Late onset familial and sporadic AD is associated with the apolipoprotein E allele ApoE4 on chromosome 19. Gross pathologic features are nonspecific. There is cortical atrophy and ventricular dilatation . Also seen, but not required for diagnosis are varying degrees of amyloid angiopathy , granulovacuolar generation , Hirano bodies and spongiform change. Plaques are formed by abnormal neurites, extracellular amyloid, microglia and astrocytes.
Tangles are intracellular inclusions formed by bundles of twisted filaments.
In general, Alzheimer s disease affects principally the large neurons of the neocortex and of the hippocampal formation. The only pharmacological therapies currently available are choloinergic agonits which are effective in a few patients. Recent research has shown that this group may be linked to a gene on Chromosome 12. Disturbances of posture, equilibrium, and autonomic function may occur. It may antedate the motor findings.