could embrace all the addictive drugs without offense to the standard hypocrisy. The problem here is not merely semantic; it reflects a profound gulf between the science and the perceptions of politicians and the public. One way we, as scientists, can raise the profile of drug abuse research among the politicians and public who fund our work is to educate them about the neurobiologic underpinnings of this curious medical, behavioral, societal disease.

I think an essential first step is to call a drug a drug. There are seven families of addictive drugs, which comprise the drug abuse problem. These are, in descending order of societal importance: alcohol, nicotine, cocaine and amphetamines, heroin and other opiates, hallucinogens, cannabis, and caffeine.

The field of drug abuse—substance abuse, whatever you call it—must seem a bewildering morass to the newcomer, especially to the young scientist trained in the cutting-edge techniques of molecular biology. Raising the profile of drug abuse research among scientists means identifying those critical questions that can be attacked by the most up-to-date techniques of molecular genetics and neurobiology as well as by carefully designed, controlled experiments on animal and human behavior.

Drug self-administration is a behavior—a remarkably specific behavior, for just these seven chemical families of drugs are self-administered, and laboratory animals self-administer the same drugs as do humans. All behaviors are determined in part by genetics, in part by environment. And all behaviors are rooted in neurobiology, in the anatomic structures and circuities, and in the neurochemical processes of the brain. There was a time, not so many years ago, when animal and human behaviors could only be studied as phenomena in their own right. But molecular neurobiology has changed that dramatically, so that the behaviors we identify as drug addiction are beginning to be understood at the most basic level. Nevertheless, the fullest understanding of a behavioral disease will require multidisciplinary approaches, and the tendency of some molecular biologists to disdain less reductionist fields of research can be a hindrance to progress.

MULTIPLICITY OF DRUG EFFECTS

Any addictive drug has multiple effects, both psychopharmacologic and toxicologic, many of them unrelated to the addictive property. These comprise the ensemble of actions that make each drug unique, with its own special dangers for the user and for society. These special pharmacologic properties of each drug should be (but rarely are) taken into account in debates and decisions about our national drug policies.

The multiple effects of any psychoactive drug pose a unique difficulty in elucidating the neurochemical basis of addictive behavior. In studying other brain diseases, it is difficult enough to sort out which neurotransmitter or receptor



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