Read More Efficiently [antikvár]

Text 1 One by one, the "wonderfull vertues of tobacco" (as a 1659 treatise put it) have aone up in, well, smoke. The belief that tobacco soothes the throat, cures colds and quenches thirst has been replaced with evidence that cigarettes can instead cause lung cancer, heart disease and early death. But one claimed benefit of tobacco is still standing: diat tobacco - or, more precisely, nicotine - improves memory. Nicotine, at the levels circulating in a smoker's bloodstream after only a single cigarette, has long been known to boost recall in simple psychology tests. Last weelc, John Dani and colleagues at Baylor College of Medicine in Houston claimed to have solved the mystery. Nicotine, thcy report in the journal Nature, strengthens communications between neurons in the hippocampus, a structure in the brain involved in learning and memory. These messages take the form of electrical impulses. As an impulse travels along a neuron, it eventually reaches die end. The next neuron lies across a gap, called a synapse. In order for die message to leap die synapse, it has to send an understudy: molecules diat can diffuse across die gap. If enough of these molecules, called neurotransmitters, reach die neuron on die other side, diey spark an electrical impulse in it. Nicotine, die Baylor team found, increases die amount of neurotransmitters released. That gready increases die odds that the message will reach the neuron on die other side. The more messages diat get through, the more die neurons in a circuit change, becoming the physical embodiments of a memory. In fact, a 1991 study found diat the risk of Alzheimer's disease is lower in smokers. Another study reported last week, by neurologists at Case Westerns Keserve University, found that nicotine seems to inhibit, in die test tűbe, formation of die plaques diat gum up the brains of Alzheimer's patients. The problem witii using nicotine as a memory aid, of course, is diat "die delivery system contains 400 known carcinogens," as biologist Dániel McGehee of die University of Chicago puts it. But people at risk for Alzheimer's may not have to choose between cancer or senüity. Last year a study found that nicotine delivered by a transdermal patch improves the performance of Alzheimer's patients on learning tests. Bodi the hippocampus research and the Alzheimer's study were funded in part by tobacco money, from The Smokeless Tobacco Research Council and Philip Morris. At fírst blush, it seems diat the tobacco industry would reap die benefits of reports about "good" nicotine. But in fact die diseoveries, by pinpointing how nicotine acts in the brain, strengthen the argument that nicotine is a drug. That is die conclusion the industry is working madly to avoid, since it direatens ever tighter government regulation.