Cognitive & neuro

BDNF (brain-derived neurotrophic factor)

The brain's main growth factor for plasticity: essential, widely measured, and not something a supplement can deliver.

Anecdotal evidenceNot approvedAdd to compare

What it is

Brain-derived neurotrophic factor is a protein of the neurotrophin family, not a small peptide, that supports neuron survival and synaptic plasticity. It is the molecule most often cited in exercise, sleep and antidepressant research. It is not a medicine: swallowed it is digested, and injected it does not cross the blood-brain barrier in useful amounts, so products sold as BDNF boosters do not deliver the protein.

How it works

1
Binds the TrkB receptor, triggering survival and plasticity signalling in neurons.
2
Supports long-term potentiation, the cellular basis of learning.
3
Promotes dendritic branching and, in some regions, adult neurogenesis.
4
Its production rises with exercise, sleep and some antidepressants.
5
Delivery to the brain from the blood is the unsolved problem.

What it's studied for

Depression and antidepressant response (as a measured biomarker)

Exercise and cognition

Alzheimer's disease and synaptic loss

Motor neurone disease (intrathecal delivery attempts)

Reported and studied effects

Blood and brain BDNF correlate with memory performance and mood in observational studies
Direct administration has not produced a usable therapeutic effect
Intrathecal delivery in motor neurone disease trials caused pain, spasticity and weight loss

Research protocol notes

Research context only

Research context only - there is no approved human protocol, and none is likely without a delivery method that reaches the brain. Human research measures BDNF in blood as a biomarker rather than dosing it; the intrathecal trials that did dose it were stopped for adverse effects.

These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.

Possible side effects and contraindications

Safety profile

Possible side effects

Not established for supplemental use
Intrathecal administration produced pain, spasticity and weight loss in trials
Seizure threshold changes are theoretical at high exposure

Contraindications and cautions

No approved therapeutic use
Any product claiming to raise brain BDNF directly should be treated with scepticism
Not for people with seizure disorders outside specialist care

A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.

Evidence assessment

Anecdotal evidenceNo controlled human data

No controlled human data

Strong observational and mechanistic literature, but no human trial shows benefit from administering BDNF itself; supplement claims have no supporting data.

References

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.

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