Introduction
While GLP-1 receptor agonists (GLP-1RAs) were originally developed to improve glycemic control in type 2 diabetes, there is growing evidence from randomized clinical trials that these therapies also provide benefits in obesity, cardiovascular disease, chronic kidney disease, obesity-related heart failure with preserved ejection fraction, metabolic dysfunction-associated liver disease, and sleep apnea1,2,3,4,5,6,7,8,9. These successes raise the question of which treatment-related benefits are due to direct pharmacology and which are secondary to weight loss or other systemic metabolic changes?
The answer is unlikely to come from whole-body summary measures alone. Human and translational studies have established that the GLP-1 receptor plays important roles in hypothalamic homeostatic circuits, hindbrain interoceptive pathways, and reward-linked striatal systems, while peripheral tissues such as heart, vasculature, gut, and endocrine organs may add additional on-target or context-dependent effects10,11,12,13,14,15,16,17. At the same time, tissue-level localization of the GLP-1 receptor transcript and protein outside canonical pancreatic compartments remains sensitive to assay choice and bulk-tissue composition, making direct translational inference challenging.
To help deconvolute complex pharmacology of GLP-1RAs, particularly in the context of cognitive and neuropsychiatric outcomes, this work leverages electronic health record (EHR) data from a federated network of 489,785 semaglutide-treated patients18,19,20. We assessed 24 neuropsychiatric outcomes in a two-year period following semaglutide exposure to identify phenotypes associated with GLP-1 receptor agonism, which could be related to treatment-driven broad metabolic improvements, direct pharmacologic activity in the central nervous system (CNS), or other indirect mechanisms. We then integrated these findings with publicly available transcriptomic datasets to provide descriptive molecular context and generate hypotheses for future mechanistic investigation.
Results
Semaglutide is associated with reduced rates of affective, substance-use, vascular, and neurocognitive outcomes
From a cohort of 489,785 patients with at least one semaglutide prescription, a neuropsychiatric analysis cohort of 63,215 patients with baseline neurological conditions was assembled (see Methods). Of these, 56,859 could be propensity matched 1:1 to metformin-treated patients, 4757 to DPP-4 inhibitor-treated patients, and 30,680 to SGLT2 inhibitor-treated patients. Across 24 incident neuropsychiatric outcomes, we evaluated approximate 2-year event risk after treatment initiation.
Semaglutide was associated with lower two-year event risk than metformin for dementia/degenerative CNS disease (0.95% versus 1.96%; P < 0.001), cognitive symptoms (3.1 versus 4.3%; P < 0.001), substance-related neuropsychiatric disorders (3.8 versus 6.1%; P < 0.001), psychotic disorders (0.31 versus 0.93%; P < 0.001), speech/language symptoms (0.63 versus 1.21%; P < 0.001), cerebrovascular disease (2.6 versus 3.7%; P < 0.001), polyneuropathies (3.5 versus 4.5%; P < 0.001), mood disorders (10.5 versus 13.2%; P < 0.001), personality/impulse-control disorders (0.53 versus 1.06%; P < 0.001), perceptual symptoms (0.24 versus 0.60%; P < 0.001), and neurocognitive disorders (1.0 versus 1.7%; P < 0.001) (Fig. 1A). By contrast, metformin was associated with a lower rate of incident neuromuscular disease (1.1 versus 0.7%; P < 0.001). There was no significant difference in the risk of the negative control outcomes (eczema, kidney stones, rotator cuff disorders, hernia, tinea corporis) between semaglutide and metformin (Fig. S1).
Heat map showing 2-year Kaplan–Meier event-rate differences, in percentage points (pp), for semaglutide relative to metformin (top), DPP-4 inhibitors (bottom left) and SGLT2 inhibitors (bottom right) across baseline neurological condition (rows) and incident outcome (columns). Negative values (blue) indicate lower cumulative-incidence outcomes with semaglutide, whereas positive values (red) indicate lower cumulative incidence with the comparator medication. Cell annotations show the absolute 2-year difference in event probability, with the number of patients contributing to that comparison shown in parentheses; asterisks indicate statistical significance levels: * for p < 0.05, ** for p < 0.01, *** for p < 0.001, and no asterisk for p ≥ 0.05.
