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Expectations and placebo responses to caffeine-associated stimuli.
Psychopharmacology (Berl) 2003; 169(2):198-204P

Abstract

RATIONALE

To test the theory that expectations control placebo responses.

OBJECTIVE

Subjects (n=20) were asked how much they expected their arousal to increase after one or two cups of coffee, and were subsequently exposed to one or two cups of decaffeinated coffee, or to caffeine equivalent to one or two cups of coffee (200 and 400 mg). The expectancy theory of placebo responses predicts a positive correlation between expectations and actual placebo responses.

METHODS

Dependent variables were acoustic startle eyeblink and skin conductance responses, blood pressure and heart rate, and measures of subjective arousal.

RESULTS

Caffeine increased startle eyeblink and skin conductance responses, as well as blood pressure and subjective arousal. Decaffeinated coffee increased startle eyeblink and skin conductance responses, but had no effect on subjective arousal, although the participants clearly expected increased subjective arousal after both one and two cups of coffee. However, there were significant correlations between the alertness expected after coffee, and the actual alertness recorded after decaffeinated coffee.

CONCLUSIONS

The main finding in this study was that relatively strong expectations about the effects of coffee did not generate placebo responses after administration of decaffeinated coffee. Expectations were dose dependent, whereas the placebo response was not. However, expected alertness after coffee predicted recorded alertness after coffee. In sum, the expectancy theory of placebo effects received only limited support.

Authors+Show Affiliations

Department of Psychology, SV-Fak, University of Tromsø, 9037 Tromsø, Norway. magnef@psyk.uit.noNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12759808

Citation

Flaten, Magne Arve, et al. "Expectations and Placebo Responses to Caffeine-associated Stimuli." Psychopharmacology, vol. 169, no. 2, 2003, pp. 198-204.
Flaten MA, Aasli O, Blumenthal TD. Expectations and placebo responses to caffeine-associated stimuli. Psychopharmacology (Berl). 2003;169(2):198-204.
Flaten, M. A., Aasli, O., & Blumenthal, T. D. (2003). Expectations and placebo responses to caffeine-associated stimuli. Psychopharmacology, 169(2), pp. 198-204.
Flaten MA, Aasli O, Blumenthal TD. Expectations and Placebo Responses to Caffeine-associated Stimuli. Psychopharmacology (Berl). 2003;169(2):198-204. PubMed PMID: 12759808.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Expectations and placebo responses to caffeine-associated stimuli. AU - Flaten,Magne Arve, AU - Aasli,Ole, AU - Blumenthal,Terry D, Y1 - 2003/05/21/ PY - 2003/01/27/received PY - 2003/03/18/accepted PY - 2003/5/22/pubmed PY - 2004/2/11/medline PY - 2003/5/22/entrez SP - 198 EP - 204 JF - Psychopharmacology JO - Psychopharmacology (Berl.) VL - 169 IS - 2 N2 - RATIONALE: To test the theory that expectations control placebo responses. OBJECTIVE: Subjects (n=20) were asked how much they expected their arousal to increase after one or two cups of coffee, and were subsequently exposed to one or two cups of decaffeinated coffee, or to caffeine equivalent to one or two cups of coffee (200 and 400 mg). The expectancy theory of placebo responses predicts a positive correlation between expectations and actual placebo responses. METHODS: Dependent variables were acoustic startle eyeblink and skin conductance responses, blood pressure and heart rate, and measures of subjective arousal. RESULTS: Caffeine increased startle eyeblink and skin conductance responses, as well as blood pressure and subjective arousal. Decaffeinated coffee increased startle eyeblink and skin conductance responses, but had no effect on subjective arousal, although the participants clearly expected increased subjective arousal after both one and two cups of coffee. However, there were significant correlations between the alertness expected after coffee, and the actual alertness recorded after decaffeinated coffee. CONCLUSIONS: The main finding in this study was that relatively strong expectations about the effects of coffee did not generate placebo responses after administration of decaffeinated coffee. Expectations were dose dependent, whereas the placebo response was not. However, expected alertness after coffee predicted recorded alertness after coffee. In sum, the expectancy theory of placebo effects received only limited support. SN - 0033-3158 UR - https://www.unboundmedicine.com/medline/citation/12759808/Expectations_and_placebo_responses_to_caffeine_associated_stimuli_ L2 - https://dx.doi.org/10.1007/s00213-003-1497-8 DB - PRIME DP - Unbound Medicine ER -