Photo of marijuana plantSeveral states have legalized medical and recreational marijuana use despite lack of research on what sort of impact the drug may have on users’ health.

Colorado and Washington State both began permitting the sale and use of marijuana for recreational purposes at the beginning of the year. New York, Pennsylvania, Ohio, Florida, Minnesota, West Virginia, Tennessee, Kentucky and Missouri have  all considered legislation to legalize marijuana in recent months.  And earlier this year in his State of the State address, New York Governor Andrew Cuomo outlined  a proposal to launch a medical marijuana program that would allow 20 hospitals in New York State to provide medical marijuana to chronically ill patients.

Meanwhile, another 20 states and the District of Columbia currently allow limited use of medical marijuana.

Despite the ability to legally use marijuana in some places and in some situations, there are still many unanswered questions about how the drug may affect your heart or brain. At this point there are unknown consequences, according to Ralph Sacco, M.D., M.S., a past president of the American Heart Association and Chairman of Neurology at the University of Miami Miller School of Medicine.

Marijuana is one of the top three recreational drugs after alcohol and tobacco, with an estimated 200 million users worldwide. Sometimes referred to as grass, pot, weed, and cannabis, marijuana has proven to help reduce pain from cancer and treat seizures caused by epilepsy, although the U.S. Food and Drug Administration does not approve of marijuana to treat medical conditions.

One study from New Zealand presented at the 2013 American Stroke Association’s International Stroke Conference found that marijuana use actually doubled the risk of stroke among young people. The results were based on participants’ urine samples, which also showed traces of tobacco use. That, says Dr. Sacco, is a big problem in studying any potential health consequences of marijuana.

“Marijuana users may also use other drugs, such as tobacco or cocaine, that we know increase the risk for heart attack and stroke,” says Dr. Sacco. “We can’t tease out what marijuana does to the heart and blood vessels versus other drugs the person may use. We just don’t know enough.”

Given the shortage of scientific evidence, Dr.Sacco says there are some reasons to be cautious about marijuana use. Marijuana use may be linked to a couch potato lifestyle of inadequate physical activity, eating unhealthy foods or drinking too much alcohol, he says. Obesity, a top risk factor for heart disease and stroke, is currently a major public health threat with nearly 155 million Americans age 20 and older either overweight or obese. Physical inactivity and a poor diet contribute to obesity and increase the chances of high blood pressure, high cholesterol, heart attack and stroke.

“We also know that marijuana use can temporarily raise blood pressure or contribute to an irregular heartbeat, which can be problems for anyone who has a known cardiac condition or perhaps has undiagnosed high blood pressure especially  since hypertension is often a silent condition,” says Dr. Sacco.

So far, researchers have only looked at the effects of smoking marijuana, not ingesting it with food.

“That’s another reason to be cautious,” says Dr. Sacco. “Marijuana is typically smoked in small amounts but if it’s baked into brownies, which is a popular  choice, there’s a greater risk of overdosing or eating too much. We have a lot of questions and we need more research.”

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