Research in Developmental Disabilities 35 (2014) 917–921
Contents lists available at ScienceDirect
Research in Developmental Disabilities
The developmental health of children of parents with intellectual disabilities: Cross sectional study Eric Emerson a,*, Philip Brigham b a b
Centre for Disability Research and Policy, University of Sydney, Sydney, NSW 2141, Australia Public Health, Cornwall Council, NHS England, Peninsula House, Kingsmill Road, Saltash PL12 6LE, UK
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 November 2013 Accepted 3 January 2014 Available online 29 January 2014
In a representative population-based sample of 46,025 families caring for a young child, parental intellectual disability (identified in 588 families) was associated with increased risk of child developmental delay, child speech and language problems, child behaviour problems and frequent child accidents and injuries. Parental intellectual disability was also associated with increased risk of exposure to a wide range of environmental adversities such as poverty, poor housing and social isolation. Adjusting for betweengroup differences in exposure to low socio-economic position reduced the risk of adverse child outcomes by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Parents with intellectual disability Child wellbeing
1. Introduction A growing body of research has addressed parenting by people (primarily mothers) with intellectual disabilities (Collings & Llewellyn, 2012; IASSID, 2008). While it is clear that parents with intellectual disabilities are at increased risk of contact with child welfare services and of having their children removed (IASSID, 2008), surprisingly little is known about the wellbeing or developmental health of children with a parent with intellectual disability (Collings & Llewellyn, 2012).A recent review of this area highlighted both the diversity of results reported and the significant widespread methodological weaknesses which characterise this field of study (Collings & Llewellyn, 2012). A small number of studies have reported that mothers with intellectual disability have a higher risk of adverse events during pregnancy and poorer birth outcomes (Ho¨glund, Lindgren Larsson, 2012a,b; McConnell, Llewellyn, Mayes, Russo, & Honey, 2003; McConnell, Mayes, & Llewellyn, 2008). Studies of subsequent child development have produced conflicting results. While several studies have indicated that the children of parents with intellectual disability are at risk of poorer developmental outcomes (Feldman & Walton-Allen, 1997; Keltner, Wise, & Taylor, 1999; Mørch, Ska˚r, & Andersga˚rd, 1997), others have failed to find an association between parental intellectual disability and child development (Aunos, Feldman, & Goupil, 2008; McConnell et al., 2003; McGaw, Shaw, & Beckley, 2007).The two most problematic methodological weaknesses in this literature are the use of small and unrepresentative (e.g., service or clinic based) samples and the absence of appropriate comparison groups. A common conceptual weakness is the failure to attempt to isolate the association between child development and parental intellectual
* Corresponding author. E-mail addresses: [email protected] (E. Emerson), [email protected] (P. Brigham). 0891-4222/$ – see front matter ß 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2014.01.006
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E. Emerson, P. Brigham / Research in Developmental Disabilities 35 (2014) 917–921
disability from other adverse contextual factors to which children of parents with intellectual disability are more likely to be exposed. This is particularly relevant given the evidence that parents with intellectual disability are more likely to be single parents, unemployed and to live in poverty, in poor housing and in deprived neighbourhoods (Booth & Booth, 1993; Feldman & Walton-Allen, 1997; Ho¨glund et al., 2012b; Llewellyn, McConnell, & Mayes, 2003), all factors that are associated with poorer developmental outcomes (Grantham-McGregor et al., 2007; Walker et al., 2011). The aims of the present study, therefore, are (within a large-scale representative population-based sample): (1) to describe the developmental outcomes of children of parents who do and do not have intellectual disability; and (2) to estimate the extent to which any between-group differences in child outcomes may be attributable to parental intellectual disability once potentially relevant between-group differences in broader social context have been controlled for. 2. Method The research reported in this paper is based on secondary analysis of confidentialised needs analysis data collected in three Primary Care Trusts (PCTs) in England covering a total population of 1.25 million people. The data were collected between 2008 and 2012 in the context of surveys undertaken to estimate the needs of families with young children. Data were collected in all three areas by Health Visitors. 