Study Title and Description
Caffeine choice prospectively predicts positive subjective effects of caffeine and d-amphetamine.
Key Questions Addressed
|1||For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on behavior*?|
Primary Publication Information
|Title||Caffeine choice prospectively predicts positive subjective effects of caffeine and d-amphetamine.|
|Author||SC Sigmon,RR Griffiths,|
Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Behavior - Design Details - INCLUDED Studies
No arms have been defined in this extraction form.
|Question... Follow Up||Answer||Follow-up Answer|
|What outcome is being evaluated in this paper?||Behavior|
|What is the objective of the study (as reported by the authors)?||The present study sought to determine whether individual differences in caffeine choice prospectively predict subjective response to acute doses of caffeine and d-amphetamine.|
|Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods)||This double-blind, placebo-controlled study was 10–14 weeks in duration (including an initial 1-week caffeine abstinence period). Subjects were informed that its purpose was to examine how commonly-used medications may influence mood and medication preference and that they could receive placebo or a variety of commonly-prescribed or over-the-counter sedatives, stimulants or antihistamines. In Phase 1, Choosers and Nonchoosers of caffeine were identified using 10 independent choice trials in which subjects repeatedly chose between caffeine (200 mg/70kg) or placebo. The 30 sessions in Phase 1 were comprised of 10 sequences of 3 sessions (Sample-Sample-Choice) per sequence. Each test sequence began with two "no-choice" drug-sampling days during which participants received 2 different types of color-coded capsules on different days (e.g., red capsules on Monday and green capsules on Tuesday). Participants always received placebo on one sample day and caffeine anhydrous (200 mg/70 kg) on the other sample day, with the order of exposure to caffeine and placebo counterbalanced across trials. After leaving the laboratory, participants completed the DEQ at 1, 2, 4, and 8 hours after capsule ingestion, which assessed drug effects and drug liking (described in more detail below). On the subsequent "choice session" day, they were shown their self-report data from the prior two sample days to help them recall specific drug effects associated with each pair of capsules. They then chose to ingest one of the two color-coded capsule pairs. The content of the colorcoded capsules was always the same as during the preceding 2 sample sessions (one pair contained placebo and the other 200 mg caffeine anhydrous).Choosers were defined as those who chose caffeine over placebo on ≥ 7 of the 10 trials; Nonchoosers were those who chose placebo on ≥ 7 trials. In Phase 2, Choosers and Nonchoosers were compared in their subjective response to caffeine (100, 200, 400 mg/70kg) and d-amphetamine (5, 10, 20 mg/70kg). These sessions were similar to the drug sampling days of Phase 1 except that there was never an opportunity for choosing between capsules during Phase 2. Phase 2 capsules contained placebo, caffeine anhydrous (100, 200 or 400 mg/70 kg), or d-amphetamine sulfate (5, 10 or 20 mg/70 kg), with order of exposure to caffeine and d-amphetamine doses and to placebo counterbalanced across subjects and trials in a Latin Square sequence. Capsules were not color-coded but rather were identical across all 7 sessions. After leaving the laboratory, subjects completed the DEQ at 1, 2, 4 and 8 hours post-capsule|
|How many outcome-specific endpoints are evaluated?||5|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||Anxious|
|List additional health endpoints (separately).||Tired/Sluggish|
|List additional health endpoints (separately)|
|What is the study design?||Controlled Trial|
|Randomized or Non-Randomized?||NCT|
|What were the diagnostics or methods used to measure the outcome?||Subjective|
|Optional: Name of Method or short description||Drug effect questionnaire|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||Placebo vs various doses of caffeine|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||None stated|