Subgroup-specific comparator analyses were then performed within individual baseline neurological condition strata (see Methods, Tables 1–3, and Tables S1–4). The largest associations with semaglutide were observed in patients with baseline neurocognitive disorders, where semaglutide was associated with a lower subsequent incidence of mood disorders. (13.7 versus 18.0%; P = 0.017). The strongest metformin-favored effects included lower rates of incident seizure and paroxysmal neurologic disorders among patients with baseline neurocognitive disorders (33.2 versus 24.3%; P = 0.015), as well as lower rates of incident neuromuscular disease among those with baseline polyneuropathy/peripheral nervous system disorders (3.0 versus 1.1%; P < 0.001) and Parkinson’s/movement disorders (2.2 versus 0.8%; P < 0.001). Broadly similar but mixed patterns were observed in the corresponding comparisons with DPP-4 inhibitors (Fig. 1B) and SGLT-2 inhibitors (Fig. 1C), with semaglutide generally associated with a lower incidence of several neuropsychiatric outcomes.
Maximum attained semaglutide dose was associated with greater maximum weight loss through the pre-landmark period
Maximum attained semaglutide dose during the first 2 years after treatment initiation, defined as the pre-landmark period for subsequent analyses, was associated with greater maximum weight loss achieved within that same interval (Fig. 2). Patients whose maximum dose remained at 0.25 mg or 0.5 mg showed the least weight reduction, whereas those reaching 1.7, 2.0, and especially 2.4 mg had progressively greater negative body weight change distributions. The maximum achieved body weight change increased by about 3.01% for each 1 mg increase in semaglutide dose.
Violin plots and embedded box plots show the distribution of maximum percent body weight change from baseline across semaglutide maximum dose groups attained within the 2-year pre-landmark period (0.25, 0.5, 1.0, 1.7, 2.0, and 2.4 mg). Black dots denote group means, white horizontal lines denote medians, boxes denote interquartile ranges, and whiskers denote distribution spread. The dotted regression line summarizes the dose-response trend, indicating progressively greater weight reduction with higher attained semaglutide dose. Sample sizes for each dose group are shown beneath the x-axis labels.
Weight loss-stratified analyses show little association with most neuropsychiatric outcomes
When patients were stratified by maximum achieved weight loss during the pre-landmark period, most post-landmark neuropsychiatric and neurological outcomes did not differ significantly across weight loss categories (Fig. 3 and Fig. S2). Baseline characteristics and semaglutide prescription patterns across weight loss strata are summarized in Table 1. Global weight loss-strata tests were non-significant for substance-related neuropsychiatric disorders (P = 0.15), mood/affective disorders (P = 0.96), and hereditary/systemic CNS atrophies (P = 0.99), with cumulative event curves showing no significant separation across the <5, 5–10, 10–15, 15–20, and ≥20% weight loss groups. These findings suggest that, within this landmark framework, achieved weight loss was not strongly associated with the subsequent incidence of neuropsychiatric conditions. The negative control outcomes were also not significantly associated with the magnitude of weight change (Fig. S3).
Cumulative event curves and corresponding event-rate summaries are shown for A, B substance-related neuropsychiatric disorders, C, D mood/affective disorders, E, F hereditary/systemic CNS atrophies, and G, H residual CNS and neurologic disorders across five pre-landmark maximum weight loss strata: <5, 5–10, 10–15, 15–20, and ≥20%. Panels on the left show post-landmark cumulative event probability from the time of landmark, and panels on the right show the corresponding event rates by weight loss category. Global log-rank and event-rate P-values are displayed within each panel.
Reduced rates of neuropsychiatric outcomes in patients achieving higher semaglutide doses
In the landmark analysis (Fig. 4 and Fig. S4), higher attained semaglutide dose (≥1.7 mg) during the pre-landmark period was associated with lower post-landmark event rates than lower dose regimens (0.25–1.0 mg). Baseline characteristics and pre- versus post-landmark semaglutide prescription patterns across these dose strata are summarized in Table 2. Higher attained dose was associated with lower post-landmark event rates for substance-related neuropsychiatric disorders (RR 0.71, 95% CI 0.62-0.81; P < 0.001), mood/affective disorders (RR 0.82, 95% CI 0.75–0.89; P < 0.001, hereditary/systemic CNS atrophies (RR 0.59, 95% CI 0.45–0.78; P < 0.001), anxiety/trauma/OCD/somatoform disorders (RR 0.88, 95% CI 0.81–0.94; P < 0.001), neuromuscular junction or muscle disease (RR 0.72, 95% CI 0.55–0.93; P = 0.013), eating/sleep/behavioral syndromes (RR 0.87, 95% CI 0.76–0.99; P = 0.037), personality/impulse-control disorders (RR 0.68, 95% CI 0.48–0.96; P = 0.028), and neurologic signs and symptoms (RR 0.87, 95% CI 0.76–0.99; P = 0.037). On the other hand, a higher attained dose was not significantly associated with any of the negative control outcomes (Fig. S5).
