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Last Updated: Monday, 22 August 2005, 23:14 GMT 00:14 UK
Drug 'reverses sleep lack effect'
Junior doctors
The researchers say the drug could help busy doctors
A drug could reverse the effects of sleep deprivation in the brain, a US study of monkeys has suggested.

The drug comes from a class of molecules called ampakines which enhance how some chemical receptors work in the brain.

It helped monkeys overcome their lack of sleep, the study in the Public Library of Science - Biology showed.

Researchers from North Carolina's Wake Forest University hope it could help people like doctors and shift workers.

The study was partly funded by the US Department of Defense Advanced Research Projects Agency as part of a project to reduce of eliminate the effects of sleep deprivation on soldiers.

Juice rewards

The drug, currently known as CX717, is designed to act on a type of chemical receptor that is involved in cell-to-cell communication involving the neurotransmitter glutamate.

The more we know about the brain, the more medicines can be targeted
Dr Neil Stanley
British Sleep Society

The drug prolongs the action of glutamate, allowing more effective communication.

In the study, alert monkeys were given a task where each was shown a picture in one position on the screen.

After a delay of up to 30 seconds, they were asked to pick the original out of a random display of two to six different images. If they picked correctly, they were given juice.

When the monkeys were given varying doses of the drug and re-tested, their performance improved to near perfect for the easier trials and by about 15% overall.

They were then deprived of sleep for between 30 and 36 hours - which the researchers say is equivalent to humans going for 72 hours without sleep.

The animals were tested again, and fared worse on all the tests.

But after being sleep-deprived once more and re-tested after being given the drug, their performance was restored to normal levels.

Mental 'enhancement'

The researchers used positron emission tomography (PET) scanning to examine the animals' brain activity throughout the study.

When the monkeys were performing the task while sleep-deprived, activity in the frontal cortex, an area of the brain associated with higher mental processing, decreased and activity in the temporal lobe, associated with memory for recent events, increased.

The researchers said this might be the brain's way of compensating for the effects of sleep deprivation.

After the drug was administered, the brain patterns in these regions returned to normal.

Samuel Deadwyler, of who led the Wake Forest University School of Medicine research, said: "The drug didn't cause overall brain arousal, but increased the ability of certain affected areas to become active in a normal, non-sleep-deprived manner."

He added: "It's possible that ampakines could also be used to enhance other cognitive deficits, such as occur in Alzheimer's disease, after a stroke or other forms of dementia."

The researchers said the drug did not appear to be linked to side effects such as hyperactivity, distorted thinking or extended wakefulness.

The drug's manufacturer, Cortex Pharmaceuticals, has also reported positive results from tests on sleep-deprived humans with positive results.

Dr Neil Stanley, of the British Sleep Society, who was involved in the human study, said: "The more we know about the brain, the more medicines can be targeted.

"Ampakines are an exciting class of drug.

"If you can keep the brain thriving, more people may have benefits than shift workers - it may have benefits for people with conditions such as Alzheimer's disease."




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