The idea for Buzz came to the author while he was a science writing fellow in the neuroscience summer course at the Woods Hole Marine Biological Laboratory. Science writing fellowships give writers the opportunity to experience the practical aspects of science firsthand by learning techniques at the bench from some of the best experimentalists in the business. Perhaps it was this stimulating intellectual atmosphere that suggested to Braun the idea of writing a book about the biological effects of the world's two most popular mind-altering drugs.

Well, maybe. On the other hand, another hypothesis presents itself. When I took Woods Hole's embryology course, we had three temperature-controlled rooms. One at 25?C for Drosphila. Another was 18?C for nematodes. But the largest, at 4?C, was for beer. As lab sessions stretched late into the night, a bottle of Bud would be an essential accompaniment by the dissecting scope. It certainly helped to cure unsteady hands, but then the unsteady hands could well have been caused by the unfeasibly large quantity of coffee we consumed to keep pace with the grueling schedule and to recover from tequila-induced hangovers.

Woods Hole summer course students aren't the only ones with serious caffeine and alcohol habits. Braun cites figures indicating that more than half of the U.S. population sometimes drinks alcohol, and "over 80% of Americans consume caffeine in some form every day." Alcohol and caffeine are so familiar that we take them for granted, but in the last few years, molecular biology and clinical trials have begun to reveal interesting and often surprising facts about these molecules and the way they effect our minds.

Braun describes in some detail what is known about the molecular basis for alcohol's effects. We follow an ethanol molecule on its epic (and picturesquely described) journey from glass to brain. The microvilli of a taste bud, we read, "[look] like a bed of kelp waving slowly in what is now a rather viscous mixture of Scotch and saliva."

The molecular effects of alcohol contrast sharply with those of other drugs with more specific mechanisms of action. Cocaine and heroin act as "pharmacological scalpels" having precise, targeted effects on particular receptor types in the brain. In contrast alcohol acts, in Braun's words, more like "a pharmacological hand-grenade", affecting in one way or another nearly every major neurological pathway. This may account for the wide range of responses experienced by different people following the same dose of alcohol, and also for the distinctly different effects that different doses of alcohol can have on the same individual.

One striking example in which human beings differ in their responses to alcohol is the genetic predisposition toward alcoholism seen in certain families. Research in mice is now starting to provide a molecular foundation for this observation. The study of alcoholism in mice got off to a slow start, unfortunately, because nearly all mice dislike the taste of alcohol and refuse to drink it. Luckily, a strain was eventually found that actually liked the stuff, and since then research has progressed rapidly.

Caffeine is often seen as the polar opposite of alcohol in its mood altering effects, and indeed, the major neural signaling pathway (adenosine) stimulated by caffeine is depressed by alcohol. Unfortunately, though, as mentioned earlier, alcohol affects many different pathways, and caffeine reverses just this one. So offering caffeine to someone who is drunk will only produce, to quote Braun, "a wide-awake drunk."

To the comfort of compulsive coffee drinkers, however, Braun reports that caffeine seems to be, as far as can be determined from current research, the safest recreational drug around. Despite extensive efforts, no one has succeeded in conclusively establishing a relationship between chronic caffeine consumption and any serious disease in humans. Experiments with extremely high doses of caffeine in rats suggest that pregnant mothers should probably err on the side of caution, but everyone else, it would seem, can probably drink coffee without fear of significant long-term effects. In fact, Braun makes the point that, quite probably, caffeine actually saves lives by helping people to avoid falling asleep at the wheel.

On the downside, caffeine certainly does produce dependency. If regular coffee drinkers are deprived of their daily fix, the symptoms of withdrawal can be quite severe. Extreme cases may include vomiting and hallucinations. Headaches are the most common symptom and are thought to be to be the result of a rebound effect that causes the dilation of blood vessels in the brain. (Caffeine normally constricts these vessels, which is one of the reasons that a good cup of coffee can help a hangover). The discovery of this relationship between caffeine withdrawal and headaches was, says Braun, largely fortuitous. Surgeons were trying to understand why some of their patients suffered postoperative headaches while others did not. It turned out that non-coffee drinkers almost never had postoperative headaches, but habitual coffee drinkers did. Thanks to a 24-hour fast prior to the operation, by the time the coffee drinkers woke up following their operations, they were already suffering from caffeine withdrawal.

It's not all bad news for headache sufferers, though. Caffeine has been consistently shown to improve the effectiveness of analgesics such as aspirin by up to 40%. For this reason, caffeine is included in many over-the-counter pain remedies (Caffeine, then, is great for headaches, just so long as you don't stop taking it).

Caffeine's effects on physical and mental performance are interesting. For athletes, caffeine clearly does produce significant benefits, and excessive use can now lead to disqualification in many sports. In the case of intellectual performance, however, the data are more difficult to interpret. Certainly, there is much anecdotal evidence that caffeine can act as a spur to creativity and cognitive function. Many authors, from Balzac to Hemingway, have found coffee to be a prerequisite for the writing process. Bach was so keen on coffee that he dedicated an entire piece, The Coffee Cantata, to the brew. The consensus seems to be that although caffeine won't make anyone into an instant Einstein, many people do perform intellectual tasks more accurately and more productively when they are on a caffeine high.

Braun's writing style is both entertaining and comprehensible. He manages the difficult balancing act of explaining things in ways that a layperson can understand, without appearing patronizing to professional scientists. The impressive reference list means that those curious to know more will not be frustrated.

As an accessible but scientifically literate study of the two most widely consumed recreational drugs in the world, Buzz makes fascinating reading. Just watch out for the inevitable sequel: Puff: The Science and Lore of Nicotine and THC.

Excerpts from Gregory A. Austin's Perspectives on the History of Psychoactive Substance Use - offers a chronology of psychoactive substance use and a fascinating history of the shifting perceptions of drugs, including caffeine and alcohol, in society.

The Frequently Asked Questions about Coffee and Caffeine - offers extensive information, ranging from a molecular model of caffeine to recipes for consuming the stimulant.

The Caffeine Page - offers "an experience in caffeination." A colorful source of information on everyone's favorite morning molecule.

The Joy of Coffee: The Essential Guide to Buying, Brewing and Enjoying by Corby Kummer - the quintessential coffee book?

Water Joe - the seriously addicted can now buy caffeinated mineral water.

Web Book Reviews - a listing of selected Web sites that offer science book reviews.