Cumulative event curves (left panels) and corresponding event-rate summaries (right panels) are shown for A, B substance-related neuropsychiatric disorders, C, D mood/affective disorders, E, F hereditary/systemic CNS atrophies, and G, H residual CNS and neurologic disorders during the two-year post-landmark period. Patients were grouped by maximum semaglutide dose attained during the pre-landmark window as low dose (0.25–1.0 mg; N = 39,795) or high dose (≥1.7 mg; N = 15,515). Across all outcomes shown, the high-dose group had lower post-landmark event rates than the low-dose group. Event-rate ratios and P values are displayed within the event-rate panels, and log-rank p values are shown within the cumulative-incidence panels.
Weight loss-dominant outcomes separate from the dose-dominant cluster
To distinguish dose-associated from weight loss-associated patterns, post-landmark neurological and neuropsychiatric outcomes were next evaluated along two complementary axes: the strength of association with attained dose and the strength of association with achieved weight loss. Under this framework, substance-related neuropsychiatric disorders, mood/affective disorders, hereditary/systemic CNS atrophies, anxiety/trauma/OCD/somatoform disorders, and residual CNS and neurologic disorders were more strongly associated with dose, whereas cognitive symptoms and speech/language symptoms showed stronger associations with weight change (Fig. 5 and Table 3). This association with weight loss was particularly strong for cognitive symptoms (global P < 0.001), with approximate post-landmark event rates of 2.1% in the <5% weight loss group compared to 5.5% in the 15–20% group and 4.7% in the ≥20% group (Fig. S6). Speech/language symptoms showed a similar but less prominent pattern (global P = 0.003). Together, these findings suggest that at least some of the neuropsychiatric associations observed with semaglutide are more closely correlated with maximum prescribed dose than with weight reduction.
Each bubble represents one incident outcome, assessed during the two-year post-landmark period in semaglutide-treated patients with prior neurological burden. The x-axis shows the strength of association with the maximum achieved semaglutide dose during the pre-landmark period, defined as the −log10(P value) for the low- versus high-dose comparison. The y-axis shows the strength of association with maximum achieved weight loss during the pre-landmark period, defined as the −log10(P value across weight loss strata. The bubble area is proportional to the total number of incident events for that outcome. Outcomes are categorized as dose-associated (blue), weight loss-associated (red) or null (gray). Higher values indicate stronger statistical evidence of association.
A descriptive atlas of GLP1R transcript expression across human tissues and CNS cell populations
As expected, bulk RNA-sequencing data across human tissues highlighted the pancreas as the highest GLP1R-expressing tissue, including endocrine and exocrine components (Fig. 6A and Table S3). However, several non-pancreatic sites with median GLP1R expression of at least 1 transcript per million (TPM) were noted, including in the heart (atrial appendage), CNS (hypothalamus, caudate), and the peripheral nervous system (tibial nerve) (Fig. 6B). Among the CNS sites of possible expression, the highest expression was seen in the caudate nucleus of the basal ganglia (median 1.50 TPM, n = 300) and hypothalamus (median 1.21 TPM, n = 257) (Fig. 6B), although the observed transcript abundance remained low and should be interpreted cautiously given the known challenges of detecting low-abundance GLP1R transcripts in bulk RNA-sequencing datasets.21,22,23,24,25. Other regions of the brain, including the cortex, cerebellum, hippocampus, and amygdala, show minimal GLP1R expression in bulk RNA-sequencing.
A Mean GLP1R transcript abundance across the indicated tissues or tissue-specific compartments, shown in transcripts per million on a log-transformed scale. B Non-pancreatic tissues shown on a linear scale. C CNS cell populations ranked using a descriptive GLP1R engagement-potential metric, calculated as mean transcript expression multiplied by the fraction of cells with detectable transcript. The metric reflects transcript detection only and does not indicate receptor protein abundance, ligand binding, signaling activity, or pharmacological engagement.
Single-cell transcriptomic analysis identifies candidate CNS cell populations with detectable GLP1R transcripts
Single-cell RNA-seq analysis of the CNS using the CELLxGENE census obtained from the Chan Zuckerberg Initiative21 identified a restricted set of GLP1R-enriched cell types when ranked by GLP1R engagement potential (GEP), defined as mean expression multiplied by the fraction of expressing cells (Fig. 6C). The highest-ranking populations were vascular-associated smooth muscle cells in spinal cord (GEP = 0.0351), contractile cells in spinal cord (0.0213), and GABAergic neurons in spinal cord (0.0183), followed by secretory cells in spinal cord (0.0125), cerebellar granule cell precursors in brain (0.0121), noradrenergic cells in brain (0.0121), perivascular cells in spinal cord (0.0089), Bergmann glial cells (0.0076), cerebellar granule cells (0.0067), cerebellar glutamatergic neurons (0.0066), hippocampal astrocytes (0.0062), and brain vascular cells (0.0055). Together, these analyses identify low-level GLP1R transcript detection across a limited number of CNS cell populations. These observations are descriptive and should not be interpreted as evidence of receptor protein expression, functional signaling, or semaglutide engagement within these cell populations.
