Edoardo Moretto leaned over a microscope in a London lab, watching tiny fluorescent parcels move like glowing trains along the axons of a living mouse brain—until they didn’t. In the early stages of tauopathy, these vital cargo carriers slowed and stalled, not because neurons were dying, but because pathological tau had begun to clog the neural highways. What surprised the team most was what happened next: when they blocked a single stress-linked enzyme, the traffic started moving again.
At the UK Dementia Research Institute at University College London, Moretto, Giampietro Schiavo, and Marc Busche have uncovered a reversible phase in the progression of tauopathies—neurodegenerative diseases like Alzheimer’s and frontotemporal dementia that affect millions worldwide. For years, scientists have known that axonal transport, the process by which neurons shuttle proteins and signaling molecules along their lengthy projections, falters in these conditions. But until now, it was unclear whether this breakdown was an early, potentially reversible event or a final consequence of irreversible damage.
Using rTg4510 mice, a model that mimics human tau pathology, the team tracked axonal transport in real time with two-photon imaging in the visual cortex. They labeled brain-derived neurotrophic factor (BDNF) with a fluorescent tag to follow secretory granules as they moved along microtubule tracks. At the earliest detectable stages of tau accumulation—before tangles formed and neurons died—transport was already impaired. The culprit? Hyperphosphorylated tau molecules clustering into structures the researchers call “tau envelopes,” which physically obstruct kinesin motors, the proteins that carry cargo along axons.
The breakthrough came when they inhibited MAPK p38α, a kinase activated during cellular stress. In both cultured neurons and live mice, blocking this enzyme restored axonal transport. This suggests that the damage isn’t permanent—at least not at first. “The observed transport deficits are caused by the presence in the brain tissue of hyperphosphorylated tau and were reversed by inhibiting MAPK p38α both in vitro and in vivo,” Schiavo explained. It’s a window of opportunity: a phase where intervention might halt or even reverse neurological decline before it becomes irreversible.
While these findings are from mouse models, they open a new path for early therapeutic strategies in Alzheimer’s and related diseases. If a similar mechanism exists in humans, drugs targeting MAPK p38α could one day be administered during the pre-symptomatic phase, potentially delaying or preventing cognitive decline. The study, published in Nature Neuroscience, doesn’t offer a cure—but it does offer hope: that before the tangles take hold, there may be time to act.