New York, Feb 15 (IANS): Patients who frequently consume opioid medicines or painkillers to manage chronic pain are more likely to experience depression, says a new research.

Previous research had found depression to be linked with patients' opioid use, but this study has identified the association between an increase in opioid use and an increase in depression.

Jeffrey Scherrer, associate professor for family and community medicine at the Saint Louis University in the US, and his colleagues studied questionnaires from 355 patients who reported chronic low back pain initially and at one-year and two-year follow ups.

The patients also reported the number of years they had been suffering from chronic pain.

"Better understanding of temporal relationship between opioids and depression, and the dose of opioids that places patients at risk for depression may inform prescribing, pain management and improve outcomes for patients with chronic, non-cancer pain," Scherrer wrote.

Contributing factors for cases of new-onset depression, according to this study and previous research conducted, may include both the amount of daily morphine exposure and the duration of exposure.

"This would expand intervention targets to limit the risk of depression in patients who need long-term opioid therapy," he added.

The study appeared in the journal Pain.