BDNF

The BDNF gene codes for brain-derived neurotrophic factor (BDNF). A neurotrophic factor is a compound that supports the growth and development of brain cells (neurons). 

BDNF is one of the main factors responsible for making new neurons (neurogenesis). It also helps existing neurons develop new connections with other neurons, or adjust their existing connections (synaptic plasticity) [R, R, R].

BDNF is important for learning and memory. BDNF also influences [R, R]: 

• Sleep
• Body weight
• Stress response
• Depression
• Anxiety

To learn more about BDNF, check out these SelfHacked posts: 

• All About rs6265
• Factors That Boost BDNF

The BDNF gene provides instructions for making a protein found in the brain and spinal cord called brain-derived neurotrophic factor. This protein promotes the survival of nerve cells (neurons) by playing a role in the growth, maturation (differentiation), and maintenance of these cells. In the brain, the BDNF protein is active at the connections between nerve cells (synapses), where cell-to-cell communication occurs. The synapses can change and adapt over time in response to experience, a characteristic called synaptic plasticity. The BDNF protein helps regulate synaptic plasticity, which is important for learning and memory.

The BDNF protein is found in regions of the brain that control eating, drinking, and body weight; the protein likely contributes to the management of these functions.

Read: Are You a High BDNF Producer? The BDNF Gene

Read: A Comprehensive List of Natural Ways to Increase BDNF

Neurotrophins are chemicals that help to stimulate and control neurogenesis, BDNF being one of the most active. (R)

In the brain, BDNF is active in the hippocampus, cortex, and forebrain”areas vital to learning, memory, and higher thinking.  Hence, BDNF is important for long-term memory. (R)

BDNF has been shown to play a role in neuroplasticity, which allows nerve cells in the brain to compensate for the injury, new situations or changes in the environment. (R)

BDNF helps to support the survival of existing neurons and encourages the growth, regeneration and creation of new neurons and synapses. (R) It's important to realize that BDNF levels can be different in different places.  So you have blood BDNF levels, CSF BDNF levels and BDNF levels in various brain locations.

In healthy people, there's actually no correlation between BDNF in the blood and CSF. (R)

Increasing BDNF can potentially help a number of devastating brain disorders, including Alzheimer's disease, Parkinson's disease, Lou Gehrig's disease, and Huntington's Disease (HD). (R) Decreased levels of blood BDNF have been found in underweight women with anorexia. (R)

BDNF and Sleep

BDNF in rats is higher after wakefulness than after sleep, and BDNF increases after sleep deprivation. (R) BDNF triggers slow wave sleep by promoting synaptic potentiation. (R)

In mice, the level of exploratory behavior induces BDNF (R)- in humans, this would equate to mental and physical stimulation or novelty.

BDNF, in turn, is the signaling molecule that causes an increase in slow wave sleep. (R, R2) So the more stimulated or sleep-deprived you are, the more you need slow wave sleep, and the molecular link is BDNF.

BDNF and Wellness

When BDNF levels are high, acquiring new knowledge is easier, memories are retained, and people feel happier. So BDNF can even be thought of as a natural anti-depressant (R), and when levels fall depression can ensue (R).

BDNF levels are decreased in the brains of Huntington's patients, which might be partly responsible for the degenerative processes of the disorder. (R)

Low BDNF could be one of the many possible links between depression and heart disease. (R)

BDNF prevents exhaustion of the pancreas in diabetic mice by restoring the level of insulin-secreting granules in beta cells. (R)

BDNF also improved insulin resistance in the oral glucose tolerance test in mice. (R)

Studies have shown that brain size is correlated with lifespan and BDNF may be that link, since it increases insulin sensitivity. (R) BDNF causes blood pressure to increase, which is perhaps the most significant risk factor for heart disease. When BDNF is injected in the rostral ventrolateral medulla (mice), blood pressure increases. (R)

BDNF overexpression in the paraventricular nucleus (rats) increases blood pressure via angiotensin type-1 receptor-mediated mechanisms. (R)

Indeed, people who are genetically lower BDNF producers have lower systolic blood pressure. (R) One of the mechanisms by which salt increases blood pressure is by increasing vasopressin, which is mediated by an increase in BDNF. (R)

BDNF and The Circadian Rhythm

BDNF has a circadian rhythm and decreases as the day goes on. (R)

When light hits your retina, it gets transmitted to your hypothalamus and in a particular suprachiasmatic nucleus (SCN).  This causes the SCN neurons to fire, via the neurotransmitter glutamate.

