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Journal of Intellectual Disability Research 1131

doi: 10.1111/jir.12107

volume 58 part 12 pp 1131–1140 december 2014

A prospective study of the relationship between adverse life events and trauma in adults with mild to moderate intellectual disabilities S. Wigham,1 J. L. Taylor2 & C. Hatton3 1 Institute of Health and Society, Sir James Spence Institute, Newcastle University, Newcastle, UK 2 Northumbria University, Northumberland Tyne and Wear NHS Trust, Morpeth, Northumberland, UK 3 Division of Health Research, Lancaster University, Lancaster, UK

Abstract Background Research has demonstrated a relationship between the experience of life events and psychopathology in people with intellectual disabilities (ID), however few studies have established causal links and to date no prospective studies have utilised a measure of trauma that has been developed specifically for this population group. Method This 6-month prospective study examined longitudinal relationships between adverse life events and trauma in 99 adults with mild to moderate ID. Results Life events during the previous 6 months were significantly predictive of levels of trauma as measured by the self-report Lancaster and Northgate trauma scales (LANTS), and the informant LANTS behavioural changes, frequency and severity sub-scales. This prospective causal relationship was demonstrated while controlling for any prior life events or pre-existing trauma, though the relationship was not moderated by social support.

Correspondence: Dr Sarah Wigham, Institute of Health and Society, Sir James Spence Institute, Newcastle University, Newcastle NE1 4LP, UK (e-mail: [email protected]).

Conclusions Evidence of a causal relationship between adverse life events and trauma symptoms is important for treatment planning and funding allocation. Keywords adverse life events, intellectual disabilities, social support, trauma.

Introduction People with intellectual disabilities (ID) are more likely to be exposed to traumatic life events than the general population (Hatton & Emerson 2004) given the unique circumstances of their lives, such as an increased likelihood of experiencing institutionalised living and dependency on carers, for example a parental bereavement for a person with ID may also mean the loss of a home and the loss of a carer (Hollins & Esterhuyzen 1997; Levitas & Gilson 2001). There is much evidence of the potential adverse impact of life events on mental health in the general population (e.g. Tennant 2002; Kitzman et al. 2003), and also though less extensive evidence for similar patterns in the ID population (e.g. Hastings et al. 2004; Hamilton et al. 2005) with life events in the latter group being predictive of

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

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Journal of Intellectual Disability Research 1132 S. Wigham et al. • Life events and trauma: a prospective study

psychopathology including depression, and also reduced self care and behavioural problems (Monaghan & Soni 1992; Esbenson & Benson 2006; Tsakanikos et al. 2007). Although studies have demonstrated evidence of the possible adverse effects of life events on mental health few empirical studies have focussed on trauma as a specific outcome in people with ID (McCarthy 2001; Doyle & Mitchell 2003; Mitchell & Clegg 2005), though preliminary findings do suggest a relationship between the experience of adverse life events and the development of trauma in the form of posttraumatic stress disorder (PTSD) in this cohort (Sequeira et al. 2003; Mitchell et al. 2006; Murphy et al. 2007). However, evidence of a causal relationship between adverse life events and PTSD in people with ID is scarce, and research has been constrained by the lack of an appropriate measure of trauma (Wigham et al. 2011). One factor which may promote resilience in the face of adverse life events (Bonanno 2004) is social support, and the moderating effects of social support on the development of PTSD have been described (Joseph 1999; Brewin et al. 2000) and are underpinned theoretically by the work of Cohen & Wills (1985). The stress buffering effects of organisational support to disaster workers have been described (Alexander & Wells 1991, and conversely an increased likelihood of guilt or shame after rape has been suggested if social support is inadequate (Resick 1993). People with ID may be socially isolated (Feldman et al. 2002; Lippold & Burns 2009) or more susceptible to negative aspects of interpersonal relationships (Lunsky & Benson 2001), and may have relatively reduced access to more efficacious forms of support for example with self esteem bolstering support being more effective than tangible or practical support (Hyman et al. 2003). Given the effectiveness of interventions for trauma in people with ID (Stenfert-Kroese & Thomas 2006; Mevissen & de Jongh 2010; Mevissen et al. 2010) clinical consideration of trauma as one potential outcome for people with ID who experience adverse life events is important, as is examination of any moderating effects of social support. The aims of this prospective study are therefore to examine causal relationships between adverse life

events and trauma using a measure of trauma developed for people with ID; and to examine for any buffering effects of social support on the effects of adverse life events.

