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

9. Cocaine and Stimulants 193heritabilities ranging from 69 to 81%. However, both the environmental andgenetic factors appeared nonspecific. A third, large-scale twin study examinedlifetime history of use and abuse/dependence of cocaine and other drugsin 1,196 male–male twin pairs ascertained by the Virginia Twin Registry(Kendler, Jacobson, Prescott, & Neale, 2003). Ultimately, one must concludethat while cocaine use, abuse, and dependence seem to be strongly influencedby genetic factors, evidence for a cocaine-specific genetic effect is currentlylacking.PSYCHIATRIC COMORBIDITY AND SEQUELAEMore than one-half of all cocaine abusers meet criteria for a current psychiatricdiagnosis and nearly three-fourths for a lifetime psychiatric diagnosis (Ziedonis,Rayford, Bryant, Kendall, & Rounsaville, 1994). The most common comorbidpsychiatric diagnoses among cocaine abusers include alcohol dependence,affective disorders, anxiety disorders, and antisocial personality disorder(Kleinman et al., 1990; Marlowe, Husband, Lamb, & Kirby, 1995; Mirin,Weiss, Griffin, & Michael, 1991; Rounsaville et al., 1991; Weiss, Mirin, Griffin,Gunderson, & Hufford, 1993). For most cocaine users, co-occurring psychiatricdisorders (including agoraphobia, alcohol abuse, alcohol dependence,depression, posttraumatic stress disorder (PTSD), simple phobia, and socialphobia) precede cocaine use (Abraham & Fava, 1999; Shaffer & Eber, 2002).The most frequent co-occurring substance use disorder is alcoholism; 29%of cocaine abusers have a current alcoholism diagnosis, and 62% a lifetime alcoholismdiagnosis (Rounsaville et al., 1991). These findings are alarming consideringthat individuals with comorbid cocaine and alcohol use disorders manifesta more severe form of cocaine dependence, and comorbid alcohol abuse is associatedwith poorer retention in treatment and poorer treatment outcomes forboth disorders (Brady, Sonne, Randall, Adinoff, & Malcolm, 1995). Cocaineuse disorders also are common among opioid abusers. In addition, 66% ofmethadone-maintained patients abuse cocaine (Kosten, Rounsaville, & Kleber,1987), and 75% of the heroin addicts admitted to methadone programs identifycocaine as their secondary drug of abuse (New York State Division of SubstanceAbuse Services, 1990). A national survey of 15 clinics (General AccountingOffice, 1990) revealed continued cocaine use in as many as 40% of patientsafter 6 months of treatment. Marijuana is also commonly misused amongcocaine-dependent patients. Studies have found that 25–70% of cocainedependentpatients also abuse marijuana (Higgins, Budney, Bickel, & Badger,1994). Similarly, 80.5% of cocaine-dependent patients smoke tobacco cigarettes(Patkar et al., 2002), and the heavier the tobacco smoking, the heavierthe use of cocaine (Henningfield, Clayton, & Pollin, 1990). In addition,cocaine-dependent individuals who smoke tobacco report an earlier age of