WEDNESDAY, June 15 (HealthDay News) -- Being depressed doesn't reduce the effectiveness of weight loss surgery, a new study finds.

University of Michigan researchers analyzed data from more than 25,469 patients who had weight loss surgery and found that patients who were depressed or depression-free before the surgery all lost nearly 60 percent of their excess weight within one year. They also reported an average 30 percent improvement in quality of life, including greater mobility, social interactions, family life and independent living.

Patients with depression did have a higher rate of minor complications (4 percent versus 3.3 percent), but there were no significant differences in major complications between the two groups. (The average rate of major complications from weight loss surgery is 4 percent.)

The study also found that the use of antidepressants by patients who had depression decreased by about 20 percent (from 72 percent to 60 percent of patients) one year after weight loss surgery and remained at that level after three years of follow-up.

The study was slated for presentation Wednesday at the annual meeting of the American Society for Metabolic & Bariatric Surgery (ASMBS).

"Depression and anxiety are relatively common among those with chronic diseases like obesity and type 2 diabetes, and these conditions can sometimes interfere with treatment," lead author Dr. Jonathan F. Finks, an assistant professor of surgery at the University of Michigan, said in an ASMBS news release.

"This study suggests bariatric patients suffering from depression can experience health outcomes and quality of life improvements comparable to non-depressed patients. However, doctors and patients still need to consider psychological issues, state of mind and commitment to lifestyle changes after surgery in assessing whether bariatric surgery is appropriate and indicated for any particular patient," he added.

Because this study was presented at a medical meeting, the findings should be viewed as preliminary until they are published in a peer-reviewed journal.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about weight loss surgery.