Discussion
This study demonstrated that in the real-world clinical setting, the maximum attained semaglutide dose during the first two years after the first prescription were more closely associated with the subsequent incidence of neuropsychiatric outcomes than achieved weight loss. Specifically, a higher attained dose was associated with lower subsequent incidence of conditions related to mood/affect, anxiety, substance-use, neuromuscular function, and sleep disturbances. In contrast, most of these disease categories did not show significant separation across weight loss strata. This dissociation suggests that the observed neurological associations with semaglutide may not be fully explained by body weight reduction alone and supports the need for future prospective studies, including randomized trials and long-term observational studies during treatment and after treatment cessation.
Given the retrospective nature of this study, it is important to recognize that the observed dose associations reflect more than pure pharmacologic exposure. Maximum prescribed dose is not an independent pharmacological variable but also encompasses multiple factors, including but not limited to tolerability, adherence, access to care, and insurance status. The cohort of patients who did not achieve a higher dose of semaglutide is likely enriched for patients who did not actually begin taking semaglutide, did not tolerate the medication, or discontinued the medication before or during the recommended dose escalation phase. On the other hand, it is likely that the high-dose cohort is generally healthier, more engaged with the healthcare system, and demonstrates higher treatment adherence. Thus, healthy-adherer bias is a possible explanation for the observed associations between higher dose and lower rates of neuropsychiatric outcomes. While weight loss magnitude during the pre-landmark period would also be expected to reflect several of these same treatment adherence-related factors, it is possible that the null findings in the weight loss-stratified analyses simply indicate that the dose axis absorbs a larger component of the healthy-adherer signal, which is not captured by weight loss. In light of this, the dose associations reported in this study should not be interpreted as a dose-response signal in the pharmacological sense, and further randomized prospective studies evaluating neuropsychiatric outcomes in dose-stratified cohorts will be needed to tease apart these axes.
The findings presented in this study should not be interpreted as a benefit–risk assessment or as support for off-label semaglutide prescribing. The present landmark cohort was constructed among patients with preexisting neuropsychiatric disease to evaluate subsequent diagnosis incidence, whereas valid adverse-event analyses require event-specific baseline-negative populations, washout and latency windows, and exposure definitions that distinguish actual initiation, escalation, interruption, and discontinuation. Applying the present post-landmark framework to gastrointestinal, hepatobiliary, pancreatic, metabolic, or acute psychiatric events would be particularly problematic because many such events occur during treatment initiation or dose escalation, within the two-year pre-landmark period, and may themselves prevent attainment of a higher dose. Maximum attained dose, therefore, partly reflects tolerability and persistence, potentially enriching the high-dose group for patients who tolerated and continued treatment. Prior studies using the same federated EHR and AI-curation infrastructure have evaluated 16 label-identified gastrointestinal, systemic, and metabolic adverse events across propensity-matched tirzepatide and semaglutide cohorts and have shown that gastrointestinal adverse effects were among the leading documented reasons for treatment interruption22,23 {refs}. A prespecified safety analysis in adults with type 1 diabetes additionally identified increases after treatment initiation in nausea or vomiting, hypoglycemia, constipation, diarrhea, decreased appetite, and acute kidney injury, while diabetic ketoacidosis, severe hypoglycemia, pancreatitis, gallbladder disease, gastroparesis, and retinopathy progression did not increase significantly after multiplicity correction; diabetic ketoacidosis was increased among patients with greater than 30% reduction in insulin total daily dose24. These dedicated event-specific studies complement, but do not substitute for, the present hypothesis-generating analysis. Accordingly, the lower incidence of broad neuropsychiatric diagnosis families reported here does not exclude acute psychiatric events and should not be used to infer the absence of treatment-emergent adverse events.
