Drug sensitization, substance abuse, and chemical sensitivity.

Substance abuse, involving drugs such as cocaine, heroin, alcohol, marijuana, nicotine, barbiturates, etc., is by far by the most prevalent psychiatric disorder. Much has been learned about the abuse of these substances that may be useful to consider in designing and analyzing research concerning multiple chemical sensitivities (MCS). We review the central role of sensitization in this literature, including its definition, measurement, and expression in animals and human volunteers. Common factors among abused drugs, including sensitization, are discussed. Finally, empirical studies are delineated or proposed to test some of the notions presented in this paper.