Dementia in Intellectual Disability: An Exploratory Investigation of Comorbidity Patterns and Diagnostic Outcomes

Dementia is more prevalent and tends to manifest earlier in individuals with intellectual disabilities (ID) compared to the general population. Acquiring specific knowledge about comorbidities and diagnostic findings in individuals with ID who have dementia, as opposed to those with ID without dementia, is essential. Such insights are crucial for enhancing the quality of care.

The study was applied in a German outpatient clinic for people with ID and mental illnesses from February 2018 to September 2022. An exploratory comparison was conducted to identify differences in somatic and psychiatric comorbidities, laboratory results, cerebrospinal fluid results, neuroimaging, medication and challenging behaviour in people with ID with (n = 13, mean age: 54 years, 69% female) and without dementia (n = 73, mean age: 53 years, 48% female).

In this sample, persons with ID who have dementia are more likely to have Down syndrome and less likely to have affective disorders. They received antidementia drugs more often and atypical high-potency antipsychotics less often compared to persons with ID without dementia. All other clinical data showed no differences.

Interestingly, no differences in somatic diseases (except Down syndrome) or laboratory and neuroimaging results could be found between people with ID with and without dementia. However, the diagnosis of dementia was associated with a reduced frequency of affective disorders and a reduced prescription of antipsychotics compared to the clinical sample without dementia. Due to the exploratory character of the study, replication in a much larger sample is necessary.