PQQ

Here are some of the effects noted in the animal studies:

PQQ reverses cognitive impairment caused by chronic oxidative stress and improves performance on memory tests in animal models.
PQQ supplementation stimulates the production and release of nerve growth factor.
PQQ protects against the self-oxidation of the DJ-1 gene, an early step in the onset of Parkinson’s disease.
PQQ protects brain cells against oxidative damage following ischemia-reperfusion injury.
PQQ blocks the formation of inducible nitric oxide synthase (iNOS), a major source of reactive nitrogen species (RNS) that are so damaging to neurons.
PQQ protects against the likelihood of severe stroke in an experimental animal model for stroke and brain hypoxia.
PQQ protects the brain against neurotoxicity induced by other powerful toxins, including mercury, glutamate and oxidopamine (a potent neurotoxin used by scientists to induce Parkinsonism in laboratory animals by destroying dopaminergic and noradrenergic neurons).
PQQ prevents development of alpha-synuclein, a protein associated with Parkinson’s disease.
PQQ also protects nerve cells from the oxidizing ravages of the beta-amyloid-protein linked with Alzheimer’s disease.