In a study published in this month's APA Journal of Experimental Psychology: Animal Behavioral Processes, psychologists Shepard Siegel, PhD, and Lorraine Weise-Kelly, PhD, show that drugs have a different effect if they are self-administered as opposed to administered by a researcher. And, subjects tend to develop a higher tolerance to drugs that are self-administered, the authors note.
Siegel and Weise-Kelly, of McMaster University in Ontario, evaluated these effects using groups of rats. One group was allowed to self-administer ethanol. Whenever a self-administering rat chose to drink some of the beverage, a "yoked alcohol" partner was infused at the same time, through a stomach catheter, with the same amount of ethanol. The rats who drank the ethanol solution on their own accord were visibly less "drunk" than the "yoked" rats. They found similar results in an experiment that replaced ethanol with heroin.
Research has long-documented that drug effects are smaller when people take the drugs in "the context of a usual drug-administration environment than if administered in an environment not usually paired with drug administration." For example, many people say they become more inebriated if they consume alcohol in an unusual setting or time or when they drink an unfamiliar beverage.
The researchers found that "internal self-administration clues function like external clues." These internal cues are paired with the drug effect and come to "elicit conditional compensatory responses that act to cancel the effect of the drug," they note. When the alcohol-drinking rats self-administered a nonalcoholic beverage, they displayed an alcohol-compensatory conditional response--they became "hypertaxic" and not ataxic.
"The findings have several implications," says Siegel. "They suggest that the effect of the drug is very different if administered by the subject, rather than by the experimenter. Thus, some of our knowledge of drug effects may not be readily applicable to situations in which a drug is self-administered."
Furthermore, self-administration cues may be important to consider in drug treatment strategies. Some cue-exposure treatments use passive exposure to patients' drug-related environmental cues. Siegel and Weise-Kelly suggest that mere exposure to predrug environmental cues may not "effectively extinguish the association between pre-drug cues and the drug effect.
"Extinction treatments should incorporate opportunities for the patient to engage in the behaviors that previously had culminated in drug administration," says Siegel.