Though psychiatric disorders (PD) are three to four times more prevalent in people with intellectual disability (PwID) compared to the general population, research indicates that the impact of PD on adaptive functioning in PwID has been only minimally investigated with results that are not sufficiently clear. The few contributions present in the literature focus on children, adolescents and individuals with autism spectrum disorders (ASD). There are no studies evaluating the unspecific impact of any type of PD on the abilities of PwID, even if additional knowledge would be useful in explaining dysfunction and planning treatment. Moreover, for many years, particular interest was reserved to “behavioral phenotypes”, or the possibility that certain maladaptive patterns of behaviour are the result of specific genetic alterations. The most studied phenotypes were Down, X Fragile and Prader-Willi syndromes. Literature reports have noted significant correlations between ASD and difficulties in the areas of socialisation, communication and motor-skills in early adulthood or younger. Other correlations have been reported between ADHD and deficits in executive functions in children and between mood disorders and some verbal skills in adults. Significantly high scores were found in the areas of communication and motor-skills in PwID and schizophrenia. Epilepsy appears to have the highest impairment in the areas of socialisation and motor-skills. Comparisons between PD and organic disorders, including neurological disorders (ND), have not been performed.
The aim of this study was to assess the impact of the presence of a PD on adaptive functioning of adults with ID.
Sixty-eight adults with ID, clients of residential facilities and day centres in Tuscany, were randomly assessed with the Psychiatric Instrument for the Intellectually Disabled Adult (SPAID-G), the Diagnostic Manual – Intellectual Disability (DM-ID) criteria and the Vineland Adaptive Behaviour Scales (VABS). Twenty-four individuals were previously diagnosed with a PD and 24 with a ND. The scores were compared and the results were examined for level of mental retardation and other background variables.
The group with ID and PD scored significantly worse on the VABS than the group with only ID, especially in the area of daily skill for life. The level of interference with the adaptive functioning of PD was higher than that of ND.
The presence of a PD seems to have a relevant negative impact on functioning of PwID that is higher than that of ND. Adequate psychiatric assessment would facilitate the understanding of the individual processes that modulate and differentiate adaptive skills in adults with ID. It would also be very useful in the planning of rehabilitative interventions.
Relationship between psychiatric disorders and adaptive functioning in individuals with intellectual disabilities