Halting Marijuana Use Might Improve Memory
Researcher Amanda Roten reported at the 2014 meeting of the American Academy of Child and Adolescent Psychiatry that adolescents who stopped heavy marijuana use showed improvements in multiple areas of learning and memory. These data support previous findings that pot can cause impairments in cognitive functioning, but that abstaining from the drug can bring about improvement relative quickly.
These data contrast with some others. A 2009 study by J. Jacobus et al. in the journal Pharmacology Biochemistry and Behavior suggested that some changes in brain structure resulting from marijuana use, such as decreases in cortical volume, can persist for one to three months following abstinence.
Madeline Meier, another researcher at the meeting, reported that 1,037 participants who used marijuana persistently from about age 13 to age 38 lost an average of 8 IQ points. Controlling for years of education and other potential confounds such as alcohol and drug use did not affect these findings. Moreover, Meier found that “cessation of cannabis use did not fully restore IQ among adolescent-onset cannabis users.”
Editor’s Note: The popular view that marijuana is a benign substance overlooks some key facts. The main pharmacological effect of pot is an amotivational syndrome, causing apathy and lack of drive to participate in work, study, and other activities. Heavy use of pot doubles the risk of psychosis, and this risk is further increased if a user has a common genetic variation in the enzyme catechol-o-methlyl transferase (COMT), which metabolizes dopamine. The more efficient allele of COMT (known as val-56-val, identifying two valine amino acids) lowers frontal cortex dopamine more, and increases the risk of delusions and hallucinations. Marijuana alters brain structure and impairs memory. It may now be legal in some states, and while reducing penalties for smoking marijuana may be a good idea, this does not mean the drug is a harmless substance.
The moral of the story is that avoiding marijuana use in the first place, especially for people with bipolar disorder, should make it easier to get well and stay well. For current marijuana users, N-acetylcysteine (NAC, a nutritional supplement available without a prescription from health food stores) has been shown to help adolescents decrease marijuana use more than placebo.
