Marijuana, schizophrenia link needs further study
DEAR DOCTOR: Could you comment on the marijuana study done in early 2016 at the University of Exeter and University College London? I’m worried about the 14-year-olds with whom I work and their dangers of psychosis. I was hoping we might start a dialogue about the risky business of marijuana.
DEAR READER: One of the big concerns about marijuana use, especially among adolescents and young adults, is the connection to psychotic episodes and lifelong schizophrenia. In people with a family history of schizophrenia, marijuana can increase the risk of such episodes and decrease the age of schizophrenia onset.
The study to which you refer focused on the AKT1 gene, which has been proposed as a possible genetic connection to this response to marijuana. The gene produces the enzyme serine-threonine protein kinase, necessary for many cellular processes throughout the body, including the transmission of dopamine, which carries signals between brain cells. This function is known as dopamine signaling, and proper
signaling is necessary for the brain responses controlling behavior and emotion.
The study looked at 422 people, ages 16 to 23, who used marijuana at least once a month. Participants were given a pair of psychological tests: once without the use of marijuana and once with use. One psychological test was designed to detect psychotic symptoms; the other test was designed to detect dissociative and imaginative states, also called schizotypal symptoms, similar to those seen in schizophrenia.
Overall, the study points to a genetic link between psychotic symptoms and marijuana use, but the link is more complicated than the presence of a specific genotype. The data show something else is occurring to push some people toward schizophrenia; we just don’t know what.
For now, we simply know that a family history of schizophrenia increases the risk among people who use marijuana, making it risky business indeed.