Vaping cannabis just one time can cause prolonged brain changes, according to the first-ever study of brain impacts of vaping by University of Guelph researchers – a finding that raises further concerns about the practice growing in popularity among youth.

The study revealed that a single exposure to THC can change brain activity in ways that resemble changes seen in schizophrenia, especially in regions involved with cognitive function, even in individuals lacking risk factors for the illness.

It also found that these changes last for up to a week after the exposure.

“Even a single exposure to THC can change brain patterns and function,” said study co-author Prof. Jibran Khokhar, Department of Biomedical Sciences.

The Canadian Press covered the research, with articles appearing in the Toronto Star, the National Post, CBC.ca.

Published this week in the Canadian Journal of Addiction, the study was performed on rats and is the first to investigate the brain effects of vaping THC in animals or humans.

Vaping of cannabis has grown among Canadians and especially among young people.

Nearly 30 per cent of youth in Grade 7 to 12 used cannabis in the previous 12 months, according to a 2019 report from the Canadian Centre on Substance Use and Addiction. Another study found that “vaping” cannabis increased by about 50-60 per cent in high school students between 2017 and 2018.

“Vaping is more common in youth, and these findings definitely apply to youth,” said Khokhar, who worked on the study with Prof. Melissa Perreault, Department of Molecular and Cellular Biology. “Because adolescence is a critical period for brain development in its endocannabinoid system, it is possible that the duration of these effects may be different in that population.”

Cognitive effects of cannabis vary with how it’s ingested, frequency of use, and concentration of THC and the non-psychotic cannabidiol.

Earlier studies have found that cannabis alters activity in brain regions involved in cognitive function and schizophrenia, although it is difficult to assess what causes those changes, said Khokhar.

Those human studies have often used subjects who had formerly consumed cannabis, he added.

Khokhar wanted to learn how vaping THC affects brains without previous exposure, and in animals with no risk factors associated with schizophrenia.

Studying brain electrical activity, he found THC – used even once — affected regions associated with such cognitive functions as decision-making, memory, attention and habit formation.

Those effects lingered for up to a week and resembled changes seen by researchers in brains of people with schizophrenia and people given intravenous THC.

He said vaping’s brain impact is similar to that of smoking cannabis but different from that of ingesting the drug.

Scientists have also found memory impairment and psychosis-like symptoms after vapourized cannabis exposure in seasoned cannabis users.

Any novice user vaping cannabis or THC should exercise caution in experimenting with vaping or consuming cannabis in various ways, said Khokhar.

“If we want to reduce harm from cannabis, the really high THC forms should probably be avoided or not available.”