Method Participants Participants were 99 adults (85 men and 14 women) with ID receiving services from National Health Service (NHS), day centre, social services and independent service providers in northeast England. The high number of male participants reflects the proportion resident in the NHS inpatient and independent service provider sites. The proportion of males in the sample population also influenced the informant participant male-to-female ratio. In the judgement of the service providers, study participants had mild or moderate ID. Forty-six lived in community settings and 53 in inpatient settings. Of the inpatients 7 were from mental health wards and the rest from forensic wards, with 19 from low or enhanced low secure, 10 from medium secure and 17 from open or rehabilitation wards. Of the community participants 29 were recruited from day centres, 8 from an independent residential service provider, 2 from an NHS supported residential service, 4 from a community residential forensic service, and 3 lived independently. The mean age of service user participants was: male = 40.2 years (SD = 13.9; range = 19–75); female = 45.6 years (SD = 12.2; range = 21–60). The informant participant group comprised 88 paid carers (44 men and 44 women), who had known the service user for a minimum of a year. On average six months after their first interview (mean = 5.8 months, SD = 1.2) service users were interviewed again if they consented to this. At this second wave of data collection 84 service users (attrition rate 15%) and 66 informants (attrition rate 25%) participated.

Procedure Practitioners in participating sites were contacted by letter and asked to draw up a list of potential service user participants who they considered to have the capacity to consent to participate in the study, and

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

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were interested in participating in the project. If the service user was interested and agreeable to their details being passed to the researcher, and staff judged they had the capacity to make a decision regarding participation, the researcher was introduced to them. The researcher then formally assessed their capacity to consent by reading an accessible information sheet with them and then asking them questions to assess their understanding. Their capacity to understand and remember the information about the study was assessed using an empirical assessment of capacity to consent (Hulbert-Williams 2007). Capacity was defined as a respondent’s ability to understand and remember information then utilise it to make a decision (Wong et al. 2000). Data were collected from service users by the first author over a maximum of 3 × 30 min interview sessions, and in the presence of a regular carer subject to service user preference. Most of the informant data were collected by interview, apart from a small number of cases when for reasons of convenience they requested surveys to complete in their own time. The study received a favourable ethical opinion from County Durham and Tees Valley Research Ethics Committee.

Informant measures Lancaster and Northgate trauma scales – informant Questions in the 43-item informant Lancaster and Northgate trauma scales (LANTS) pertain to the observable effects of trauma seen during the last month, for example ‘Fearful – expressing an expectation that something bad will happen’. Each item is rated in three ways: ‘behavioural changes’, ‘frequency’ and ‘severity’. Each question is rated for frequency on a 6-point scale (‘none’, ‘monthly’, ‘weekly’, ‘several times a week’, ‘daily’ and ‘several times a day’) and severity on a 3-point scale (‘mild’, ‘moderate’ and ‘severe’). The response option for the ‘behavioural changes’ sub-scale prompts respondents to indicate whether the behaviour is the ‘same as usual’ for the person. Preliminary findings on the psychometric properties of the measure indicate good internal and test– retest reliability, plus promising convergent and construct validity (Wigham et al. 2011).

Bangor Life Events Scale for Intellectual Disabilities – informant The informant version of the Bangor Life Events Scale for Intellectual Disabilities (BLESID) (Hulbert-Williams et al. 2013) has 38 items rated on a 3-point frequency scale, and a 5-point impact scale. Individual item scores are calculated by multiplying the frequency of negatively rated life events by their impact, and the addition of these gives a total score. Internal reliability in the current study was good with alpha at 0.87 before missing values were substituted.

