Higher semaglutide dose is associated with lower neuropsychiatric event incidence independent of weight loss

GLP1 receptor agonists (GLP-1RAs) have transformed obesity treatment, but their impact on neuropsychiatric outcomes remains poorly understood. We conducted an observational study of 63,215 patients with preexisting neuropsychiatric conditions and evaluated 24 incident neuropsychiatric outcomes following treatment initiation. In propensity-matched analyses, semaglutide was associated with broadly lower neuropsychiatric event risk over two years compared with metformin, SGLT2 inhibitors, and DPP-4 inhibitors. Within the semaglutide-treated cohort, higher attained dose during the first two years after treatment initiation ("pre-landmark period") was associated with significantly lower incidence during the subsequent two years ("post-landmark period") of substance-related disorders (P < 0.001), mood disorders (P < 0.001), anxiety- and stress-related disorders (P < 0.001), central nervous system (CNS) atrophies (P < 0.001), neuromuscular disorders (P = 0.013), eating/sleep/behavioral disorders (P = 0.022), and personality/impulse-control disorders (P = 0.028). Consistent with prior clinical trials, the post-landmark incidence of dementia or CNS degenerative diseases was similar between the high-dose and low-dose semaglutide cohorts (P = 0.15). For most neuropsychiatric diagnoses, post-landmark incidence was strongly associated with the maximum attained dose. In contrast, incident cognitive symptoms and speech/language symptoms were more closely associated with weight loss (p < 0.001 and p < 0.003, respectively). Bulk and single-cell transcriptomic analyses identified low-level, regionally restricted GLP1R transcript signals in central and peripheral nervous system tissues, providing hypothesis-generating context for future experimental investigation. Together, these findings support an association between semaglutide exposure and multiple neuropsychiatric outcomes, and motivate prospective mechanistic and clinical studies.