press. Taffe, J., Tonge, B. J., Gray, K. M., & Einfeld, S. L. (2008). Extracting more information from behaviour checklists by using components of mean based scores. International Journal of Methods in Psychiatric Research, 17, 232–240. Taylor, J. L., Hatton, C., Dixon, L., & Douglas, C. (2004). Screening for psychiatric symptoms: PAS-ADD checklist norms for adults with intellectual disabilities. Journal of Intellectual Disability Research, 48, 37–41. Thorpe, L., Davisdson, P., & Janicki, M. (2001). Healthy ageing – Adults with intellectual disabilities: Biobehavioural issues. Journal of Applied Research in Intellectual Disabilities, 14, 218–228. Urv, T. K., Zigman, A., & Silverman, W. (2003). Maladaptive behaviors related to adaptive decline in aging adults with mental retardation. American Journal on Mental Retardation, 108, 327–339. Walker, J. C., Dosen, A., Buitelaar, J. K., & Janzing, J. G. E. (2011). Depression in Down syndrome: A review of the literature. Research in Developmental Disabilities, 32, 1432–1440. World Health Organisation (WHO). (1992). The International Classification of Disease (ICD-10). Geneva, Switzerland: World Health Organization (WHO). Zigman, W., Silverman, W., & Wisniewski, H. M. (1996). Aging and Alzheimer’s disease in Down syndrome: Clinical and pathological changes. Mental Retardation and Developmental Disabilities Research Reviews, 2, 73–79.


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