Motor excitability and motor behaviour after modafinil ingestion ? a double-blind placebo-controlled cross-over trial

Effect of psychostimulant medications on physical function in children with cerebral palsy: scoping review

The aim of this scoping review is to examine the extent and depth of the literature on effects of central nervous system (CNS) stimulant medications on physical function in children with cerebral palsy (CP). A systematic search for relevant peer-reviewed studies was conducted of PubMed, CINAHL, Cochrane, SPORTDiscus, Embase, & Scopus (January 2002 & August 2022). We included studies that examined the effects of CNS stimulants on physical function in children with CP. Four studies met our selection criteria. All studies explored the effect of Modafinil on physical function outcomes. Three studies of the four included studies reported positive effects of Modafinil on spasticity, motor performance, and gait, whereas one study reported no significant effects of Modafinil. Our findings suggest that there is very low-quality evidence that suggests that Modafinil may enhance physical improvements in body structure and function, including reduction in spasticity and improvements in gait parameters. IMPACT: Central nervous system stimulants were examined for efficacy on physical function and spasticity in children with cerebral palsy. The evidence on the effects of central nervous system stimulants on physical function in children with CP is limited and inconsistent.

Modafinil for cognitive neuroenhancement in healthy non-sleep-deprived subjects: A systematic review

Modafinil is an FDA-approved eugeroic that directly increases cortical catecholamine levels, indirectly upregulates cerebral serotonin, glutamate, orexin, and histamine levels, and indirectly decreases cerebral gamma-amino-butrytic acid levels. In addition to its approved use treating excessive somnolence, modafinil is thought to be used widely off-prescription for cognitive enhancement. However, despite this popularity, there has been little consensus on the extent and nature of the cognitive effects of modafinil in healthy, non-sleep-deprived humans. This problem is compounded by methodological discrepancies within the literature, and reliance on psychometric tests designed to detect cognitive effects in ill rather than healthy populations. In order to provide an up-to-date systematic evaluation that addresses these concerns, we searched MEDLINE with the terms "modafinil" and "cognitive", and reviewed all resultant primary studies in English from January 1990 until December 2014 investigating the cognitive actions of modafinil in healthy non-sleep-deprived humans. We found that whilst most studies employing basic testing paradigms show that modafinil intake enhances executive function, only half show improvements in attention and learning and memory, and a few even report impairments in divergent creative thinking. In contrast, when more complex assessments are used, modafinil appears to consistently engender enhancement of attention, executive functions, and learning. Importantly, we did not observe any preponderances for side effects or mood changes. Finally, in light of the methodological discrepancies encountered within this literature, we conclude with a series of recommendations on how to optimally detect valid, robust, and consistent effects in healthy populations that should aid future assessment of neuroenhancement.

Modafinil reverses hypoexcitability of the motor cortex in narcoleptic patients: a TMS study

OBJECTIVE

Although many animal and human studies have been performed, the exact mechanisms of action whereby modafinil promotes wakefulness are still not completely understood. We aimed to investigate the functional effects of modafinil on motor cortex excitability in patients with narcolepsy by means of transcranial magnetic stimulation (TMS) techniques.

METHODS

In a double-blind and placebo-controlled design, 24 drug-naive narcoleptic patients with cataplexy and 20 control subjects were administered modafinil or placebo over a period of 4 weeks. TMS was performed twice during the awake state before and at the end of treatment; measures of cortical excitability included central motor conduction time, resting motor threshold, short latency intracortical inhibition (SICI) and intracortical facilitation to paired-TMS. TMS measures were correlated with the conventional neurophysiological method of Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS).

RESULTS

As previously reported, motor threshold and SICI were significantly increased in patients with narcolepsy; modafinil reversed this cortical hypoexcitability, but only SICI differences reached statistical significance. The Spearman rank correlation analysis revealed the highest correlation between SICI and the MSLT; a positive correlation was also found between SICI and the ESS, as well as between RMT and both measures of daytime sleepiness.

CONCLUSIONS

This represents the first report investigating effects of modafinil on cortical excitability in human narcolepsy. Since SICI is thought to be directly related to GABA(A) intracortical inhibitory activity, we demonstrated that the dose of modafinil that induces a satisfactory wakefulness-promoting response in narcoleptic patients also causes decrease in GABAergic transmission.

State of the art: Pharmacologic effects on cortical excitability measures tested by transcranial magnetic stimulation

The combination of brain stimulation techniques like transcranial magnetic stimulation (TMS) with CNS active drugs in humans now offers a unique opportunity to explore the physiologic effects of these substances in vivo in the human brain. Motor threshold, motor evoked potential size, motor evoked potential intensity curves, cortical silent period, short-interval intracortical inhibition, intracortical facilitation, short-interval intracortical facilitation, long-interval intracortical inhibition and short latency afferent inhibition represent the repertoire for investigating drug effects on motor cortical excitability by TMS. Here we present an updated overview on the pharmacophysiologic mechanisms with special emphasis on methodologic pitfalls and possible future developments or requirements.

Cognitive effects of modafinil in student volunteers may depend on IQ

The results of two previous studies on the effects of modafinil, a selective wakefulness-promoting agent, in healthy university students were combined in a retrospective analysis. This allowed determination of whether the effects of modafinil were dependent on IQ and whether the larger sample size (n=89) would reveal more cognitive benefits. A battery of cognitive tests was completed 2-3 h after dosing. In the whole sample, modafinil (200 mg) significantly reduced the number of missed targets in a test of sustained attention (RVIP). However, interestingly, several interactions between modafinil and IQ emerged. Modafinil (100 and 200 mg) significantly improved target sensitivity in the RVIP test, but only in the group of 'lower' IQ (mean+/-sem=106+/-0.6), not in the 'higher' IQ group (mean+/-sem=115.5+/-0.5). Furthermore, there were significant modafinil x IQ interactions in two further tests. Modafinil significantly reduced speed of responding in a colour naming of dots, and in clock drawing, but only in the 'lower' IQ group. Thus, the cognitive benefits of modafinil seem particularly marked in tests of vigilance and speed, in which sleepiness would be an important factor. Furthermore, the results indicate that high IQ may limit detection of modafinil's positive effects.