Expectation versus conditioning in human tolerance to alcohol

James Byron Thomson, Purdue University

Abstract

The purpose of the present study was to independently measure the contributions to the phenomena of conditioned tolerance, of expectation and conditioning history. Siegel (1983) has described a theory of tolerance that employs a homeostatic drug-opponent mechanism to explain the reduction of a drug's effects over time. This compensatory response can become conditioned to the stimuli associated with drug ingestion, and is thought to comprise the withdrawal phenomena in the absence of drug. Conditioned tolerance in humans can be researched with the balanced placebo design, which provides specific predictions for each cell, including loss of tolerance and the conditioned compensatory response in the two placebo cells. Application of this paradigm has resulted in a confounding of expectation and conditioning history phenomena, as conditioned responses have been elicited with placebo procedures. This study was an examination of the independent contributions of expectation and conditioning history, with relevance to treatment of drug dependency. Two groups of college-aged social drinkers were exposed to four laboratory sessions with either a vodka (.5 g/kg) and tonic or tonic-only beverage and unique laboratory stimuli. Psychophysiological (heart rate, pulse transit time, finger and cheek temperature), behavioral (activity, and static ataxia) and cognitive/attentional (coding-vigilance performance) measures were collected before and after drinking. Repeated measures analyses of variance revealed that laboratory-specific tolerance was not statistically significant over four sessions. In later test sessions, the basic tenets of the model including main effects for conditioning history with alcohol, expectation of alcohol, loss of tolerance with disguised drug and compensatory response with placebo did not prove statistically significant. Placebo effects were significant only for drug-isodirectional "social" expectation responses in Subjective Intoxication and Static Ataxia. Post hoc analyses as well as a priori contrasts failed to expose the conditioned tolerance phenomena. Many conditioning sessions maya be required before unique laboratory conditioning can be demonstrated. The alternative is the placebo-elicited measurement of conditioned responses developed in the subject's native environment, although these are very difficult to control and quantify.

Degree

Ph.D.

Advisors

Santogrossi, Purdue University.

Subject Area

Psychotherapy

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