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also serve as an outcome measure for evaluating the efficacy of treatment. It is perhaps more usual for studies to use consumption rates as measures of outcome; however, since it is notoriously difficult, not least because of the amount of time required, accurately to measure consumption for the purposes of routine evaluation, it has been proposed that the measurement of dependence, having been shown to be brief, would constitute a useful proxy measure. Level of substance dependence has been shown to correlate highly with consumption of alcohol and heroin in patients at the start of treatment, in a general practice sample and in a college sample (Raistrick et al. 1994). Consumption also correlates highly with harm to the individual and in the population (Holder and Edwards 1995). Measures of consumption shed no light on underlying psychological processes particularly once consumption has ceased, hence the proposed greater utility of charting the nature of decline in dependence over time and during abstinence.
One of the cornerstones of the philosophical and theoretical debates on the nature of dependence is the role of volition. In the simply stated dichotomy described at the beginning of the chapter, dependence is a state that is broadly seen as being beyond the volition of the individual in disease theories while volition plays a different role in social learning theories. Crudely put, is dependence something one has or something one does? And what, therefore, is the relationship between dependence and other behaviours? For example, does one cope less well with temptations to drink or take drugs because one is dependent, or is one dependent because one copes less well with temptations to drink or take drugs; or is one simply not so tempted if one is not dependent or less dependent? Definitive answers to these questions are beyond the scope of this study, but the decision regarding the behaviours which would be examined in the process of elucidating the nature of change in dependence was guided by them.
The origins of the broadly dichotomous positions regarding the nature of dependence described above are clinical observation and personal account, discussed later in this chapter. Diverse clinical populations and accounts of the nature of dependence have resulted in polarised positions that may well be reconciled in the identification of a continuum of severity of dependence which accounts for different experiences and different outcomes in different individuals. While this approach is not new - it informed the development of the syndrome approach to the understanding of dependence also described later in this chapter - elucidation of the course of change, if change occurs, with reference to degrees of severity, has not previously been the subject of studies in dependence and informed the formulation of the hypotheses in the present study.
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