Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

258 IV. SPECIAL POPULATIONSdrug is associated with a marked increase in the probability of abusing otherclasses of drugs (Tsuang et al., 1998). One of the strongest predictors for presenceof an SUD is the presence of another SUD (Bierut et al., 1998).Much of the evidence for the heritability of the general and specific vulnerabilityfor SUD is taken from studies of familial aggregation. Bierut and colleagues(1998) compared siblings of probands with alcohol dependence andthose of a control group for the presence of lifetime SUDs. Siblings of alcoholicprobands were not only more likely to have a lifetime alcohol use disorder, butthey also had an increased risk of cannabis, cocaine, and nicotine dependence.Fifty percent of the alcohol-dependent siblings of alcohol-dependent probandshad an additional diagnosis of cannabis and/or cocaine dependence. What iscompelling with respect to understanding the risk for multiple substancedependence is that the siblings of cannabis-dependent probands had an increasedrisk of cannabis dependence, siblings of cocaine-dependent probandshad an increased risk for cocaine dependence, and siblings of habitual smokerswere at higher risk for nicotine dependence (Bierut et al., 1998). In anotherstudy, Tsuang and colleagues (1998) demonstrated that there is a general drugabuse vulnerability factor with genetic, family, and nonfamily environmentalcomponents that is shared across all drugs of abuse, in addition to genetic factorsthat appear to be unique for most classes of drug abuse. So although thereappear to be nongenetic general and specific factors for familial transmission ofvulnerability to SUDs, multiple SUDs among probands render increased vulnerabilityto multiple SUDs in relatives, at least through both drug-specific andcommon genetic factors.NEUROPSYCHOLOGICAL IMPACTOF MULTIPLE SUBSTANCE USE DISORDERSAs compared with non-polysubstance-using drug abusers, those with multipleSUDs demonstrate the greatest degree of chronic neuropsychological impairmentand recover the least function with long-term abstinence (Beatty et al.,1997; Medina, Shear, Schafer, Armstrong, & Dyer, 2003). This may be due inpart to the increased cumulative exposure of the brain to drugs and alcohol:Multiple substance users tend to use as much of a particular substance (e.g.,alcohol or cocaine) as those who use only alcohol or cocaine (Selby & Azrin,1998). Selby and Azrin (1998) conducted a comprehensive neuropsychologicalbattery with 355 prison inmates classified by DSM-IV criteria into four groups:those with alcohol use disorders, cocaine use disorders, multiple SUDs, and nohistory of SUD. The multiple SUDs and the alcohol groups demonstrated significantimpairment on most measures compared to the cocaine or no-druggroups, but the multiple SUDs group performed worse than the cocaine alone,alcohol alone or no SUD groups on measures of short-term memory, long-term