Lifewatch: Marijuana Study

FLORIDA -- Some people argue marijuana is safe and should be legalized in the United States.

But, new research is showing that pot can be detrimental to your health.

Researchers checked MRI scans in men who smoked more than five marijuana cigarettes a day for ten years.

Participants were given a memory test which showed certain parts of the brain in pot smokers were smaller than those who didn't smoke marijuana.

"What the investigators found was that long term very heavy use of cannabis marijuana results apparently in a smaller hippocampus and migdala. Those parts of the brain involved in emotion and memory," said Dr. Huntington Potter, a scientific director of the Byrd Alzheimer Institute.

He said patients with early Alzheimer show a similar abnormality on MRIs.

"Loss of hippocampus volume is one of the precursors of Alzheimer disease," said Dr. Potter.

Heavy marijuana users were also found to be more depressed.  Researchers don't know if the brains of the men in the study were abnormal before they started using the drug.

When it comes to drug use, the results of this study gives researchers one more reason to recommend caution.

"Drugs are not something to play around with. They have some benefits in small douses as is the case of THC the active ingredient in marijuana but long term heavy duty use is bound to cause unexpected problem," said Dr. Potter.

The White House is sending a warning that depressed teens and marijuana are a bad combination.

But, the government isn't sure which comes first: the depression or the use of pot.

For the full government report on the link between marijuana use and teen depression, click here.

Reported by Kristy Ondo