"THC is the main active ingredient in marijuana because it affects the brain by binding to and activating specific receptors, known as cannabinoid receptors. "These receptors control memory, thought, concentration, time and depth, and coordinated movement. THC also affects the production, release or re-uptake (a regulating mechanism) of various neurotransmitters."(2) Neurotransmitters are chemical messenger molecules that carry signals between neurons. Some of these affects are personality disturbances, depression and chronic anxiety. Psychiatrists who treat schizophrenic patient advice them to not use this drug because marijuana can trigger severe mental disturbances and cause a relapse"