Induction of Physical Dependence upon Alcohol in Nonhuman Primates

Abstract

Ethanol-induced physical dependence is generally viewed as a concept which is empirically anchored to observations of alcohol intake for a period of time followed by a set of behavioral responses which are reliably associated with the cessation of alcohol intake. As such, it has the logical status of an intervening variable which must be carefully defined in terms of the operations used to measure the antecedent and consequent events which are presumed to be causally related to physical dependence. It is now generally agreed that exposure of an organism to ethanol for a period of time is both a necessary and sufficient antecedent event for the development of physical dependence. Although the underlying biological basis for this condition is not known, it is generally assumed that the presence of ethanol in nervous tissue results in the gradual development of adaptive changes in the functional state of the central nervous system. When ethanol is withdrawn, the functional balance of the system is disturbed, thus producing what is termed the withdrawal reaction. The set of behaviors which are generally observed following ethanol withdrawal constitute the consequent empirical events that must be carefully measured along with the antecedent conditions if the concept of physical dependence is to be meaningfully established. This operational specification of the concept of physical dependence is important because it provides a sound scientific framework within which previous experiments can be evaluated and new research projects planned. Since the measurement process involved in quantifying both antecedent events and consequent behaviors must also be specified, discrepancies in results from different experiments should be more readily understood, thus encouraging more standardization between laboratories in the techniques and procedures used.