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.
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ABSTRACT: The purpose of this study was to evaluate the effects of acute, oral modafinil (200 mg) exposure on daytime sleepiness in methamphetamine (Meth)-dependent individuals. Eighteen Meth-dependent subjects were enrolled in a 7-d inpatient study and were administered placebo or modafinil on day 6 and the counter-condition on day 7 (randomized) of the protocol. Subjects completed several subjective daily assessments (such as the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Beck Depression Inventory and visual analogue scale) throughout the protocol as well as objective assessments on days 5-7, when the Multiple Sleep Latency Test was performed. The results of the current study suggest that short-term abstinence from Meth is associated with increased daytime sleepiness and that a single dose of 200 mg modafinil reduces daytime somnolence in this population. In addition, a positive correlation was found between subjective reporting of the likelihood of taking a nap and craving and desire for Meth, as well as the likelihood of using Meth and whether Meth would make the participant feel better. The results of this study should be considered when investigating candidate medications for Meth-dependence, especially in those individuals who attribute their Meth use to overcoming deficits resulting from sleep abnormalities.The International Journal of Neuropsychopharmacology 01/2012; 15(9):1241-9. DOI:10.1017/S1461145711001805 · 5.26 Impact Factor
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ABSTRACT: Methamphetamine affects the hippocampus, a brain region crucial for learning and memory, as well as relapse to drug seeking. Rats self-administered methamphetamine for 1 h twice weekly (intermittent-short-I-ShA), 1 h daily (limited-short-ShA), or 6 h daily (extended-long-LgA) for 22 sessions. After 22 sessions, rats from each access group were withdrawn from self-administration and underwent spatial memory (Y-maze) and working memory (T-maze) tests followed by extinction and reinstatement to methamphetamine seeking or received one intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) to label progenitors in the hippocampal subgranular zone (SGZ) during the synthesis phase. Two-hour-old and 28-day-old surviving BrdU-immunoreactive cells were quantified. I-ShA rats performed better on the Y-maze and had a greater number of 2-h-old SGZ BrdU cells than nondrug controls. LgA rats, but not ShA rats, performed worse on the Y- and T-maze and had a fewer number of 2-h-old SGZ BrdU cells than nondrug and I-ShA rats, suggesting that new hippocampal progenitors, decreased by methamphetamine, were correlated with impairment in the acquisition of new spatial cues. Analyses of addiction-related behaviors after withdrawal and extinction training revealed methamphetamine-primed reinstatement of methamphetamine-seeking behavior in all three groups (I-ShA, ShA, and LgA), and this effect was enhanced in LgA rats compared with I-ShA and ShA rats. Protracted withdrawal from self-administration enhanced the survival of SGZ BrdU cells, and methamphetamine seeking during protracted withdrawal enhanced Fos expression in the dentate gyrus and medial prefrontal cortex in LgA rats to a greater extent than in ShA and I-ShA rats. These results indicate that changes in the levels of the proliferation and survival of hippocampal neural progenitors and neuronal activation of hippocampal granule cells predict the effects of methamphetamine self-administration (limited vs extended access) on cognitive performance and relapse to drug seeking and may contribute to the impairments that perpetuate the addiction cycle.Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 12/2011; 37(5):1275-87. DOI:10.1038/npp.2011.315 · 7.83 Impact Factor
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ABSTRACT: Although methamphetamine and alcohol are commonly used together in a binge-like pattern, there is a dearth of empirical data investigating the repeated effects of this drug combination. The current study examined acute and residual mood, performance, and physiological effects of methamphetamine alone, alcohol alone, and the combination. Nine adult male volunteers completed this 20-day within-participant, residential laboratory study. During four 5-day blocks of sessions, participants were administered oral methamphetamine (0, 10 mg) combined with alcohol (0, 0.375, 0.75 g/kg) three times (day 2: AM, day 2: PM, and day 3: PM). Breath alcohol concentrations, cardiovascular, subjective, and cognitive/psychomotor performance effects were assessed before drug administration and repeatedly thereafter. Subjective and objective sleep measures were also assessed; residual effects were assessed on days 3-5 of each block. Following the first drug administration, the methamphetamine-alcohol combination produced greater elevations of heart rate and ratings of "good drug effect" compared to either drug alone. Methamphetamine attenuated alcohol-related performance decrements and feelings of intoxication, whereas alcohol attenuated methamphetamine-related sleep disruptions. By the third administration, many of these effects were significantly diminished, suggesting that participants developed tolerance. Few residual effects were observed. These data show that methamphetamine combined with alcohol produced a profile of effects that was different from the effects of either drug alone. The largely positive effects of the drug combination (i.e., greater euphoria, and fewer performance and sleep disruptions) might explain why these drugs are often used in combination.Psychopharmacology 07/2011; 219(1):191-204. DOI:10.1007/s00213-011-2390-5 · 3.99 Impact Factor