Self-report measures Lancaster and Northgate trauma scales – self-report The 29-item self-report LANTS includes questions about the frequency of subjective states during the previous week, for example ‘Worries have been going round and round in my head’, to be rated on a visual 4-point adjectival response scale (‘no’; ‘a little’; ‘sometimes’; ‘a lot’). A visual scale, short sentences, and large text increase the measure’s accessibility (Stenfert-Kroese 1997). Initial screening questions check response validity and comprehension of the response scale. To reduce the chances of acquiescence half the questions are reverse worded (Finlay & Lyons 2001). Preliminary findings indicate good internal and test–retest reliability, plus promising convergent and construct validity (Wigham et al. 2011). Bangor Life Events Scale for Intellectual Disabilities – self-report The self-report BLESID (Hulbert-Williams et al. 2012) is the self-report version of the informant BLESID described above. The measure comprises 24 life events, rated for frequency and impact both on a 3-point scale. Total scores are calculated by multiplying the frequency and impact of each life event rated as having a negative effect, and totalling these. Internal reliability in the current study was good (alpha = 0.73). Social support questionnaire An 8-item questionnaire was devised for the requirements of this study to collect information regarding social support.

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

volume 58 part 12 december 2014

Journal of Intellectual Disability Research 1134 S. Wigham et al. • Life events and trauma: a prospective study

The questionnaire asked the informant to list any relationships with family or friends that the person perceived as positive or supportive, and to indicate how often they were in contact. Responses were scored as follows: contact with parents was scored on a 6-point scale, where 0 indicated no contact with parents and 5 indicated that the person lived with their parents. The number of parents they were in contact with was also rated on a 3-point scale including no contact, contact with one parent, or contact with both parents. Contact with children, siblings, nephews and nieces, plus contact with extended family were each scored on a 2-point scale as either present or not. Number of friends was rated on a 4-point scale where more than one friend plus acquaintances was scored as 3. Frequency of contact with friends was scored on a 6-point scale where 0 indicated no contact, and 5 indicated daily contact. A total social support score was calculated by adding the individual scores. As the measure was not based on a reflective model and so not necessarily representative of a unidimensional construct, psychometric tests were not deemed appropriate (Bollen & Lennox 1991; Streiner 2003; Mokkink et al. 2010).

Design and analyses Missing values were found to be random on the LANTS measures and were substituted with the mean score. There were no missing values on the life events measure or the social support measure. A number of variables were non-normally distributed and not improved by transformation so non parametric tests were used. Significance levels were set at 0.05, and sample sizes were in accordance with

Block 1

Block 2

Block 3

Time 1 Life events

Social support

Time 1 life events X social support

Time 1 Trauma

Time 2 Life events

those recommended by Cohen (1992) for a power of 0.80 and a medium to large effect size and sufficient for logistic regression (Green 1991). Path analyses using binary logistic regressions were used to investigate prospective relationships between variables. Longitudinal relationships between recent life events and trauma reactions were examined whilst controlling for previous life events and pre-existing symptoms of trauma. All of the potential predictor (independent) variables in each of the regressions were significantly correlated with each criterion variable using one-tailed Spearman’s correlations. Dependent variables were split at the median for the logistic regressions. To examine which variables were predictive of Time 2 trauma the predictor variables were entered in three blocks as shown in Fig. 1. A series of path analyses were performed, with each variable regressed on the variables that preceded it in Fig. 1. For example, if a variable in Block 3 was significantly associated with Block 4, a further logistic regression with Block 3 as the dependent variable and all the variables in Blocks 1 and 2 as predictor variables was carried out. Whether Time 1 Trauma (Block 2) predicted Time 2 Trauma (Block 4) or not, a logistic regression was still carried out with Block 2 as the dependent variable and all the variables in Block 1 as potential predictor variables. This assumes that variables preceding a certain variable in the model temporally have a potentially direct causal effect on it. Potential moderator effects (Baron & Kenny 1986) were investigated by including the interaction term of life events and social support in Block 1. Standardised beta weights were used to estimate path coefficients and are shown in Figs 2 and 3.

Block 4 Time 2 Trauma

Figure 1 Preliminary model for the relationship between adverse life events, social support and trauma.

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

volume 58 part 12 december 2014

Journal of Intellectual Disability Research 1135 S. Wigham et al. • Life events and trauma: a prospective study

Block 1

Block 2

Block 3

B = 1.05, p = 0.23

Time 1 Life events

B = 1.11, p = 0.009

Social B=,p=. support

Time 1 life events X social support

Block 4

B = 0.84, p = 0.011

Time 1 Self Report Trauma

Time 2 Life events

B = 1.124, p = 0.001

B = 1.18, p = 0.05

Time 2 Self Report Trauma

B = 1.1, p = 0.011

B = 1.00, p = 0.73

Figure 2 Model for the relationship between adverse life events, social support and self-report trauma.