2.1. Sampling The sampling frame was households with children under five years in PCTs A and B and households with children under three years in PCT C. Health visitors were asked to note the presence or absence of 31 need variables for every family on their caseload. 2.2. Data collection Based upon their professional judgement and survey training, a health visitor assessed each family against a set of factors using standardised definitions and a common survey form (available on request from the authors). These factors covered observations of the health, social and lifestyle situation of the family together with details of illnesses and disabilities in the family. The association of a family with a particular health factor was therefore dependent upon the judgement of a heath visitor based upon their observations of the case in question, but the definitions for each variable are common to all the PCTs using the survey. In PCTs A and B the number of parents in the household exhibiting a parental characteristic (e.g., alcohol abuse) was recorded. In PCT C whether any parent in the household exhibited a parental characteristic (e.g., alcohol abuse) was recorded. 2.3. Measures Specific items used in the present analyses are presented in Table 1. Four child developmental outcomes were recorded by health visitors: whether the child had developmental delay; whether the child had a speech and language problem; whether the child had behaviour problems; and whether the child had frequent accidents and injuries. All variables were simple binary measures of presence/absence. Two of the measures (speech and language problem, frequent accidents and injuries) were only collected in one of the PCT areas. Five indicators of low socio-economic position (low income, major wage earner unemployed, poor housing, temporary accommodation, three or more changes of address in last year) were combined to produce a single measure of breadth/depth of exposure to low socio-economic position. Intellectual disability was identified by the item ‘parent(s) have learning difficulties (recognised learning difficulties that required or still require additional educational support)’. ‘Learning difficulties’ is commonly used in England as a synonym for the term intellectual disability. 2.4. Approach to analysis Multivariate logistic regression was used to determine the unadjusted and adjusted risk for adverse child developmental outcomes among children whose parents did and did not have intellectual disabilities. The following variables were added into the model (forced entry) in sequential blocks: (1) presence of parental intellectual disabilities (unadjusted risk); (2) breadth of exposure to five indicators of socio-economic disadvantage; (3) social support (social isolation, single parent family, parent(s) have difficulty with spoken English); (4) exposure to other adversities (violence within the family, separation or divorce, one or more parent was in care or abused as a child, a bereavement which is significant to the family, previous sudden infant death, parent(s) abuse alcohol; parent(s) abuse drugs; parent(s) have mental health problems; (5) parenting (parent(s) have parenting difficulties, parent(s) have failed to seek medical advice when needed). 3. Results Information was collected on 46,025 households with young children, 588 (1.3%) of which contained a parent with intellectual disability. Among two parent headed households, 1.0% (n = 404) were identified as containing one or more
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Table 1 Prevalence of adverse child developmental outcomes and exposure to indicators of environmental adversity. Variable Child developmental outcomes Developmental delay Speech and language problem Behaviour problems Frequent accidents and injuries Exposure to environmental adversities Socio-economic position Low income, dependant on benefits Major wage earner is unemployed Poor housing In temporary accommodation Three or more changes of address in last year Social Support Family affected by social isolation Single-parent family Parent(s) have difficulty with spoken English Other Adversities Violence within the family Parent(s) ‘in care’ or abused as a child Separation and/or divorce in last year A bereavement which is significant to the family Previous sudden infant death in the family Parent(s) abuse alcohol Parent(s) abuse drugs Parent(s) have mental health problems Parenting problems Parenting problems Failed to seek medical opinion
Parental ID (%)
No ID (%)
OR
30 26 32 5
5 5 7 1
8.92*** 6.60*** 5.93*** 4.96***
78 59 34 10 9
19 11 5 3 1
14.59*** (11.99–17.74) 12.50*** (10.57–14.77) 9.99*** (8.38–11.91) 4.16*** (3.17–5.47) 7.89*** (5.89–10.56)
29 31 4
8 11 3
4.68*** (3.90–5.62) 3.62*** (3.04–4.33) 1.34 (0.89–2.02)
33 36 18 8 2 13 11 51
7 3 5 2 1 2 2 15
6.97*** (5.84–8.31) 16.39*** (13.75–19.54) 4.58*** (3.70–5.67) 3.90*** (2.90–5.26) 3.49*** (1.84–6.61) 7.16*** (5.56–9.21) 6.85*** (5.24–8.96) 6.18*** (5.25–7.28)
56 18
6 2
18.49*** (15.64–21.85) 11.64*** (9.32–14.53)
(7.43–10.70) (4.93–8.82) (4.97–7.07) (2.71–9.07)
