C'mon get happy: reduced magnitude and duration of response during a positive-affect induction in depression

Abstract

Background: Depression involves decreased positive affect. Whether this is due to a failure to achieve or maintain positive emotion in response to discrete stimuli is unclear. Understanding the nature of decreased positive affect could help to address how to intervene in the phenomenon, for example, how to structure interventions using positive and rewarding stimuli in depression. Thus, we examined the time course of affect following exposure to positive stimuli in depressed and healthy individuals.

Methods: Seventy-one adults with major depressive disorder and thirty-four never-depressed controls read a self-generated highly positive script and continuously rated their affect for 7 min.

Results: Both groups quickly achieved increased positive affect, however, compared to controls, depressed participants did not achieve the same level of positive affect, did not maintain their positive affect, spent less time rating their affect as happy, and demonstrated larger drops in mood.

Conclusions: These data indicate that depressed and nondepressed individuals can generate positive reactions to happy scripts, but depressed individuals cannot achieve or sustain equivalent levels of positive affect. Interventions for depression might fruitfully focus on increasing depressed individuals' ability to maintain initial engagement with positive stimuli over a sustained period of time.

Trial registration: ClinicalTrials.gov NCT00183664 NCT00787501.

Keywords: depression; emotion; information processing.

Figure 1

Mean percentage of time spent within each emotion rating cue for healthy and depressed participants. Statistically significant differences between groups p < 0.01 are marked with asterisks. Error bars represent 95% confidence intervals around the mean for each bar, computed separately within each affect label within each group.

Figure 2

Continuous affect ratings, over seven minutes, for each participant. Control participants are shown in pink. Depressed participants are shown in blue. Dotted lines represent the “Neutral affect” anchor at the 0.5 rating. Participants whose affect after one minute feel below this anchor are highlighted. Participants assessed in the behavioral lab rather than the scanner are marked with the word “lab”.

Figure 3

Mean continuous affect ratings for control participants (pink) and depressed participants (blue). Regions of statistically significant differences between the waveforms are highlighted below the x-axis. Yellow indicates differences significant at p < 0.1. Red indicates differences significant at p < 0.05.