In a recent study published in The BMJ, researchers evaluated the long-term effects of antidepressant medication on weight gain.
Obesity has become and continues to be a worldwide health problem. With 69% of the US adult population being overweight or obese and 61% of UK adults being overweight or obese, it has become a serious health concern which the health and government sectors are desperately trying to manage. It has also been shown that severe obesity is greatly linked to socioeconomic inequality in the United Kingdom and the United States. When an individual reaches obesity status, it is difficult to achieve a significant and maintained weight loss.
Obesity associated with depression
Antidepressant prescriptions have also increased. Between 1995 and 2011, within the primary care population, 23% of 1.5 million participants were prescribed an antidepressant on a minimum of one occasion. With obesity being associated with depression, particularly severe obesity, further research has shown that antidepressant use may be linked to weight gain through mechanisms that are not entirely understood. Therefore, the high rate of antidepressant prescriptions worldwide could be having an effect on the public health sector by potentially contributing to important health factors such as weight gain, although this is not fully understood at this time.
It has already been established from short-term studies that there is a link between antidepressant use and weight gain. Researchers from King’s College London have set out to investigate the long-term effects of antidepressants on weight gain and their results have subsequently been published within The BMJ.
During this study, researchers examined data from 136,762 men and 157,957 women within primary care. It became apparent that a high number of these people received antidepressants and their body mass index (BMI) had been recorded, and the data had been collected over a 10-year follow-up period.
Individuals who had been on antidepressants had an increased risk of weight gain
The results of the study showed that during the 10-year follow-up, individuals who had been prescribed an antidepressant had an increased risk of weight gain of more than 5% when compared to those who had not received an antidepressant medication. This link was observed across a wide range of population subgroups. This increased risk of weight gain was seen during the second and third years of treatment. However, the results showed that less than 12 months of antidepressant use did not seem to lead to an increase in weight. Of all the antidepressants observed during this study, mirtazapine was associated with the highest rate of weight gain.
Despite the strengths of this study, such as the use of a large primary care database from the United Kingdom to collect the data, there are certain limitations to this study which need to be addressed, most importantly the infrequent documentation of BMI.
To conclude, the results of this recent study supports the evidence that anti-depressants show a strong association with weight gain, which seems to be greatest during the second and third year of treatment. It is during the second year of treatment that the risk of weight gain of more than 5% is 46.3% higher than in those individuals who are not receiving antidepressants. This link remains consistent across a variety of clinical, social and demographic characteristics. Therefore, the increasing use of antidepressants is a concern as the numbers of obesity continue to increase worldwide.
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
