BDNF
BDNF (brain-derived neurotrophic factor) is a protein that supports the development and survival of nerve cells and appears essential to synaptic plasticity, the strengthening and weakening of connections between neurons.
What it means in practice
BDNF is a mechanism term, and in human studies it is a marker, not an outcome. It was first purified in 1982 [1]. Besides its part in brain development and cell survival, it appears essential to the molecular machinery of synaptic plasticity [1]. Basic activity-related changes in the brain are thought to depend on BDNF's effects on synaptic transmission, especially in the hippocampus and neocortex [1].
Human studies measure BDNF levels and report how they change. A 2015 meta-analysis pooled 29 studies with 1,111 participants across three exercise designs [2]. BDNF rose after a single exercise session, a moderate effect (Hedges' g = 0.46) [2]. Regular exercise made that rise larger (g = 0.59), and its effect on resting BDNF was small (g = 0.27) [2]. Studies with more women showed less BDNF change [2].
Why it matters when reading nootropics research
A rise in BDNF can read like a benefit, but it is a change in a marker. The same meta-analysis describes the idea that BDNF carries the cognitive and mood effects of exercise as preliminary [2].
Under our editorial policy, BDNF is a mechanism and never a graded outcome. Compound pages grade outcomes measured in people, such as memory or attention, and report BDNF changes under how a compound may work, labeled as mechanism. When a study reports BDNF, check whether it also measured an outcome, and whether that outcome was compared with a placebo.
References
- Binder DK, Scharfman HE. Brain-derived neurotrophic factor. Growth Factors. 2004.
- Szuhany KL, Bugatti M, Otto MW. A meta-analytic review of the effects of exercise on brain-derived neurotrophic factor. J Psychiatr Res. 2015.