|Provide a general description of results (as reported by the authors).||Examination of subjective response to caffeine and placebo for the total sample (N=22) during Phase 1 showed significant effects of drug (caffeine vs. placebo) on 16 items on the Drug Effect Questionnaire (F=5.02–23.14, p≤.05), and a significant drug x time interaction for 11 items (F=3.16–15.32, p≤.05). For most of these items, caffeine effects were significantly different from placebo at the 1-, 2- and 4-hr post-capsule timepoints. Ratings typically peaked at 2-hrs post-capsule, remained significantly elevated at 4 hrs and decreased thereafter, with 7 of these measures remaining significant at 8 hrs postadministration. Caffeine increased ratings on 14 items (i.e., Drug Effect, Arousing Effect, Good Effects, Bad Effects, Refreshed, Talkativeness, Anxious, Happy, Elated, Overjoyed, Energy/Active, Jittery/Shaky, Self-confidence and Heart pounding) and decreased ratings on 3 items (i.e., Depressant Effect, Drowsy, Tired/Sluggish). Examination of peak subjective effects of the seven drug conditions in Phase 2 for the total sample (N=22) showed significant effects of drug condition on 11 items (i.e., Drug Effect, Arousing Effect, Good Effects, Bad Effects, Talkativeness, Anxious, Jittery/Shaky, SelfConfidence, Overjoyed, Energy/Active and Pleased, F=2.27–8.65, p≤.05). For both caffeine and d-amphetamine, the magnitude of effects generally increased with dose, with the highest dose showing the largest effects. As shown in Figure 3, compared to placebo, both caffeine and d-amphetamine produced significant increases on ratings of Drug Effects, Arousing Effect and Good Effects, while only caffeine produced significant increases in Bad Effects (p≤.05). For rated items that showed significant effects of drug condition, but that are not shown in Figure 3, the high dose of caffeine significantly increased ratings of Anxious and Jittery/Shaky, whereas the high dose of d-amphetamine significantly increased ratings of Talkativeness, Overjoyed, Energy/Active and Jittery/Shaky.|
|Did the authors perform a dose-response analysis (or trend/related analysis)?||No|
|What were the authors's observations re: trend analysis?|
|What were the author's conclusions?||In phase 1, the subjective effects of caffeine during sampling sessions differed between caffeine Choosers and Nonchoosers, with Choosers reporting significantly more positive effects and Nonchoosers more unpleasant effects of caffeine. Previous choice or reinforcement studies with caffeine reporting subjective effect differences are difficult to interpret because they have been confounded by the subjective effects of caffeine abstinence (Griffiths and Woodson, 1988; Stern et al., 1989). The differences between Choosers and Nonchoosers in the present study are analogous to subjective effect differences noted with drugs such as amphetamine and diazepam which were also tested in the absence of physical dependence (de Wit et al., 1986). A primary aim of the present study was to determine whether individual differences in caffeine choice prospectively predict subjective effects of d-amphetamine. In Phase 2, caffeine Choosers (as determined in Phase 1) reported significantly more positive (i.e., pleasant) subjective effects of caffeine and d-amphetamine, particularly at the highest doses, in contrast to Nonchoosers who reported more negative (i.e., unpleasant effects).|
|What were the sources of funding?||Funding for this study was provided by grants R01-DA03890 (RRG) and T32-DA07209 (GEB) from the National Institute on Drug Abuse (NIDA). The NIDA had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the paper for publication.|
|What conflicts of interest were reported?||The authors have no known conflicts of interest related to this work, have full control of all primary data and agree to allow the journal to review our data if requested.|
|Does the exposure (dose) need to be standardized to the SR?||No|
|Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).|
|List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot. Characterize value as LOAEL/NOAEL, etc. if possible.||Phase 1: Anxious LOAEL = 200 mg/d Jittery/shaky LOAEL = 200 mg/d Depressant Effect NOAEL = 200 mg/d Drowsy NOAEL = 200 mg/d Tired/Sluggish NOAEL = 200 mg/d Phase 2: Anxious LOAEL = 400 mg/d Anxious NOAEL = 200 mg/d Jittery/shaky LOAEL = 400 mg/d Jittery/shaky NOAEL = 200 mg/d Depressant Effect NOAEL = 400 mg/d Drowsy NOAEL = 400 mg/d Tired/Sluggish NOAEL = 400 mg/d|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||Uncertain if LOAELs for Anxious and Jittery/shaky are based on a significant association from Phase 1. In Phase 2 significant increases in ratings for anxious and Jittery/shaky were not observed at 200 mg/d showing inconsistency within the study. Phase 1 of the study only included one exposure level (200 mg/d) while phase 2 included 100, 200, or 400 mg/d dose levels.|
|What is the importance of the study with respect to the adverseness of the outcome?||Important|
No baseline characteristics have been defined for this extraction form.
Results & Comparisons
No Results found.
|Arm or Total||Title||Description||Comments|
No quality dimensions were specified.
No quality rating data was found.