Biomedical subjects

Harriet de Wit

Publications and source records attributed to Harriet de Wit.

43 records · Page 3Linked to original sources

PubMed2002

Differential subjective effects of D-amphetamine by gender, hormone levels and menstrual cycle phase.

Estrogen and progesterone interact with monoamines in ways that suggest the potential modulation of responses to psychoactive drugs by endogenous steroids, both between menstrual phases and between the sexes. The present study assessed the subjective and physiological effects of a single dose of D-amphetamine (AMPH; 15 mg oral) in healthy, normally cycling women (n=13), who received amphetamine and placebo (PL) during both the follicular and luteal phases of a single menstrual cycle, and in healthy men (n=7). Females reported greater amphetamine-induced subjective stimulation [Addiction Research Center Inventory (ARCI)-A, ARCI-MBG; Drug Effects Questionnaire (DEQ) Feel Drug, Feel High, Want More] during the follicular phase than the luteal phase. Within the follicular phase, the magnitude of individuals' AMPH-induced stimulation was positively associated with baseline (predrug) salivary estradiol [r=+.55-.78; Profile of Mood States (POMS) Vigor, Positive Mood, Elation], and negatively associated with salivary progesterone [r=-.66-.68; POMS Friendliness; Subjective States Questionnaire (SSQ) Pleasant Sedation]. Sex differences also emerged. Males reported feeling greater AMPH-induced stimulation (ARCI-A, ARCI-MBG; DEQ Feel Drug, Want More) than females in the luteal phase. Thus, higher levels of estrogen and lower levels of progesterone are associated with greater subjective stimulation after AMPH in women, and these hormonal influences contribute to sex differences in amphetamine responding.

Adolescent↗

PubMed2002

Acute administration of d-amphetamine decreases impulsivity in healthy volunteers.

This study investigated the acute behavioral effects of d-amphetamine on several behavioral indices of impulsivity. Impulsivity has been defined, variously, as difficulty in inhibiting inappropriate behaviors, inability to wait, insensitivity to delayed consequences or an alteration in the perception of time; standardized procedures have been developed to measure these behavioral dimensions. However, it is not known how drugs affect these measures, and few studies have examined more than one measure in a single study. In this study, 36 healthy men and women participated in three sessions, in which they received placebo, 10 mg, or 20 mg d-amphetamine in randomized order. On each session they performed the following five tasks: the Stop Task, which measures behavioral inhibition, a delay discounting task, which measures the relative value of immediate vs. delayed rewards, a delay of gratification task, a Go/No-Go task, and a time estimation task. Subjects also completed mood questionnaires. Amphetamine produced its expected subjective, mood-altering effects, including increases in POMS Friendliness and Elation scales, and ARCI Euphoria and Stimulant scales. On the measures of impulsivity, amphetamine decreased impulsive responding on three of the tasks: on the Stop Task it decreased Stop reaction times without affecting Go reaction time, on the Go/No-Go task, it decreased the number of false alarms, and on the delay discounting measure, amphetamine (20 mg) decreased k values indicating less discounting of delayed reward. Other measures of impulsive behavior were unaffected. These results suggest that acute doses of amphetamine decrease several forms of impulsive behavior. These findings extend and confirm previous findings in humans and laboratory animals.

Adolescent↗

PubMed2002

Effects of stress and alcohol on subjective state in humans.

BACKGROUND: There is increasing evidence that stress and hypothalamic-pituitary-adrenal axis activation interact with drugs of abuse and influence drug-taking behaviors. Both studies with laboratory animals and survey data with alcohol users suggest that acute or chronic stressful events increase alcohol intake. One mechanism for the increase in alcohol intake may be that stress alters the subjective effects produced by the drug in ways that enhance the reinforcing properties of alcohol. Therefore, in this study we determined whether an acute social stressor alters subjective responses to ethanol in humans. The stressor was a modified version of the Trier Social Stress Test, an arithmetic task that increases cortisol levels. METHODS: Twenty male volunteers participated in two laboratory sessions, in which they performed the Trier Social Stress Test on one session and no task on the other session, immediately before consuming a beverage that contained ethanol (0.8 g/kg in juice) or placebo (juice alone). Eleven subjects received ethanol on both sessions, and nine subjects received placebo on both sessions. Primary dependent measures were self-report questionnaires of mood states. Salivary levels of cortisol were obtained to confirm the effectiveness of the stress procedure. RESULTS: Stress alone produced stimulant-like subjective effects. In the group who received ethanol, stress increased sedative-like effects and decreased stimulant-like effects. CONCLUSIONS: At this relatively high dose of ethanol, stress increased sedative effects of alcohol and did not increase desire for more alcohol. It is possible that in some individuals, the increased sedative effects after stress may increase the likelihood of consuming more alcohol. The effects of stress on consumption at this, or lower, doses of alcohol remain to be determined.

