The direct and interactive effects of neuroticism and life stress on the severity and longitudinal course of depressive symptoms

Abstract

The direct and interactive effects of neuroticism and stressful life events (chronic and episodic stressors) on the severity and temporal course of depression symptoms were examined in 826 outpatients with mood and anxiety disorders, assessed on 3 occasions over a 1-year period (intake and 6- and 12-month follow-ups). Neuroticism, chronic stress, and episodic stress were uniquely associated with intake depression symptom severity. A significant interaction effect indicated that the strength of the effect of neuroticism on initial depression severity increased as chronic stress increased. Although neuroticism did not have a significant direct effect on the temporal course of depression symptoms, chronic stress significantly moderated this relationship such that neuroticism had an increasingly deleterious effect on depression symptom improvement as the level of chronic stress over follow-up increased. In addition, chronic stress (but not episodic stress) over follow-up was uniquely predictive of less depression symptom improvement. Consistent with a stress generation framework, however, initial depression symptom severity was positively associated with chronic stress during follow-up. The results are discussed in regard to diathesis-stress conceptual models of emotional disorders and the various roles of stressful life events in the onset, severity, and maintenance of depressive psychopathology.

Figure 1

Nature of the Interaction of Neuroticism and Chronic Stress on Depression Symptoms at Intake. DEP = depression, CS_I = chronic stress in the 6 months preceding the intake evaluation. The possible range of scores for the unstandardized DEP latent variable is 0 to 42.

Figure 2

Longitudinal Measurement Model of Depressive Symptoms. Completely standardized parameter estimates are provided (all ps < .001). For presentational clarity, correlated error estimates are not presented (range = .19 to .42). T1 = Intake, T2 = 6-month follow-up, T3 = 12-month follow-up; DASS-D = Depression scale of Depression Anxiety Stress Scales; BDI = Beck Depression Inventory; ADIS-D = ADIS-IV dimensional ratings of major depression.

Figure 3

Conditional Latent Growth Model of Depressive Symptoms. N = neuroticism, CS_F = chronic stress during the follow-up period, N × CS_F = neuroticism by chronic stress product term, DEP = Depression, T1 = Intake, T2 = 6-month follow-up, T3 = 12-month follow-up, * = freely estimated parameter. Completely standardized estimates are shown. Overall fit of model: χ²(46) = 126.30, p < .001, SRMR = .03, RMSEA = 0.05 (90% CI = 0.04 to 0.06, CFit = .74), TLI = 0.98, CFI = .98. **p < .01 ***p < .001

Figure 4

Model-Implied Trajectories of Depression as a Function of Neuroticism Within High and Low Chronic Stress. The conditional model-implied trajectories are provided in parentheses within the figure legend. N = neuroticism. The possible range of scores for the unstandardized Depression latent variable is 0 to 42.