Classification of alcohol and drug problems

Systems of classifying alcohol and drug problems have developed through the disease model of the 19th century, which allows categorical diagnosis and facilitated the 12-step approach to behavioural models and to socioeconomic models where substance use is seen as part of the environment in which an individual functions. DSM and ICD classified drug and alcohol use separately in their early versions, although they are now subject to the same criteria and both systems make a distinction between dependant and non-dependant use. DSM-IV and ICD-10 classify dependence as a cluster of cognitive, behavioural and physiological systems applicable across all substances. The criteria are broadly tolerance and withdrawal, impaired control and compulsion and salience and continued use despite harm. Dependence symptoms, substance-related problems and consumption form separate but related axes. Both DSM-IV and ICD-10 contain categories of abuse and harmful use respectively for substance users who do not meet the criteria for dependence. ICD-10 has a greater emphasis on the physical and psychological consequences of substance abuse. A substantial body of work on the validity of the dependence syndrome has generally found the dependence abuse model to be useful across the range of substances, although for cannabis the there are problems defining the withdrawal syndrome. Recent work to define DSM-V may change classification systems. Other forms of typology which are clinically useful also exist; for instance, the distinction between injecting and non-injecting drug users, and systems that detect substance-related problems rather than diagnostic criteria.