The SCN is the central clock and is the conductor of your circadian rhythm. When the SCN fires, that's when the circadian rhythm starts and you wake up.

BDNF can enhance glutamate neurotransmission in SCN neurons and potentiates glutamate-induced shifts of the circadian rhythm. (R) BDNF secreted at night is probably required for light-induced shifts in the circadian rhythm (R).

In mice, BDNF injection during 4PM caused the circadian rhythm to be pushed off by 2.3 hours (so if you wake up at 8AM, you wake up at ~10AM). BDNF treatment during 10PM caused the circadian rhythm to be pushed back 2.3 hours (so if you wake up at 8AM, you would wake up at ~6AM).  

No phase shift occurred when BDNF was applied during the day at 7AM. BDNF-induced circadian shifts were dependent on Glutamate/NMDA receptor stimulation of the SCN. (R) So it's quite plausible to say that if you've got low BDNF, it could be harder to set your circadian rhythm.

On the other hand, if you're a high BDNF producer, your SCN may over-fire and burn out more quickly. If you're getting the sun, that increases BDNF and so you're covered if you get adequate sun.

BDNF, Socializing, and Love

BDNF blood levels were correlated with romantic attachment, but only in women.  The higher the BDNF, the lower women scored on an avoidance test (ie, they were more friendly and likely to form bonds). (R) So BDNF may play a role in promoting social relationships through a specific decrease of avoidance and fear of the stranger and unfamiliar individuals. (R)

Estrogens induce BDNF synthesis in several brain regions. (R) This may be one reason why women score higher on anxiety scales than men. (R)

Lifestyle to Increase BDNF:

Sleep. In rats, chronic sleep deprivation led to increased IL-1b and TNF and reduced BDNF (R)

Stress reduction. Chronic or acute stress and cortisol decrease BDNF in the rat hippocampus (R) and prefrontal cortex (R, R2). 

Acute stress more significantly decreases BDNF. (R)  People who are under a lot of stress show less BDNF. (R)

Sun. In an analysis of 2,851 individuals in the Netherlands, it was found that blood BDNF increased in the spring and summer and decreased in the fall and winter.  BDNF levels correlated to the number of hours a person was exposed to sunshine. (R)

Supplemental vitamin D in a human trial does not increase BDNF. (R) Supplemental vitamin D in postmenopausal women actually decreases BDNF. (R)

Exercise. Exercise is certainly one of the best way to boost BDNF levels.  (R, R2) In sedentary male college students, high intensity exercise boosted both the BDNF levels and memories. (R) The changes in BDNF levels were found in nerve cells within days after exercise in both male and female rats and were sustained even several weeks after exercise. (R) 

In rats, low intensity is actually better than high intensity at increasing BDNF.  (R) This accords with evidence in normal rats that show low intensity exercise can improve synaptic plasticity better than high intensity exercise. (R)

Cold and Heat (Sauna). In chicks, cold or heat exposure increased BDNF.  (R, R2) I have an Infrared Sauna and then take a cold shower.  I also expose myself to cold often.  I also have many cold devices such as an Ice Helmet/Cryohelmet and even an ice vest.

Calorie Restriction (R) -in rodents, but not in humans in this study. Intermittent Fasting.  Alternate-day fasting, with a single meal of about 600 calories on the fast day, can boost the production of BDNF by 50 to 400 percent, depending on the brain region. (R, R2, R3)

Cognitive Stimulation.  A highly stimulating early social environment in animals increases BDNF. (R) In mice, the level of exploratory behavior induces BDNF (R)- in humans this would equate to mental and physical stimulation or novelty. When you learn things or challenge your brain, the brain increases BDNF because of its important role in memory. (R)

Diet/Foods to Increase BDNF:

• Ketogenic Diet (R)
• Stay away from SAD diet – stay away from a high sugar and high saturated fat diet i.e. SAD diet…(R)
• Fish or Fish oil (R, R2),
• Hi-maize/Resistant starch – converts to butyrate, which causes an increase in BDNF (R)
• Honey: FOS, GOS (Prebiotics)(R)…
• Blueberries (R),
• Cocoa (flavanoids) (R),
• Soy – Both estradiol and soy phytoestrogens significantly increased BDNF in the frontal cortex of female rats. (R)
• High salt intake (R)