APOE and Leukoencephalopathy: An increase in tau protein was observed (suggestive of axonal damage) in association with a worsening of attention deficit and a reduction in intelligence quotient; an increase in glial fibrillary acidic protein (GFAP) concentration in patients with an altered allele of the apolipoprotein E (APOE) gene (associated with deficiency of attention); and an increase in leukoencephalopathy, with compromised white matter especially in the frontal (particularly in the dopaminergic circuits) and parietal [36] lobes.