Parkinson's disease (PD) can be categorized into two types: one of gut origin and one of brain origin. Gut-first PD originates in the peripheral nervous system of the gut and spreads to the brain.

Exercise affects bone marrow activity and reduces pro-inflammatory leukocytes. Exercising caused mice to produce less leptin, a hormone that suppresses appetite and increases inflammatory leukocytes.

A dose of gene therapy using a virus which delivers three longevity-associated genes improved or reversed weight gain, type II diabetes, kidney failure, and heart failure in mice.

Certain gut microbes can upregulate butyrate production, which increases BDNF (brain-derived neurotrophic factor) levels, which serves a crucial role in cognitive function.