Maladaptive behaviours and symptoms of dementia in adults with Down's syndrome compared with adults with intellectual disability of other aetiologies.

Dementia commonly occurs in elderly people with intellectual disability, especially those with Down's syndrome. The non-cognitive symptoms of dementia can be of greater significance to individuals and carers than the cognitive changes caused by this condition. It is not known whether there are differences between people with Down's syndrome and those with intellectual disability of other causes with regard to the prevalence of such symptoms. The present study was undertaken to draw a comparison between a group with Down's syndrome and dementia (n = 19), and a group with intellectual disability of other causes and dementia (n = 26). Maladaptive behaviours and psychiatric symptomatology were assessed in both groups. The group with Down's syndrome had a higher prevalence of low mood, restlessness/excessive overactivity, disturbed sleep, being excessively uncooperative and auditory hallucinations. Aggression occurred with greater frequency in those subjects with intellectual disability of other causes. These findings are of epidemiological importance in terms of service planning and understanding psychiatric presentation.