Long-Term Effects of Antidepressants on Weight Gain

Overview of Obesity as a Global Health Issue

A recent study featured in The BMJ has shed light on the long-term impacts of antidepressant medications concerning weight gain. Obesity remains a significant global health challenge, with 69% of adults in the United States and 61% in the United Kingdom classified as overweight or obese. This pervasive issue has prompted health authorities and government organizations to seek effective management strategies. Notably, severe obesity has been closely linked to socioeconomic disparities in both the UK and the US. Once an individual reaches obesity status, achieving substantial and sustained weight loss becomes increasingly difficult.

Connection Between Obesity and Depression

The frequency of antidepressant prescriptions has risen sharply. From 1995 to 2011, 23% of 1.5 million participants in the primary care population were prescribed antidepressants at least once. Given that obesity is often associated with depression—especially severe forms of it—further investigations have indicated a potential connection between antidepressant use and weight gain, although the exact mechanisms remain unclear. Consequently, the widespread prescription of antidepressants may influence public health by contributing to weight gain, even as the full scope of this impact is not yet fully understood.

Study Focus and Methodology

Previous short-term studies have established a correlation between antidepressant use and weight gain. Researchers from King’s College London aimed to analyze the long-term effects of these medications on weight. Their findings were published in The BMJ. The study examined data from 136,762 men and 157,957 women in primary care, revealing that many participants had received antidepressants and had their body mass index (BMI) recorded over a 10-year follow-up period.

Key Findings on Weight Gain Risks

The study’s results indicated that, over the 10-year follow-up, individuals prescribed antidepressants had an increased risk of weight gain exceeding 5% compared to those who did not receive such medications. This association was consistent across various population subgroups. Notably, the heightened risk of weight gain was particularly evident during the second and third years of treatment. However, the data suggested that less than 12 months of antidepressant use did not correlate with significant weight increase. Among the antidepressants analyzed, mirtazapine was linked to the highest rates of weight gain.

Study Strengths and Limitations

While the study benefits from a comprehensive primary care database in the UK, certain limitations must be acknowledged, particularly the sporadic documentation of BMI.

Conclusion and Implications for Public Health

In conclusion, this recent study reinforces the notion that antidepressants are strongly associated with weight gain, especially during the second and third years of treatment. The risk of weight gain exceeding 5% is 46.3% higher for individuals on antidepressants compared to those not receiving them, a pattern that persists across various clinical, social, and demographic factors. As the prevalence of obesity continues to rise globally, the increasing use of antidepressants raises important public health concerns.

Author Information

Written by Jade Marie Evans, MPharm, Medical Writer

Reference

Gafoor, E et al. 2018. Antidepressant utilisation and incidence of weight gain during 10 years’ follow-up: population-based cohort study. [Online]. [17 June 2018]. Available from: https://www.bmj.com/content/361/bmj.k1951