BDNF: A key molecule for cognition and eye health

April 1st, 2022

Brain-derived neurotrophic factor (BDNF) is a protein highly expressed in the central nervous system, especially in the brain. BDNF promotes the growth of dendrites and dendritic spines, contributing to synaptic strength and plasticity in the hippocampus, thus important for learning and long-term memory. Research shows that increased levels of BDNF in serum are correlated with improved cognitive functions while decrease in BDNF is associated with neurodegenerative and mental illnesses. Moreover, new scientific evidence suggests that BDNF is also an important factor in eye health.

What is BDNF and why is it so important?

BDNF belongs to the neurotrophin family of growth factors and plays an important role in brain development, mainly growth and maturation of neurons and synapses.

Highest levels of BDNF can be found in hippocampus, amygdala, cerebellum and cerebral cortex in both rodents and humans [1]. As well as in the brain, BDNF has been detected in other tissues such as the eye, lung, liver and skeletal muscle.

Today we know that BDNF is also crucial for the adult brain, where it regulates synaptic changes and efficacy.

BDNF is believed to be involved in the cellular mechanisms underlying memory formation and consolidation, learning and other complex behaviors by promoting long term potentiation in hippocampus [2].

BDNF in disease and the ageing brain

BDNF also seems to play a significant role in brain damage repair. Studies have shown that following traumatic brain injury, the mRNA expression level of BDNF is temporarily significantly upregulated in the injured cortex and in the hippocampus. These findings suggest that BDNF acts as an endogenous neuroprotective mechanism attenuating cell damage [3].

In addition, emerging scientific data suggest that BDNF could be involved in the pathophysiology of brain-associated diseases. Impaired BDNF signaling has been observed in several diseases, such as Huntington’s disease, Alzheimer’s disease, depression, schizophrenia, and bipolar and anxiety disorders.

Finally, part of the natural process of ageing is reduction of hippocampal volume and decrease in BDNF expression, which is associated with age-related cognitive decline [4].

What is the role of BDNF in eye health?

BDNF is produced by neurons and glial cells in the retina. Similarly to the brain, research indicates that BDNF could be involved in retinal development by modifying neuronal cell number or synapse formation [5].

Nowadays, our eyes are constantly being overworked as a consequence of increased usage of visual display terminal (VDT) devices, such as smartphones, computers or tablets. This can negatively affect blink frequency, which can induce dry eye and associated symptoms including pain, burning and visual disturbances.

Interestingly, BDNF knockdown mice showed decreased basal tear secretion, pointing at the role of BDNF in tear secretion and to the pathology of dry eye disease [6].

Moreover, recent studies show that BDNF plays a vital role in other eye diseases, such as age-related macular degeneration (AMD) or diabetic retinopathy (DR). In AMD patients, serum BDNF levels are decreased and the same trend is observed in DR patients.

These findings suggest that optimal BDNF levels may be necessary to exert protective effects on the eye and that decreased levels of BDNF signal eye disease [7, 8].

How can you increase BDNF naturally?

Control your stress levels
Acute stress down-regulates hippocampal BDNF mRNA expression and interestingly, antidepressants up-regulate BDNF expression [9]. Practicing yoga or other stress management techniques therefore seem to be an efficient way how to boost your BDNF [10].

Exercise
Some studies have shown that exercise enhances the expression of BDNF. The reasoning is not fully understood but one possible explanation is that exercise leads to the release of the ketone body β-hydroxybutyrate, which in turn induces the activity of BDNF promoters [11].

Practice occasional fasting
Not every stress is bad for your brain: it appears that mild metabolic stress associated with dietary restriction leads to significantly enhanced expression of various neurotrophic factors, BDNF included. A study showed that following 48-hour fasting, BDNF was significantly upregulated in human skeletal muscle [12].

Eat anthocyanin rich foods
Apart from the above mentioned, dietary interventions have been also gaining on attention as a potential strategy to elevate BDNF levels. There is extensive scientific evidence that foods high in anthocyanins, such as edible berries, are good for your brain health [13]. A recent study showed that 6-week supplementation of pure anthocyanins increased BDNF expression and improved spatial and psychomotor performances in aged rats [14].

Aronia melanocarpa anthocyanins and BDNF

Aronia melanocarpa is a berry native to North America, which is higher in anthocyanins than any other berries. Aronia-specific anthocyanin, cyanidin-3-O-galactoside (Cy3Gal), crosses the blood brain barrier and interacts with BDNF sinaling pathway, thereby contributing to a better neuronal signalling.

In a double-blind placebo-controlled crossover study, we recently demonstrated that short-term supplementation of Brainberry®, aronia melanocarpa extract with a standardized content of Cy3Gal, significantly increased BDNF levels in healthy young adults.

The bottom line

Given all the scientific evidence, BDNF plays a huge role in brain fitness, brain disease and eye health.

Manipulating BDNF levels through dietary factors might be a promising strategy to not only treat various neurological and psychiatric disorders, but also to naturally boost memory and learning.

To level-up BDNF is desirable for everyone: not only for the ageing population but also for young professionals seeking ways to enhance their cognition.