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to the desire to continue drinking once started, the ability to stop if there were other things that had to be done, difficulty in stopping before getting drunk, planning to drink without control and planning to limit the amount consumed. Stockwell et al. developed this short instrument in order further to validate the unidimensional nature of the alcohol dependence syndrome as items referring to the altered subjective state had not been included in the earlier measurement of the alcohol dependence syndrome (the SADQ) and to examine the possibility that the scale might improve the predictive validity of degrees of syndrome severity.
In a review of the impaired control literature, Heather et al. (1993) concluded that the clinical evidence was tipped in favour of a continuous variable, “reflecting the frequency with which episodes of impaired control occur” (Heather et al. 1993 p. 701), as opposed to an all-or-none variable, in much the same way as dependence itself had been shown to be. The question of intention remains a problem in response to which the authors opted to follow Storm and Cutler (1975) who define loss of control as a breakdown of an intention to limit consumption in a particular situation. Heather et al. have included items which refer both to the ability to keep to a limit in a given situation as well as more general questions of not being able to stop once started. They further include items referring to the ability or difficulty in abstaining in given situations. Although previously referred to as a separate type of alcoholism (Jellinek 1960), Edwards and Gross (1976) combined impaired control and inability to abstain, referred to above as within session impaired control and between session impaired control respectively, into the broader component of a 'subjective awareness of a compulsion to drink' (Edwards and Gross 1976 p. 1060) and Heather et al. adopted this approach in the development of their measurement scale. Beyond the above, they offered no further explanation of impaired control but expressed the belief that once a satisfactory instrument was devised it would be possible to elucidate the nature of the phenomenon, to examine the relationship between the impaired control construct and dependence and to examine its predictive and clinical utility.
The Impaired Control Scale (ICS) devised by Heather et al. (1993) is a questionnaire in three parts. The first part measures the frequency of attempts to control drinking in the past six months (subsequently named Attempted Control; ICSAC), the second part measures the frequency of failures to control drinking in the past six months (and subsequently named Failed Control: ICSFC) and the third part measures beliefs about the person's current ability to control drinking (subsequently named Perceived Control: ICSPC, see Heather et al. 1998). The point was to distinguish those who were successfully controlling their drinking from those who were not trying to control it at all: both would achieve low scores on Part 2 items but the former group would gain
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