Marijuana may up heart attack, stroke risk: study

By Will Dunham

WASHINGTON (Reuters) - Heavy marijuana use can boost blood levels of a particular protein, perhaps raising a person's risk of a heart attack or stroke, U.S. government researchers said on Tuesday.

Dr. Jean Lud Cadet of the National Institute on Drug Abuse, part of the National Institutes of Health, said the findings point to another example of long-term harm from marijuana. But marijuana activists expressed doubt about the findings.

Cadet said a lot of previous research has focused on the effects of marijuana on the brain. His team looked elsewhere in the body, measuring blood protein levels in 18 long-term, heavy marijuana users and 24 other people who did not use the drug.

Levels of a protein called apolipoprotein C-III were found to be 30 percent higher in the marijuana users compared to the others. This protein is involved in the body's metabolism of triglycerides -- a type of fat found in the blood -- and higher levels cause increased levels of triglycerides, Cadet added.

High levels of triglycerides can contribute to hardening of the arteries or thickening of the artery walls, raising the risk of stroke, heart attack and heart disease.

The study did not look at whether the heavy marijuana users actually had heart disease.

"Chronic marijuana use is not only causing people to get high, it's actually causing long-term adverse effects in patients who use too much of the drug," Cadet, whose study is in the journal Molecular Psychiatry, said in a telephone interview. "Chronic marijuana abuse is not so benign."

The marijuana users in the study averaged smoking 78 to 350 marijuana cigarettes per week, based on self-reported drug history, the researchers said.