Scientists studying mice say they better understand how marijuana impairs working memory, the ability to momentarily retain and utilize information needed for comprehension and learning.

The study, published in the March 2 print issue of Cell, found that THC, the chief psychoactive ingredient in marijuana, impairs memory by affecting passive support cells known as astroglia, not active neurons as previously thought.

The memory changes are a major downside to the use of medical marijuana, the researchers said.

With these experiments in mice, “we have found that the starting point for this phenomenon — the effect of marijuana on working memory — is the astroglial cells,” researcher Giovanni Marsicano, of INSERM in France, said in a journal news release. Evidence is mounting that these cells play a more active role than once believed in connecting neurons, not just nourishing them, he noted.

The study authors said these cells, also known as astrocytes, could have additional effects on other forms of memory. They said their findings shed light on how the brain works and could eventually help scientists find a way to deal with working memory problems stemming from other causes.

Research involving animals should be considered preliminary because the results often don’t have implications for humans.

More information

The U.S. National Institute on Drug Abuse has more about the health effects of marijuana.

– Mary Elizabeth Dallas

SOURCE: Cell, news release, March 1, 2012

Last Updated: March 01, 2012