Drugs used to treat diabetes and obesity do not appear to increase the risk of mental health conditions such as depression, anxiety, or suicide. A new study that combined genetic analysis and real-world clinical data found no evidence linking glucagon-like peptide-1 receptor agonists to psychiatric disorders. The study results were published in the Journal of Affective Disorders.
Glucagon-like peptide-1 is a natural hormone produced in the intestine. When a person eats, this hormone prompts the pancreas to release insulin to manage blood sugar levels. It also sends signals to the brain that promote satiety. Pharmaceutical companies have developed synthetic versions of this hormone to help patients manage type 2 diabetes.
These drugs are known as glucagon-like peptide-1 receptor agonists. It has recently become very popular as a weight loss treatment because it effectively slows down digestion and reduces appetite. But as millions of people began taking these drugs, health officials began receiving alarming reports.
Patients and doctors submitted reports detailing psychiatric adverse events to the European Medicines Agency and the US Food and Drug Administration. Some people reported experiencing high anxiety, new symptoms of depression, or suicidal thoughts after starting the injections. Medical experts were concerned about potential psychiatric side effects because the drug interacts with brain regions involved in reward and emotion regulation.
Investigating these reports using standard observational data has proven extremely difficult. Patients prescribed these drugs typically have chronic conditions such as diabetes or clinical obesity. These underlying health problems are already associated with increased baseline risk of depression and anxiety, making it difficult to distinguish between the effects of the disease and the effects of the medication.
Moreover, rapid weight loss itself can cause significant psychological changes. Although some early studies suggested that the drug could cause mental health problems, other reviews found that it actually reduced suicidal thoughts compared to alternative treatments. To circumvent the limitations of observational studies, researchers Chenhao Ouyang and colleagues at China’s Nanchang University devised an alternative approach.
The research team used an epidemiological technique called Mendelian randomization. This method is based on the fact that genetic variations are randomly passed from parent to child at conception. This genetic lottery is unaffected by lifestyle choices or environmental factors, so scientists can use it as a natural experiment to prove cause and effect.
Researchers searched a large genetic database for specific DNA mutations that naturally alter the function of the body’s glucagon-like peptide-1 receptor. These gene adjustments act as lifelong surrogates for taking drugs. If the biological pathways activated by weight loss drugs really cause mental health problems, people with these particular genetic variations should have higher rates of mental illness.
To perform the Mendelian randomization analysis, the researchers needed highly specific genetic data. They used two layers of biological information to create genetic proxies. First, the researchers focused on mutations that change gene expression, which determines how aggressively the body reads the DNA code to produce receptors. They then looked at the variations that affect the actual abundance of receptor proteins circulating in the body. Finding consistent results across both biological variables will help verify the reliability of the overall conclusions.
The research team accessed data from large international genetics initiatives, including the FinnGen project and the Psychiatric Genomics Consortium. FinnGen alone contains biological samples and health records of over 500,000 Finnish citizens. The Psychiatric Genomics Consortium involves hundreds of researchers worldwide and features data from hundreds of thousands of participants, ensuring a robust sample size to detect rare conditions.
The researchers used these databases to compare genetic proxies of receptor activity to the genetic profiles of seven different psychiatric disorders. Conditions covered include anxiety disorders, bipolar affective disorder, chronic depression, major depression, eating disorders, suicide, and schizophrenia.
The researchers applied several statistical models to look for overlapping patterns. They tested whether genes that determine receptor activity and genes associated with mental illness are inherited together. They also checked whether there was a common genetic structure across different traits.
Genetic results showed no association between the drug’s biological targets and psychiatric pathology. Natural changes in receptors did not change a person’s risk for any of the seven mental health disorders. The researchers found that there is no common causative variant that causes both receptor function and the development of mental illness.
To test these genetic findings against real-world practice, Ouyang and the research team also conducted an extensive review of existing clinical data. They performed a meta-analysis. This is a statistical process that combines the results of multiple independent studies to identify broader trends. They collected 35 previous studies that documented real-world mental health outcomes for patients.
This pooled data compared individuals taking the drug to a control group receiving an alternative treatment or a placebo. The clinical review fully reflected the genetic analysis. There were no statistically significant differences in rates of anxiety, depressive symptoms, or suicidal behavior in patients taking weight loss and diabetes medications.
The researchers found one exception in the clinical data, specifically regarding eating disorders. Patients taking the drug showed significant improvement in eating disorder symptoms compared to patients not taking the drug. The authors suggest that this may occur because the drug affects the brain’s reward center, reducing the frequency and severity of binge eating behavior.
Despite the encouraging results, the researchers noted some limitations to their study. Their analysis of clinical data did not allow them to distinguish between patients with a history of mental illness and those without such a background. Making this distinction in future studies may help researchers better understand why isolated reports of depression and suicide still occur in some patients.
The genetic data utilized in this study were primarily obtained from individuals of European descent. This focus means that the results may not be fully generalizable to other global populations with different genetic backgrounds. The project also did not consider how changes in medication dosage affect psychological health over time.
The available receptor genetic data are somewhat sparse and statistical estimates may be unstable. The authors recommend future prospective clinical trials to track mental health outcomes in diverse populations over time. They specifically highlight the need for studies focusing on subgroups, such as patients with pre-existing binge eating disorder, to validate the potential benefits observed in this review.
Overall, the combined genetic and real-world results provide theoretical support for the psychological safety of these widely used treatments. The biological mechanisms that enable drugs to affect metabolic conditions do not appear to inherently cause psychological distress.
The study, “A causal relationship between glucagon-like peptide-1 receptor agonists and psychiatric disorders: Insights from genetic and real-world evidence,” was authored by Chenhao Ouyang, Xiaoyue Zhang, Minhai Zhang, Yan Miao, Zicheng Zhu, Yunting Zeng, Hong Ban, Yuting Wu, Nanqin Peng, Jitao Ling, Chen Li, Deju Zhang, Peng Yu, and Jing Zhang. Xiao Liu and Tongsheng Huang.
