Brain-derived neurotrophic factor (BDNF) is a protein that aids in cell function and promotes the growth of new nerve cells (neurogenesis). Studies have shown that BDNF plays a critical role in neuroplasticity (the brains ability to build new nerve connections) and motor recovery after a stroke. Furthermore, decreased BDNF levels are associated with many neurodegenerative diseases including Parkinson’s disease, Huntington’s disease, and multiple sclerosis.
In this article you will learn a little bit about the brain as it related to learning and memory, what BDNF is, and things that you can start doing today to improve the amount of BDNF.
The Human Brain
The human brain is an intricate communication network made up of billions of nerve cells (neurons) controlling everything from the most primitive biological functions to complex motor (movement) and cognitive (thinking) tasks. Neurons communicate with one another through electrical impulses that travel along long tails called axons.
At the end of each axon is an axon terminal where one neuron will synapse with another neuron called synaptic connections. At the synaptic connections, neurochemicals are released from the axon terminal where they are received by an adjoining neuron allowing the electrical impulse to continue.
The number of synaptic connections in the brain is constantly changing with new connections constantly being made and “non-working” synapses being removed. Hence the terms “use-it-or-lose-it” and “use-it and-improve-it.”
Equally important, the brain is constantly making and eliminating neurons. The formation of new neurons is called neurogenesis and the safe elimination of neurons is called apoptosis. Neurogenesis occurs throughout life however, the rate declines with age and favors certain brain areas (hippocampus, cortex, and forebrain). The proteins that are responsible for regulating neurogenesis and apoptosis are called neurotrophins. Brain-derived neurotrophic factor is one such neurotrophin.
What is Brain-derived Neurotrophic Factor (BDNF)?
BDNF is a protein that is produced in brain cells called astrocytes and the gut. There is also some evidence that suggests BDNF is produced in other tissues in the periphery including the lymphocytes and macrophages (immune cells), and the blood vessel walls.
How Does BDNF work?
BDNF acts on specific receptors -Tropomyosin receptor kinase B (TrkB)- to support cell survival, encourage growth of new neurons, strengthen synaptic connections, and promote the formation of new synaptic connections. BDNF also plays an integral role in long term potentiation. Long term potentiation (LTP) is the strengthening of a synaptic connection based on recent activity. LTP is the process that helps to explain learning and memory. With that said, BDNF expression is the most evident in the areas of the brain responsible for learning, memory, and higher level thinking (hippocampus, cortex, and basal forebrain).
On the other hand, low levels of BDNF are associated with metabolic changes, cardiovascular risk, endocrine abnormalities, mood changes, and impairment of cognitive functions.
How do you increase Brain-derived Neurotrophic Factor (BDNF)?
With all of this great evidence, increasing the amount of circulating BDNF should be a no-brainer. And yes, there are things you can do to accomplish this. Two of the most well documented lifestyle/behavior factors that can increase the amount of BDNF are exercise and Omega-3 fatty acids (supplementation but preferably through food).
Exercise and BDNF
Studies have shown that three months of moderate-intensity aerobic exercise, three times per week for a minimum of 20 min increased BDNF levels with some studies showing an association with improved cognitive function, improve memory, and decreased depression.
There is also evidence that BDNF levels increase with moderate intensity exercise following a stroke. Noteworthy, “movement retraining”, constraint induced movement therapy (CIMT), and the like did not show a change in serum BDNF. These findings suggest that aerobic training is equal if not more important than your post stroke movement retraining exercises.
Omega 3 Fatty Acids
Omega-3 fatty acids are polyunsaturated fatty acids (PUFA) proven to be critical in proper cell function. There are three types of Omega-3 fatty acids, a-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA can be found in plants, while EPA and DHA are found in algae and fish.
Also known as the “healthy fats” omega-3 fatty supplementation for one week increased serum BDNF levels in healthy people. Additionally, studies have shown that DHA and ALA supplementation in people who have had a stroke increased levels of BDNF in the cortex and hippocampus.
Important note, too much Omega-3 can cause adverse effects. The food and drug administration recommend no more than 3 grams of EPA and DHA per day. Taking too much may cause gastrointestinal symptoms.
Foods with ALA (a-linoleic acid)
- Flaxseed
- Chia seed
- Hemp seed
- Canola oil
- Soybean oil
- Edamame
- Navy beans
- Avocado
Foods that contain DHA and EPA
- Mackerel
- Salmon
- Cod liver oil
- Herring
- Oysters
- Sardines
- Anchovies
- Caviar