Mr. ATOD's wild ride: what do alcohol, tobacco, and other drugs have in common?

All researchers agree that individuals can become intoxicated by and dependent on alcohol, tobacco, and other psychoactive drugs. But they have disagreed over whether, and to what extent, drug pathologies comprise a unitary medical problem. Most critically, does addiction have a biological common denominator? Consensus on this question has shifted back and forth. In the late nineteenth and early twentieth centuries, physicians often studied and treated various drug addictions together, working under the "inebriety" paradigm. By the mid-twentieth century the inebriety paradigm had collapsed. Tobacco and alcohol had split off, both in the medical research community and in western popular culture. This article argues that neuroscientific, genetic, epidemiological, and historical evidence helped to reunify the addiction field in the late twentieth century. A new unifying paradigm emerged, variously called chemical dependency, substance abuse, or simply ATOD -- alcohol, tobacco, and other drugs.