Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Substance Abuse and Addiction Health Center

Font Size

Why Marijuana May Affect Memory

Study in Rats Shows Pot-Like Substance Disrupts Brain Cell Coordination
WebMD Health News
Reviewed by Louise Chang, MD

Nov. 20, 2006 -- A new study on marijuana and memory may show why using pot hampers memory.

The study appears in Nature Neuroscience's advance online edition.

Researchers included David Robbe, PhD, of the Center for Molecular and Behavioral Neuroscience at Rutgers, the State University of New Jersey.

The study was in rats, not people.

The researchers gave rats shots of a synthetic cannabinoid drug that resembles marijuana's active ingredient, THC (tetrahydrocannabinol).

The drug doses were "comparable with recreational and palliative [pain relief] uses in humans," note Robbe and his colleagues.

For comparison, other rats got saltwater shots without cannabinoids.

Twenty minutes later, the scientists started monitoring the activity of certain nerve cells, or neurons, in the rats' brains.

Those neurons normally send chemical signals to communicate with each other. The process occurs seamlessly, like musicians playing in sync with each other in an orchestra.

But after the cannibinoid shots, the rats' neurons lost their coordination.

The neurons sent their chemical signals at the usual rate, but they were out of step with each other, like an orchestra in which musicians play without working together.

The problem was not seen with the saltwater shots.

The findings may explain how marijuana impairs memory, Robbe's team notes. However, the scientists didn't test the rats' memory.

Today on WebMD

child ignored by parents
prescription pain pills
Woman experiencing withdrawal symptoms
Teen girl huddled outside house
Man with glass of scotch
overturned shot glass
assortment of medication
Depressed and hurting