Brain-derived neurotrophic factor (BDNF) – help for the aging brain
If you’re interested in optimising your brain health and cognition the chances are you have heard of Brain derived neurotrophic factor (BDNF). Neurotrophins like BDNF are brain nourishers and without optimal levels our memory, cognitive function and mood can suffer.
We have 86 billion neurons in our brain and to function our brain needs vasts amount of energy and nutrients. In fact 20% of our total body energy goes to fuel our brain. Being so hungry for energy if anything adversely affects our energy power houses – the mitochondria it is likely to affect how we think and feel.
BDNF is an important growth factor that influences how our brain develops and grows and changes over time. It is essential for neuron signalling and the passage of nutrients to our brain cells.
It is not the only growth factor that appears to be important when it comes to brain health – other examples of neurotrophins include nerve growth factor NGF and Glial cell derived neurotrophic factor (GDNF) but it perhaps is the most widely researched and known to be important when it comes to creating new neurons (referred to as neurogenesis) and helping existing neurons develop new connections and adjust connections (synaptic plasticity). As it plays a role in neuroplasticity this enables nerve cells in the brain to compensate for injury and adapt to new situations or changes in the environment making it useful when it comes to brain trauma. It is of little surprise that dysregulation or disruption of our neural plasticity is associated with neuropsychiatric and neurodegenerative diseases and BDNF plays a key role in this respect.
In addition BDNF has been shown both to facilitate glutamate release and to increase postsynaptic glutamate receptor synthesis which appears important for overall energy production in the brain and mitochondrial function. It is also important when it comes to depression.
One of the reasons it is so important for cognitive function and mood is that it is active in the hippocampus as well as the cortex and forebrain. These areas in the brain are important when it comes to learning, memory and other cognitive functions.
There are many factors that can influence how much BDNF a person produces and while genetic factors can play a role, many are modifiable and involve diet, certain nutrients and lifestyle.
Health Implications
Weight
One area of research is the role BDNF may play when it comes to food intake. As it works at the hippocampus it may help to suppress appetite.
Interestingly one study found that the more overweight women have lower levels of BDNF. They also appear to be lower in diabetics and obese children. Although interestingly Anorexic women also have decreased levels and this may also be linked to greater depression in these women.
Sleep
Levels of BDNF may influence the quality of your sleep. It appears important for the production of slow wave sleep which is very restorative sleep. In animal studies sleep deprivation leads to an increase in BDNF levels – researchers think this link which may then help increase slow wave sleep is a strategy to compensate for previous lost sleep although human studies are limited.
Mood
Higher BDNF levels are associated with improved cognition, memory and mood. It can almost be seen as the antidepressant of the brain. Low levels are associated with depression and anxiety.
In fact one of the mechanisms of antidepressants is to increase levels of BDNF in the brain
There may be links to other health conditions too – for example BDNF may influence the insulin secreting granules in the beta cells which are lost / exhausted in type 1 diabetes.
This does not mean more is necessarily better as the distribution of BDNF in the brain may play a role when it comes to healthy cognition and aging. For example while low levels have been linked to issues with memory – very high levels may also cause a problem.
Circadian Rhythm
Like our organs BDNF follows a circadian rhythm and tends to be higher earlier in the day. Our master clock – located in the suprachiasmatic nucleus is activated with exposure to light and this leads to higher levels of glutamate and wakefulness.
Shifts in the Glutamate/NMDA receptor stimulation of the SCN can alter our circadian rhythm and BDNF levels.
Potentially therefore if your levels of BDNF are very low you may have issues with your 24 hour sleep- wake cycle.
Women, Emotions and Oestrogen
The hormone oestrogen appears to influence levels of BDNF production and levels of BDNF in women have been linked to romantic attachment. Higher levels appear to be linked to promoting more social relationships and friendliness.
Brain Health / Cognition
Neurotrophic factors including BDNF levels may be associated with certain brain health conditions including Parkinson’s disease, Alzheimer’s and Huntington’s.
The Genetic Link
While there are a number of variants the most well studies is known as the rs6265 variant. Studies suggest that the C/G (val) allele has a relatively higher level of BDNF while the A/T (met) allele has lower levels. This may actually influence the amount of BDNF produced and / or released or even made available to areas of the brain.
