Heavy Burden: Weight Gain, Genetics, and Antipsychotics
Antipsychotic drugs can be a godsend, relieving some of the worst symptoms of mental disorders. Second generation antipsychotics in particular have shown success in restoring normalcy to schizophrenics and bipolar patients. However, psychiatric drugs are also notorious for a high incidence of adverse drug events. Patients often find the side effects too severe and will abandon treatment regimens. Sometimes the effects are dangerous, like increased suicidal tendencies, but even the relatively minor ones can be difficult to manage.
Now scientists have identified a possible genetic cause for one particularly problematic side effect, weight gain. The researchers studied and genotyped four cohorts of psychiatric patients from the US and Europe, seeking possible single-nucleotide polymorphisms. They hoped to explain why some, but not all, patients get heavier on medications like aripiprazole, quetiapine, risperidone, or olanzapine.
The scientists found that mutations near the MC4R gene may be responsible. Twenty different mutations were identified as signficantly correlated with weight gain. These mutations were all recessive, meaning that patients needed two mutant copies to be affected, but those who were affected showed an average of six kilograms (nearly 15 pounds) more weight gain than the other genotypes. This gene region was previously known to be correlated with obesity in the general population, now scientists believe that it may prove useful in preventing adverse drug events in psychiatric patients a priori.
High body weight is correlated with an increased risk for heart disease and type II diabetes.