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Cannabis Less Damaging to Brain than Alcohol

With legalization of recreational use on the horizon in Canada, there has been an increased interest in studies on the effects of cannabis, and a new report suggests that alcohol is far more damaging when it comes to brain health.

Scientists at the University of Colorado Boulder compiled existing images and data that looked at the effects of marijuana, and compared them to those of alcohol. Their findings linked the consumption of alcohol with changes to the physical structure of grey and white matter over a long-term period. However, the use of cannabis appeared to show no significant far-reaching effects in the same areas of the brain.

Rachel Thayer, of the Department of Psychology and Neuroscience at the University of Colorado Boulder, who led the study, reported the results in Addiction, the journal of the Society for the Study of Addiction (SSA).

Research Fills a Knowledge Gap

For the study, Thayer and her colleagues set out to learn more about how cannabis physically affects the brain. Co-author Kent Hutchson, of the Department of Psychology and Neuroscience, found that other investigations have delivered mixed results. He explains, “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. The next study then comes around, and they say that marijuana use is related to changes in the cerebellum.” He notes that there is no consistency across any findings related to the brain’s structure.

With the intent of filling this knowledge gap, the researchers carried out a fresh analysis on the image data. It was important to distinguish between the different structures of the brain. Grey matter comprises the tissue on the surface of the brain, and is primarily nerve cell bodies, but white matter resides deeper in its structure and contains myelinated nerve fibres. These are part of nerve cells and send electrical pulses to other tissues and cells.

The report noted that a reduction in size of white or grey matter, or even a loss in their structural integrity could be a cause of functional impairment. Hutchison added, “With alcohol, we’ve known it’s been bad for the brain for decades, but for cannabis, we know so little.”

The Findings

The brain images of 439 teenagers aged between 14 and 18, along with 853 adults aged between 18 and 55 were used in the study. All those taking part had a varied use of alcohol and marijuana.

It was found that alcohol was closely associated in a reduction of the amount of grey matter and structural impairment in white matter. However, marijuana appeared to have no affect on the structure of both types of brain matter in either teenagers or adults.

Based on these findings, the team concluded that cannabis was significantly less likely to be harmful to the brain than alcohol.

How Many Canadians use Cannabis?

These findings are an important piece of the puzzle that is mapping the effects cannabis has on the body, and have come at a time of ever-increasing scrutiny of the impact it could have on the health of the public. The latest figures compiled and published by Statistics Canada show that five million Canadians had used cannabis in 2015. This was an overall increase, and shows a demographic shift in usage rates. Less than 6% were in the 15 – 17 age range, while two-thirds of consumers were aged 25 or older. In fact the number of minors consuming the substance was the lowest for decades, with 22% using in 1980 and 12% in 2000.

With increased usage anticipated, researchers have been devoting more time and effort in a quest to discover the benefits and detriments associated with it, but much evidence is contradictory.

For example, 2017 saw a study, carried out by Georgia State University in Atlanta, which concluded that it is “worse than cigarettes” for cardiovascular well-being, while the National Academies of Sciences, Engineering and Medicine found evidence that cannabis was not connected to the lung, head, and neck cancers associated with smoking tobacco.

When it came to the possible benefits of marijuana use, Thayer’s team noted that the jury is still out and that much more research is needed to draw definite conclusions.