Importantly, this study also highlighted heterogeneity in neuropsychiatric outcomes during and after semaglutide exposure. For example, cognitive symptoms and speech/language symptoms aligned more strongly with weight loss strata than attained dose, and cognitive-symptom event rates increased in the higher achieved weight loss groups. These findings should not be interpreted as evidence that semaglutide worsens cognition, and indeed, prior studies have demonstrated a positive association between weight loss and improved cognitive function25. Rather, like the other results presented here, this trend likely reflects a mixture of biology and bias, including frailty enrichment, illness-related catabolism, differential surveillance, reverse causation, heterogeneous symptom coding, and the clinical reality that the first recorded diagnosis often lags far behind biological onset. Weight loss magnitude is challenging to consider as an exposure variable in retrospective analyses, as weight loss can be driven by both intentional (e.g., pharmacotherapy, lifestyle adjustments) and non-intentional (e.g., known or undiagnosed illnesses, declining reserve, and malnutrition) factors. Future prospective studies will help to disentangle these confounders and more definitively characterize the impacts of semaglutide exposure and therapy-induced weight loss on neuropsychiatric phenotypes.
Existing literature evaluating the association between incretin therapies and neuropsychiatric outcomes has yielded mixed results. Recent clinical trials studying the impact of semaglutide on clinical progression in patients with early Alzheimer’s disease showed no benefit compared to placebo26. In line with this, our analysis did not find any significant difference between the high-dose and low-dose cohorts in the incident diagnosis rates of dementia or residual CNS and neurologic disorders during the post-landmark period. In a retrospective study of nearly 96,000 patients with depression and/or anxiety, semaglutide use was associated with significantly lower risk of worsening depression, worsening anxiety, and worsening substance-use27. Conversely, in a propensity-matched retrospective analysis of over 300,000 obese patients without baseline neuropsychiatric conditions (bipolar disorder, schizophrenia, depression, anxiety, or suicidal ideation), use of GLP-1RA therapy was associated with significantly increased incidence of major depression, anxiety, and suicidal behavior28. Independent of the GLP-1 axis, multiple prior studies have found that intentional weight loss is associated with improvements in some neuropsychiatric outcomes, including depression and cognitive function25,29. Mechanistically, there is strong evidence that incretin therapies function at least in part via CNS signaling pathways, with preclinical data demonstrating that GLP-1RAs activate hypothalamic neurons and establishing that CNS GLP1R expression is necessary to mediate their appetite suppression, weight loss, and counteracting of “molecular age30,31,32,33 Whether broader CNS pathways that impact mood, anxiety, personality, and cognition are engaged by these medications warrants further exploration.
The tissue-resolved GLP1R transcriptomic analyses provide descriptive molecular context for the observed clinical associations and identify candidate tissues and cell populations for future investigation. Bulk transcriptomic data identified multiple potential CNS sites of GLP1R expression, including the hypothalamus, caudate, putamen, and nucleus accumbens. These findings are compatible with human neuroimaging studies and recent hypothalamic and hindbrain expression atlases that localize GLP1R to neuronal populations involved in satiety, aversion, interception, and neuroendocrine output33,34,35,36,37. However, the low transcript abundance and observational nature of the analyses preclude inference regarding the cellular mechanisms underlying the clinical associations. The single-cell RNA-seq analyses identified a limited number of CNS cell populations with detectable GLP1R transcripts. The engagement-potential metric was used solely as a descriptive ranking measure and should not be interpreted as evidence of receptor function or pharmacological engagement. While these observations identify candidate tissues and cell populations for future investigation, they do not establish protein expression, receptor signaling, or the biological mechanisms responsible for the clinical associations observed in this study.
This study has several limitations. First, it is a retrospective observational study and is thereby vulnerable to multiple sources of bias, including healthy-adherer and other forms of selection bias, ascertainment bias, and confounding by unmeasured variables. Second, given the large cohorts analyzed in the study, there is adequate statistical power to detect very small differences between the analyzed cohorts. In this setting, there may be statistically significant results that arise for a number of reasons, including true treatment effects and residual confounding despite attempted balancing via propensity-score matching. Thus, it is important to consider not only the level of statistical significance but also the magnitude of difference (effect size) and potential confounding factors that could influence each analysis. Third, disease incidence was defined by the first instance of a diagnostic code documented in the EHR, which inherently reflects diagnostic capture rather than biological onset and is prone to variability based on diagnostic coding practices. Fourth, there are challenges associated with retrospective analysis of both medication dosing (e.g., variable treatment adherence, which is not well captured in the EHR) and weight loss (e.g., selection bias and classification of intentional versus unintentional weight loss). For example, by definition, the low-dose cohort includes patients who never received a prescription for a recommended maintenance dose of semaglutide. It is likely that some of these patients never actually initiated semaglutide or took very few doses before their dose escalation was discontinued. Without access to prescription claims data or detailed narratives of medication adherence, it is difficult to establish the degree of longitudinal medication exposure in this group, which likely varies widely between patients in the group. Fifth, this study did not include an assessment of treatment-related adverse events experienced after semaglutide initiation. The adverse event profile of semaglutide has been characterized in randomized trials and real-world studies, and it is known that adverse events can significantly impact patient adherence and maintenance dose attainment38,39,40,41,42. Further characterization in these dose-stratified patient populations with preexisting neuropsychiatric disease could be informative. Sixth, the broad CNS and symptom-level groupings applied here are analytically useful but clinically heterogeneous. More fine-grained analyses are warranted. Additionally, the analysis indiscriminately considered patients who were prescribed any formulation of semaglutide. These different formulations have shown varying levels of cardiometabolic improvements, with important differences relating to their dose escalation regimens, approval timelines, typical clinical use cases, and underlying characteristics of the patient populations receiving these prescriptions. Regarding the molecular analyses, GLP1R transcript abundance was generally low across CNS tissues evaluated in this study. Consequently, transcript detection may be influenced by sequencing depth, tissue composition, transcript dropout, and cell-type annotation. Furthermore, RNA abundance does not necessarily correlate with receptor protein expression, membrane localization, ligand accessibility, or downstream signaling. Accordingly, these transcriptomic analyses should be interpreted as descriptive and hypothesis-generating rather than mechanistic43.
