A new study has found that a synthetic form of THC, the active ingredient in cannabis, is an effective anti-depressant at low doses.

However, at higher doses, the effect reverses itself and can actually worsen depression and other psychiatric conditions like psychosis.

The study is published in The Journal of Neuroscience.

Scientists have been known for many years that depletion of the brain neurotransmitter serotonin, leads to depression.

The anti-depressant and intoxicating effects of cannabis are due to its chemical similarity to natural substances in the brain known as “endo-cannabinoids,” which are released under conditions of high stress or pain, explained Dr. Gobbi.

“We know that it’s entirely possible to produce drugs which will enhance endo-cannabinoids for the treatment of pain, depression and anxiety,” she said.