BACKGROUND Little data are available about the course or incidence of depression in dementia sufferers.

METHOD Monthly follow-up data over one year is reported regarding depression in a cohort of 124 dementia sufferers. Dementia was diagnosed according to DSM-III-R criteria. Depression was assessed with the Cornell Depression Scale and diagnosed according to RDC criteria. Cognitive functioning was assessed with the CAMCOG:

RESULTS Eighty-nine of the 124 patients completed the follow-up. The annual incidence rates of RDC major depression and RDC minor depression were 10.6% and 29.8%, respectively. Twenty per cent of patients with depression experienced these symptoms for six months or longer. Patients with vascular dementia were significantly more likely to experience three or more months of depression than patients with other dementias. RDC minor depression was highly persistent among 23.8% of sufferers.

CONCLUSION Depression is persistent in patients with vascular dementia. Some patients with minor depression have a dysthymia-like disorder.