Differential diagnosis personality disorder versus autism spectrum disorder in older adults

Scientific knowledge of autism spectrum disorders (ASD) in older adults is still scarce. Differential diagnosis of ASD and personality disorders is complicated, especially in later life. There is overlap between ASD and personality disorders, both conceptually and descriptively. The manifestation of both disorders is heterogeneous, influenced by age specific factors and characterised by similar behavioural symptoms and the lack of a sound developmental history. In both disorders, age specific changes can exceed adaptive abilities of patients, so ASD and personality disorders may become manifest for the first time in old age. More research is needed to fully understand the relationship between ASD and personality development across the life span. Also, there is a need for assessment instruments for both adults and older people with comorbid mental disorders and personality disorders in particular. As comorbidity of ASD and personality disorders appears to be common, more research should be done into treatment of comorbid personality disorders, also in later life.