BDNF: How Chronic Stress "Dries Out" the Brain and Why Tea Has Become One of My Gentlest Companions on This Journey
Marianna BaryloWhen my daughter received her ASD diagnosis and I finally acknowledged my own ADHD, something shifted.
I did not start exploring neuroscience out of curiosity. I was searching for real, gentle tools that could help both of us find more calm and regulation. What began as a practical search became something much deeper. Step by step, I fell in love with the quiet intelligence of the brain — and the way everything in nature is connected to it.
One of the most significant discoveries on that journey has been BDNF — Brain-Derived Neurotrophic Factor.
What BDNF is.
BDNF is a protein that does three essential things:
- It stimulates neurogenesis — the birth of new neurons, particularly in the hippocampus, the brain's centre of memory, emotion, and learning.
- It strengthens synaptic plasticity — the brain's ability to form and reorganise connections.
- It supports the survival of existing neurons and protects them from damage.
When BDNF levels are healthy, the brain is flexible, resilient, and capable of recovery. When they drop — which happens reliably under chronic stress — focus becomes harder, memory less reliable, emotional regulation more effortful.
How chronic stress depletes BDNF.
Short-term stress can briefly elevate BDNF — the brain adapting quickly to demand. But sustained, ongoing stress does the opposite. Prolonged high cortisol suppresses the BDNF gene, increases neuroinflammation, and disrupts key signalling pathways.
The result is gradual atrophy of the hippocampus, reduced neuroplasticity, and increasing difficulty with memory and emotional balance. It becomes a cycle: lower BDNF leads to less resilience, which creates more stress, which further suppresses BDNF.
Understanding this cycle was one of the most clarifying moments of my neuroscience training. It explained a great deal about what I had observed — in myself, and in my daughter.
How tea interacts with BDNF.
EGCG — the primary catechin in green and white tea — does two things relevant to BDNF. It helps raise BDNF levels directly, and it makes neurons more responsive to BDNF by supporting sustained TrkB receptor signalling. TrkB is BDNF's primary receptor; when BDNF binds to it, it triggers cascades responsible for growth, plasticity, and cell survival.
L-theanine complements this by calming the HPA axis — the stress-response system that, when chronically activated, suppresses BDNF production. It also improves the balance between mature BDNF and its precursor form.
Together, EGCG and L-theanine create conditions in which the brain can restore rather than simply endure.
The ritual as part of the mechanism.
What I find most significant is that the act of brewing and mindfully drinking tea also supports BDNF — independently of the compounds.
Activating the parasympathetic nervous system, lowering cortisol, creating a consistent daily pause — these are all conditions that support BDNF production. The ritual is not separate from the science. It is part of it.
For me, this has become a daily practice that is both evidence-based and deeply personal. The cup is a small, repeatable act of care for the brain — mine, and my daughter's.
References:
- Ding, M.L. et al. (2017) 'Protective effects of EGCG against sevoflurane-induced neuronal apoptosis involve regulation of CREB/BDNF/TrkB and PI3K/Akt/mTOR signalling pathways', Canadian Journal of Physiology and Pharmacology, 95(12), pp. 1390–1398.
- Gundimeda, U. et al. (2014) 'Green tea polyphenols potentiate the neuritogenic action of BDNF', Biochemical and Biophysical Research Communications, 453(3), pp. 434–439.
- Murakami, S. et al. (2005) 'Chronic stress reduces BDNF mRNA expression in the rat hippocampus', Neuroscience Research, 53(2), pp. 129–139.
- Nowacka, M. and Obuchowicz, E. (2013) 'BDNF and VEGF in the pathogenesis of stress-induced affective diseases', Pharmacological Reports, 65(3), pp. 535–546.
Slow down. Sip deeply. Stay present.
