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

• Affective instability predicts multiple aspects of depression's course.

• Affective instability does not predict remission from depressive episodes.

• Affective instability remains a key predictor of depression in older adults.

Abstract

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.

Introduction

Emotion dysregulation is highly characteristic of Major Depressive Disorder (MDD), one of the world's most common and debilitating psychiatric disorders (Kessler et al., 2003). Existing emotion research has largely focused on two key facets of emotion dysregulation in MDD: aberrant levels of positive and negative affect (e.g., Brown et al., 1998, Hofmann et al., 2012) and emotion regulation strategy use (e.g., Ehring et al., 2010, Garnefski and Kraaij, 2006). However, elevated affective instability, intense and frequent shifts (i.e., variability) in emotional experience (e.g., Larsen and Diener, 1987), is another facet of emotion dysregulation that characterizes various mental health disorders, such as bipolar disorder (Henry et al., 2001) and borderline personality disorder (Koenigsberg, 2010, Trull et al., 2008). Affective instability is also relevant for MDD (e.g., Peeters et al., 2006). Individuals with a lifetime history of MDD have higher affective instability than do those without a lifetime history of MDD (Angst et al., 2003, Thompson et al., 2011), and a meta-analysis found that individuals with MDD have greater affective instability than do individuals without MDD (Houben et al., 2015). There is also empirical support for the temporal association between affective instability and depression; greater affective instability prospectively predicted changes in depressive symptoms in young adult women (Thompson et al., 2011).

One period of life that is especially important to consider when examining the course of MDD is older adulthood since MDD prevalence is lower during this life stage. Decreased prevalence may be partly due to the normative age-related decrease in affective instability (e.g., Brose et al., 2015, Carstensen et al., 2000). Thus, older adults who do not show a decrease in affective instability may be more likely to experience MDEs and have greater depressive symptoms. Indeed, although MDD is more common in younger adults than in older adults, it is still the most prevalent of all the psychiatric disorders among older adults (Fiske et al., 2009). Furthermore, older adults with MDD have a worse prognosis than younger adults with MDD, such as a reduced likelihood of going into remission and higher suicide rates. A growing number of studies indicate that affective instability consistently plays a critical role in MDD. However, most studies that have examined the relevance of affective instability in MDD have largely focused on how affective instability corresponds to MDEs at one time point (e.g., Angst et al., 2003). Thus, it is not clear how affective instability may be relevant for changes in MDD over time (e.g., remission). Addressing this question is important because MDD is a highly complex and recurrent disorder (Monroe and Harkness, 2011). Further, most studies on this topic have used younger adult or middle-aged adult samples (e.g., Peeters et al., 2006, Thompson et al., 2012). And although a meta-analysis on affective variability and psychological well-being (Houben et al., 2015) suggests that affective instability remains a relevant predictor of MDD later in life, these samples consisted of few older adults. Thus, it is unclear whether affective instability continues to predict MDD later in life.

In the present research, we extend prior work in two important ways. First, we examine how affective instability prospectively predicts the course of MDD, including the onset and remission of major depressive episodes (MDE). Second, we investigate whether affective instability remains a key risk factor later in life by examining it as a predictor of MDD in late middle-age and older adults. We address these gaps in the literature by investigating how affective instability predicts MDD's course in a 5-year longitudinal study with a large sample of late middle-aged and early older adults, and evaluate MDEs and depressive symptoms. Based on studies showing a positive association between affective instability and MDD (e.g., Thompson et al., 2011), we hypothesized that middle-aged and older adults who have greater affective instability would be more likely to have lifetime and first-time MDEs and less likely to recover from MDEs. We hypothesized that they would also report more depressive symptoms over time.

To isolate the unique effect of affective instability on MDD, we controlled for neuroticism and the other remaining Borderline Personality Disorder (BPD) symptoms. Neuroticism is key a risk factor of MDD (e.g., Kendler et al., 2004) that is largely characterized by negative affectivity (e.g., Watson et al., 1999). Although neuroticism is related to affective instability (Miller and Pilkonis, 2006, Miller et al., 2009), it has been shown to be a broader, distinct construct (Peeters et al., 2006). We controlled for BPD symptoms because BPD is highly comorbid with MDD (Grant et al., 2008).