Block 1

Time 1 Life events

Block 2

*B = 1.03, p = 0.68

Block 3

**B = 1.033, p = 0.497

*B = 1.182, p = 0.001 **B = 1.17, p = 0.001 ***B = 1.14, p = 0.002

Time 1 Informant Trauma

Time 2 Life events

*B = 1.022, p = 0.657

Block 4

***B = 1.075, p = 0.252

*B = 1.39, p = 0.001

Time 2 Informant Trauma

**B = 1.14, p = 0.028

**B = 1.0, p = 0.990

***B = 1.401, p = 0.001

***B = 0.999, p = 0.985

*B = 0.853, p = 0.160 Social support B=,p=. **B = 0.856, p = 0.306

***B = 0.899, p = 0.229

Time 1 life events X social support

*B = 1.05, p = 0.510

**B = 1.01, p = 0.782

***B = 1.06, p = 0.375

*B = 0.872, p = 0.061

**B = 0.899, p = 0.120 ***B = 0.938, p = 0.287

Figure 3 Model for the relationship between adverse life events, social support and informant trauma. *Behavioural changes sub-scale; **Frequency sub-scale; ***Severity sub-scale.

Results Self-report LANTS trauma The addition of Block 3 variables into the model showed a significant improvement and accounted for 22.9% of the variance (see Table 1). Time 1 trauma and Time 2 life events were significantly predictive of Time 2 trauma in Block 4. When Block 2 variables were regressed on Time 2 life events the model showed a significant improvement

and accounted for 8.5% of the variance. Time 1 trauma was significantly predictive of Time 2 life event scores. When Block 1 variables were regressed on Time 1 self-report trauma this was a significant improvement to the model with 11.6% of variance accounted for, indicating that time 1 life events and social support were both significantly predictive of time 1 trauma scores. When the interaction term of social support by life events was added to the regression none of the independent variables were

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

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Journal of Intellectual Disability Research 1136 S. Wigham et al. • Life events and trauma: a prospective study

Table 1 Path analysis Time 2 self-report trauma

Variables

B

Wald

Significance

Exp (B)

Time 2 self-report trauma (n = 83; −2LL = 83.596, χ2 = 31.36, P < 0.001)

Time 1 trauma Time 1 life events Time 2 life events

0.099 0.051 0.17

6.48 1.18 3.98

0.011 0.23 0.05

1.10 1.05 1.18

Time 2 self-report life events (n = 83; −2LL = 96.18, χ2 = 16.84, P < 0.001)

Time 1 trauma Time 1 life events

0.117 −0.006

0.036 0.042

0.001 0.885

1.124 0.994

Time 1 self-report trauma (n = 78; −2LL = 90.512, χ2 = 17.16, P < 0.001)

Time 1 life events Social support

0.107 −0.178

6.73 6.40

0.009 0.011

1.113 0.837

Time 1 self-report trauma (n = 78; −2LL = 90.4, χ2 = 17.27, P = 0.001)

Time 1 life events Social support Life events by social support

0.080 −2.029 0.004

0.785 3.8 0.114

0.376 0.051 0.736

1.083 0.816 1.004

Table 2 Path analysis Time 2 informant trauma (behavioural changes)

Variables

B

Wald

Significance

Exp (B)

Time 2 informant trauma (behavioural changes) (n = 61; −2LL = 56.91, χ2 = 27.5, P < 0.001)

Time 1 trauma Time 1 life events Time 2 life events

0.046 0.025 0.329

0.435 0.166 10.98

0.510 0.683 0.001

1.05 1.03 1.39

Time 2 informant life events (n = 62; −2LL = 73.81, χ2 = 10.52, P = 0.005)

Time 1 trauma Time 1 life events

0.021 0.113

0.198 5.197

0.657 0.023

1.022 1.119

Time 1 informant trauma (behavioural changes) [n = 79; −2LL = 82.3, χ2 (2, n = 79) = 27.2, P < 0.001]

Time 1 life events Social support

0.167 −0.136

0.001 0.061

1.182 0.872

Time 1 informant trauma (behavioural changes) (n = 79; −2LL = 82.23, χ2 = 27.27, P < 0.001)

Time 1 life events Social support Life events by social support

0.138 −0.159 0.004

0.249 0.160 0.789

1.147 0.853 1.004

significantly predictive of Time 1 trauma, suggesting social support did not moderate the relationship between life events and trauma (see Fig. 2).