In summary, this retrospective study identified hypothesis-generating associations between higher attained semaglutide dose and lower subsequent incidence of several broad neuropsychiatric diagnosis families, largely independent of maximum achieved weight loss. These associations may reflect pharmacology, tolerability, treatment persistence, access, healthy-adherer effects, or residual confounding and require rigorous prospective validation.
Methods
Data sources and study design
This study was a retrospective observational analysis using de-identified longitudinal electronic health record data from the nference Federated EHR Network20. All analyses were performed on de-identified data. The study integrated semaglutide-associated neurological and neuropsychiatric outcome analyses from the federated EHR platform with GTEx-derived GLP1R mRNA expression data across tissues and sample-level metadata.
The clinical outcomes component comprised summary analyses spanning 24 neurological or neuropsychiatric outcomes, including counts, event-rate ratios, dose-group P values, and weight loss-strata P values. The transcriptomic component comprised GTEx-based GLP1R sample-level gene expression measurements, in transcripts per million (TPM), together with tissue summaries and metadata-stratified association analyses12.
Study cohorts and exposure definitions
The primary analytic cohort comprised 63,215 semaglutide-treated patients with at least one baseline neurological or neuropsychiatric condition before treatment initiation. Medication exposure was ascertained from prescription or medication event records using the recorded event timestamp. The index date was defined as the date of the first qualifying prescription for the cohort-defining medication or medication class. Follow-up data were available through December 31, 2025. To create incident-user comparator cohorts with minimal treatment contamination, separate mutually exclusive cohorts were defined for metformin, DPP-4 inhibitors, and SGLT2 inhibitors using the same index-date framework and exclusion logic. Other GLP-1RA medications were treated as exclusion exposures when defining the semaglutide cohort.
Demographic and clinical covariates
Demographic variables included age and sex. Age at index was obtained from the index medication record. Baseline body mass index (BMI) was defined as the BMI measurement closest to the index date, recorded from 365 days before through 1 day after the index date. Baseline weight for weight loss analyses was defined separately as the weight measurement closest to the index date, recorded from 90 days before through 14 days after the index date. Baseline type 2 diabetes was defined by the presence of at least three encounters carrying a type 2 diabetes International Classification of Diseases (ICD) code on three distinct dates before the index date. Baseline neurological and neuropsychiatric disease burden was defined using prespecified ICD-9 and ICD-10 code prefixes across 31 clinically relevant domains, including mood/affective disorders, anxiety/trauma/OCD/somatoform disorders, substance-related neuropsychiatric disorders, cognitive symptoms, neurocognitive disorders, speech/language symptoms, neuromuscular disease, cerebrovascular disease, seizure, and paroxysmal neurologic disorders, and hereditary or degenerative CNS syndromes. The union of these domains defined an overall baseline neurological-burden cohort for the semaglutide landmark analyses, whereas individual baseline neurological subgroups were examined separately in comparative analyses. Complete diagnosis code definitions are provided in Table S1.
Propensity-matched comparative neuropsychiatric analyses
For comparator analyses, three mutually exclusive incident-user cohorts were constructed for metformin, DPP-4 inhibitors, and SGLT2 inhibitors using the same index date and exclusion logic described above. Within each baseline neurological or neuropsychiatric subgroup, we compared the rates of each individual incident neuropsychiatric outcome between the semaglutide cohort and the matched cohorts of patients taking metformin, DPP-4 inhibitors, or SGLT2 inhibitors. Propensity scores were estimated with logistic regression using age at index, sex, baseline BMI, and baseline type 2 diabetes status. Patients were matched 1:1 without replacement using nearest-neighbor matching and a caliper of 0.2 on the propensity-score scale.
