MAPT and proteostasis deficiencies: Importantly, the neurobiological mechanism of neuronal slowing differs between acute brain injury and neurodegenerative disease processes: slowing in brain injury is putatively caused by axonal shearing at the grey–white matter boundary,81 whereas in neurodegeneration, slowing is caused by proteinopathy, such as microtubule degradation, hyperphosphorylation of tau and resultant neurofibrillary tangles (NFTs).82,83 For example, in both civilian and military mTBI, multimodal neuroimaging with MEG detected neuronal slowing and diffusion tensor imaging (DTI) found proximal axonal/WM damage.84