Drugs May Save Memory of the Sleep-Deprived

Oct. 21, 2009 -- Memory fuzzy after missing out on sleep? Researchers may be one step closer to figuring out what to do about it.

Sleep deprivation makes it harder for the brain to memorize newly learned information, and scientists may have found a way around that problem.

Writing in Nature, University of Pennsylvania graduate student Christopher G. Vecsey, professor Ted Abel, PhD, and colleagues identify a chemical chain reaction linked to sleep deprivation -- and a possible solution.

The researchers used electrical shocks to train lab mice not to move in certain cages, and then deprived some of the mice of sleep for five hours. Those sleep-deprived mice were worse at remembering not to move around in those cages than mice that had been allowed to sleep.

When deprived of sleep, the mice made more of an enzyme called phosphodiesterase 4 (PDE4). In turn, the surplus of PDE4 caused a shortfall of a compound called cAMP, which is involved in forming new memories in a brain area called the hippocampus.

The researchers ran the tests on more mice. And this time, they injected some of the mice with rolipram, an experimental drug that blocks PDE4. For comparison, other mice got placebo shots.

The mice got those shots right after being trained not to move in certain cages, but before sleep deprivation. Sleep-deprived mice that had gotten the rolipram shot aced the memory test; they remembered not to scurry around the cages where they were likely to get shocked.

The researchers aren't recommending rolipram for sleep-deprived people.

But they say their study shows that "it may be possible" to make drugs that target PDE4, and that such drugs "may prove useful in the treatment of the cognitive effects of sleep deprivation."