Dendritic spines are synaptic real estate each represents a connection. Oxidative stress builds actin rods inside dendrites, physically severing spines and dismantling neural circuits.

The Mechanism:

Oxidative Trigger: ROS from mitochondria or amyloid activates NADPH oxidase, generating localized oxidative bursts within dendritic compartments.

Cofilin Activation: Oxidative stress inactivates slingshot phosphatases, leaving cofilin (actin-severing protein) chronically active instead of cycling off.

Rod Formation: Active cofilin binds F-actin, creating stable cofilin-actin rods within dendritic shafts. These rigid structures physically occlude the dendrite.

Transport Blockade: Rods obstruct mitochondrial and vesicle trafficking to distal spines. Synapses lose energy supply and receptor recycling.

Spine Collapse: Without trophic support, spines retract first thin spines, then mushroom spines. Synaptic loss correlates directly with cognitive decline.

Persistence: Rods resist degradation, persisting for hours to days. Repeated stress accumulates permanent synaptic disconnection.

Therapeutic Implications:

NADPH oxidase inhibitors (apocynin) preventing oxidative trigger

Cofilin phosphorylation enhancers inactivating severing activity

Actin stabilizers preventing rod formation

Rhod kinase modulators regulating downstream effectors

This reframes cognitive decline as structural disconnection actin rods physically breaking synaptic links.