Does depression prior to caregiving increase vulnerability to depressive symptoms among caregivers of persons with Alzheimer's disease?

Based on the vulnerability model of depression, this study tested the hypothesis that caregivers with prior depression are more likely to be depressed during caregiving than caregivers without prior depression. We further hypothesized an interaction effect in which caregivers with prior depression would be affected more by care-recipient dependency in activities of daily living and care-recipient depressive symptoms than those without prior depression. In a sample of 111 caregivers of persons with Alzheimer's disease, in an additive regression model, neither 'prior depressive symptoms' nor the clinically more serious 'prior depressive syndrome' was related to depressive symptoms during caregiving. In an interaction model, for caregivers with either 'no prior depression' or 'prior depressive symptoms,' the greater the care-recipient dependencies in instrumental activities of daily living (IADL), the greater were the depressive symptoms during caregiving. For caregivers with a 'prior depressive syndrome', however, the greater the IADL dependency, the fewer were the depressive symptoms during caregiving. This unexpected finding suggests that caregivers with a history of clinically significant depression are not necessarily more prone to depressive symptoms when caregiving responsibilities, at least for instrumental activities, are high. This result questions the vulnerability model of depression when applied to older caregivers.