title: Effects of caffeine on alcohol reinforcement: beverage choice, self-administration, and subjective ratings.
abstract: Combining alcohol and caffeine is associated with increased alcohol consumption, but no prospective experimental studies have examined whether added caffeine increases alcohol consumption.
  
  
  
  This study examined how caffeine alters alcohol self-administration and subjective reinforcing effects in healthy adults.
  
  
  
  Thirty-one participants completed six double-blind alcohol self-administration sessions: three sessions with alcohol only (e.g., beverage A) and three sessions with alcohol and caffeine (e.g., beverage B). Participants chose which beverage to consume on a subsequent session (e.g., beverage A or B). The effects of caffeine on overall beverage choice, number of self-administered drinks, subjective ratings (e.g., Biphasic Alcohol Effects Scale), and psychomotor performance were examined.
  
  
  
  A majority of participants (65%) chose to drink the alcohol beverage containing caffeine on their final self-administration session. Caffeine did not increase the number of self-administered drinks. Caffeine significantly increased stimulant effects, decreased sedative effects, and attenuated decreases in psychomotor performance attributable to alcohol. Relative to nonchoosers, caffeine choosers reported overall lower stimulant ratings and reported greater drinking behavior prior to the study.
  
  
  
  Although caffeine did not increase the number of self-administered drinks, most participants chose the alcohol beverage containing caffeine. Given the differences in subjective ratings and pre-existing differences in self-reported alcohol consumption for caffeine choosers and nonchoosers, these data suggest that decreased stimulant effects of alcohol and heavier self-reported drinking may predict subsequent choice of combined caffeine and alcohol beverages. These predictors may identify individuals who would benefit from efforts to reduce risk behaviors associated with combining alcohol and caffeine.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224, USA. marymsweeney@jhmi.edu.
authors.forename: Mary M
authors.initials: MM
authors.lastname: Sweeney
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224, USA.|University of Connecticut Health Center, Calhoun Cardiology Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Meredith
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224, USA.|Defense Centers of Excellence for Psychological Health and Traumatic Brain Injury, 1335 East-West Highway, Silver Spring, MD, 20910, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Evatt
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Behavioral Pharmacology Research Unit, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224, USA.|Department of Neuroscience, Johns Hopkins University School of Medicine, 5510 Nathan Shock Drive, Baltimore, MD, 21224, USA.
authors.forename: Roland R
authors.initials: RR
authors.lastname: Griffiths
mesh_terms: D000328:Adult; D000428:Alcohol Drinking; D000434:Alcoholic Beverages; D001944:Breath Tests; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002755:Choice Behavior / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects*; D012054:Reinforcement, Psychology; D012309:Risk-Taking; D012646:Self Administration; D057566:Self Report; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine
keywords: Alcohol; Alcohol reinforcement; AmED; Caffeine; Caffeine and alcohol; Energy drinks; Human; Sedative effects; Self-administration; Stimulant effects