Month: September 2004

Both nicotine and caffeine enhance memory, which accounts in part for their popularity. New drugs are even better at this, and without the addictive potential. Here’s part of a premium content article from The Economist on one of them:

Last year, Nancy Jo Wesensten, a research psychologist at the Walter Reed Army Institute of Research in Silver Spring, Maryland, compared the effects of three popular alertness drugs?modafinil, dextroamphetamine and caffeine?head to head, using equally potent doses. Forty-eight subjects received one of the drugs, or a placebo, after being awake for 65 hours. The researchers then administered a battery of tests. All of the drugs did a good job restoring wakefulness for six to eight hours. After that, says Dr Wesensten, the performance of the subjects on caffeine declined because of its short half-life (a fact that could be easily remedied by consuming another dose, she points out). The other two groups reached their operational limit after 20 hours?staying awake for a total of 85 hours.

When the researchers looked at the drugs’ effects on higher cognitive functions, such as planning and decision-making, they found each drug showed strengths and weaknesses in different areas. Caffeine was particularly effective in boosting a person’s ability to estimate unknown quantities. When asked 20 questions that required a specific numeric answer?such as ?how high off a trampoline can a person jump???92% of volunteers on caffeine and 75% on modafinil showed good estimation skills. But only 42% on dextroamphetamine did so?the same proportion as the sleep-deprived subjects who had received a placebo.

The Defence Advanced Research Projects Agency (DARPA), the research arm of America’s defence department, is funding an initiative to find new and better ways to sustain performance during sleep deprivation. Among its collaborators are Yaakov Stern, a neuroscientist, and Sarah Lisanby, a psychiatrist, both of Columbia University. Using functional magnetic-resonance imaging, Dr Stern has been observing the brains of healthy volunteers before and after forgoing sleep.

In the process, he has discovered a neural circuit that is linked to prolonged periods of wakefulness while performing memory tasks. Interestingly, its areas of activation vary from person to person, depending on the ability to tolerate sleep deprivation. Dr Lisanby is an expert in transcranial magnetic stimulation, the use of strong magnetic fields to facilitate or impede the communication of nerve cells using a coil held close to the head. She now plans to test stimulating the very regions in the brain that appear to correspond to better cognitive performance during long hours of wakefulness.

DARPA is also supporting the research of Samuel Deadwyler, a neuroscientist at Wake Forest University in Winston-Salem, North Carolina, who is studying the effects of ampakines, so called because they bind to AMPA receptors. There, they amplify the actions of glutamate, a neurotransmitter involved in two-thirds of all brain communications. Roger Stoll, the boss of Cortex Pharmaceuticals, which has been developing the compounds, has called them ?a hearing aid for the brain?.

According to Dr Deadwyler’s tests in primates, Cortex’s new drug candidate, CX717, which just entered human clinical trials, appears to eliminate the cognitive deficits that go hand in hand with sleep loss. Monkeys deprived of sleep for 30 hours and then given an injection of the compound even do slightly better in short-term memory tests than well-rested monkeys without the drug. And unlike amphetamines, which put the whole body in a state of alert, CX717 only increases activity in key brain areas?without any addictive potential.

Interesting.