*** p < 0.001.
parents with intellectual disabilities. In the two PCTs which recorded the number of parents with intellectual disability, in 22% of two parent headed households in which at least one parent has intellectual disability both parents were identified as having intellectual disabilities. Among single parent headed households, 3.2% (n = 184) were identified as being headed by a parent with intellectual disabilities. The prevalence of poorer child outcomes and of exposure to environmental adversities is presented in Table 1 for families including and not including one or more parents with intellectual disability. As can be seen: (1) significantly higher rates of poorer outcomes were apparent for families including a parent with intellectual disability across all four measures of child developmental health; and (2) significantly higher rates of exposure to environmental adversity were apparent for families including a parent with intellectual disability for 17 of the 18 measures of environmental risk. The majority (59%) of families not containing a parent with intellectual disability were not exposed to any of the environmental adversities listed in Table 1. In contrast, the majority (54%) of families containing a parent with intellectual disability were exposed to five or more of these environmental adversities. Unadjusted and sequentially adjusted risk for adverse child development outcomes are presented in Table 2. Percentage reduction in risk (odds ratio) was calculated by the formulae 100 (unadjusted OR adjusted OR)/(unadjusted OR 1). As can be seen, sequentially adjusting for between-group differences in exposure to environmental adversity resulted in significant reductions in risk of poorer child development associated with parental intellectual disability. Adjusting for between-group differences in exposure to low socio-economic position reduced risk by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. 4. Discussion 4.1. Main finding of this study In a large representative population-based sample parental intellectual disability was associated with increased risk of child developmental delay, child speech and language problems, child behaviour problems and frequent child accidents and injuries. Parental intellectual disability was also associated with increased risk of exposure to a wide range of environmental adversities. Adjusting for between-group differences in exposure to low socio-economic position reduced risk by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were
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Table 2 Unadjusted and adjusted risk of poorer child developmental outcomes in families containing one or more parents with intellectual disability. Child developmental outcomes
Unadjusted
Adjusted (SEP)
Adjusted (SEP + social support)
Adjusted (SEP + social support + other adversities)
Adjusted (SEP + social support + other adversities + parenting problems)
Developmental delay (n = 46,020) % Reduction in OR from unadjusted Speech and language problem (n = 13,841) % reduction in OR from previous step Behaviour problems (n = 46,020) % Reduction in OR from previous step Frequent accidents and injuries (n = 13,841) % Reduction in OR from previous step
8.94 (7.45–10.73)
4.36 (3.60–5.28) 58% 3.25 (2.40–4.40) 60% 2.56 (2.13–3.08) 68% 2.10 (1.13–3.92) 72%
4.06 (3.34–4.93) 61% 2.95 (2.17–4.01) 65% 2.46 (2.04–2.97) 70% 1.97 (1.05–3.68) 76%
3.57 (2.92–4.36) 68% 2.76 (2.02–3.76) 69% 1.93 (1.569–2.35) 81% 1.75 (0.92–3.35) 81%
2.39 (1.94–2.95) 82% 1.91 (1.37–2.65) 84% 0.88 (0.71–1.10) 102% 1.05 (0.54–2.02) 99%
6.60 (4.93–8.82) 5.90 (4.94–7.04) 4.96 (2.71–9.07)
no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. 4.2. What is already known on this topic Previous studies of the association between parental intellectual disability and child development have produced conflicting results. While several studies have indicated that the children of parents with intellectual disability are at risk of poorer developmental outcomes (Feldman & Walton-Allen, 1997; Keltner et al., 1999; Mørch et al., 1997), others have failed to find an association between parental intellectual disability and child development (Aunos et al., 2008; McConnell et al., 2003; McGaw et al., 2007). 4.3. What this study adds The present study adds to the existing literature in two ways. First, by using a relatively large representative population based sample of families containing parents with and without intellectual disability, it avoids two of the significant methodological weaknesses that pervade this field of research. Second, by sequentially adjusting risk estimates for betweengroup rates of exposure to environmental adversities associated with compromised child development (e.g., low socioeconomic position, social isolation, parenting problems), the study attempts to partial out primary effects of parental intellectual disability on child development from potentially confounding effects associated with differences in family context. The results suggest that residual risk of poorer child outcomes may vary across developmental areas and be specific to intellectual and language development. 4.4. Limitations of this study The major limitations of the study are: (1) the use of survey questions of unknown psychometric characteristics; (2) the exclusion of parents who have had their child removed by child welfare agencies; and (3) the extent to which the statistical modelling and design can effectively isolate effects attributable to parental intellectual disability. The use of administrative data in public health research typically represents a trade off between sample size/representativeness and data fidelity. In the present study, the use of consistent definitions across areas and the use of training in case note review should have improved the reliability and validity of the data collected. However, future research in this area would benefit from the use of well validated screening measures of child development. While the use of a relatively large representative population based sample of families is one of the major strengths of the study, the sampling