Recreational marijuana use proven safe to brain, study finds

 

You can now smoke pot without fear of damaging your brain, a new study finds. New research published in the journal JAMA Psychiatry studied the brain patterns between siblings and twins ages 22 to 35, reports Time.

Two recent studies documenting the effects of cannabis use on the brain did not do much for the many questions that remain about the safety and long-term implications of using marijuana. Similarly, today’s JAMA study “casts considerable doubt on hypotheses that cannabis use … causes reductions in amygdala volumes”.


“That means there could be widespread elements, genetic and environmental, that predispose us to utilizing marijuana that additionally contribute to variations in our mind volumes”, Agrawal advised Reside Science.

Cortical thickness indicates “how “bushy” the cells are, how many branches they have, how good they might be at processing information”, said senior author Dr. Tomas Paus of the Rotman Research Institute in Toronto. “If you know these disorders run in your family, then I would be super, super careful”. Both studies were published online August 26 in JAMA Psychiatry.

But the problem plaguing all of these studies is that people who smoke marijuana are different from those who don’t in lots of ways, and untangling cause and effect can be incredibly tricky, the researchers said. Cannabis users were found to have smaller amygdalas than nonusers, a result that agreed with earlier findings, Agrawal told HealthDay.

In some pairs, only one sibling had smoked marijuana; in others, both had smoked pot; and in some, neither sibling had used cannabis.

In the case of the amygdala, the researchers write that the smaller brain region may be explained by genetic factors – their analysis didn’t show a significant contribution from environment. For example, childhood exposure to adversity can affect amygdala size, and also can make a person more likely to try drugs.

The authors relied on interview, behavioral and neuroimaging data. While both high-and low-risk females and low-risk males had no changes in their cortical thickness upon marijuana use, high-risk males responded differently.

To get a better picture of the effects of marijuana on the teenage brain, Arpana Agrawal, a geneticist at Washington University in St. Louis, and her colleagues looked at magnetic resonance imaging (MRI) studies of the brains of 241 pairs of same-sex siblings, including some who were twins. Thus, males who are at a high risk for schizophrenia show changes in their brain when they use marijuana. Some experts have expressed concerns that the drug could alter the structure of a user’s brain, but the new research suggests this may not be strictly true. In addition, the male hormone testosterone influences changes in the cortex, and may interact in some way with substances in marijuana.

Goldman, who wrote an editorial accompanying the new studies, added in his email, “What this new research shows is that it is also unsafe to make assumptions about causality from correlation”.

Study participants who’d used pot had on average, a slightly smaller amygdala and a slightly smaller right ventral striatum (another brain region, associated with the reward system). Others worry that making marijuana legal for recreational or medicinal purposes will convey the message that the drug is generally safe when actually it may be risky.

“We do not know almost enough about effects of cannabis on the brain, especially the developing brain”, said Dr David Goldman of the National Institute on Alcohol Abuse and Alcoholism in Rockville, Maryland, in email to Reuters Health.

Accordingly, the conclusion is that marijuana use continues to fluctuate throughout the United States, which may or may not be related to similar fluctuations in psychiatric illness.