(HealthDay News) — A new small study is adding evidence to the theory that insulin resistance may play a leading role in some cases of depression. Findings from the study were published in Psychiatry Research.

The study included 37 adults — 29 women and 8 men — recruited at Stanford University in California. The study volunteers were aged 21 tp 75 years and their weight ranged from underweight to severely obese. None had diabetes, but some were insulin-resistant or had prediabetes

All of the study volunteers had depression for longer than a year. Study volunteers received 12 weeks of treatment with pioglitazone or an inactive placebo. Patients were allowed to stay on their current antidepressant treatment as well.

Participants who were insulin-sensitive had improvements in their depression whether they were taking the drug or a placebo. However, those who were insulin-resistant only saw improvement in their depression symptoms if they were taking the insulin-sensitizing drug. 

People who were insulin-resistant who took the placebo did not see improvement. The more insulin-resistant someone was, the better the drug worked on their depression, the researchers noted.

These findings “add to the neurobiological explanation of what’s going on when people are depressed, and it should help de-stigmatize depression. It’s a disease of the brain,” lead author Natalie Rasgon, MD, PhD, a professor of psychiatry and behavioral sciences at the Stanford University School of Medicine, told HealthDay.

One author disclosed financial ties to the pharmaceutical industry.


  1. Lin KW, Wroolie TE, Ronakis T, Rasgon NL. Adjuvant pioglitazone for unremitted depression: Clinical correlates of treatment response. Psychiatry Res. 2015;doi:10.1016/j.psychres.2015.10.013.