Drugs and placebos: The effects of instructions upon performance and mood under amphetamine sulfate and chloral hydrate.

Abstract

The experiment reports the effects of appropriate and inappropriate instructions and 2 drugs (.5 g chloral hydrate and 10 mg racemic amphetamine sulphate) on motor performance and mood measures. The Ss were 90 older men randomly assigned to 9 experimental groups. The design used was expansion of a model design involving Drug Disguised groups, Placebo groups (300 mg lactose), an Untreated group, and Amphetamine, Chloral Hydrate, and Neutral instructions. The drugs and placebos were given to the Ss in capsules, and all Ss received orange juice, which was also the vehicle for the disguise. The Untreated group received orange juice only. Instructions alone affected performance, but had little or no effect on mood. Instructions appropriate to the presumed drug effects produced performance deterioration on the simple motor tasks used. Instructions inappropriate to the presumed drug effects counteracted much of the drug produced decrement. A slight decrement in performance was found in the Placebo group which received Amphetamine instruction. Amphetamine treated Ss produced reports of greater comfort on the mood index than did chloral hydrate. On the other hand, the chloral hydrate instructions resulted in greater comfort than the Amphetamine instructions. There was no interaction between drug effects and instructional effects. The 2 Placebo groups did not differ significantly on the mood index. The effects of instructions on mood were found only when the drug was present. Several suggestions are offered for further research.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

“…Findings from these studies using the open/hidden drug paradigm are supported by investigations that explicitly modulated the expectancy concerning a given drug by verbal instructions (Lyerly et al, 1964;Kirk et al, 1998;Metrik et al, 2009). The detrimental influence of negative expectations on the drug response became, for instance, apparent in a behavioral experimental study by Dworkin et al (1983), who reported a reversal of 716 analgesia by nitrous oxide in dental pain when participants expected the drug to increase awareness of bodily sensations.…”

Placebo Effects in Sport and Exercise: A Meta-Analysis

“…In several studies, differences were found in self-rated alertness and/or mood among groups ingesting placebos with different suggestions (walacH et al 2002;brodeur 1965;kirscH 1997;lyerly et al 1964;ross et al 1962;zwyGhuizen-dooreNbos et al 1990) and placebos with different perceptual characteristics (blackwell et al 1972). In the study of kirscH & weixel (1988), participants experienced significant changes in perceived alertness and tension but not in relaxation after receiving placebos with deceptive stimulant suggestion.…”

“…Research has demonstrated that in addition to perceived changes in internal states, placebos given with proper suggestion could also affect cognitive tasks as well as psychomotor performance either positively (lyerly et al 1964;ross et al 1962;zwyGHuizeN-dooreNbos et al 1990;fraNkeNHauser et al 1963;kirscH & rosadiNo 1993;lieNert 1955lieNert ) or negatively (e.g. walacH et al 2002MoerMaN 2002).…”

The doctor‐patient relationship and drug effect

“…15 At the end of the first week, patients on dextroamphetamine had lost an average of 2.64 pounds while those on the placebo had gained an average of 0.15 pound. At the end of 4 weeks, the mean weekly weight loss of patients who received dextroamphetamine had dropped to 1.16 pounds, while the mean weight loss of placebo patients was only 0.54 pound.…”