Heavy drinking affects long term memory

Large amounts of alcohol cause brain cells to release steroids that block the formation of long-term memories.

Last Updated: Jul 10, 2011, 21:58 PM IST

Washington: Ever wondered why you end up in missing some memories after a good night out? It`s because your brain cells release steroids that block formation of
long-term memories, scientists say.

It`s been believed that heavy drinking kills brains cells which in turn causes memory losses. But, the new study found that isn`t true.

"Alcohol isn`t damaging the cells in any way that we can detect," said study researcher Charles Zorumski of the Washington University School of Medicine in St Louis.

"As a matter of fact, even at the high levels we used here, we don`t see any changes in how the brain cells communicate," Zorumski was quoted as saying by LiveScience.

According to Zorumski, after heavy drinking one still processes information. "You`re not anaesthetised. You haven`t passed out. But you`re not forming new memories."

Even high levels of alcohol applied directly to brain cells didn`t damage them, found the researchers who carried out tests on mice in the study, published in the Journal of
Neuroscience.

Instead, the researchers found that large amounts of alcohol cause brain cells to release steroids that block the formation of long-term memories -- a process called long-term
potentiation, or LTP.

"It takes a lot of alcohol to block LTP and memory," Zorumski said.

"The alcohol triggers these receptors to behave in seemingly contradictory ways, and that`s what actually blocks the neural signals that create memories. It also may explain
why individuals who get highly intoxicated don’t remember what they did the night before."

In their study the researchers exposed brain cells of rats to varying levels of alcohol. It wasn`t until they reached "large amounts" of alcohol that the memory-making machinery was affected. At low levels they didn`t see any change in the cells` ability to connect with each other.

The alcohol seems to interfere with receptors (proteins that sense what`s going on outside of the cell) on the brain cells, blocking the actions of some and activating others. The activated receptors tell the brain cell to make these memory-blocking steroids.

When the researchers blocked the formation of these steroids, the rat brain cells could still make memories, even at high alcohol levels. The drugs used to stop the steroid-making process were commonly used prostate-reduction drugs.

"We would expect there may be some differences in the effects of alcohol on patients taking these drugs," said study researcher Yukitoshi Izumi, also of Washington University School of Medicine.

"Perhaps men taking the drugs would be less likely to experience intoxication blackouts."

PTI