These supplements may change the functioning of the brain in ways that affect the ability to think well. This could be through affecting neurotransmission (signaling between neurons), bioenergetics (the use of energy by the brain), or protecting neurons from damage and dysfunction. Such supplements may influence cognitive functions such as memory, alertness, attention, and various faculties that determine intelligence.
Supplements may affect cognitive function directly or indirectly. Direct effects include things like altering or participating in neurotransmission and participating in or influencing energy metabolism. Indirect effects include things like altering the levels of hormones that affect the brain, protecting the brain from damage and dysfunction, and ameliorating disorders that can affect cognitive functioning, such as depression, anxiety, and insomnia.
Supplements that affect cognitive function are supplements that, when taken, have a measurable impact on cognitive function specifically. That is, even if a supplement may have indirect effects that could be expected to affect the brain, unless studies have measured their specific impact on cognitive function, they’re not included in this category.