AMYLOID PLAQUES IN GUAM AMYOTROPHIC LATERAL SCLEROSIS PARKINSONISM-DEMENTIA COMPLEX CONTAIN SPECIES OF A-BETA SIMILAR TO THOSE FOUND IN THEAMYLOID PLAQUES OF ALZHEIMERS-DISEASE AND PATHOLOGICAL AGING/

The Guamanian amyotrophic lateral sclerosis/parkinsonism-dementia comp lex (ALS/PDC) is characterized by abundant neurofibrillary pathology a nd neuron loss. In contrast to Alzheimer's disease (AD), where extensi ve neurofibrillary lesions always occur with deposits of A beta in num erous amyloid plaques, A beta-rich amyloid plaques are absent or rare in most ALS/PDC patients. To characterize the amyloid plaques in the l atter patients, we probed plaque-rich sections of their brains by immu nohistochemistry using well-characterized antibodies to specific epito pes in the N and C termini of A beta as well as to defined epitopes in hyperphosphorylated tau (PHFtau). The results indicate that the speci es of AP in the amyloid plaques of ALS/PDC patients resemble those det ected in the amyloid plaques of cognitively intact subjects with patho logical aging as well as patients with AD. However, the paucity of PHF tau-positive neurites in the ALS/PDC plaques suggests that they reflec t pathological aging rather than AD.