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Chronic Cannabis Use May Affect Brain Structures, Memory and Mental Health (Interview with Murat Yücel, PhD)
Chronic Cannabis Use May Affect Brain Structures, Memory and Mental Health (Interview with Murat Yücel, PhD)

(June 2, 2008 - Insidermedicine) Heavy, long-term use of cannabis may have some minor effects on some brain structures as well as on memory and mental health, according to research published in the Archives of General Psychiatry.

Here are some facts about cannabis:

•    It is by far the most widely cultivated, trafficked, and abused illegal drug.

•    An estimated 147 million people – about 2.5% of the world population – use cannabis.

•    Since the 1960s, use of cannabis has grown most rapidly in the developed world, including North America, Western Europe, and Australia.

Researchers out of ORYGEN Research Centre, the University of Melbourne, and the University of Wollongong examined the brains of 15 men who had smoked more than five joints a day for more than ten years as well as 16 men who had not used cannabis. The researchers produced images of the men's brains using high-resolution MRI. They also compared the two groups of men with respect to verbal memory and symptoms of psychiatric illness that were too mild or minor to be considered signs of true disease.

Two areas of the brain – the hippocampus and the amygdala – tended to be somewhat smaller in men who smoked cannabis. These brain areas are involved in memory, emotion, and aggression. The cannabis users also did poorer on tests of verbal memory and were more likely to have minor or mild symptoms of psychiatric illness.

We had a chance to speak with Dr. Murat Yücel from the ORYGEN Research Centre and the Melbourne Neuropsychiatry Centre, who discussed the implications of this study.

Today's research challenges the belief that chronic cannabis use does not alter the brain. Very heavy, long-term use may affect brain structures and even have an impact on memory and mental health.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.