Methamphetamine attenuates disruptions in performance and mood during simulated night-shift work.
ABSTRACT Increased sleepiness while working and sleep disruptions are common complaints among shift workers. Consequently, shift workers may be more susceptible to diminished performance and work-related accidents.
To examine the effects of the central nervous system stimulant methamphetamine on psychomotor task performance, subjective effects, and food intake during shift work under laboratory conditions.
Seven participants completed this 23-day, within-participant design, residential laboratory study. They received a single oral methamphetamine dose (0, 5, 10 mg) 1 h after waking for three consecutive days under two shift conditions: (1) during the day shift, participants performed computerized psychomotor tasks from 0830 hours to 1730 hours and went to bed at 2400 hours and (2) during the night shift, participants performed tasks from 0030 hours to 0930 hours and went to bed at 1600 hours. Shifts alternated three times during the study; shift conditions were separated by an "off" day during which participants were not on a schedule and data were not collected.
When participants received placebo, psychomotor task performance and subjective effects were disrupted during the night shift, relative to the day shift. Changing shift conditions did not alter food intake significantly. Methamphetamine reversed performance and subjective-effects disruptions, and decreased food intake during the night shift.
These data indicate that shift changes produce performance impairments and mood alterations, and that a single low to moderate dose of methamphetamine attenuates many shift change-related disruptions in performance and mood.
- SourceAvailable from: Margaret Haney[show abstract] [hide abstract]
ABSTRACT: Although methamphetamine use has increased over the past several years, few studies have evaluated the effects of repeated methamphetamine administration in humans. Because methamphetamine is often taken in a pattern of repeated use followed by a period of abstinence, the present study sought to evaluate the effects of repeated methamphetamine administration in humans. The hypothesis was that tolerance would develop to methamphetamine's effects. Seven normal, healthy volunteers participated in a 15-day residential study. Participants completed subjective-effects questionnaires and psychomotor performance tasks repeatedly throughout the experimental day. Oral methamphetamine (5, 10 mg BID) was administered on days 4-6 and 10-12; placebo was administered on all other study days. Relative to placebo baseline, only two "positive" subjective ratings ("I feel a good drug effect" and "I feel high") were significantly elevated, and only on the 1st day of methamphetamine administration. In contrast, numerous "negative" ratings, including "I feel..." "a bad drug effect," "dizzy," and "flu-like symptoms" were elevated on the 3rd day of methamphetamine administration. Total caloric intake decreased and sleep was disrupted after methamphetamine administration, relative to baseline. The pattern of methamphetamine's positive subjective effects were altered with chronic administration such that tolerance, or a decreased effect, occurred after repeated administration. In contrast, methamphetamine's negative subjective effects increased over days. These results suggest that in this population of normal volunteers, the abuse liability of oral methamphetamine is relatively low.Psychopharmacology 07/2001; 155(4):397-404. · 4.06 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: In this paper two experiments are reported which were designed to investigate the effects of smoking on the performance of a rapid information processing task. The task involves the detection of sequences of three consecutive digits of the same parity from a series of digits presented visually at the rate of 100/min. In the first experiment smoking improved both the speed and accuracy of performance above rested baseline levels, the greatest improvement occurring with the highest nicotine and tar delivery cigarette. In the second experiment smoking again improved the speed and accuracy of performance above baseline levels, while performance deteriorated over time after not smoking as well as after smoking a nicotine-free cigarette. These findings demonstrate that smoking produces absolute improvements in performance and are explained in terms of the action of nicotine on central cholinergic pathways.Neuropsychobiology 02/1983; 9(4):223-9. · 2.37 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Although the ability to perform complex cognitive operations is assumed to be impaired following acute marijuana smoking, complex cognitive performance after acute marijuana use has not been adequately assessed under experimental conditions. In the present study, we used a within-participant double-blind design to evaluate the effects acute marijuana smoking on complex cognitive performance in experienced marijuana smokers. Eighteen healthy research volunteers (8 females, 10 males), averaging 24 marijuana cigarettes per week, completed this three-session outpatient study; sessions were separated by at least 72-hrs. During sessions, participants completed baseline computerized cognitive tasks, smoked a single marijuana cigarette (0%, 1.8%, or 3.9% Delta(9)-THC w/w), and completed additional cognitive tasks. Blood pressure, heart rate, and subjective effects were also assessed throughout sessions. Marijuana cigarettes were administered in a double-blind fashion and the sequence of Delta(9)-THC concentration order was balanced across participants. Although marijuana significantly increased the number of premature responses and the time participants required to complete several tasks, it had no effect on accuracy on measures of cognitive flexibility, mental calculation, and reasoning. Additionally, heart rate and several subjective-effect ratings (e.g., "Good Drug Effect," "High," "Mellow") were significantly increased in a Delta(9)-THC concentration-dependent manner. These data demonstrate that acute marijuana smoking produced minimal effects on complex cognitive task performance in experienced marijuana users.Neuropsychopharmacology 12/2001; 25(5):757-65. · 8.68 Impact Factor