Is psychomotor retardation associated with treatment response in adults with depression? A secondary analysis of nine randomised controlled trials

Abstract Background Psychomotor retardation is characterised by slowed motor and cognitive processes. Although associated with greater illness severity in depression, its relationship with treatment response is unclear. We examined whether psychomotor retardation is associated with treatment outcomes in depression. Methods We conducted a secondary analysis of individual participant data from nine randomised controlled trials of pharmacological, psychological and exercise-based treatments for unipolar depression in primary care. Self-reported psychomotor retardation was assessed at baseline using the Revised Clinical Interview Schedule. The primary outcome was the standardised z -score of each trial’s validated self-report depression measure at 3–4 months post-randomisation; the secondary outcome was remission. Within-study regression models were adjusted for established prognostic factors, with secondary analyses additionally adjusting for baseline core depressive symptoms and depression severity. Effect estimates were pooled using random-effects meta-analysis. Results Among 4,290 participants, 2,754 (64.2%) reported psychomotor retardation. Psychomotor retardation was associated with greater depression severity at follow-up (pooled z -score = 0.184, 95% CI 0.059–0.309, p = 0.004, I ² = 68.7%) and lower odds of remission (pooled OR = 0.737, 95% CI 0.577–0.941, p = 0.015, I ² = 57.7%), adjusting for age, sex, ethnicity, marital status, employment status and allocated treatment. Findings were robust to adjustment for baseline core depressive symptoms but not after adjustment for full baseline severity. Conclusions Psychomotor retardation is associated with poorer treatment outcomes in depression, though this may reflect underlying severity. Recognition of psychomotor retardation may help identify patients at risk of poorer response and inform clinical management.