BDNF, or brain-derived neurotrophic factor, is a protein produced inside nerve cells. The reason why it is so important to a healthy brain is because it serves as Miracle-Gro for the brain, essentially fertilizing brain cells to keep them functioning and growing, as well as propelling the growth of new neurons.
Although neurotransmitters like dopamine and serotonin are important in helping the brain function because they carry the signals of neurons, the protein BDNF build and maintain the brain circuits which allow the signals to travel.
BDNF improves the function of neurons, encourages their growth, and strengthens/protects them against premature cell death. It also binds to receptors at the synapses, to improve signal strength between neurons.
Essentially, the more BDNF in the brain, the better the brain works.
What Happens When There’s Not Enough?
Naturally, we want more of this protein in the brain. But what exactly happens when there is a lack of BDNF or when something prevents it from working properly? Along with impaired learning, decreased levels have been associated with a variety of neurological/mental conditions such as alzheimer’s, epilepsy, anorexia nervosa, depression, schizophrenia, and OCD. Let’s talk about the specifics of a few of them.
Connection Between Depression and BDNF
Although researchers do not say that low levels of the protein is the cause of depression, many studies have found a connection between the two. In the book Spark, Dr. John Ratey pointed out that a study of 30 depressed people found that every single one of them had low levels of the protein. In a postmortem study of people who committed suicide and had depression, the researchers also found significantly decreased levels of the protein.
Even in individual without a mental illness, lower levels of the protein have been correlated with personality traits that make them less mentally resilient and more vulnerable to depression.
Again, researchers have not been able to find a single cause of depression and saying that low BDNF is the cause of depression would be irresponsible. But it looks to be a factor.
Connection Between Anxiety and BDNF
Anxiety is fear. Fear, to the brain, means a memory of danger. Danger means something different to someone with a diagnosed anxiety disorder than someone without.
Here’s how anxiety works in the brain. When confronted with real threat, there is no difference in brain scans of someone who doesn’t have anxiety disorder and someone who does. However, the difference comes into play when it comes to everyday life, when situations are non-threatening. A brain with anxiety cannot distinguish between a threatening situation and a nonthreatening situation, so it is always on high alert and fearful. So to someone with an anxiety disorder, every situation is a dangerous situation.
The National Institute of of Mental Health labels anxiety a learning deficit—because the brain is unable to learn to discriminate between dangerous situations and benign situations.
Recent research has led scientists to believe that the protein is an essential ingredient in combating anxiety. Scientists think this is due to the fact that it helps the brain learn to essentially work around the fear and create positive memories. In addition, higher levels of the protein ramps up levels of serotonin, which calms the brain down and increases the sense of safety.
Low BDNF and Impaired Learning
Since BDNF provides the infrastructure for effective learning, it follows that the lack of the protein impairs effective learning. Additionally, people with gene mutations that robs them of the ability to produce the Miracle-Gro are more likely to have learning deficiencies.
In a 2007 study of humans, German researchers found that people learned vocabulary words 20 percent slower when compared to people that increased BDNF levels right before learning (by exercising).
Essentially, the protein is a mechanism for the brain to learn. It gives the synapses the tools it needs to take in information, process it, associate it, remember it, and put it in context to see the big picture.
Age as a Factor
Alike many other chemicals in the human body, aging decreases BDNF levels. That’s why it takes us longer to learn to do complex tasks as we age. Remember, the protein is instrumental in learning quickly and learning well.
To make matters worse, it is estimated that 1 in 3 people have a genetic mutation that makes BDNF levels fall much faster than average.
Just how fast do the levels drop when you have this genetic mutation? A study at Stanford University sought to answer this question. The study took 144 airplane pilots ages 40 to 69. They had the pilots do annual flight simulator test over a few years time. The end result? The test scores of pilots who had the genetic mutation dropped twice as fast as the scores of the pilots that did not have the mutation.
But luckily, we don’t have to live with ever-decreasing levels. That is because we can increase them through various ways, whether we have the genetic mutation or not.
