Summary: In a manufacturer-sponsored post hoc analysis of the STEP 1, 2, 3, and 5 trials, once-weekly semaglutide 2.4 mg did not increase depressive symptoms or suicidal ideation versus placebo in adults with overweight or obesity and no known major psychopathology. The PHQ-9 treatment difference was -0.56 (95% CI -0.81 to -0.32; P<.001), a small reduction the authors judged statistically significant but not clinically meaningful.
PICO Summary
| Element | Detail |
|---|---|
| Population | Adults with overweight or obesity without known major psychopathology; STEP 2 participants also had type 2 diabetes. Pooled phase 3a STEP 1, 2, 3 (n=3377; 69.6% women; mean age 49 years) plus phase 3b STEP 5 (n=304; 77.6% women; mean age 47 years). Multinational, multicenter randomized double-blind trials. |
| Intervention | Subcutaneous semaglutide 2.4 mg once weekly for 68 weeks (STEP 1, 2, 3) or 104 weeks (STEP 5). |
| Comparison | Matching placebo injection under identical trial conditions (68 or 104 weeks). |
| Outcome | PHQ-9 estimated treatment difference at week 68 (STEP 1/2/3): -0.56 (95% CI -0.81 to -0.32; P<.001), statistically significant but deemed not clinically meaningful. Odds of shifting to a more severe PHQ-9 depression category: OR 0.63 (95% CI 0.50-0.79; P<.001), favouring semaglutide. Suicidal ideation/behaviour on the Columbia-Suicide Severity Rating Scale: reported in 1% or fewer of participants, with no between-group difference. Psychiatric disorder adverse events were generally balanced between groups. Similar findings in STEP 5. No absolute risk reduction or NNT applies (safety analysis, not an efficacy endpoint). |
Psychiatric safety of semaglutide 2.4 mg
Post hoc RCT analysis · overweight/obesity · 68-104 wk
Semaglutide 2.4 mg did not worsen depressive symptoms or suicidality versus placebo, with a small PHQ-9 advantage that was statistically significant but not clinically meaningful. People with major psychopathology were excluded.
Expert Commentary
The verdict is reassuring but narrow: across more than 3,600 participants, semaglutide 2.4 mg was not associated with worsening depressive symptoms or emergent suicidality, and a small PHQ-9 advantage favoured the drug. That signal should be read with care. This is a post hoc analysis of trials designed to assess weight loss, so the psychiatric findings are secondary and associational rather than confirmatory, and the PHQ-9 difference was explicitly judged not clinically meaningful. The most important limitation is the enrolled population itself: people with known major psychopathology, recent suicidal behaviour, or PHQ-9 scores indicating significant depression were excluded, so baseline mood was near-normal and there was little room to detect harm in those most likely to be vulnerable. Manufacturer sponsorship and authorship also warrant disclosure, and prescribers should weight independent pharmacovigilance accordingly. Can I use this with my patients? Yes, to reassure a patient with overweight or obesity and no active or severe psychiatric illness that semaglutide 2.4 mg is unlikely to provoke depression or suicidal thoughts. It does not clear the drug for patients with active major depression, recent suicidality, or unstable psychiatric disease, who were not studied here and still need individualized assessment and monitoring. Continue to screen mood at follow-up; I would welcome prospective data in higher-risk psychiatric populations before extending this reassurance further.
References
Wadden TA, Brown GK, Egebjerg C, et al. Psychiatric safety of semaglutide for weight management in people without known major psychopathology: post hoc analysis of the STEP 1, 2, 3, and 5 trials. JAMA Intern Med. 2024;184(11):1290-1300. doi:10.1001/jamainternmed.2024.4346