As seen in Psychology Today.
The human brain is by far the most complex and intricate organ in the body. Apart from regulating our most basic biological functions, the brain is also the seat of consciousness. When something is not right, either due to an irregularity in neurochemical signaling or because of structural deficits caused by either injury or old age, this can often affect how we experience consciousness and how we perceive the world around us.
The brain is made up of billions of neurons that communicate with one another through electrical impulses (via nerve fibers known as axons) or by sending neurochemical signals to one another via synapses. New connections are constantly being made, and old, no longer useful connections are being pared throughout each individual’s life, which means the precise number of synaptic connections is always in a state of flux, though at any given time there may be upwards of 100 trillion of these connections in an adult brain.
Equally important, the number of neurons in the brain is constantly changing. Though there is still some debate on the matter, it appears that new neurons are constantly being formed (via a process called neurogenesis) in certain parts of the brain. Meanwhile, it has been established that degrative enzymes lead to the controlled death (apoptosis) of other neurons. The proteins responsible for regulating these processes of cell birth and cell death in the brain are known as neurotrophic factors (or neurotrophins), one of which is brain-derived neurotrophic factor (BDNF).
What Is BDNF?
Neurotrophic factors are produced in the brain and the gut in limited quantities from the time we are in the womb until the time we pass away. When a neuron obtains an adequate amount of these proteins during development, it survives, while neurons that do not receive enough do not survive. As these proteins are not abundant, neurons must constantly compete for them during development and even into old age.
Researchers have discovered numerous neurotrophins, including nerve growth factor (NGF), neurotrophic factor-3 (NT-3), neurotrophic factor-4/5 (NT-4/5), as well as BDNF. BDNF is regarded as the most active neurotrophin, and it is also extremely important to energy homeostasis and neuronal plasticity, which is crucial to learning and memory. Decreased levels of BDNF have been associated with neurodegenerative disorders such as Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, and Huntington’s disease. Reduced BDNF levels may also be associated with type-2 diabetes.
Conversely, higher levels of the protein are associated with improved cognitive functioning, mental health, and short- and long-term memory. While it is not clear at this time if increasing BDNF levels can reverse or prevent neurodegenerative conditions, normal levels of BDNF are typically associated with better cognitive performances and overall brain function in individuals with the conditions noted above.
Can I Increase My BDNF Levels?
The short answer is yes. Research has found that several factors, particularly obesity, may influence BDNF levels—obese individuals have lower BDNF levels while non-obese individuals have higher BDNF levels. Additionally, research indicates that other lifestyle changes (explored below) may positively impact BDNF levels.
Rigorous exercise has been shown to increase BDNF levels. A study published in 2011 found that three weeks of high-intensity cycling and five weeks of aerobic exercise improved cognitive functioning and increased levels of BDNF. Yet another study found that BDNF levels increased with aerobic exercise and that this corresponded with an increase in hippocampal volume by 2%. (The hippocampus plays a major role in the creation and storage of memories and tends to decrease in volume with age.)
On top of helping to combat obesity and increase BDNF, thereby improving overall brain function, these studies suggest that exercise can be especially beneficial to memory.
The typical American diet is high in calories and often contains excessive saturated fats and processed sugars. Additionally, many individuals tend to eat dinner fairly late at night. Taken in conjunction, such dietary habits can lead to obesity, which, as noted above, can negatively impact BDNF levels and overall cognitive health. These habits can also independently lead to reduced BDNF levels.
Several studies have found that intermittent fasting and caloric restriction is associated with increased BDNF levels. Additionally, diets that are high in processed sugars and saturated fats can affect neurotrophin levels, including BDNF levels, which in turn can lead to a reduction in hippocampal volume and neuroplasticity. To avoid these detrimental effects, individuals should stay away from processed sugars and saturated fats, and switch to a diet that is based largely on leafy vegetables, fruits, lean proteins, and whole grains.
Drugs and Supplements
In addition to making dietary changes, some supplements have been shown to increase BDNF levels. They include:
· Curcumin, which is found in turmeric;
· Green tea;
· Omega-3 fatty acids, which are found in fish, flaxseed, and fish oil;
· Resveratrol, which is found in grapes (and wine), dark chocolate, pistachios, blueberries, and peanuts.
Additionally, data suggests that some drugs may increase BDNF levels though this is not an accepted indication for any of these drugs. These include: ampakines, cystamine, nootropic drugs, and selective-serotonin reuptake inhibitors (SSRIs). More importantly, they should only be taken if prescribed by a medical professional.
While it is well known that the winter months can oftentimes affect one’s mood, the precise neurobiological mechanism behind this change is not entirely known. One possible mechanism could be decreased levels of BDNF, which is correlated positively with levels of Vitamin D, a vitamin our skin makes from cholesterol when it is exposed to sunlight. In other words, more sunlight appears to lead to increases in BDNF levels.
A Dutch study involving 2,851 participants found significant fluctuations in serum BDNF concentrations throughout the year. Notably higher concentrations were found in the spring-summer months and lower concentrations were found in the autumn-winter months. The study suggests that Vitamin D could play a role in the regulation of this protein.
Social engagement appears to also affect BDNF levels, particularly in developing brains. While it has been well documented that a stimulating and welcoming social environment early in life produces positive behavioral results later in life, a Roman study from 2006 found that these benefits can be observed on the neurochemical level. The study discovered that mice raised in a communal nest had significantly increased neurotrophin levels in several brain areas, particularly the hippocampus and hypothalamus, even later in life. It seems reasonable to assume that a similar phenomenon would be observable in humans, though it is unclear if adults can experience similar benefits from being in a stimulating social environment.
Ultimately, the best way to increase BDNF levels is to adopt a healthier overall lifestyle that can also contribute positively to one’s mental health and cardiovascular health, while also reducing one’s level of body fat. These changes include exercising, being social, getting outside, and eating a diet that is rich in nutrient-dense foods and devoid of processed sugars and saturated fats.
Dr. Ahmad reports no conflict of interest. He is not a speaker, advisor, or consultant and has no financial or commercial relationship with any biopharmaceutical entity whose product/device may have been mentioned in this article.