Depression in dementia: a study of mood in a community sample and referrals to a community service.

The association between degree of cognitive impairment and severity of depressive symptoms was examined in a randomly selected community-based sample of elderly people and in a sample of patients referred to an old age psychiatry service. Findings contradict previous reports of less cognitive impairment in demented patients with depressive symptoms. We suggest that sample selection bias has contributed to the earlier reports.