APA Dictionary of Psychology

a group of neural phosphoproteins encoded by the MAPT gene and essential for binding and stabilizing microtubules, which maintain neuronal structure and enable axonal transport of nutrients, organelles, and signaling molecules. Tau activity is dynamically regulated through phosphorylation–dephosphorylation cycles, ensuring proper microtubule binding and neuronal function. Abnormal hyperphosphorylation and resulting conformational changes cause it to detach from microtubules, disrupting their stability and the neuronal transport system. Once detached, the tau protein begins to misfold from its normal shape, forming insoluble aggregates, known as neurofibrillary tangles and filaments, which impair axonal transport, synaptic function, and mitochondrial integrity, while activating neuroinflammatory pathways and propagating misfolded tau to connected neurons in a prion-like manner. Cumulatively, these processes lead to synaptic and mitochondrial dysfunction, neuronal death, and the characteristic clinical and neuropathological features of tauopathies, a type of neurodegenerative disease.