Informant LANTS behavioural changes When Block 3 variables were regressed on Time 2 informant trauma as measured by the LANTS informant behavioural changes sub-scale there was a significant improvement to the model with 27.8% of variance accounted for (see Table 2). Time 2 life events were significantly predictive of Time 2 trauma scores. When Block 2 variables were

11.45 3.5 1.327 1.976 0.072

regressed on Time 2 life event scores the addition of the two independent variables was a significant improvement to the model with 14.5% of variance accounted for. Time 1 life events were significantly predictive of Time 2 life event scores. When Block 1 variables were regressed on the Time 1 informant behavioural changes trauma sub-scale the addition of the independent variables significantly improved the model, and accounted for 20.3% of variance. Time 1 life events, but not social support, were significantly predictive of Time 1 informant behavioural changes trauma scores. This did not vary when the social support by life events interaction

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

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Journal of Intellectual Disability Research 1137 S. Wigham et al. • Life events and trauma: a prospective study

Table 3 Path analysis Time 2 informant trauma (frequency)

Variables

B

Wald

Significance

Exp (B)

Time 2 informant trauma (frequency) (n = 60; −2LL = 71.73, χ2 = 10.85, P < 0.05)

Time 1 trauma Time 1 life events Time 2 life events

0.010 0.033 0.131

0.076 0.462 4.81

0.782 0.497 0.028

1.01 1.033 1.14

Time 2 informant life events (n = 62; −2LL = 74.009, χ2 = 10.321, P < 0.01)

Time 1 trauma Time 1 life events

0.000 0.123

0.000 5.931

0.990 0.015

1.0 1.130

Time 1 informant trauma (frequency) (n = 79; −2LL = 85.5, χ2 = 23.91, P < 0.001)

Time 1 life events Social support

0.154 −0.107

0.001 0.120

1.17 0.899

Time 1 informant trauma (frequency) (n = 79; −2LL = 85.102, χ2 = 24.3, P < 0.001)

Time 1 life events Social Support Life events x Social support

0.096 −0.155 0.008

0.139 0.306 0.515

1.101 0.856 1.008

term was added. Social support therefore did not moderate the relationship between life events and trauma (see Fig. 3).

11.2 2.42 1.047 2.188 0.423

between social support and life events in the prediction of trauma was not found (see Fig. 3).

Informant LANTS severity sub-scale Informant LANTS frequency When Block 3 variables were regressed on Time 2 informant trauma as measured by the LANTS frequency sub-scale as the dependent variable, addition of the independent variables was a significant improvement to the model, with 16.7% of variance accounted for. Time 2 life events were significantly predictive of Time 2 trauma scores. When Block 2 variables were regressed on Time 2 life events 14.5% of variance was accounted for. As shown in Table 3 Time 1 informant life events were significantly predictive of Time 2 informant life event scores. A third regression was carried out with Time 1 informant frequency trauma scores as the dependent variable; the addition of Block 1 variables was a significant improvement to the model, with 22.8% of variance accounted for. Informant life events at Time 1 were significantly predictive of Time 1 informant trauma. Social support was not significantly predictive of Time 1 informant trauma measured by the frequency sub-scale. When the interaction term between life events and social support was included no Block 1 variables were significantly predictive of Time 1 informant frequency trauma scores. Therefore, a moderating effect

When Block 3 variables were regressed on Time 2 trauma as measured by the LANTS severity subscale they made a significant contribution to the model, with 29.5% of variance accounted for (see Table 4). Time 2 life events were significantly predictive of time 2 trauma scores, while Time 1 trauma was not. When Block 2 variables were regressed on Time 2 informant life events there was a significant improvement, with 14.5% of variance accounted for. Time 1 life events were significantly predictive of Time 2 life event scores. When Block 1 variables were regressed on Time 1 informant severity scores 22.8% of variance was accounted for, and Time 1 life events were significantly predictive of Time 1 trauma. Social support was not significantly predictive of trauma severity scores, and there was no significant interaction effect between social support and life events (see Fig. 3).

