The Role of Expectancies in Drug Withdrawal: An Experimental Analysis Using Caffeine

Abstract

The placebo literature suggests that people’s beliefs about: (i) what will occur when they ingest or do not ingest a drug, (ii) whether they have or have not ingested a drug, can elicit involuntary responses consistent with those beliefs independently of the pharmacological effects of the drug in question. This thesis aimed to test whether caffeine withdrawal symptoms could be affected by manipulating moderate to heavy coffee drinkers’ beliefs concerning: (i) the likelihood of experiencing caffeine withdrawal symptoms, (ii) how much caffeine they had in their system. Studies 1 and 2 demonstrated that the caffeine withdrawal symptoms experienced by 24-h abstinent caffeine consumers can be significantly reduced simply by their being told they had consumed caffeinated coffee, even though they had consumed only decaf. However while manipulating beliefs concerning the ingestion of caffeine did affect self-reported withdrawal symptoms, attempts to affect caffeine withdrawal by providing information about the likelihood of experiencing those symptoms was not. Study 3 suggested the possibility that placebo caffeine withdrawal relief may be a conditioned response, occurring in the absence of both conscious expectancies and caffeine. Studies 4 and 5 demonstrated the practical potential of blinded dose tapering regimens, with participants who were made aware of their true dose reduction schedule showing steeper rates of withdrawal increase over time than (i) participants who were deceived about their dose reduction schedule, and (ii) participants who were given no information about their dose reduction schedule. The studies in this thesis indicate that individuals’ beliefs about how much of a drug they have in their system can have a significant effect on withdrawal symptoms. Interventions that utilise this knowledge, such as the blind dose tapering procedure modelled in studies 4 and 5, may reduce withdrawal and help addicted individuals transition to a drug-free state.