Follow-up for comparative outcome analyses began on the treatment initiation date. The outcomes were the same as the baseline neurologic and neuropsychiatric diseases listed above. As negative control analyses, we also assessed the incidence of eczema, kidney stones, hernia, rotator cuff disorders, and tinea corporis, which are not expected to be impacted by semaglutide or the other comparator medications. Patients were followed until the outcome of interest, death, or the last observed clinical record. For incident neurological and neuropsychiatric outcomes, patients with a documented diagnosis of the given condition at baseline were excluded from that specific analysis. We summarized matched cohort size, event counts, person-time, and cumulative 2-year event estimates using Kaplan–Meier methods and log-rank P values.
Neuropsychiatric outcomes and landmark analyses
Two-year landmark analyses were conducted within the semaglutide cohort to assess associations of attained dose intensity and achieved weight loss with subsequent neurological and neuropsychiatric outcomes.
For dose-response analyses, each patient’s maximum achieved dose within two years after treatment initiation (defined as the “pre-landmark period”) was paired with that patient’s maximum achieved change in total body weight during the same interval. Dose categories corresponded to labeled dosing increments for injectable semaglutide formulations: 0.25, 0.5, 1.0, 1.7, 2.0, and 2.4 mg or greater. Observed dose values were used when directly available in the medication record, and missing dose values were extracted from medication descriptions using a large language model-assisted dose-mapping workflow44.
For post-landmark outcome analyses, the landmark date was defined as the two-year timepoint after treatment initiation for both dose- and weight loss-based analyses. For weight loss-based analyses, maximum percent body weight reduction was calculated from the lowest observed weight recorded from day 15 after index through the landmark date, and patients were categorized into prespecified weight loss strata of <5, 5–10, 10–15, 15–20, 20–25, and ≥25%. For dose-based analyses, the maximum semaglutide dose reached between the index and the landmark date was classified as low dose (0.25–1.0 mg) or high dose (≥1.7 mg). For each incident outcome analysis, patients with evidence of that same condition before follow-up were excluded. Outcomes were the same as defined above for the propensity-matched comparative analyses, including the negative control outcomes. Post-landmark follow-up extended for 24 months and continued until the outcome of interest, death, or the last observed clinical record, whichever occurred first. To compare dose-associated and weight loss-associated patterns across outcomes, the corresponding dose- and weight-stratified P values were jointly visualized in a two-axis bubble plot.
Assessment of GLP1R expression in bulk and single-cell RNA-sequencing datasets
The GTEx-derived GLP1R atlas comprised 18,576 bulk RNA-sequencing samples, with sample-level expression measurements and demographic metadata across 64 tissues. Tissue-level ranking was based on mean TPM values from the tissue summary table. Single-cell RNA-sequencing data were obtained from the CELLxGENE census from the Chan Zuckerberg Initiative21. Summary data for all CNS cell types, including the percentage of cells with transcripts detected and the mean expression level in expressing cells were downloaded from the portal. A composite metric termed GLP1R engagement potential (GEP) was defined as the mean expression multiplied by the fraction of expressing cells and was used to rank the list of candidate expressing cell types.
Statistical analysis
Continuous variables were summarized as means with standard deviations or medians with interquartile ranges, and categorical variables were summarized as counts and percentages. In the comparative neuropsychiatric analyses, between-cohort outcome differences were summarized using the Kaplan–Meier method, with significance assessed by log-rank testing; comparative heatmaps displayed absolute differences in approximate two-year Kaplan–Meier event risk. In the semaglutide weight loss landmark analyses, cumulative event distributions and corresponding event-rate comparisons across weight loss strata were assessed using a global log-rank test. In the dose landmark analyses, cumulative event distributions were compared between low-dose and high-dose groups using log-rank tests, whereas post-landmark event-rate comparisons were summarized as relative risks with 95% confidence intervals and Wald-type chi-square P values derived from log risk-ratio estimates. Bubble-plot visualizations displayed dose- and weight loss-associated evidence as -log10(P) values derived from these corresponding dose- and weight-stratified analyses.
For the GTEx analyses, tissue-level and sample-level summary statistics were analyzed descriptively and visualized directly from the available TPM, P value, and q value outputs. For plotting purposes, P values reported as zero in summary exports were truncated to 1 × 10−6 to enable log-scale visualization. Because the clinical outputs were analyzed in aggregated form and the molecular outputs reflected summary-level bulk-tissue statistics, mechanistic interpretations were treated as hypothesis-generating rather than causal, and no attempt was made to infer mediation or patient-level counterfactual effects.