Discussion The study findings indicate that life events during the previous 6 months were predictive of levels of trauma as measured by the self-report LANTS, and

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

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Journal of Intellectual Disability Research 1138 S. Wigham et al. • Life events and trauma: a prospective study

Table 4 Path analysis Time 2 informant trauma (severity)

Variables

B

Wald

Significance

Exp (B)

0.79 1.31 10.32

0.375 0.252 0.001

1.055 1.075 1.401

Time 2 informant trauma severity (n = 61; −2LL = 54.53, χ2 = 30.02, P < 0.001)

Time 1 trauma Time 1 life events Time 2 life events

0.053 0.072 0.34

Time 2 informant life events (n = 62; −2LL = 74.009, χ2 = 10.32, P < 0.01)

Time 1 trauma Time 1 life events

−0.001 0.123

0.000 5.418

0.985 0.020

0.999 1.131

Time 1 informant trauma severity (n = 79; −2LL = 91.75, χ2 = 17.75, P < 0.001)

Time 1 life events Social support

0.132 −0.064

9.52 1.14

0.002 0.287

1.14 0.938

Time 1 informant trauma severity (n = 79; −2LL = 91.31, χ2 = 18.195, P < 0.001)

Time 1 life events Social support Life events by social support

0.08 −0.107 0.007

0.979 1.445 0.475

0.322 0.229 0.491

1.084 0.899 1.007

the informant LANTS behavioural changes, frequency and severity sub-scales. This prospective causal relationship was demonstrated while controlling for any prior life events or pre-existing trauma. Time 1 informant trauma was not significantly predictive of Time 2 trauma, with the only significant informant predictor of Time 2 trauma being Time 2 life events, however on the self-report measures Time 1 trauma was significantly predictive of Time 2 trauma. In fact this relationship was stronger than that between Time 2 self-report life events and Time 2 trauma. It would seem entirely plausible that trauma present at Time 1 could still be present six months later, nevertheless and importantly, Time 2 life events were also independently significantly predictive of Time 2 trauma. In addition to the main study findings Time 1 self-report trauma was found to be predictive of Time 2 self-report life events. This is in accordance with research suggesting a susceptibility to further adverse life events after a trauma (Maes et al. 2001), which may be related to dysfunctional coping strategies (Ehlers & Clark 2000), though this relationship did not hold with the informant measures of life events and trauma. One reason for the variation in results subject to whether the measures employed in the analyses were self or informant report, could be that although conceptually related the self-report and informant LANTS each have a different focus capturing predominately internalising and externalising behaviours respectively (Wigham et al. 2011).

Although independently predictive of self-report trauma at Time 1, social support was not predictive of informant trauma levels and did not moderate the relationship between either self-report, or informant life events and trauma. This is in contrast to research, suggesting that social support can buffer against the effects of adverse life events. The findings may be highlighting a relative lack of social support in this population group (Feldman et al. 2002) and the potential for both social support and social strain (Lunsky & Benson 2001). Also measuring social support at one time point may not best capture its relationship with trauma in light of purported sequential variations in the interaction (Kaniasty & Norris 2008). However, the main limitation of the study is the measure of social support used. The measure was designed by the authors for the purposes of the study, and was not appropriate for psychometric validation. The measure was informant rated and therefore only describes some aspects of the concept of social support, and although a frequency count of contact was allowed, any measurement of quality, such as how appropriate social support is perceived to be by the recipient was not (Hyman et al. 2003; Uchino 2009). Similarly, some potential members of a social circle were included, but this could be wider and include for example intimate partners. Future research would therefore benefit from a more comprehensive measure of social support. A further limitation of the study is the representativeness of the sample. A

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high proportion of participants with ID were drawn from secure inpatient settings which may have curtailed social support opportunities. Plus a high proportion were male, and as rates of PTSD are suggested to be higher in females (Tolin & Foa 2006), the levels of trauma seen in this study may be less than would have been seen in a sample with a more equal gender balance. The study serves to highlight the potential causal relationship between the experience of adverse life events and trauma in people with mild to moderate ID, which is an important consideration for screening, case recognition, treatment planning and funding allocation in clinical settings.

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Accepted 15 November 2013

© 2013 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd

A prospective study of the relationship between adverse life events and trauma in adults with mild to moderate intellectual disabilities.

Research has demonstrated a relationship between the experience of life events and psychopathology in people with intellectual disabilities (ID), howe...
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