Affective instability predicts the course of depression in late middle-age and older adulthood

Background: Affective instability is a facet of emotion dysregulation that characterizes various mental disorders, including Major Depressive Disorder (MDD). However, it is unclear as to how affective instability predicts the course of MDD. It is also unknown whether affective instability is a relevant predictor of MDD in later adulthood, a period when there is a decrease in both affective instability and MDD prevalence. Thus, we investigated the role of affective instability in the course of MDD in a sample of late middle-age and older adults. Methods: Using a longitudinal design over five years, 1,630 adults aged 55–64 years (M = 59.60, SD = 2.70) completed a baseline assessment of affective instability (self-report, informant-report, interviewer-report), three assessments of MDD (computerized interview), and eight assessments of depressive symptoms (self-report). Results: Baseline affective instability positively predicted the likelihood of having lifetime major depressive episodes (MDE) and first-time MDEs, as well as depressive symptoms up to five years later. However, affective instability did not predict remission or having more depressive symptoms over time. These findings held when controlling for neuroticism. Limitations: We only assessed affective instability at the baseline, did not investigate specific mechanisms or recurrence, and focused on middle-age and older adults. Conclusions: Our findings replicate and extend prior work by showing that affective instability is differentially related to multiple aspects of MDD's course and remains an important predictor of MDD even in older age. We discuss implications for the role of affective instability in MDD across the lifespan.