Are secular trends in major depression an artifact of recall?

There is evidence that rates of major depression have increased over this century, with successive birth cohorts showing increased lifetime risks and earlier ages of onset. Two memory effects have been considered possible artifactual causes of these trends: age-related forgetting and postdating early episodes. In this study, relatives were reinterviewed six years after study entry using interviewers blind to initial reports. We examined the stability of lifetime diagnoses of MDD and ages of first onset. Older relatives were no more likely than younger ones to lose diagnoses nor to postdate their ages of first MDD onset. This is evidence that memory artifacts are not solely responsible for the observed secular trends.