Cognitive enhancement
There is disagreement to whether the cognitive effects modafinil showed in healthy non-sleep-deprived people are sufficient to consider it to be a cognitive enhancer.[57][58][59] The researchers agree that modafinil improves some aspects of working memory, such as digit span, digit manipulation and pattern recognition memory, but the results related to spatial memory, executive function and attention are equivocal.[57][58][59][60]Some of the positive effects of modafinil may be limited to "lower-performing"[60] individuals.[61] One study found that modafinil restored normal levels of learning ability in methamphetamine addicts, but had no effect on non-addicts.[62]
There is evidence of neuroprotective effects in rats.[63]
Pharmacology
Despite extensive research into the interaction of modafinil with a large number of neurotransmitter systems, its precise mechanism or mechanisms of action remain unclear.[4][5] Modafinil elevates hypothalamic histamine levels,[6] leading some researchers to consider modafinil a "wakefulness promoting agent" rather than a classic amphetamine-like stimulant.[7] Modafinil seems to inhibit the actions of the dopamine transporter, thus leading to an increase in extracellular and thus synaptic concentrations of dopamine.[8]The locus of the monoamine action of modafinil has also been the target of studies, identifying effects on dopamine in the striatum and nucleus accumbens,[9][10] noradrenaline in the hypothalamus and ventrolateral preoptic nucleus,[11][12] and serotonin in the amygdala and frontal cortex.[13]
