EFFECTS ON THE BODY AND BRAIN

Alcohol has been associated with cancers of the larynx, esophagus, breast, colon and liver. The greatest risks come with heavy, long-term use, the American Society of Clinical Oncology reported in January. In 2016, about 77,000 Canadians were hospitalized as a direct result of alcohol, compared to about 75,000 for heart attacks, according to the Canadian Institute for Health Information. Alcohol is also blamed for more than 4,000 premature deaths each year.

In February, a study published in The Lancet Public Health Journal based on more than one million adults diagnosed with dementia in France concluded chronic, heavy drinking is a major preventable risk factor for the brain disease. The same month, a study by American researchers who examined the brain scans of more than 1,000 people found long-term alcohol use was associated with a decrease in grey and white matter volume in adults, and lower grey matter volume in adolescents. Pot use isn’t associated with changes in brain structure. The University of Colorado Boulder team didn’t see anything that reached statistical significance. The caveat, of course, is that the absence of evidence doesn’t necessarily mean something doesn’t exist, said co-author Kent Hutchison, a professor of behavioural neuroscience. “But clearly (alcohol) seems to have a more profound effect than cannabis,” he said.

Still, weed isn’t benign. One study of more than 1,000 New Zealanders who started using cannabis in their teens, and kept using it for years, showed an average decline in IQ of eight points between age 13 and 38. People who started using marijuana after adolescence, however, didn’t show notable drops in IQ .

Smoking cannabis alone doesn’t appear to increase the risk for cancers of the lung, head or neck, although there’s modest evidence linking it to one type of testicular cancer.