The neostriatum and nucleus accumbens in parkinsonism-dementia complex of Guam: a pathological comparison with Alzheimer's disease and progressive supranuclear palsy.

The neostriatum, nucleus accumbens and basal nucleus of Meynert (bnM) in the parkinsonism-dementia complex of Guam (Guam PDC) were examined immunohistologically, ultrastructurally, quantitatively and topographically, and the results were compared with those in Alzheimer's disease (AD) and progressive supranuclear palsy (PSP). Compared to neurologically normal controls, the number of large neurons in Guam PDC was reduced by approximately 70% in the caudate nucleus and putamen and by more than 90% in the nucleus accumbens. The decreased number of large neurons in the neostriatum was significantly correlated to that in the bnM. The remaining large neurons and many of the medium-sized neurons in the neostriatum and nucleus accumbens were immunopositive for tau protein and contained varying amounts of 21- to 25-nm-wide paired helical filaments (PHFs) admixed with straight tubules. Curly fibers and circularly arranged reactive astrocytes were seen in the nucleus accumbens of many PDC patients. Collectively, these findings, which are similar in part to those of AD and differ from those of PSP, suggest that the large neurons in the neostriatum and nucleus accumbens in Guam PDC degenerate through PHF formation, and that extremely severe loss of large neurons in the nucleus accumbens may be linked to marked degeneration of the limbic and ventral tegmental areas and nucleus dorsal raphe.