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  • 1
    ISSN: 1432-2072
    Keywords: Balanced placebo design ; Expectancy ; d-Amphetamine ; Subjective effects ; Self-administration ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The study examined the effects of expectation on the subjective effects and oral self-administration of 15 mgd-amphetamine (AMP) and placebo in 40 volunteers who reported no prior use of stimulants other than caffeine. A balanced placebo design was used to create four groups: told Placebo/got Placebo (P/P), told Placebo/got Stimulant (P/S), told Stimulant/got Placebo (S/P), told Stimulant/got Stimulant (S/S). There were three sessions. On one session (INFO), participants received a capsule containing AMP or placebo and were given information about the contents of the capsule according to the balanced placebo design. On another session (NO INFO), participants received no information about the capsule's contents and were given placebo. On the final session, participants were allowed to choose either the INFO or NO INFO capsule. Participants came to the laboratory to ingest their capsules, and then returned to their normal environments where they completed subjective effects questionnaires every 2 h for 8 h. Expectancies influenced the subjective effects reported during the INFO session, regardless of whether subjects actually received AMP or placebo: subjects who expected a stimulant had higher ratings of “feel drug” and “like drug”. The pharmacological effects of AMP were also evident on the INFO sessions: AMP produced its prototypic subjective effects regardless of subjects' expectancies. Significant interactions between drug and expectancy were obtained on self-report measures of anxiety and arousal: anxiety was higher for groups who received substances that did not match their expectations (P/S and S/P) and arousal increased most in volunteers who expected placebo but received stimulant. Choice of drug was determined primarily by pharmacology: participants who received AMP on the INFO session usually chose that capsule, regardless of information about its identity (P/S: 8/10; S/S: 9/10). In contrast, participants who received placebo on the INFO session chose this capsule at chance levels, regardless of information about its identity (S/P: 3/10; P/P: 6/10). Thus, expectancy influenced some of the subjective effects of AMP and placebo, but the pharmacological effects of the AMP were instrumental in determining whether volunteers would self-administer the drug.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 145 (1999), S. 67-75 
    ISSN: 1432-2072
    Keywords: Key words Menstrual cycle ; Estrogen ; Progesterone ; d-Amphetamine ; Subjective effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: Little is known about the interactions between ovarian hormones across the menstrual cycle and responses to psychoactive drugs in humans. Preclinical studies suggest that ovarian hormones such as estrogen and progesterone have direct and indirect central nervous system actions, and that these hormones can influence behavioral responses to psychoactive drugs. Objectives: In the present study, we assessed the subjective and behavioral effects of d-amphetamine (AMPH; 15 mg orally) at two hormonally distinct phases of the menstrual cycle in women. Methods: Sixteen healthy women received AMPH or placebo capsules during the follicular and mid-luteal phases of their cycle. During the follicular phase, estrogen levels are low initially and then rise while progesterone levels remain low. During the mid-luteal phase, levels of both estrogen and progesterone are relatively high. Dependent measures included self-report questionnaires, physiological measures and plasma hormone levels. Results: Although there were no baseline differences in mood during the follicular or luteal phase, the effects of AMPH were greater during the follicular phase than the luteal phase. During the follicular phase, subjects reported feeling more “High”, “Energetic and Intellectually Efficient”, and “Euphoric” after AMPH than during the luteal phase, and also reported liking and wanting AMPH more. Further analyses showed that during the follicular phase, but not the luteal phase, responses to AMPH were related to levels of estrogen. Higher levels of estrogen were associated with greater AMPH-induced increases in “Euphoria” and “Energy and Intellectual Efficiency”. During the luteal phase, in the presence of both estrogen and progesterone, estrogen levels were not related to the effects of AMPH. Conclusions: These findings suggest that estrogen may enhance the subjective responses to a stimulant drug in women, but that this effect may be masked in the presence of progesterone.
    Type of Medium: Electronic Resource
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