Critical slowing down in momentary affect as early warning signal of impending transitions in depression

Based on dynamical systems theory, the current study aimed to investigate if recurrence of depression is systematically preceded by within-person early warning signals (EWS) in positive and negative affect. Ecological momentary assessments were collected 5 times a day for a period of 4 months (averaging 524 assessments per individual) in 37 formerly depressed individuals discontinuing antidepressant medication. EWS (increases in window autocorrelation and variance) preceded recurrence of depression in 32.9% of the participants across robustness checks. Compared to participants that remained in remission, participants with a recurrence showed (1) significantly more positive trends in the variance, but not in autocorrelation, and (2) the average number of significant EWS was over three times larger across tested affect variables. Although the results provide the first systematic evidence that EWS occur more often before the recurrence of depression, the low sensitivity of EWS poses a substantial challenge for clinical applications.