Individuals with Intellectual Disability (ID) experience higher rates of psychiatric disorders than the general population, although findings are mixed with regard to the determinants of this increased prevalence. Despite growing recognition of the prevalence of mental health problems among individuals with ID, and the consequences this comorbidity carries for individuals, families and the wider community, there are multiple challenges in identifying and managing these concerns. Accurate diagnosis and effective intervention is currently hindered by factors including the applicability of standardised psychiatric classification systems, gaps in service delivery models and access to such services, as well as unmet training needs.
TopBackground
Intellectual Disability (ID) is characterised by deficits in both intellectual and adaptive functioning beginning during childhood or adolescence (APA, 2013). Adaptive behaviour includes conceptual skills (e.g., language, money and time concepts), social skills (e.g., interpersonal skills and social problem solving), and practical skills (e.g., activities of daily living and occupation) (Maulik, Mascarenhas, Mathers, Dua, & Saxena, 2011).
A recent meta-analysis found that the overall global prevalence of ID was approximately 1%, with higher prevalence rates found in low- and middle-income countries, and among child and adolescent populations (Maulik et al., 2011). Social gradients and ethnic disparities have been reported in previous research on the prevalence of ID. For example, lower socio-economic status (SES) has been found to be associated with a marked increase in the prevalence of ID, particularly mild ID (Emerson, 2012; Leonard et al., 2005; Leonard & Wen, 2002; Roeleveld & Zielhuis, 1997; Stromme & Magnus, 2000), and higher rates of ID have been found among African-American and Indigenous Australian children (Croen, Grether, & Selvin, 2001; Leonard, Petterson, Bower, & Sanders, 2003; Leonard et al., 2005; Yeargin-Allsopp, Drews, Decouflé, & Murphy, 1995). In a recent epidemiological study to estimate the burden of disease caused by ID in Australia, the authors estimated that ID was responsible for 1.7% of the total disease burden in all Australians, and 5.5% of the total disease burden in Indigenous Australians (Begg et al., 2007; Vos, Barker, Stanley, & Lopez, 2007). Of particular concern is the evidence that an “inverse care law” applies, in that the greater number of risk factors a child may have for ID, the less access they have to preventative and comprehensive health care (Woolfenden et al., 2013). This creates a vicious cycle whereby the risk factors that may predispose a child to ID are also the same risk factors that may mean they are likely to miss out on timely and effective identification and intervention.