frame consisted of families caring for young children. As such, families with a young child who had been removed from their care by child welfare agencies were not included in the sample. Given that parents with intellectual disabilities are at increased risk of contact with child welfare services and of having their children removed (IASSID Special Interest Research Group on Parents and Parenting with Intellectual Disabilities, 2008) and that these children may have poorer developmental health, the sampling strategy may have underestimated the strength of the association between parental intellectual disability and child outcomes. No information is available on the proportion of parents with intellectual disability in the samples areas who may have had their child removed by child welfare agencies. The use of a cross-sectional design clearly precludes the drawing of conclusions regarding causal relationships between parental intellectual disability and child development. The statistical modelling attempts to control for the potentially ‘confounding’ effects of factors that are associated with parental intellectual disability but are not a necessary component or outcome of intellectual disability. For the vast majority of the variables used to adjust risk a clear case can be made that they
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represent environmental risks that are not a necessary component or outcome of intellectual disability. For example, while parents with intellectual disabilities in the study were more likely to live in poor quality housing, housing quality and inequalities in access to decent housing are determined by social policy, not by intellectual disability per se. As such, most of these factors can be considered correlates of parental intellectual disability that are amenable to change though policy interventions. This is also, to an extent, the case for parenting problems. Indeed, there is growing evidence for the efficacy of interventions aimed at increasing the parenting capabilities of parents with intellectual disability (Feldman, 2010; Wade, Llewellyn, & Matthews, 2008). However, given that parenting is a complex skill, it is likely that parenting difficulties may be an inevitable outcome of intellectual disability for a proportion of people with more severe intellectual disability. Ethical approval The research was undertaken using confidentialised household-level data collected for local administrative purposes. Funding None. Competing interests None. References Aunos, M., Feldman, M., & Goupil, G. (2008). Mothering with intellectual disabilities: Relationship between social support, health and well-being, parenting and child behaviour outcomes. Journal of Applied Research in Intellectual Disabilities, 21, 320–330. Booth, T., & Booth, W. (1993). Parenting with learning difficulties: Lessons for practitioners. British Journal of Social Work, 23, 459–480. Collings, & Llewellyn, G. (2012). Children of parents with intellectual disability: Facing poor outcomes or faring okay? Journal of Intellectual & Developmental Disability, 37, 65–82. Feldman, M. (2010). Parenting education programmes. In G. Llewellyn, R. Traustadottir, D. McConnell, & B. Sigurjonsdottir (Eds.), Parents with intellectual disabilities: Past, present and futures (pp. 107–136). Chichister, UK: John Wiley & Sons. Feldman, M., & Walton-Allen, N. (1997). Effects of maternal mental retardations and poverty on intellectual, academic, and behavioural status of school-age children. American Journal of Mental Retardation, 101, 352–364. Grantham-McGregor, S., Cheung, Y. B., Cueto, S., Glewe, P., Richter, L., & Strupp, B. (2007). Developmental potential in the first 5 years for children in developing countries. Lancet, 369, 60–70. Ho¨glund, B., Lindgren, P., & Larsson, M. (2012a). Newborns of mothers with intellectual disability have a higher risk of perinatal death and being small for gestational age. Acta Obstetricia et Gynecologica Scandinavica, 91, 1409–1414. Ho¨glund, B., Lindgren, P., & Larsson, M. (2012b). Pregnancy and birth outcomes of women with intellectual disability in Sweden: A national register study. Acta Obstetricia et Gynecologica Scandinavica, 91, 1381–1387. IASSID. Special Interest Research Group on Parents and Parenting with Intellectual Disabilities. (2008). Parents labelled with intellectual disability: Position of the IASSID SIRG on parents and parenting with intellectual disabilities. Journal of Applied Research in Intellectual Disabilities, 21, 296–307. Keltner, B., Wise, L., & Taylor, G. (1999). Mothers with intellectual limitations and their 2-year-old children’s developmental outcomes. Journal of Intellectual and Developmental Disability, 24, 45–57. Llewellyn, G., McConnell, D., & Mayes, R. (2003). Health of mothers with intellectual limitations. Australian and New Zealand Journal of Public Health, 27(1), 17–19. McConnell, D., Llewellyn, G., Mayes, R., Russo, D., & Honey, A. (2003). Developmental profiles of children born to mothers with intellectual disability. Journal of Intellectual and Developmental Disability, 28, 122–134. McConnell, D., Mayes, R., & Llewellyn, G. (2008). Women with intellectual disability at risk of adverse pregnancy and birth outcomes. Journal of Intellectual Disability Research, 52, 529–535. McGaw, S., Shaw, T., & Beckley, K. (2007). Prevalence of psychopathology across a service population of parents with intellectual disabilities and their children. Journal of Policy and Practice in Intellectual Disabilities, 4, 11–22. Mørch, W.-T., Ska˚r, J., & Andersga˚rd, A. (1997). Mentally retarded persons as parents: Prevalence and the situation of their children. Scandinavian Journal of Psychology, 38, 343–348. Wade, C., Llewellyn, G., & Matthews, J. (2008). Review of parent training interventions for parents with intellectual disability. Journal of Applied Research in Intellectual Disabilities, 21, 351–366. Walker, S. P., Wachs, T. D., Grantham-McGregor, S., Black, M. M., Nelson, C. A., & Huff man, S. L. (2011). Inequality in early childhood: Risk and protective factors for early child development. Lancet, 378, 1325–1338.
