Which is worse? Alcohol or marijuana?

It’s a modern-day question that, honestly, can’t be answered. There’s plenty of research about alcohol’s long-term effect on your brain and overall health. The amount of research regarding marijuana’s long-term effect on brain health, however, is not so ample.

Kent Hutchison, a professor of behavioral neuroscience at the University of Colorado Boulder and co-director of the CU Change Lab, co-authored a study that serves as a conversation starter for which substance is worse. In the study, published in the journal Addiction, researchers looked at brain scans of 853 adults between the ages of 18 and 55 and 439 teenagers between the ages of 14 and 18. Each of the participants reported their alcohol and marijuana use.

The scans revealed that the drinkers’ brains had reduced gray matter and compromised white matter. Gray matter contains the majority of neuron cell bodies and axons and is responsible for helping the brain process information. White matter lies beneath the gray matter. It contains nerve fibers that help neuron cells communicate across different brain regions.

The pot smokers’ brains did not show a reduction or change in either gray or white matter in Hutchison’s study. When gray and white brain matter is reduced, cognitive impairment and memory loss can occur.

But experts are cautious to declare that marijuana is not harmful to the brain based on the evidence of this study.

“Absence of evidence is not the evidence of absence,” said Dr. Christian Hopfer, professor of psychiatry in the Division of Substance Dependence at the University of Colorado School of Medicine and an attending psychiatrist at UCHealth’s CeDAR. “The cannabis story is less clear, and I don’t know if it’s even fair to compare the two substances in the way the media headlines [have done about this study].”

Some of the headlines of articles covering this study included, “Cannabis safer for the brain than booze,” “Weed won’t cause brain damage the way alcohol will, study finds,” and “Cannabinoids are easier on the brain than booze, study finds.”

Voters legalize recreational marijuana

Since 2012 when voters in Colorado and Washington legalized recreational marijuana, and subsequently seven other states followed, science has been trying to catch up to the law. Years of studies on excessive alcohol use demonstrates its negative effects on brain and general health.

With marijuana, the studies on its effects on brain health are limited and, also, the findings are across the board. Hutchison said that this variety of outcomes with previous studies led him and his team to investigate marijuana’s impacts on brain health and function.

“The problem with these studies on marijuana use is that one will show that cannabis use is related to smaller brain volume matter in the hippocampus, and another will come along and report that cannabis doesn’t affect the hippocampus but it does affect the cerebellum,” Hutchison said. “When you combine all those studies, you see they’re all over the map, which makes them appear spurious.”

Hutchison’s study, he said, was different than other studies in the fact that he looked at gray and white matter across all regions of the brain, and also compared the two vices.

Some people may find the outcomes of his study surprising since pot has long been associated with decreased brain functioning based on stoner characters in the media (remember Jeff Spicoli?) and general associations of being stoned and giggly and goofy.

More research needed

Martin Maxwell, a social worker and program coordinator for the Adult Behavioral Health Intensive Outpatient program at UCHealth Mountain Crest Behavioral Health – Fort Collins, points out that just because marijuana appears not to have an effect on gray and white matter in the brain does not mean it does not affect the brain.

“I think the headlines regarding this study may lead people to think that marijuana use does not pose a risk. The study is only saying that decreasing the integrity or volume of white and gray matter may not be one of the ways that marijuana affects one’s health,” Maxwell said.

In his clinical experience, Maxwell said, smoking pot can exacerbate existing anxiety and depression, as well as psychotic conditions. Studies have found a connection between increased psychotic episodes and regular pot use.

While Maxwell points out that pot does not appear to shrink the brain but may affect the brain in other ways, Hopfer notes that brain size isn’t always associated with cognitive function.

“Women have smaller brains but are thought to be equally as intelligent as men. Autism is associated with having a bigger brain. As people age their brain shrinks but it’s not always associated with major cognitive impairment,” Hopfer said.

Study a good start

Both Maxwell and Hopfer agree that Hutchison’s study was a quality study and a good start, but they’d like to see more research related to the long-term effects of marijuana use. Hopfer would like to see a standardized way of assessing marijuana use with regards to frequency and quantity. “You need long-term studies that image the brain where you follow people over the years and look with each person how their brain changes in response to their use pattern.”

Maxwell thinks we need to learn more about how marijuana affects people not just physiologically but also mentally and spiritually. He also points out that since the legalization of marijuana, there has been increased hospitalizations in psychiatric and inpatient hospital settings.

There is no disagreement among experts, and most likely the population at large, about the need for more studies on the effects of marijuana use on our bodies and brains as more states vote to legalize it.

Next up for Hutchison and his team is a state-funded study on the short-term effects of concentrate, which is a highly potent marijuana product available at most dispensaries. “[Concentrates] is one of the products that’s increasing the fastest in terms of sales, and we need to understand the effects of people using these more potent products.”