Caffeine expectancies influence the subjective and behavioral effects of caffeine
Harrell PT, Juliano LM
Psychopharmacology · 32 citas
Etiquetas de revisión
Financiación no declaradaDatos neutrales que nuestra revisión registró sobre cómo se hizo este estudio. Describen el método, nunca si nos gusta el resultado.
Cómo se estudió
- Diseño
- Ensayo controlado aleatorizado (indexado por PubMed)
- Estudiado en
- Personas
- Resultado principal
- Marcadores de salud y funcionamiento
Quién lo pagó
- Financiación
- Financiación no declarada
Publicación
- Publicado
- 2009-09-16 · Psychopharmacology (Berl) · vol. 207 · número 2 · págs. 335–342
- Editorial
- Springer Science+Business Media
- Citado
- 55 citas · más que el 89% de estudios similares · 2.8× el promedio de su campo
- Referencias
- 31 trabajos
- Acceso
- De pago
- Áreas de investigación
- Coffee research and impacts · Pain Management and Placebo Effect · Neurotransmitter Receptor Influence on Behavior
- Palabras clave
- caffeine, expectancy effects, placebo effect, caffeine withdrawal, sustained attention, reaction time, psychomotor performance, mood, caffeine dose
- MeSH
- humans, substance withdrawal syndrome, caffeine, central nervous system stimulants, double-blind method, affect, psychomotor performance, attention, coffee, female, male, young adult
2 autores
- Paul Truman Harrell🇺🇸American University
- Laura M. Juliano🇺🇸 · autor de correspondenciaAmerican University
Resumen
El texto original del estudio, en el idioma en que se publicó.
Objectives
This study investigated the independent and interactive effects of caffeine pharmacology and expected effects of caffeine on performance and subjective outcomes.
Methods
Abstinent coffee drinkers (n = 60) consumed decaffeinated coffee with either 280 mg or 0 mg added caffeine. Caffeine dose was crossed with varying instructions that the coffee would either enhance or impair performance in a 2 x 2 factorial design. Performance, mood, caffeine withdrawal, and negative somatic effects were assessed.
Results
Relative to placebo, caffeine improved reaction time and accuracy on the rapid visual information processing task, a measure of vigilance. However, there was a significant dose by expectancy interaction that revealed that among participants given placebo coffee, "impair" instructions produced better performance than "enhance" instructions. Caffeine also improved psychomotor performance as indicated by a finger tapping task with no main effects of expectancy or interactions. Impair instructions produced greater reports of negative somatic effects than enhance instructions, but only when caffeine was administered.
Conclusions
Manipulating the expected effects of caffeine altered the behavioral and subjective effects of caffeine. A significant dose by expectancy interaction revealed a somewhat paradoxical outcome in the placebo conditions whereby those told "impair" performed better than those told "enhance." This may reflect compensatory responding as has been observed in similar studies using alcohol (Fillmore et al. Psychopharmacology 115:383-388, 1994). Impair instructions led to greater negative somatic effects only when caffeine was administered supporting the active placebo hypothesis.
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