According to a new study published in the October 24 issue of The Journal of Neuroscience indicates that while a synthetic form of THC, the active ingredient in cannabis, is an effective anti-depressant at low doses, at higher doses, the effect reverses itself and can actually worsen depression and other psychiatric conditions like psychosis.

"Low doses had a potent anti-depressant effect, but when we increased the dose, the serotonin in the rats' brains actually dropped below the level of those in the control group. So we actually demonstrated a double effect: At low doses it increases serotonin, but at higher doses the effect is devastating, completely reversed."

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. They interact with the brain through structures called cannabinoid CB1 receptors. This study demonstrates for the first time that these receptors have a direct effect on the cells producing serotonin, which is a neurotransmitter that regulates the mood.

Because of the high risk posed by the use of cannabis in treating depression, the researchers are now focusing their research on a new class of drugs which enhance the effects of the brain's natural endo-cannabinoids.

Source: McGill
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