Pyrroloquinoline quinone (PQQ) is a coenzyme and antioxidant that may support mitochondrial function and biogenesis, provide cardioprotection (e.g. limiting the damage done to the heart by a myocardial infarction), and stimulate nerve growth factors in the brain, leading to improved memory and brain function. Most studies thus far (it seems) have been performed on rats, although there is a large body of anecdotal evidence from human biohackers.

See https://selfhacked.com/2014/09/11/pqq-review/ When combined with CoQ10, PQQ may significantly preserve and enhance memory, attention, and cognition in ageing humans.