Researchers at the University of California speculate that THC and other cannabinoids may be useful in the treatment of schizophrenia.
Some forms of schizophrenia are believed to be caused by a hyperactive dopamine system, and dopamine is regulated by anandamide, a chemical similar to THC but produced naturally in the body. Analysis of the cerebro-spinal fluid extracted from schizophrenics in Germany found levels of anadamide twice as high as a normal person's.

Daniele Piomelli, who heads the research team, speculates that the higher anadamide levels are "the brain's response to bring this dopamine activity down, but the brain cannot keep the amount of anandamide high enough." This might explain why schizophrenics use marijuana at higher rates than the general population.

THC and anandamide both bind to the brain cannabinoid receptor CB1, which is mostly found in regions of the human brain that have been implicated in schizophrenia, including prefrontal cortex, basal ganglia and hippocampus.