Are there long-term effects on the brain in marijuana users?

Now that more states are beginning to legalize the sale and consumption of marijuana, it is important to assess its safety, especially in our youth. Of course, there is conflicting data on whether the use of this drug has any potentially harmful effects.

Some studies using imaging studies suggest regular use of marijuana in adolescence is associated with altered connectivity and reduced volume in specific areas of the brain that are involved in memory, learning and impulse control.

Other studies have shown that IQ scores are diminished by 6-8 IQ points when teenagers have a history of heavy marijuana usage. If they quit as adults they do not recover the lost IQ points.

Using marijuana causes an increase in Alpha brain waves. Alpha brain waves are rhythmical and with high amplitude, easily spotted on the raw EEG. Alpha is 9-12 hertz (cycles/second) causing a relaxed, day-dreamy state. Alpha initiates sleep. If Alpha brainwaves are high amplitude, the individual is often in a trance or inattentive state and may have attention difficulties.

Until more definitive data is reported, it seems wise for parents to be informed and to discourage the use of this potent drug in their children and teenagers. The brain continues to develop through adolescence, even up to the age of 25 plus years.

From National Institute on Drug Abuse