Contents lists available at ScienceDirect
Research in Developmental Disabilities
The developmental health of children of parents with intellectual disabilities: Cross sectional study Eric Emerson a,*, Philip Brigham b a b
Centre for Disability Research and Policy, University of Sydney, Sydney, NSW 2141, Australia Public Health, Cornwall Council, NHS England, Peninsula House, Kingsmill Road, Saltash PL12 6LE, UK
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 November 2013 Accepted 3 January 2014 Available online 29 January 2014
In a representative population-based sample of 46,025 families caring for a young child, parental intellectual disability (identified in 588 families) was associated with increased risk of child developmental delay, child speech and language problems, child behaviour problems and frequent child accidents and injuries. Parental intellectual disability was also associated with increased risk of exposure to a wide range of environmental adversities such as poverty, poor housing and social isolation. Adjusting for betweengroup differences in exposure to low socio-economic position reduced the risk of adverse child outcomes by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Parents with intellectual disability Child wellbeing
1. Introduction A growing body of research has addressed parenting by people (primarily mothers) with intellectual disabilities (Collings & Llewellyn, 2012; IASSID, 2008). While it is clear that parents with intellectual disabilities are at increased risk of contact with child welfare services and of having their children removed (IASSID, 2008), surprisingly little is known about the wellbeing or developmental health of children with a parent with intellectual disability (Collings & Llewellyn, 2012).A recent review of this area highlighted both the diversity of results reported and the significant widespread methodological weaknesses which characterise this field of study (Collings & Llewellyn, 2012). A small number of studies have reported that mothers with intellectual disability have a higher risk of adverse events during pregnancy and poorer birth outcomes (Ho¨glund, Lindgren Larsson, 2012a,b; McConnell, Llewellyn, Mayes, Russo, & Honey, 2003; McConnell, Mayes, & Llewellyn, 2008). Studies of subsequent child development have produced conflicting results. While several studies have indicated that the children of parents with intellectual disability are at risk of poorer developmental outcomes (Feldman & Walton-Allen, 1997; Keltner, Wise, & Taylor, 1999; Mørch, Ska˚r, & Andersga˚rd, 1997), others have failed to find an association between parental intellectual disability and child development (Aunos, Feldman, & Goupil, 2008; McConnell et al., 2003; McGaw, Shaw, & Beckley, 2007).The two most problematic methodological weaknesses in this literature are the use of small and unrepresentative (e.g., service or clinic based) samples and the absence of appropriate comparison groups. A common conceptual weakness is the failure to attempt to isolate the association between child development and parental intellectual
* Corresponding author. E-mail addresses: [email protected] (E. Emerson), [email protected] (P. Brigham). 0891-4222/$ – see front matter ß 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2014.01.006
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disability from other adverse contextual factors to which children of parents with intellectual disability are more likely to be exposed. This is particularly relevant given the evidence that parents with intellectual disability are more likely to be single parents, unemployed and to live in poverty, in poor housing and in deprived neighbourhoods (Booth & Booth, 1993; Feldman & Walton-Allen, 1997; Ho¨glund et al., 2012b; Llewellyn, McConnell, & Mayes, 2003), all factors that are associated with poorer developmental outcomes (Grantham-McGregor et al., 2007; Walker et al., 2011). The aims of the present study, therefore, are (within a large-scale representative population-based sample): (1) to describe the developmental outcomes of children of parents who do and do not have intellectual disability; and (2) to estimate the extent to which any between-group differences in child outcomes may be attributable to parental intellectual disability once potentially relevant between-group differences in broader social context have been controlled for. 2. Method The research reported in this paper is based on secondary analysis of confidentialised needs analysis data collected in three Primary Care Trusts (PCTs) in England covering a total population of 1.25 million people. The data were collected between 2008 and 2012 in the context of surveys undertaken to estimate the needs of families with young children. Data were collected in all three areas by Health Visitors. 