Effects of glucagon-like peptide-1 receptor agonists on psychiatric disorders: a systematic review

Extant literature pertaining to the administration of glucagon-like peptide-1 receptor agonists (GLP-1RAs) for Alzheimer's disease, Parkinson's disease, major depressive disorder, bipolar disorder, substance-, alcohol- and nicotine-use disorders, suggests promising efficacy beyond the current FDA-approved indications (e.g., type 2 diabetes mellitus, obesity). The implicated brain regions of the aforementioned mental disorders contain glucagon-like peptide 1 (GLP-1) receptors associated with improving cognitive and behavioral functioning. Therefore, we aimed to systematically review the treatment effects of GLP-1RAs in various neurocognitive and psychiatric disorders. Online databases including PubMed, OVID, MEDLINE, Embase, PsycINFO and Google Scholar, were searched from inception until October 1, 2024. Additional studies were identified from the reference lists of the included articles. 22 studies were identified, with a total of 186,847 participants included. Results reported that GLP-1RAs meaningfully improved cognitive and affective functioning (e.g., memory), which in some cases was sustained beyond exposure to the agent. Separately, multiple epidemiological studies reported that GLP-1RAs have protective effects, with a suggestion of decrease in the incidence of mental disorders. These results provides the impetus for large, long-term, randomized controlled trials for GLP-1 RAs for the treatment of various mental disorders. This review is not registered in PROSPERO or any other registry.