Depression in mild dementia: associations with diagnosis, APOE genotype and clinical features

Depression is common in dementia, with important clinical implications. Few studies of depression in dementia with Lewy bodies are available, and the results are inconsistent.

To examine the frequency of depression and its characteristics and correlates, in people with mild dementia.

All referrals for patients with a first time diagnosis of dementia to geriatric and older psychiatry outpatient clinics in the counties of Rogaland and Hordaland in Western Norway from March 2005 to March 2007 were screened for the study. Participants and their caregivers underwent a comprehensive and standardised diagnostic and assessment procedure. The depression subitem of the neuropsychiatric inventory (NPId) and Montgomery and Åsberg depression rating scale (MADRS) were used to estimate depression. Cut-off scores for any depression were 0/1 (NPId) and 6/7 (MADRS), and for clinically significant depression 3/4 and 14/15, respectively.

Two hundered and twenty-three subjects with dementia participated, of whom 59 and 50% showed symptoms of depression assessed by NPI or MADRS, respectively, and 25 and 16% had clinically significant depression as measured by NPI and MADRS, respectively. Depression was more frequent in dementia with Lewy bodies (DLB) than in Alzheimer's disease (AD; p < 0.05). APOE genotype was available in 153 patients, and in AD, but not in DLB, a general linear model showed that the presence of APOEε4 allele was significantly associated with depression (F = 4.14; p = 0.045).

Depression is common even in mild dementia, and more common and severe in DLB compared to AD. Future studies should explore the longitudinal course of depression in DLB, and the neural underpinnings of depression in DLB.