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requirement that three or more of these symptoms must have been present for at least a month. Since there are just three criteria that refer to tolerance, withdrawal and withdrawal relief, it was possible to make a diagnosis of dependence in the absence of these phenomena. Indeed this reflected the growing awareness, arising out of epidemiological studies and clinical observation, that drugs lacking clear symptoms of tolerance or withdrawal appeared to have substantial addiction forming potential if patterns of use and the remaining symptoms were anything to go by (see for example Carroll et al. 1994). The substance abuse classification in DSM-III-R was a default category which required the fulfilment of only one of the criteria of continued use despite knowledge of consequences or in conditions where use is physically hazardous and where the diagnosis of dependence could not be made.
In DSM-IV, tolerance is described as a need for more of the drug or the experience of a diminished effect, while withdrawal may be defined either as the experience of withdrawal symptoms characteristic of the particular drug, or as relief use. Again, diagnosis of dependence can occur without the fulfilment of either of these criteria and the specification of physiological dependence is separately made. The duration requirement is changed to “three or more of the following (criteria) occurring at any time during the same twelve month period”. Although the criteria for abuse appear to have been extended, the content of the previous criteria has merely been elaborated and this remains a default category for those with impaired control who do not fulfill the criteria for dependence. Widiger and Smith (1994) have commented that this version does not add clarity to the definition of dependence. Indeed, it appears to cover all possibilities by including the requirement to state whether the person has physiological dependence in addition to the three or more dependence criteria, one of which includes the possibility of manifest withdrawal symptoms. These authors suggest that the distinction between abuse and dependence has been made on the grounds of severity in the different versions of the DSM, it is a quantitative distinction that appears at once to be both quantitative and qualitative. A clear distinction between the behavioural, affective and cognitive components of dependence and the sequelae of persistent use has not been made in the DSM-IV. Retaining withdrawal symptoms as part of the condition of dependence precludes the possibility of measuring severity across different drug use.
In spite of the call made by Edwards et al. (1982) for the sake of clarity to distinguish dependence as a psychological construct from neuroadaptation as the consequence of the regular excessive use of some psychoactive substances, it seems likely that the terms physical and psychological dependence, or dependence meaning either the physical or the psychological, will remain in common use, supported as they are by definition in the major classification systems. In
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