Increasing BDNF Levels
As the Miracle-Gro of the brain, the more of it we have, the better. Although it is a relatively new discovery, scientists do know that it can be increased in several ways.
Aerobic exercise increases its production. But science thinks exercise not only increases production the protein, but it also adjusts it to optimal levels that have been programmed into our DNA through evolution.
Carl Cotman, a neuroscientist at UC Irvine, ran an experiment with rats to see if there was a difference in BDNF production between various exercise routines. Turns out, there is. After just two weeks, those who exercised daily produced the protein much more rapidly than those who exercised on alternating days (150 percent of baseline versus 124 of baseline). However, after a month, there was no difference in production of BDNF between those who exercised daily and those who exercised every other day.
But the study also noted that the protein returned to baseline (non-exercise) levels just after two weeks of not exercising. This was true for both groups. However, it shot right back up after just two days of exercising: 139 percent for daily exercisers and 129 for alternating day exercisers.
Researchers found that exercise in old rats made the brain function (almost) just as good as young rats.
Exercising is by far the most surefire and fastest way to increase BDNF levels. That is why it is so effective in relieving stress and symptoms of mental illnesses. This is also why exercise allows the brain to learn so effectively.
Omega-3 Fatty Acids
Omega-3 fatty acids are plentiful in fish, especially deep-water fish (salmon, tuna, cod). They have been shown to lower blood pressure, cholesterol, heart problems, oxidative damage, and inflammation of the neurons. They also provide a neuroprotective layer for the brain by raising and normalizing BDNF levels.
Although some sources say that you can take omega-3 supplements, there are studies out there the question the overall efficacy of fish oil supplements. So the best way to get your omega-3 fatty acids is to eat them. But if you are interested in seeing how much (and if) omega-3 supplements increase BDNF levels in men, then keep up with this clinical trial, which has not been completed yet.
While there are other sources of omega-3 fatty acids as well like nuts, flax seeds, and chia seeds, there is insufficient evidence to show that they have the same benefits as omega-3 from fish. Omega-3 fatty acids from deep-water fish contain DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), which are essential to many of the benefits it provides.
In the book Brain Maker Dr. David Perlmutter recommends five strains of probiotics to increase BDNF levels in the brain. Those are Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus brevis, Bifodobacterium lactis, and Bifidobacterium longum. Here are the common foods in which you can find each strain:
Lactobacillus plantarum: sauerkraut, pickles, brined olives, kimchi, Nigerian ogi, sourdough, fermented sausage, stockfish, and some cheeses (such as cheddar)
Lactobacillus acidophilus: yogurt, kefir, miso, and tempeh
Lactobacillus brevis: pickles, saurkraut, and beer hop
Bifodobacterium lactis: yogurt, miso, tempeh, pickled plum, pickles, kim chi, and many other forms of fermented and pickled fruits/vegetables that have not gone through the manufacturing process
Bifidobacterium longum: yogurt, milk, fermented dairy foods, saukraut, and soy-based products
For those that are not familiar, intermittent fasting is a form of dietary restriction in which the person goes without food for a certain amount of time (usually 12 to 24 hours).
Although the evidence is still thin, there are some studies out there that show intermittent fasting can increase brain-derived neurotrophic factor. Dietary restriction seems to stimulate the production of new neurons, increase the brain’s ability to resist aging, and restore function to the brain following injury. More specifically, intermittent fasting appears to result in a stress response at a cellular level that stimulates neuronal plasticity and the production of certain proteins, like BDNF.
Again, more research needs to be done on the connection between intermittent fasting and brain-derived neurotrophic factor but results so far look promising.
Brain-derived neurotrophic factor is the foundation of all things good in the brain. It allows the brain to work effectively and efficiently. When there is enough Miracle-Gro in the brain and it is allowed to work efficiently, it enables the brain to create more memories, learn quicker, and operate at a higher level. When there’s a deficiency of it in the brain, it causes all kinds of cognitive and mental issues.