People taking certain drugs used to treat schizophrenia and depression are more likely to put on weight and have an increased risk of type 2 diabetes, American research shows.

The discovery could pave the way for the elimination of this mechanism behind the chemical process of antipsychotics. These drugs are also prescribed to people with bipolar disorder, autism and major depressive disorder.

In new research scientists, from the University of Texas Southwestern Medical Center identified a cellular receptor in mice which was central to increased weight gain.

They were able to monitor the signals responsible for this receptor, known as serotonin 2c, then block it with a weight loss drug.

Lead author Dr Chen Liu said: “This study suggests that by preventing the interaction between antipsychotic drugs and the serotonin 2c receptor we might be able to eliminate many of the metabolic side effects without interfering with the psychiatric effects. We plan to continue working to understand the mechanisms involved.”

The research team discovered that mice who had taken the antipsychotic drug olanzapine gained body fat. Then they looked at mice that were genetically engineered not to have a serotonin 2c receptor and found they did not put on as much weight.

“Our study directly demonstrates in a mouse model that this interaction with the serotonin 2c receptor is a major cause of olanzapine’s metabolic side effects,” added Liu.

Liu adds this finding is significant because lorcaseri, an FDA-approved weight loss drug, activates the serotonin 2c receptor.

When they tested if lorcaserin treatment could counteract the effects of olanzapine, they found that “co-treating with lorcaserin prevented weight gain and significantly improved the metabolic profile of mice treated with olanzapine”.

The study team will now conduct further research to assess the mechanisms behind lorcaserin and its relationship with the serotonin 2c receptor.

While people on certain schizophrenia and depression medications are at greater risk of putting on weight, it is possible to prevent this. Following a healthy lifestyle will help to reduce the likelihood of weight gain occurring.

The research was published in the Journal of Clinical Investigation.