Stress precedes negative symptom exacerbations in clinical high risk and early psychosis: A time-lagged experience sampling study.

The experience sampling method (ESM) has revealed associations between fluctuations in stress and positive symptoms in psychosis. It is unknown, however, how negative symptoms including anhedonia respond to stress. Stress is divided according to its source: event-related stress stemming from negative events, and activity-related stress stemming from engaging in tasks beyond one's skill or control. Anhedonia is divided into consummatory and anticipatory anhedonia, reflecting a lack of pleasure in current and expected activities. This study uses ESM to determine whether each form of anhedonia increases in response to stress. Antipsychotic-naïve individuals with first episode psychosis (n = 39), clinical high-risk states for psychosis (n = 44), and healthy controls (n = 34) responded to daily prompts on a palmtop computer for up to ten days by indicating levels of stress and anhedonia. Time-lagged multilevel modelling was employed to explore increases in anhedonia following increases in stress while controlling for prior levels of anhedonia. Mean levels of anhedonia were also compared across groups. Only activity-related stress produced increases in anhedonia. This effect did not vary between groups. Clinical groups showed greater overall levels of anhedonia than healthy controls, but did not differ from each other. Anhedonia responds only to activity-related stressors, suggesting that this form of stress has a specific causal role in anhedonia. The results also provide further evidence for global increases in anhedonia in antipsychotic-naïve psychosis spectrum individuals.