A daily diary study of late-life depression.

OBJECTIVE: The objective of this study was to use data from daily diaries to characterize the day-to-day variability in positive and negative affects, and the relationship between daily events and daily affects in primary care patients with late-life depression. METHOD: Daily diary data were obtained from primary care patients with major depression (N = 25) and other depressive disorders (N = 33); data from a two-week period were compared with those from elderly normal volunteer comparison subjects (N = 70) who participated in other studies. RESULTS: There was significant day-to-day variability in negative affect in patients with major depression and other depressive disorders. Dysphoric days (days with a negative affect ratings that occurred once every two weeks in normal subjects) represented 65.3% (standard deviation [SD]: 37.1) of days in those with major depression and 50.6% (SD: 37.6) in those with other depression versus 7.7% (SD: 16.3) in normal subjects (F = 36.0, p <0.001). The groups did not differ significantly in the number of positive and negative events reported, but the proportion of dysphoric days that occurred in association with negative events was greater in normal subjects than in those with major depression. Mixed-effects analyses demonstrated that patients with major depression had blunted positive affective responses to positive events, consistent with impairments in hedonic processes, and that patients with other depressions exhibited heightened negative affective responses to negative events, greater than those in normal subjects and patients with major depression. CONCLUSIONS: Diary methods demonstrated characteristics of late-life depression that have not been identified with assessment methods that have lower time resolution.