Researchers at the University of Colorado-Boulder looked at more than 850 adults and 430 teenagers to find that alcohol, but not marijuana, led to lower brain volumes of grey and white brain tissue.
Grey matter controls brain function and white matter controls communication between the nerves in the brain.
Any reduction in volume could lead to lead to impaired function but that decreased volume was not observed in participants who only consumed the drug.
“While marijuana may also have some negative consequences, it definitely is nowhere near the negative consequences of alcohol,” study co-author Kent Hutchison told Medical News Today.
However, study author Rachel Thayer warned that there is still a lot scientists do not know about how marijuana affects the human brain as opposed to numerous studies showing the same results about brain health and consuming alcohol.
The researchers also made note that studies published on how the brain and marijuana interact have contradicted each other often.
“When you look at these studies going back years, you see that one study will report that marijuana use is related to a reduction in the volume of the hippocampus [a region of the brain associated with memory and emotions]...The next study then comes around, and they say that marijuana use is related to changes in the cerebellum or the whatever,” Mr Hutchinson said.
Another recent study showed that cannabis use coupled with alcohol consumption could lead to a lower risk of liver disease.
Cannabis as also been used to treat cancer patients undergoing chemotherapy, epilepsy, and migraines as well.
In the US, Colorado, Washington State, Oregon, California, and Alaska have legalised its use for medical or recreational use and have placed tight controls on production and sale.