2.1. Sampling The sampling frame was households with children under five years in PCTs A and B and households with children under three years in PCT C. Health visitors were asked to note the presence or absence of 31 need variables for every family on their caseload. 2.2. Data collection Based upon their professional judgement and survey training, a health visitor assessed each family against a set of factors using standardised definitions and a common survey form (available on request from the authors). These factors covered observations of the health, social and lifestyle situation of the family together with details of illnesses and disabilities in the family. The association of a family with a particular health factor was therefore dependent upon the judgement of a heath visitor based upon their observations of the case in question, but the definitions for each variable are common to all the PCTs using the survey. In PCTs A and B the number of parents in the household exhibiting a parental characteristic (e.g., alcohol abuse) was recorded. In PCT C whether any parent in the household exhibited a parental characteristic (e.g., alcohol abuse) was recorded. 2.3. Measures Specific items used in the present analyses are presented in Table 1. Four child developmental outcomes were recorded by health visitors: whether the child had developmental delay; whether the child had a speech and language problem; whether the child had behaviour problems; and whether the child had frequent accidents and injuries. All variables were simple binary measures of presence/absence. Two of the measures (speech and language problem, frequent accidents and injuries) were only collected in one of the PCT areas. Five indicators of low socio-economic position (low income, major wage earner unemployed, poor housing, temporary accommodation, three or more changes of address in last year) were combined to produce a single measure of breadth/depth of exposure to low socio-economic position. Intellectual disability was identified by the item ‘parent(s) have learning difficulties (recognised learning difficulties that required or still require additional educational support)’. ‘Learning difficulties’ is commonly used in England as a synonym for the term intellectual disability. 2.4. Approach to analysis Multivariate logistic regression was used to determine the unadjusted and adjusted risk for adverse child developmental outcomes among children whose parents did and did not have intellectual disabilities. The following variables were added into the model (forced entry) in sequential blocks: (1) presence of parental intellectual disabilities (unadjusted risk); (2) breadth of exposure to five indicators of socio-economic disadvantage; (3) social support (social isolation, single parent family, parent(s) have difficulty with spoken English); (4) exposure to other adversities (violence within the family, separation or divorce, one or more parent was in care or abused as a child, a bereavement which is significant to the family, previous sudden infant death, parent(s) abuse alcohol; parent(s) abuse drugs; parent(s) have mental health problems; (5) parenting (parent(s) have parenting difficulties, parent(s) have failed to seek medical advice when needed). 3. Results Information was collected on 46,025 households with young children, 588 (1.3%) of which contained a parent with intellectual disability. Among two parent headed households, 1.0% (n = 404) were identified as containing one or more
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Table 1 Prevalence of adverse child developmental outcomes and exposure to indicators of environmental adversity. Variable Child developmental outcomes Developmental delay Speech and language problem Behaviour problems Frequent accidents and injuries Exposure to environmental adversities Socio-economic position Low income, dependant on benefits Major wage earner is unemployed Poor housing In temporary accommodation Three or more changes of address in last year Social Support Family affected by social isolation Single-parent family Parent(s) have difficulty with spoken English Other Adversities Violence within the family Parent(s) ‘in care’ or abused as a child Separation and/or divorce in last year A bereavement which is significant to the family Previous sudden infant death in the family Parent(s) abuse alcohol Parent(s) abuse drugs Parent(s) have mental health problems Parenting problems Parenting problems Failed to seek medical opinion
Parental ID (%)
No ID (%)
OR
30 26 32 5
5 5 7 1
8.92*** 6.60*** 5.93*** 4.96***
78 59 34 10 9
19 11 5 3 1
14.59*** (11.99–17.74) 12.50*** (10.57–14.77) 9.99*** (8.38–11.91) 4.16*** (3.17–5.47) 7.89*** (5.89–10.56)
29 31 4
8 11 3
4.68*** (3.90–5.62) 3.62*** (3.04–4.33) 1.34 (0.89–2.02)
33 36 18 8 2 13 11 51
7 3 5 2 1 2 2 15
6.97*** (5.84–8.31) 16.39*** (13.75–19.54) 4.58*** (3.70–5.67) 3.90*** (2.90–5.26) 3.49*** (1.84–6.61) 7.16*** (5.56–9.21) 6.85*** (5.24–8.96) 6.18*** (5.25–7.28)
56 18
6 2
18.49*** (15.64–21.85) 11.64*** (9.32–14.53)
(7.43–10.70) (4.93–8.82) (4.97–7.07) (2.71–9.07)