How Can I Increase BDNF?
Exercise
One of the easiest ways to boost your level is through exercise – both low and high intensity exercise has been shown to be beneficial. Anything that gets the heart pumping is likely to be beneficial.
Get Quality Sleep
People suffering from insomnia had lower BDNF levels compared with sleep-healthy controls. Sleep deprivation also increases inflammation markers which in itself is associated with reduced levels of BDNF. It is a complicated interplay but certainly low levels could lead to ongoing issues with restorative sleep.
Stress Reduction
Managing stress and lowering high cortisol is one of the most effective ways to improve levels of BDNF long term. Stress not only lowers BDNF but also serotonin directly. This may be one of the reasons why chronic stress has such long term effects on cognition, sleep and mood by lowering BDNF.
One of the ways that the herb Bacopa may increase BDNF is by reducing levels of stress in the body and improving resilience. Another great herb to include is Chinese Skullcap or Baicalin. This may also be why L Theanine is also beneficial for improving levels of BDNF.
Another option is to take magnesium – ideally threonate or glycinate forms which appears to cross the blood brain barrier easily without causing digestive upset. Increasing magnesium supports BNDF and levels decline sharply under high stress. In fact the higher your stress the more your magnesium need.
Sunlight
Not surprisingly due to its link with the master clock in the brain reduced levels of sunlight are associated with lower levels of BDNF. As it is likely to be linked to the SCN taking vitamin D is unlikely to help and certainly this seems to be the case in research.
Since low BDNF may adversely affect circadian rhythm it is important we do everything we can to stick to a regular 24 hour sleep -wake cycle.
Cognitive Stimulation
Throughout our lifespan one thing is clear – ongoing mental stimulation increases BDNF – learning something new or novel, challenging the brain, playing mental stimulation games all help improve BDNF. So use it and boost it!
Fasting
Fasting has been shown to have many long term health benefits particularly when it comes to healthy aging and one way it helps is though increasing the production of BDNF.
Calorie restriction in animal studies has been shown to increase production of BDNF by 50-400 percent although there are few human trials at present.
Nutrients and Foods
There is a lot of research into the use of certain nutrients or foods in helping to improve levels of BDNF directly and indirectly. Some of these nutrients appear to directly improve levels of BDNF which may be via lowering inflammation in the brain. Others can improve levels indirectly. BDNF and NGF have receptors – we now know that certain nutrients and foods can mimic these receptors so indirectly it is possible to boost the effects of BDNF in the brain. To support the receptors a traditional Mediterranean diet high in polyphenols, olive oil and oily fish can be helpful. Good foods to include regularly are Pomegranate, raspberry, strawberry cranberry, walnut and pecan. Cocoa powder is another good option. Many of these also provide resveratrol which has been shown as a supplement to increase BDNF.
Other beneficial plant nutrients include rutin (e.g found in buckwheat), hesperidin (citrus), Apigenin (parsley, chamomile, celery, oregano) and fermented foods rich in probiotics. Caffeine also appears to support the levels of BDNF in the brain.
Curcumin (found in turmeric) also helps activate the receptors in addition to its neuroprotective effects.
Fish oil particularly DHA is an area of research that has received substantial attention – and DHA supplementation may improve levels and help mitigate the effects of traumatic brain injury.
Gut Health & Butyrate
The gut may equally have an effect on BDNF in several ways – one is the production of the metabolite butyrate from the gut microbiome which in turn increases BDNF. Similarly prebiotics (like FOS) may be beneficial.
Lion’s Mane Mushroom
One of my favourite mushroom powders – Lion’s Mane (Hericium erinaceus). Known for its neuroprotective effects it appears to work directly on improving levels of NGF and in particular the effects are seen in the Hippocampus area of the brain – important for memory and cognition. One small study found a reduction of depression and of anxiety following 4 weeks of H. erinaceus intake.
Low Dose Lithium
Another key nutrient used regularly for supporting healthy mood and cognition is low dose lithium. Well it appears that low dose lithium can elevate BDNF – this may be one of the mechanisms it could be useful in cognitive decline.
Don’t also forget the importance of social connections, green spaces and having a passion in life – all these can improve BDNF and contribute to better health and happiness.
For more details on how to support a healthy brain at any age get a copy of my Brain Boost Diet
