Science Daily - In a new study, scientists in London, Ontario have discovered that early marijuana use may result in abnormal brain function and lower IQ.
Marijuana is the most commonly used illegal substance in the world. Previous studies have suggested that frequent marijuana users, especially those who begin at a young age, are at a higher risk for cognitive dysfunction and psychiatric illness, including depression, bipolar disorder and schizophrenia.
Dr. Elizabeth Osuch, a Scientist at Lawson Health Research Institute and the Dr. Joseph Rea Chair in Mood Disorders at the Schulich School of Medicine & Dentistry at Western University, is a Canadian leader in studying both mood and anxiety disorders and the effects of marijuana.
Participants underwent psychiatric, cognitive and IQ testing as well as brain scanning. The study found no evidence that marijuana use improved depressive symptoms; there was no difference in psychiatric symptoms between those with depression who used marijuana and those with depression who did not use marijuana.
In addition, results showed differences in brain function among the four groups in areas of the brain that relate to reward-processing and motor control. The use of marijuana did not correct the brain function deficits of depression, and in some regions made them worse.
Of additional interest, those participants who used marijuana from a young age had highly abnormal brain function in areas related to visuo-spatial processing, memory, self-referential activity and reward processing. The study found that early marijuana use was also associated with lower IQ scores.