Adult↗

PubMed2002

Biphasic alcohol response differs in heavy versus light drinkers.

BACKGROUND: Most studies of risk factors for alcohol-related problems have focused on biological family history as a primary risk factor. However, other factors, such as early-age heavy drinking, are also risk factors for sustained or progressive heavy consumption. Little is currently known about the mechanisms underlying binge or heavy drinking. METHODS: This study examined the acute subjective and objective effects of ethanol in heavy drinkers versus light drinkers. Thirty-four subjects participated in this within-subjects study consisting of three early-evening testing sessions in which subjects consumed a beverage containing either 0.8 or 0.4 g/kg ethanol or placebo. RESULTS: Compared with lighter drinkers, heavy drinkers were more sensitive to the positive stimulant-like effects of ethanol (p < 0.05), especially during the increasing limb of the blood alcohol curve. Heavy drinkers also showed less sedation and cortisol response after alcohol than the light drinkers (p < 0.05). CONCLUSIONS: The results indicate that young adult binge drinkers show a biphasic alcohol response, with heightened sensitivity to stimulant-like alcohol effects and greater tolerance to sedative alcohol effects compared with their light-drinking counterparts.

Adult↗

PubMed2000

Effects of d-amphetamine and alcohol on a measure of behavioral inhibition in rats.

This study was designed to develop a version of the stop task, a putative measure of behavioral inhibition, for use in rats and to assess the effects of d-amphetamine (AMP) and alcohol (ALC). The stop task provides a quantitative index of the ability to inhibit a response that has been initiated. Rats (N = 11) were tested after intraperitoneal injections of AMP (0.125, 0.25, 0.5, 1.0 mg/kg) and ALC (250, 500, 750 mg/kg). AMP improved the ability to inhibit responses only in rats with relatively poor inhibitory performance at baseline. ALC impaired inhibition at doses that did not affect simple reaction time. The results support the sensitivity, reliability, and validity of the procedure as a measure of behavioral inhibition in rats and are highly concordant with a parallel study conducted with humans.

Animals↗

PubMedDate not supplied

Lack of effects of acute estradiol on mood in postmenopausal women.

Chronic treatment with estrogen is believed to improve mood in postmenopausal women, and recent preclinical evidence suggests that estradiol may also affect mood and behavior through acute neuronal membrane-mediated effects on the central nervous system. This study was designed to characterize potential mood effects of single doses of transdermal estradiol in healthy postmenopausal women who were not taking hormone replacement therapy (HRT). Twelve women participated in a five-session, within-subjects, double-blind study, in which they received placebo, transdermal estradiol (0.2, 0.4, and 0.8 mg), or D-amphetamine (15 mg, oral) in a randomized order. Amphetamine was included as a positive control. Dependent measures included self-report measures of mood, physiological measures, and plasma hormone levels. Despite dose-dependent increases in plasma estradiol levels, and despite the fact that D-amphetamine produced its prototypic stimulant-like effects in these postmenopausal women, estradiol did not produce effects on mood. The finding that acute administration of exogenous estradiol did not alter mood suggests that more chronic exposure to estradiol is needed to produce mood-enhancing effects.

Affect↗

PubMedDate not supplied

Serotonin transporter genotype and acute subjective response to amphetamine.

The authors have previously shown an effect of dopamine transporter genotype on acute subjective responses to d-amphetamine, which may affect risk of addiction. They now report the results of an evaluation of the role of the serotonin transporter gene (HTT) using a double-blind, placebo-controlled, crossover design in which subjects (N = 101) completed self-report measures of subjective effect. The separate and combined analyses of the gene-linked polymorphic region (5-HTTLPR) and the Intron 2 VNTR suggest that these two HTT polymorphisms may contribute to acute subjective responses to d-amphetamine with a small effect.

Adolescent↗