Background: The population of older adults with intellectual disability (ID) is large and growing due to a significant increase of life expectancy caused by improvements in health and social care. Multimorbidity is highly prevalent in this population and co-morbid psychiatric disorders are especially frequent.
Subject and methods: The aim of this article is to review the prevalence and consequences of psychiatric comorbidity in the population of older adults with ID. We therefore performed a literature search of studies relevant to adults with ID, published since January 2006, using the following keywords: intellectual disability and comorbidity, intellectual disability and mental disorders, intellectual disability and polypharmacy.
Results: Psychiatric comorbidity is frequent among patients with ID and correlates with older age. Mental disorders are present in up to 40% of older adults with ID and the most prevalent are challenging behaviour, depression, anxiety and dementia. Patients with ID and at least one co-morbid mental disorder are at a high risk of polypharmacy. Importantly, psychiatric comorbidity was found to significantly increase service use and costs of care.
Conclusions: Further investigation of the population of older adults with ID is needed, with special attention to development of clear treatment guidelines in order to effectively manage co-morbid mental illnesses and physical health problems.