By Elodie Vaz | Published on April 24,
2026 | 3 min read
Alzheimer’s disease, the
most common form of dementia, is characterized by progressive
neurodegeneration. It initially affects memory, then gradually impairs all
cognitive functions, ultimately compromising daily independence. Biologically,
two major lesions are involved: extracellular deposits of beta-amyloid peptides
and intracellular aggregates of tau protein.
Normally involved in
stabilizing neuronal microtubules, tau becomes pathological when it aggregates
into neurofibrillary tangles, contributing to neuronal death and cognitive
decline.
A study published on
April 8, 2026, in Neuron addresses a key question that remains poorly
understood: the mechanism by which tau pathology spreads through the brain.
Although the progressive distribution of lesions follows a well-described
pattern—from the temporal lobe to the neocortex—the exact mechanisms of this
propagation remain hypothetical. The researchers therefore aimed to determine
whether and how tau aggregates move between neurons and across brain networks.
Combining brain
connectivity and molecular biology
To reach their
conclusions, the researchers analyzed post-mortem brain samples and
longitudinal data from 128 participants in the ROSMAP cohort, followed for
nearly ten years. Two brain regions were examined for each individual: the
inferior temporal lobe, involved in episodic memory, and the superior frontal
lobe, associated with executive functions.
The approach integrates
multiple levels of analysis: quantification of tau “seeds,” individual genetic
data, and functional magnetic resonance imaging (fMRI) acquired prior to death.
The use of Mendelian randomization allowed the team to infer causal relationships
between the presence of these seeds and the formation of neurofibrillary
tangles.
Brain connectivity: a
key driver of tau spread
As explained in a press
release by Jeremy Herskowitz, MD, PhD, professor of neurology and neurobiology
at UAB and lead author of the study: “We used a genetic approach called
Mendelian causality to conclude that neuronal seeds generated in the temporal cortex
were responsible for neurofibrillary tangle pathology in the neocortex.”
The findings provide
converging evidence supporting trans-synaptic propagation of tau protein.
“Small fragments of tau protein aggregate within neurons and spread from neuron
to neuron throughout the brain,” he adds. “Neurons are interconnected and communicate
via synapses, allowing these aggregates to travel through the brain […] until
they reach the neocortex.”
The study shows that this
spread preferentially follows each individual’s neural networks. In other
words, brain connectivity determines the trajectory, distance, and potentially
the speed of propagation of tau aggregates. Interindividual differences in neural
“wiring” thus directly influence the extent of tau pathology.
Targeting tau
propagation: a promising therapeutic strategy
This work represents “the
most extensive investigation to date of the bioactivity of tau protein
aggregates in the human brain,” combining, for the first time, post-mortem data
with fMRI. The results confirm that tau seeds originating in the temporal cortex
play a causal role in spreading pathology to broader cortical regions.
These findings strengthen
the hypothesis of active propagation of tau pathology along neural circuits,
providing a mechanistic basis for the anatomical progression of Alzheimer’s
disease. “This is a major advance […] both for the development of therapies and
for understanding how the disease works,” the researcher emphasizes.
From a therapeutic
perspective, the results shed light on the potential mechanism of action of
anti-tau antibodies. “Anti-tau antibodies could prevent tau protein from
spreading from one brain region to another. If this propagation can be stopped,
it may delay or even prevent Alzheimer’s disease.”
Precisely identifying
these propagation pathways opens the door to strategies targeting not only tau
protein itself but also the neural networks involved. Future research will need
to clarify the cellular and synaptic mechanisms at play in order to translate
this understanding into clinical interventions capable of modifying the natural
course of the disease.
Read next: Alzheimer’s
disease: a direct link with fine particulate matter
About the Author – Elodie Vaz
Health journalist, CFPJ graduate (2023).
Élodie explores the marks diseases leave on bodies and, more broadly, on
human life. A registered nurse since 2010, she spent twelve years at patients’
bedsides before exchanging her stethoscope for a notebook. She now investigates
the links between environment and health, convinced that the vitality of life
cannot be reduced to that of humans alone.