*** p < 0.001.
parents with intellectual disabilities. In the two PCTs which recorded the number of parents with intellectual disability, in 22% of two parent headed households in which at least one parent has intellectual disability both parents were identified as having intellectual disabilities. Among single parent headed households, 3.2% (n = 184) were identified as being headed by a parent with intellectual disabilities. The prevalence of poorer child outcomes and of exposure to environmental adversities is presented in Table 1 for families including and not including one or more parents with intellectual disability. As can be seen: (1) significantly higher rates of poorer outcomes were apparent for families including a parent with intellectual disability across all four measures of child developmental health; and (2) significantly higher rates of exposure to environmental adversity were apparent for families including a parent with intellectual disability for 17 of the 18 measures of environmental risk. The majority (59%) of families not containing a parent with intellectual disability were not exposed to any of the environmental adversities listed in Table 1. In contrast, the majority (54%) of families containing a parent with intellectual disability were exposed to five or more of these environmental adversities. Unadjusted and sequentially adjusted risk for adverse child development outcomes are presented in Table 2. Percentage reduction in risk (odds ratio) was calculated by the formulae 100 (unadjusted OR adjusted OR)/(unadjusted OR 1). As can be seen, sequentially adjusting for between-group differences in exposure to environmental adversity resulted in significant reductions in risk of poorer child development associated with parental intellectual disability. Adjusting for between-group differences in exposure to low socio-economic position reduced risk by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. 4. Discussion 4.1. Main finding of this study In a large representative population-based sample parental intellectual disability was associated with increased risk of child developmental delay, child speech and language problems, child behaviour problems and frequent child accidents and injuries. Parental intellectual disability was also associated with increased risk of exposure to a wide range of environmental adversities. Adjusting for between-group differences in exposure to low socio-economic position reduced risk by over 50% on each of the four measures of child developmental health. In the final fully adjusted model parental intellectual disability was associated with increased risk of child developmental delay and child speech and language problems. However, there were
920
E. Emerson, P. Brigham / Research in Developmental Disabilities 35 (2014) 917–921
Table 2 Unadjusted and adjusted risk of poorer child developmental outcomes in families containing one or more parents with intellectual disability. Child developmental outcomes
Unadjusted
Adjusted (SEP)
Adjusted (SEP + social support)
Adjusted (SEP + social support + other adversities)
Adjusted (SEP + social support + other adversities + parenting problems)
Developmental delay (n = 46,020) % Reduction in OR from unadjusted Speech and language problem (n = 13,841) % reduction in OR from previous step Behaviour problems (n = 46,020) % Reduction in OR from previous step Frequent accidents and injuries (n = 13,841) % Reduction in OR from previous step
8.94 (7.45–10.73)
4.36 (3.60–5.28) 58% 3.25 (2.40–4.40) 60% 2.56 (2.13–3.08) 68% 2.10 (1.13–3.92) 72%
4.06 (3.34–4.93) 61% 2.95 (2.17–4.01) 65% 2.46 (2.04–2.97) 70% 1.97 (1.05–3.68) 76%
3.57 (2.92–4.36) 68% 2.76 (2.02–3.76) 69% 1.93 (1.569–2.35) 81% 1.75 (0.92–3.35) 81%
2.39 (1.94–2.95) 82% 1.91 (1.37–2.65) 84% 0.88 (0.71–1.10) 102% 1.05 (0.54–2.02) 99%
6.60 (4.93–8.82) 5.90 (4.94–7.04) 4.96 (2.71–9.07)
no significant associations between parental intellectual disability and child behaviour problems or frequent accidents and injuries. 4.2. What is already known on this topic Previous studies of the association between parental intellectual disability and child development have produced conflicting results. While several studies have indicated that the children of parents with intellectual disability are at risk of poorer developmental outcomes (Feldman & Walton-Allen, 1997; Keltner et al., 1999; Mørch et al., 1997), others have failed to find an association between parental intellectual disability and child development (Aunos et al., 2008; McConnell et al., 2003; McGaw et al., 2007). 4.3. What this study adds The present study adds to the existing literature in two ways. First, by using a relatively large representative population based sample of families containing parents with and without intellectual disability, it avoids two of the significant methodological weaknesses that pervade this field of research. Second, by sequentially adjusting risk estimates for betweengroup rates of exposure to environmental adversities associated with compromised child development (e.g., low socioeconomic position, social isolation, parenting problems), the study attempts to partial out primary effects of parental intellectual disability on child development from potentially confounding effects associated with differences in family context. The results suggest that residual risk of poorer child outcomes may vary across developmental areas and be specific to intellectual and language development. 