Research done at McGill University and published in the Journal of Neuroscience showed that THC, the active ingredient found in marijuana, has a double effect.
In fact, consuming even a small amount of marijuana can have the same effects as an anti-depressant, while larger doses could cause mental health difficulties such as depression.
Depression is caused by a decrease in the neurotransmitter seratonin in the brain. Dr. Gabriella Gobbi showed that small doses of THC increased the seratonin, like anti-depressant medication such as Prozac or Celexa.
However, after a certain point, the positive effects start to reverse and produce the opposite symptoms. Consumers could become depressed and apathetic.