EFFECTS OF POSITIVE AND NEGATIVE LIFE EVENTS ON TIME TO DEPRESSION ONSET - AN ANALYSIS OF ADDITIVITY AND TIMING

While the relationship of life events to depression onset has occupied researchers for almost a quarter of a century, few studies have attem pted to account for either the temporal patterning of events relative to episode onset, or, the effect of multiple events in a study period. In this report, we attempt to address the issues of timing of events, multiple events (both positive and negative) and multiple aspects (bo th positivity and negativity) of single events on latency time to depr ession onset, while simultaneously accounting for possible decay in th e effects of events over time. We use the proportional hazards approac h to model the effects of life events and consider modelling the chang e in impact of events with the passage of time. After interviewing 142 recurrent unipolar patients using the Life Events and Difficulties Sc hedule, we rated severity and positivity of life events reported durin g the 6-month period prior to onset. As we hypothesized, additional li fe events occurring after an initial provoking agent level event signi ficantly alter the risk of illness onset. Additional severely threaten ing events decrease the time to onset, but positive events do not appe ar to delay onset. Interestingly, seemingly neutral events had a highl y significant effect in shortening the time to onset. We note the many limitations imposed on the interpretation of these findings related t o the selected group of subjects studied and encourage those who have more generalizable data to apply these methods of analysis.