4.4. Limitations of this study The major limitations of the study are: (1) the use of survey questions of unknown psychometric characteristics; (2) the exclusion of parents who have had their child removed by child welfare agencies; and (3) the extent to which the statistical modelling and design can effectively isolate effects attributable to parental intellectual disability. The use of administrative data in public health research typically represents a trade off between sample size/representativeness and data fidelity. In the present study, the use of consistent definitions across areas and the use of training in case note review should have improved the reliability and validity of the data collected. However, future research in this area would benefit from the use of well validated screening measures of child development. While the use of a relatively large representative population based sample of families is one of the major strengths of the study, the sampling frame consisted of families caring for young children. As such, families with a young child who had been removed from their care by child welfare agencies were not included in the sample. Given that parents with intellectual disabilities are at increased risk of contact with child welfare services and of having their children removed (IASSID Special Interest Research Group on Parents and Parenting with Intellectual Disabilities, 2008) and that these children may have poorer developmental health, the sampling strategy may have underestimated the strength of the association between parental intellectual disability and child outcomes. No information is available on the proportion of parents with intellectual disability in the samples areas who may have had their child removed by child welfare agencies. The use of a cross-sectional design clearly precludes the drawing of conclusions regarding causal relationships between parental intellectual disability and child development. The statistical modelling attempts to control for the potentially ‘confounding’ effects of factors that are associated with parental intellectual disability but are not a necessary component or outcome of intellectual disability. For the vast majority of the variables used to adjust risk a clear case can be made that they
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represent environmental risks that are not a necessary component or outcome of intellectual disability. For example, while parents with intellectual disabilities in the study were more likely to live in poor quality housing, housing quality and inequalities in access to decent housing are determined by social policy, not by intellectual disability per se. As such, most of these factors can be considered correlates of parental intellectual disability that are amenable to change though policy interventions. This is also, to an extent, the case for parenting problems. Indeed, there is growing evidence for the efficacy of interventions aimed at increasing the parenting capabilities of parents with intellectual disability (Feldman, 2010; Wade, Llewellyn, & Matthews, 2008). However, given that parenting is a complex skill, it is likely that parenting difficulties may be an inevitable outcome of intellectual disability for a proportion of people with more severe intellectual disability. Ethical approval The research was undertaken using confidentialised household-level data collected for local administrative purposes. Funding None. Competing interests None. References Aunos, M., Feldman, M., & Goupil, G. (2008). Mothering with intellectual disabilities: Relationship between social support, health and well-being, parenting and child behaviour outcomes. Journal of Applied Research in Intellectual Disabilities, 21, 320–330. Booth, T., & Booth, W. (1993). Parenting with learning difficulties: Lessons for practitioners. British Journal of Social Work, 23, 459–480. Collings, & Llewellyn, G. (2012). Children of parents with intellectual disability: Facing poor outcomes or faring okay? Journal of Intellectual & Developmental Disability, 37, 65–82. Feldman, M. (2010). Parenting education programmes. In G. Llewellyn, R. Traustadottir, D. McConnell, & B. Sigurjonsdottir (Eds.), Parents with intellectual disabilities: Past, present and futures (pp. 107–136). Chichister, UK: John Wiley & Sons. Feldman, M., & Walton-Allen, N. (1997). Effects of maternal mental retardations and poverty on intellectual, academic, and behavioural status of school-age children. American Journal of Mental Retardation, 101, 352–364. Grantham-McGregor, S., Cheung, Y. B., Cueto, S., Glewe, P., Richter, L., & Strupp, B. (2007). Developmental potential in the first 5 years for children in developing countries. Lancet, 369, 60–70. Ho¨glund, B., Lindgren, P., & Larsson, M. (2012a). Newborns of mothers with intellectual disability have a higher risk of perinatal death and being small for gestational age. Acta Obstetricia et Gynecologica Scandinavica, 91, 1409–1414. Ho¨glund, B., Lindgren, P., & Larsson, M. (2012b). Pregnancy and birth outcomes of women with intellectual disability in Sweden: A national register study. Acta Obstetricia et Gynecologica Scandinavica, 91, 1381–1387. IASSID. Special Interest Research Group on Parents and Parenting with Intellectual Disabilities. (2008). Parents labelled with intellectual disability: Position of the IASSID SIRG on parents and parenting with intellectual disabilities. Journal of Applied Research in Intellectual Disabilities, 21, 296–307. Keltner, B., Wise, L., & Taylor, G. (1999). Mothers with intellectual limitations and their 2-year-old children’s developmental outcomes. Journal of Intellectual and Developmental Disability, 24, 45–57. Llewellyn, G., McConnell, D., & Mayes, R. (2003). Health of mothers with intellectual limitations. Australian and New Zealand Journal of Public Health, 27(1), 17–19. McConnell, D., Llewellyn, G., Mayes, R., Russo, D., & Honey, A. (2003). Developmental profiles of children born to mothers with intellectual disability. Journal of Intellectual and Developmental Disability, 28, 122–134. McConnell, D., Mayes, R., & Llewellyn, G. (2008). Women with intellectual disability at risk of adverse pregnancy and birth outcomes. Journal of Intellectual Disability Research, 52, 529–535. McGaw, S., Shaw, T., & Beckley, K. (2007). Prevalence of psychopathology across a service population of parents with intellectual disabilities and their children. Journal of Policy and Practice in Intellectual Disabilities, 4, 11–22. Mørch, W.-T., Ska˚r, J., & Andersga˚rd, A. (1997). Mentally retarded persons as parents: Prevalence and the situation of their children. Scandinavian Journal of Psychology, 38, 343–348. Wade, C., Llewellyn, G., & Matthews, J. (2008). Review of parent training interventions for parents with intellectual disability. Journal of Applied Research in Intellectual Disabilities, 21, 351–366. Walker, S. P., Wachs, T. D., Grantham-McGregor, S., Black, M. M., Nelson, C. A., & Huff man, S. L. (2011). Inequality in early childhood: Risk and protective factors for early child development. Lancet, 378, 1325–1338.
