"Strong evidence links marijuana use to risk of developing schizophrenia and other causes of psychosis, with the highest risk among the most frequent users"

I don't know why the headline and lede in the following Daily Mail report state that marijuana use also triggers heart attacks because the claim requires clarification. It's stated in the body of the report:

There's weak evidence that suggests smoking marijuana can trigger a heart attack, especially for people at high risk of heart disease. But there's no evidence either way on whether chronic use affects a person's risk of a heart attack.

In any case the biggest news from the study is the claim of a link between marijuana use and the risk of developing serious mental disorders.     

I haven't read the scientific report but if it's citing research that demonstrates marijuana use can actually cause schizophrenia, as distinct from exacerbating a latent condition, this would be a dynamite finding -- although even the latter discovery would be serious. 

(Lobbies for the pot industry have surely sprung into action to challenge the research.)     

Marijuana DOES cause schizophrenia and triggers heart attacks, experts say in landmark study that slams most of the drug's medical benefits as unproven

By Mia De Graaf For Dailymail.com and Associated Press

PUBLISHED: 14:47 EST, 12 January 2017 

UPDATED: 19:09 EST, 12 January 2017
Daily Mail

Marijuana does raise the risk of getting schizophrenia and triggers heart attacks, according to the most significant study on the drug's effects to date.

A federal advisory panel admitted cannabis can almost certainly ease chronic pain, and might help some people sleep.

But it dismisses most of the drug's other supposedly 'medical benefits' as unproven.

Crucially, the researchers concluded there is not enough research to say whether marijuana effectively treats epilepsy - one of the most widely-recognized reasons for cannabis prescriptions.

The report also casts doubt on using cannabis to treat cancers, irritable bowel syndrome, or certain symptoms of Parkinson's disease, or helping people beat addictions.

The experts called for a national effort to learn more about marijuana and its chemical cousins, including similarly acting compounds called cannabinoids.

In fact, the current lack of scientific information 'poses a public health risk,' said the report, released by the National Academies of Sciences, Engineering and Medicine.

Patients, health care professionals and policy makers need more evidence to make sound decisions, it said.

Several factors have limited research. While the federal government has approved some medicines containing ingredients found in marijuana, it still classifies marijuana as illegal and imposes restrictions on research. So scientists have to jump through bureaucratic hoops that some find daunting, the report said.

A federal focus on paying for studies of potential harms has also impeded research into possible health benefits, the report said. The range of marijuana products available for study has also been restricted, although the government is expanding the number of approved suppliers.

Twenty-eight states and the District of Columbia have legalized marijuana for a variety of medical uses, and eight of those states plus the district have also legalized it for recreational use.

The report lists nearly 100 conclusions about marijuana and its similarly acting chemical cousins, drawing on studies published since 1999.

It found strong evidence, for example, that marijuana can treat chronic pain in adults and that similar compounds ease nausea from chemotherapy, with varying degrees of evidence for treating muscle stiffness and spasms in multiple sclerosis.

Limited evidence says marijuana or the other compounds can boost appetite in people with HIV or AIDS, and ease symptoms of post-traumatic stress disorder, the report concluded.

There may be more evidence soon: a study in Colorado is investigating the use of marijuana to treat PTSD.

Turning to potential harms, the committee concluded:

Strong evidence links marijuana use to the risk of developing schizophrenia and other causes of psychosis, with the highest risk among the most frequent users.

Some evidence suggests a small increased risk for developing depressive disorders, but there's no evidence either way on whether it affects the course or symptoms of such disorders, or the risk of developing post-traumatic stress disorder.

There's strong evidence that using marijuana increases the risk of a traffic accident, but no clear indication that it promotes workplace accidents or injuries, or death from a marijuana overdose.

There's only weak evidence for the idea that it hurts school achievement, raises unemployment rates or harms social functioning.

For pregnant women who smoke pot, there's strong evidence of reduced birth weight but only weak evidence of any effect on pregnancy complications for the mother, or an infant's need for admission to intensive care. There's not enough evidence to show whether it affects the child later, like sudden infant death syndrome or substance use.

Some evidence suggests there's no link to lung cancer in marijuana smokers. But there's no evidence, or insufficient evidence, to support or rebut any link to developing cancers of the prostate, cervix, bladder, or esophagus.

Substantial evidence links pot smoking to worse respiratory symptoms and more frequent episodes of chronic bronchitis. [emphasis mine]

There's weak evidence that suggests smoking marijuana can trigger a heart attack, especially for people at high risk of heart disease. But there's no evidence either way on whether chronic use affects a person's risk of a heart attack.

Some evidence suggests a link between using marijuana and developing a dependence on or abuse of other substances, including alcohol, tobacco and illicit drugs.

[END REPORT]

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