BDNF (Brain-derived neurotrophic factor)

BDNF is a growth-factor protein that supports neuronal survival, synapse formation, and — at least in animal models — adult hippocampal neurogenesis (its extent in adult humans remains debated). Levels rise with aerobic exercise and quality sleep; effects of intermittent fasting are well-established in rodents but less clear in humans, and levels fall under chronic stress and depression. In longevity research, lower BDNF is associated with depression and Alzheimer's risk, linking lifestyle to memory and mood regulation.