Data source
This study analyzed de-identified EHR data from academic medical centers in the United States via the nference Clinical Analytics Platform. Prior to analysis, all data underwent expert determination de-identification satisfying HIPAA Privacy Rule requirements (45 CFR §164.514(b)(1)), employing a multi-layered transformation approach for both structured data (cryptographic hashing of identifiers, date-shifting, geographic truncation) and unstructured clinical text (ensemble deep learning and rule-based methods with >99% recall for personally identifiable information detection)45. nference established secure data environments within each participating center, housing these de-identified patient data governed by expert determination. These de-identified data environments were specifically designed to enable data access and analysis without requiring Institutional Review Board oversight, approval, or exemption confirmation. Accordingly, informed consent and IRB review were not required for this study.
Data availability
This study involves the analysis of de-identified Electronic Health Record (EHR) data via the nference Federated Clinical Analytics Platform. Data shown and reported in this manuscript were extracted from this environment using an established protocol for data extraction, aimed at preserving patient privacy. The data has been de-identified pursuant to an expert determination in accordance with the HIPAA Privacy Rule. Any data beyond what is reported in the manuscript, including but not limited to the raw EHR data, cannot be shared or released due to the parameters of the expert determination to maintain the data de-identification. The corresponding author should be contacted for additional details regarding the nference Federated platform. De-identification and HIPAA compliance certification are described as follows. Prior to analysis, all EHR data were de-identified under an expert determination consistent with the Health Insurance Portability and Accountability Act (HIPAA) Privacy Rule (45 CFR §164.514(b)(1)). The de-identification methodology employed a multi-layered transformation approach to both structured and unstructured data fields37. In structured data, direct identifiers including patient names and precise geographic locations were excluded entirely, while indirect identifiers underwent specific transformations: patient identifiers, medical record numbers, and accession numbers were replaced with one-way cryptographic hashes using confidential salts to preserve linkage across patient encounters; all dates were shifted backward by patient-specific random offsets (1–31 days) to preserve temporal relationships while obscuring exact event timing; the ZIP codes were truncated to two-digit state-level resolution; and continuous variables including age, height, weight, and body mass index were thresholded to prevent identification of extreme values (for example, ages ≥89 years transformed to “89+” and BMI >40 transformed to “40+”). In unstructured clinical text, an ensemble de-identification system that combines attention-based deep learning models with rule-based methods achieved an estimated >99% recall for personally identifiable information (PII) detection, with detected identifiers replaced by plausible fictional surrogates37. To address heterogeneity in EHR data, we harmonized clinical variables including medications, anthropometric measurements, and diagnoses to standardized concepts. For medications, we first constructed a standardized drug concept database combining the nference knowledge graph with RXNorm (https://www.nlm.nih.gov/research/umls/rxnorm/index.html) hierarchies to capture ingredient, brand, and dose-specific information. EHR medication records were matched using a hierarchical approach prioritizing RXNorm codes when available, followed by ingredient-level matching, and finally natural language processing and pattern matching on free-text medication orders when structured codes were absent. For anthropometric measurements (height, weight, BMI), we created a unified vocabulary from SNOMED (https://www.snomed.org/, https://athena.ohdsi.org) and LOINC (https://loinc.org/) terminologies and matched EHR measurement descriptions using standardized text matching algorithms with abbreviation expansion and synonym resolution; ambiguous mappings were resolved using OpenAI GPT-4o46 (https://platform.openai.com/docs/models/gpt-4o) with summary statistics as context, followed by manual verification. For diagnoses, we developed a hierarchical disease concept database from the nference knowledge graph and matched EHR diagnosis descriptions and codes by identifying the most specific common child concept in the hierarchy. This approach enabled consistent identification of clinical entities while preserving granularity where available.
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Acknowledgements
We thank the nference engineering team for the development of the nference federated AI platform, and Patrick Lenehan and Christopher Gregg for critical review and manuscript feedback.
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Competing interests
The authors are employees of nference, inc., which conducts research collaborations with various biopharmaceutical companies whose therapeutic products are included in this study. None of these companies, nor any other nference collaborator, funded, supported, or had any role in the independent study design, data acquisition, analysis, interpretation, manuscript preparation, or the decision to submit this work for publication. All analyses were conducted by the authors using de-identified electronic health record data. The authors declare no additional competing interests.
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Murugadoss, K., Venkatakrishnan, A.J. & Soundararajan, V. Higher semaglutide dose is associated with lower neuropsychiatric event incidence independent of weight loss. npj Metab Health Dis 4, 36 (2026). https://doi.org/10.1038/s44324-026-00131-3
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DOI: https://doi.org/10.1038/s44324-026-00131-3