Nutraceuticals as Cognitive Enhancers

Pharmaceutical cognitive enhancers tend to target single or classes of neurotransmitters. Given that most cognitive functions are the expression of multiple physiological processes, it is unsurprising that classic drug development has resulted in a few effective cognitive enhancers. At the same time there are well-characterised botanical extracts which appear to influence numerous neurotransmitter, neurohormonal and neurovascular processes involved in cognition. While many of these botanical extracts—e.g. cannabis, opiates and alcohol—are impairing, others can act as cognitive enhancers. This chapter will focus on acute cognitive enhancement from administration of select botanical extracts including Asian and American ginseng, sage and cocoa polyphenols. When benchmarked against pharmaceutical cognitive enhancers, these extracts enhance cognition with similar effect sizes to modafinil. The mechanisms of action appear to be different to those underlying pharmaceutical interventions, with positive effects on cerebral blood flow and central glucose utilisation complementing direct neurotransmitter effects. These mechanisms may be further elucidated through recently developed neuroimaging methodologies.