Factors predicting the emotional well-being of adult siblings of those with developmental disability (DD) remain under-researched. In this study adult siblings of individuals with Down's syndrome (DS), autism (ASD), Prader-Willi syndrome (PWS) and those with DD but with unknown aetiology (DUA) were compared with each other and a closely-matched control group to ascertain if sibling disability type made a difference to anxiety and/or depression levels. Also considered was the interactive effect of gender, age, parental and sibling educational attainment levels, socio-economic status and birth order on anxiety and depression outcomes. With the exception of siblings of those with DS, adult siblings of those with ASD, PWS and DUA reported significantly higher levels of anxiety and depression than the control group. There were some predictive effects of the demographic variables upon anxiety and depression but none common to all disability types and no moderating effects of demographic factors were found. Consequently other solutions must be found as to why this important group of people have elevated rates of anxiety and depression in comparison to the general population.

Background Children growing up with a sibling with disabilities report higher levels of depression and anxiety symptoms as adults. Here, we examined whether personality characteristics also play a part in mediating this relationship. Method We tested for differences in personality traits between 132 individuals who have a sibling with developmental disabilities and 132 closely matched comparisons. Results Differences in Big Five factors of personality were demonstrated across the disability groups and between the disability groups and the comparisons, especially in Extraversion, Neuroticism and Openness. Individuals growing up alongside a sibling with developmental disabilities have a higher tendency to experience anxiety and depression symptoms, and this research is the first demonstration that personality traits mediate this relationship. Specifically, Neuroticism is a strong mediator of anxiety while both Neuroticism and Extraversion contribute mediating effects toward the development of depression. Limitations Our study made use of self-report methodology which, although having recognized limitations, is more reliable than parental reports. Given the cross-sectional nature of our design, we were not able to examine pre-existing developmental factors that may have influenced the participant's propensity to particular personality traits and affective disorders. However, we obtained a large sample and closely matched participants to examine differences between those with a sibling with disabilities and those without. Conclusions As such, differences in personality traits have important implications for the understanding and treatment of siblings presenting with anxiety and depression symptoms. We recommend that intervention should target those high in Neuroticism among individuals who have a sibling with disabilities, and that more social support is put in place for siblings to mitigate their tendency towards introversion and buffer them against psychological maladjustment.

Adult siblings of individuals with developmental disabilities often experience higher levels of anxiety than individuals in the general population. The present study tested whether perceived parenting could mediate the relationship between attachment styles and anxiety in the sibling group compared to a control group. Little association was found between perceived parenting and attachment styles or anxiety for the siblings but there were robust and expected findings for the control. Adult attachment-related-anxiety was a significant unique predictor of anxiety in the sibling group but there was no mediational role for perceived parenting. Conversely, the majority of parenting styles significantly mediated the relationship between attachment and anxiety in the control. Implications for the atypical findings in the sibling group are discussed.