Association between premorbid history of depression and current depression in Alzheimer's disease

The relationship between a premorbid history of depression and the depressive syndrome in Alzheimer's disease (AD) remains equivocal. In the current study, we compared the prevalence of depression among patients with and without a history of mood disturbance prior to the onset of dementia. The sample comprised 243 AD outpatients evaluated consecutively at a university-affiliated memory disorders center. The results indicated that a positive history of depression was more common among patients with current depression compared to those without current depression (23% vs 11%, Fisher's Exact Test, P = .03). This relationship remained significant after controlling for the effects of age, education, gender, ethnicity, and level of cognitive impairment (odds ratio = 2.6, 95% confidence interval = 1.01-6.61, P = .04). Neither gender nor the interaction of gender and history of depression was shown to confer risk for current depressive symptoms. The present investigation suggests that premorbid depression may alter the risk for mood disturbance in AD.