Is Methylphenidate Beneficial and Safe in Pharmacological Cognitive Enhancement?

Nootropics are drugs used to either treat or benefit cognition deficits. Among this class, methylphenidate is a popular agent, which acts through indirect dopaminergic and noradrenergic agonism and, therefore, is proposed to enhance performance in catecholamine-dependent cognitive domains such as attention, memory and prefrontal cortex-dependent executive functions. However, investigation into the efficacy of methylphenidate as a cognitive enhancer has yielded variable results across all domains, leading to debate within the scientific community surrounding its off-label use in healthy individuals seeking scholaristic benefit or increased productivity. Through analysis of experimental data and methodological evaluation, it is apparent that there are dose-, task- and domain-dependent considerations surrounding the use of methylphenidate in healthy individuals, whereby tailored dose administration is likely to provide benefit on an individual basis dependent on the domain of cognition in which benefit is required. Additionally, it is apparent that there are subjective effects of methylphenidate, which may increase user productivity irrespective of cognitive benefit. Whilst there is not extensive study in healthy older adults, it is plausible that there are dose-dependent benefits to methylphenidate in older adults in selective cognitive domains that might improve quality of life and reduce fall risk. Methylphenidate appears to produce dose-dependent benefits to individuals with attention-deficit/hyperactivity disorder, but the evidence for benefit in Parkinson's disease and schizophrenia is inconclusive. As with any off-label use of pharmacological agents, and especially regarding drugs with neuromodulatory effects, there are inherent safety concerns; epidemiological and experimental evidence suggests there are sympathomimetic, cardiovascular and addictive considerations, which might further restrict their use within certain demographics.

Bright light and LEET effects on circadian rhythms, sleep and cognitive performance

Shift work and jet lag can disrupt cicadian rhythms, with detrimetnal effects on alertness, performance and sleep. This study examined the effects of two interventions to adapt circadian rhythms, sleep and performance to a 10-h phase delay of the work-rest cycle. Bright light was administered from 2200 to 0200 each night to promote phase delay of circadian rhythms. Low energy emission therapy (LEET) was administered for 20 min prior to daytime sleep periods to promote sleep. Twelve subjects received bright light, 12 subjects received LEET, 11 received both interventions and 10 control subjects received only placebo treatments. Bright light accelerated phase delay of the circadian melatonin rhythms after the work-rest schedule shift. Further, subjects who received bright light had greater total sleep time (TST) and improved sleep continuity. LEET treatment produced a trend (p = 0.16) for increased TST, but LEET did not affect the melatonin circadian rhythm. After the schedule shift, cognitive performance measures showed few significant differences. Some minor improvements in cognitive performance were producced by light treatments but not by LEET.

Interest of modafinil, a new psychostimulant, during a sixty-hour sleep deprivation experiment

Modafinil, a new psychostimulant, was evaluated in eight healthy volunteers subjected to 60 hours of sleep deprivation. During continued wakefulness, vigilance was evaluated by self-assessment questionnaires, analogue visual scales, multiple sleep latency tests (MSLT), sleep logs, and continuous ambulatory electroencephalographic recordings (EEG). Modafinil (200 mg) or a placebo was given every 8 hours for three days; the sessions were separated by a 15 day wash out period. Results indicated a satisfactory level of vigilance, both subjective and objective, after the administration of modafinil, characterised by the quasi total absence of microsleep episodes which gradually occurred under placebo conditions. The confirmed wakening potency of modafinil makes this substance suitable for therapeutic use in patients with sleep disorders such as Gelineau's syndrome and hypersomnia.

Some measures to reduce effects of prolonged sleep deprivation

Prolonged sleep deprivation is an exceptional situation, encountered in special environments such as sports, civilian and military, and which induces deficits in vigilance and performance. Among the array of measures which may be used to counteract these effects, the authors described a protocol using the combination of small naps, and administration of a pharmacological aid. A detailed description of advantages and drawbacks of each one of these measures is given, illustrated by several examples extracted from different studies. Four aspects of pharmacological aid are reviewed: the effects of amphetamines and amphetamine-like substances, caffeine, eugregoric substances, and the effect of the association small nap + eugregoric substances. The use of these various aids is discussed, and findings show that each one of them finds an application in a specific context.