Bernard Blitz

The Interaction of Drugs with Placebos in the Control of Pain and Anxiety

Placebos are pharmacologically inert materials which are administered to patients, or experimental subjects, along with expressed or implied suggestions that they will produce some, usually therapeutic, effect. Despite their pharmacological inertness, placebos are moderately effective in the relief of pain and anxiety. For example, the administration of an inert material with the suggestion that it is analgesic is roughly 50 per cent as effective as morphine in controlling postsurgical pain [1]. Placebos can, moreover, affect almost any of the physiological states which are controlled by the central or autonomic nervous systems [2]. The placebo effects are based on the patients comprehension of, and emotional response to, the apparent drug administration. This comprehension and emotional response, and their physiological consequence, depend in great part on the instructions or suggestions given to the person receiving the capsule or injection of pharmacologically inert material. The placebo effects thus result from the patients knowledge that he has been treated plus his conception of the nature of the treatment. Active drugs could be, but seldom are, administered in a concealed form. Moreover, drugs are almost always given with expressed or implied suggestions concerning some expected effect. The administration of an active drug thus includes the same variables as are involved in the administration of a placebo. For this reason, active drugs always act, in part, as placebos. The observed effect of drug administration is thus a combination of the pharmacological effects and the placebo effects.

Pain attenuation by contralateral cold stimulation

Twenty Ss reported cold induced discomfort and pain thresholds for their right hand which was immersed in an ice water mixture, in trials with and without the left hand also immersed in ice water. The contralateral cold stimulation resulted in a significant elevation in both discomfort threshold and pain threshold.

Relationship between Pain Tolerance and Kinesthetic Size Judgment

40 Ss were tested in tasks measuring pain tolerance and kinesthetic size judgment. The results demonstrated a significant relationship between the two types of performance: Ss low in pain tolerance tended to make larger errors in KSJ than Ss with higher pain tolerance. Among Ss with descending series, pain tolerance correlated negatively with degree of overestimation of the standard. The results are consonant with the hypothesis that attentional function is the relevant underlying mechanism.

Effect of contralateral cold on pain tolerance

Fourteen Ss reported pain threshold and quit point in trials in which either right, left, or both hands were immersed in an ice water mixture. The contralateral cold stimulation resulted in significant elevation in both pain threshold and quit point for both right and left hands. The data also indicated that even nonpainful contralateral cold elevated pain threshold; this latter effect showed adaptation.

Perceptual Speed and Behavioral Proficiency

Perceptual speed in specific sensory modalities should lead to efficiency in behaviors governed by these modalities. To test this hypothesis, correlations were computed between measures of perceptual speed and scores on a modified Stroop test. Those correlations relevant to the hypothesis were all significant and in the expected direction. The pattern of results is thus reasonably consonant with the hypothesis. Reserpine, which might be expected to affect the above relationships, was ineffective.

Perceptual Delays and Speed of Reading and Tapping

Simultaneous presentation of two stimuli from different modalities often produces an experience of apparent sequence. There are stable individual differences in the direction and degree of this temporal displacement. Comparing the relative latency of perception of visual and tactile stimuli by the above procedure, it was hypothesized that intermodal differences in perceptual latencies will produce a corresponding hierarchy in speeds of reading and tapping. The results were in accord with this hypothesis. The relationship between perceptual latency and behavior was most evident, however, only among the older and less educated Ss.