The axonal origin of a subpopulation of dystrophic neurites in Alzheimer's disease.

Dystrophic neurites are observed characteristically in Alzheimer's disease (AD). They are thought to arise from sprouting dendrites and contribute to dementia because of their abnormal growth and close association with neurofibrillary tangles and neuritic plaques. In the present study, dystrophic neurites are demonstrated in the thalamic reticular nucleus in AD in the context of a normal neural and glial architecture. They do not collocalize with somata and dendrites identified by simultaneous labeling with the microtubule-associated protein MAP2, suggesting that they are derived from axons. Throughout the brain, dystrophic neurites may well be comprised of a heterogeneous population of both dendrites and axon terminals and preterminals. While many recent studies have focused upon the dendritic origin of dystrophic neurites, these results emphasize that the interconnectivity of certain brain regions may be compromised by cytoskeletal changes occurring in neurons and their axons in AD.