Inside the Mechanism of How Adult Brains Grow New Neurons
For years, the scientific consensus held that once we reached adulthood, the brain’s ability to generate new neurons came to a halt. But groundbreaking new research out of Sweden has overturned that assumption—confirming that adult human brains continue to produce new neurons, particularly in the hippocampus, a region vital for memory, learning, and emotional regulation. Using advanced molecular techniques and machine learning, researchers have shown that neurogenesis—previously thought to taper off after childhood—persists well into later life. This discovery not only challenges long-standing beliefs about brain development, but also opens new doors for treating depression, memory loss, and neurodegenerative diseases. Let’s explore where these new neurons form, what experts are saying, and how we can use this information to support brain health across the lifespan.
How Do New Neurons Form in Adults?
The process of adult neurogenesis is biologically distinct from the rapid, global brain cell formation seen in infancy. In adults, it’s a targeted, tightly regulated process that unfolds in stages:
- Proliferation: Neural stem cells (NSCs) in the subgranular zone (SGZ) divide, creating progenitor cells.
- Differentiation: These progenitors begin to take on specific neuronal identities (e.g., excitatory granule cells).
- Migration: Newborn neurons move a short distance into the granular layer of the dentate gyrus.
- Integration: Neurons form dendrites, axons, and synapses—joining existing hippocampal networks.
- Maturation: Over weeks, these cells develop full functionality and participate in learning, memory encoding, and mood regulation.
Key Molecules:
- BDNF (Brain-Derived Neurotrophic Factor): Enhances survival and growth of neurons.
- VEGF (Vascular Endothelial Growth Factor): Promotes neurovascular support.
- IGF-1, FGF-2: Stimulate proliferation.
- MicroRNAs & epigenetic regulators: Control gene expression patterns vital for neurogenesis (PMC6659986).
What Do the Experts Say?
Fred Gage, PhD (Salk Institute for Biological Studies):
“New neurons in adults are not just anatomical curiosities. They are functionally integrated into circuits and influence cognition and emotional behavior.”
(Source: Nature Medicine, 2000)
Maura Boldrini, MD, PhD (Columbia University):
Led a 2018 study analyzing 28 donated human brains from people aged 14 to 79. Her team found:
- Consistent numbers of new neurons across age.
- Older adults had reduced angiogenesis and neuroplasticity markers, but not fewer young neurons.
“We found preserved neurogenesis in aging brains without dementia.”
(Source: Cell Stem Cell)
Henrik Harkany, PhD (Karolinska Institute, Sweden):
One of the current leaders behind the recent Swedish study.
“Our findings reframe the hippocampus as a dynamic structure capable of responding to environment well into late adulthood.”
(Source: Science Daily, July 2025)
Lifestyle Habits That Boost Neurogenesis
Neurogenesis can be naturally stimulated or inhibited by the environment, behavior, and lifestyle.
Enhancers
- Aerobic Exercise: Increases BDNF levels and hippocampal volume (up to 2% in 1 year)
(PNAS study, Erickson et al., 2011).
- Learning & Mental Enrichment: Cognitive challenges like puzzles, language learning, and novelty stimulate neuron survival.
- Mindfulness & Meditation: Reduces stress hormones that inhibit neurogenesis (e.g., cortisol).
- Omega-3 Fatty Acids: Promote cell membrane fluidity and neuroplasticity.
- Social Interaction: Enhances resilience and brain stimulation.
Inhibitors
- Chronic Stress: Elevates cortisol and shrinks the hippocampus.
- Sleep Deprivation: Reduces proliferation of progenitor cells.
- Substance Abuse: Especially alcohol, which directly damages hippocampal cells.
Future Treatments on the Horizon
Pharmacological Boosters
- BDNF mimetics: Drugs designed to stimulate the BDNF pathway directly.
- HDAC inhibitors: Epigenetic modulators that may unlock suppressed neurogenic genes.
- Neurogenic peptides: Like NSI-189, which showed promise in early depression trials (Nature, 2015).
Gene Therapy & CRISPR
- Potential to re-activate dormant progenitor pools or modify neurogenesis pathways in cases of aging or brain damage.
Neurofeedback and Brain Stimulation
- Techniques like LENS neurofeedback and transcranial magnetic stimulation (TMS) are being explored for their ability to enhance plasticity and potentially support neurogenic niches.
Final Thoughts
For decades, the adult human brain was thought to be a fixed entity—incapable of generating new neurons after development. But as these recent findings confirm, our brains are not rigid. They’re adaptable, regenerative, and capable of rebirth.
This reframes aging, healing, and even learning not as a slow decline, but as a lifelong opportunity.
The adult brain, as it turns out, is not finished, it’s still becoming.
-A Balanced Brain is a Better Brain for a Happier Life-