Washington, August 25 : That a mood disorder increases an individual''s risk for substance abuse has been long established, but new evidence has shown that the opposite may be true.

A new study has found that repeated cocaine use increases the severity of depressive-like responses in a mouse model of depression and identified a mechanism that underlies this cocaine-induced vulnerability.

Researchers hope that their study may guide development of new treatments for mood disorders associated with substance abuse.

"Clinical evidence shows that substance abuse can increase an individual''s risk for a mood disorder," explains senior study author, Dr. Eric Nestler from Mount Sinai School of Medicine

"However, although this is presumably mediated by drug-induced neural adaptations that alter subsequent responses to stress, the mechanisms underlying this phenomenon were largely unexplored."

The researchers found that cocaine increases the susceptibility of mice to stress in a well-established model of depression.

"Together, our results provide fundamentally novel insight into how prior exposure to a drug of abuse enhances vulnerability to depression and other stress-related disorders," concludes Dr. Nestler. "Identifying such common regulatory mechanisms may aid in the development of new therapies for addiction and depression."

The study was recently published in the journal Neuron. (ANI)