Gabriel Klein's tale hints at dark truth of chronic pot use on 'susceptible' young brains, doctor says

Gabriel Klein's friends say he was smoking pot every day for the past three months.

Then one day the 21-year-old changed.

A few weeks later — on Nov. 1 —  he was accused of walking into a high school and stabbing Letisha Reimer, 13, and another teen.

Klein was admitted to hospital after his arrest, certified under the Mental Health Act by one doctor and then decertified by a psychiatrist the next day, the prosecutor said.

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Details about exactly what drugs Klein was using and his mental state are still emerging, but for Dr. Bill MacEwan the facts, so far, hint at the darker reality of heavy drug use for a certain percentage of chronic young pot smokers.

While the assistant director of UBC's department of psychiatry stresses that the percentage is tiny, he and others who study the link between pot and psychosis say it should be part of the conversation.

Marijuana — framed of late as medicinal, mainstream and benign — is in common use amongst Canadian youth, who have the highest rate of pot use in the developed world for those aged 15 to 24, according to the Canadian Centre on Substance Abuse.

And while most smokers who start using while their brain is developing risk impaired learning and motor skills, a tiny percentage of people who smoke pot — one to three per cent — will also experience psychosis.

Dr. MacEwan says the ratio approaches 30 to 40 per cent in a sub-set of young chronic pot smokers who have other risk factors.

It's worse if the person is homeless, stressed and using a cocktail of chemicals daily.

For them, MacEwan says, it's like playing Russian roulette with their brain.

A youth who is smoking excessive amounts, unsure what they are smoking and using marijuana to cope with stress, are at highest risk, MacEwan said.

"Psychosis in a drug-induced state is really quite common, particularly amongst vulnerable youth such as this young man.They will often have to use drugs, particularly drugs like cocaine and methamphetamine, to stay awake at night. They will often used drugs to cope with stress and those that are under really difficult situations like being homeless ... then the drugs will affect you worse."

In addition schizophrenia, unlike other mental illnesses, emerges in young adulthood — usually in the early 20s for men and later for women, and it's believed pot speeds the progression.

"Emerging evidence supports a number of associations between cannabis and psychosis/psychotic disorders, including schizophrenia," according to a 2014 review of the association between cannabis and psychosis led by Dr. Rajiv Radhakrishnan from Yale's School of Medicine.

A debate rages with many scientists saying abolishing pot would not prevent schizophrenia, and marijuana advocates deeming this a "scare tactic," claiming pot actually helps soothe anxiety and calm mental disorders.

But medical experts contend it is clear that for some smokers who start young,  heavy drug-use can precipitate psychosis,

For the lucky, it's temporary. For others, it's the first bout of a life-long struggle with schizophrenia.

"In some brains, we don't understand exactly why, we think maybe genetics or maybe trauma in the past, that these brains are then really susceptible to having the effects of drugs make them lose touch with reality," said MacEwan.

"The link between marijuana and particularly psychosis is significant." 

Some medical experts urge pot-avoidance under age 20, in case their brain has hidden vulnerabilities that will only emerge with drug use.

"Not every 14-year-old who smokes marijuana will have schizophrenia," said Dr. Romina Mizrahi, a director of the Youth Psychosis Prevention clinic at the Centre for Addiction and Mental Health in Toronto.

She explains a myriad of factors — from genetics to trauma history — determine the risk to an individual. 

Variables from marijuana strength, user frequency to how young they are when they start, all play a part. 

"If you smoke a lot of marijuana when you are young or in your teens, your chance of having psychosis later on in life is about eight times higher than other people," MacEwan said research has shown.

He suddenly changed

Klein's friends describe him as a genial "stoner."

He had no fixed address but lived at Covenant House, followed the rules and worked hard in school.

Then one night he "smoked a bowl" and told his friend Nathaniel Spidell the pot was spiked with acid or something stronger.

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Spidell said his friend became fearful and paranoid.

"Everything went downhill after that. He wasn't the same person," said the 23-year-old.

From the outside, people see a person withdraw in a "fearful, angry, irritable way," said MacEwan.

"That young man's friends saying, 'oh he isn't the way he used to be' — is typical."

And that makes it worse, because the person can't relate to people who could help them.

While violence isn't the norm, it can be a result of untreated psychosis.

Klein's friends say they do not recognize the man they see in the video as Klein.

He is nothing like the friend they knew, but that's exactly what psychosis looks like. 

A stranger — perhaps even in the mirror.