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Marijuana's health effects need more study, say experts

Twenty states and Washington D.C. allow medical marijuana, but is legislation ahead of the science?
Health effects of marijuana use remain unclear 05:56

Marijuana use rates have risen by 30 percent from 2006 to 2010, according to a new study from the White House Office of National Drug Control Policy and the RAND Drug Policy Research Center.

During this time frame, cocaine use fell by about half while heroin remained fairly stable throughout the decade. The surge in marijuana use may be related to an increase in the number of people who use the drug daily or on a near-daily basis, the researchers said, adding that in the past decade, Americans have spent over $100 billion on illegal drugs.

"Charlotte's Web" strain of marijuana offers hope for children with seizures 01:35
The study tracked usage before Colorado and Washington legalized marijuana, but other recent drug surveys have reported rises in marijuana use. Also in recent years, medical marijuana use -- and acceptance within the medical community -- has also gained steam. Twenty states and the District of Columbia now allow medical marijuana in some capacity, with more states mulling legislation.

Children with severe seizure disorders keep flocking to Colorado to find "Charlotte's Web," a strain of marijuana in an oil elixir form that may treat them because they are desperate and out of options. But as CBS News chief medical correspondent Dr. Jon LaPook points out, a great deal remains unknown about the drug's health effects.

Teens more likely to smoke legalized marijuana 05:01
LaPook sat down with Dr. Stephen Ross, director of addiction psychiatry at NYU Langone Medical Center in New York, to discuss what the science actually says about marijuana. (See their earlier discussion of a study that found legalization may lead to more teens smoking pot.)

According to Ross, solid research is hard to come by because marijuana is still tightly restricted by the federal government; it is classified as a Schedule I narcotic, meaning it has no medical value and has high potential for abuse. That is the same category as drugs like heroin, LSD and PCP.

"That's been the hard part -- in terms of studying the plant, and getting permission to study it for therapeutic benefit," said Ross.

What is known is that marijuana has many effects on health, but not all of them are therapeutic.

Marijuana contains more than 100 compounds called cannabinoids, which bind to receptors located throughout the body. Through this mechanism, marijuana increases heart rate and blood pressure when it hits the heart, which may be problematic for some with preexisting conditions, and dilates or relaxes the blood vessels. Many of these receptors and found in different parts of the brain, affecting areas for pleasure and cognition, but also raising risk for addiction because of a flood of the neurotransmitter dopamine, which is linked to pleasure.

Much of the research has only focused on two cannabinoids, THC and CBD, so it's unknown what health effects the others have on the body. Ross pointed out THC has been linked to anxiety, psychosis in people predisposed to schizophrenia, and addiction.

THC has been available in pill form, under the name Marinol, to help increase appetite and weight gain in people experiencing nausea from chemotherapy or HIV treatments.

CBD, on the other hand, has anti-anxiety and anti-psychotic effects, and is the primary strain in the Charlotte's Web marijuana, which may also have some anti-seizure properties.

The American Epilepsy Foundation recently called for a review of pot's Schedule I drug status to allow more research into the drug's effect on seizures, given parents growing acceptance to seek the drug for their children.

Other conditions it's been shown to affect are the eye disease glaucoma, some anti-inflammatory conditions, and pain -- which it has been used to treat for thousands of years, dating back to ancient China and India, said Ross.

But when it comes to today's medical marijuana and the absence of stringent testing, it's not known how much concentration of each component is in the drug, and the effects depend heavily on that and a person's state of mind, said Ross.

Also unclear are any effects of secondhand smoke, a potential concern in light of increasing use. While secondhand smoke has documented risks for tobacco use, there isn't research on second-hand marijuana's effects, said Ross.

Medical marijuana: What does science say? 05:44
Dr. Meg Haney, director of the Marijuana Research Laboratory at Columbia University in New York, added to in an email that smoked marijuana is a respiratory irritant "so it is not difficult to imagine it would not be similar to cigarettes in that sense." But, she pointed out research has not linked marijuana to increased lung cancer risk, unlike tobacco.

The bottom line? More research on pot is needed.

Marijuana is the only "medicine" that has ever been approved by a vote, Ross pointed out, despite lacking hard science proving it beneficial.

"Just like that, no research, nothing, just (based on) what people think," he said.

For seizures, doctors recently called on the federal government to loosen its restrictions on marijuana

Said LaPook, "We have medical marijuana legalized in 20 states and DC. We've had decades to study this. Shame on us, we haven't really adequately studied it. So we're kind of in a weird place right now."

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