November 21, 2006

Marijuana / Cannabis Harms Memory and Learning

As we've noted in the past, marijuana / cannabis is strongly linked to increased risk for developing schizophrenia. New research has recently come out that indicates that it also harms memory and learning functions (that are commonly significantly reduced in schizophrenia).

The New Scientist Magazine reported this week that on a new study demonstrating that Marijuana wreaks havoc on the brain's memory cells:

"The active ingredient in the drug, tetrahydrocannabinoid (THC), disrupts the way nerves fire in the brain’s memory centre, a new study shows." In the study, "Normal rats accurately alternate their routes about 90% of the time. But rats given THC, which caused asynchronous nerve firing, chose a random direction on each run, and so chose the correct route 50% of the time." That is, the rats in the study had a almost a 50% less accurate memory in this test.

Scientists studying people have found that long-term marijuana users gradually become worse at learning and remembering things (see Pot-smoking your way to memory loss).

The take home message is that marijuana / cannabis seems to be very bad for the brain, in many different ways.

Read the full story here.

Journal reference: Nature Neuroscience (DOI: 10.1038/nn1801)


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