Involvement of the locus coeruleus in Pick's disease with or without Pick body formation

Brains affected by the fronto-temporal type of Pick's disease were classified into two subgroups according to whether Pick bodies (PBs) were detectable in cerebral cortex (PB-positive group, six cases) or not (PB-negative group, eight cases), and examined neuropathologically. Controls included seven patients with non-degenerative diseases. The neuronal population in the locus coeruleus (LC) was estimated quantitatively in preparations from the middle part of the LC. The data were analyzed statistically by the Mann-Whitney U-test. Histological and ultrastructural studies were also carried out. The following results were obtained: (1) there were no appreciable differences between the PB-positive and PB-negative groups with regard to age at onset, age at death, duration of illness, clinical stage at death, and brain weight; (2) the mean nerve cell counts in the LC were 43.7 +/- 5.2 in the controls, 28.8 +/- 11.7 in the PB-positive group, and 42.9 +/- 7.6 in the PB-negative group. The nerve cell count in the PB-positive group was significantly lower (P less than 0.05) than those in the controls and the PB-negative group; and (3) in each of the PB-positive cases, PBs were disclosed in the LC, in medium-sized melanin-laden neurons and small neurons. PBs were globular or lobulated, and their fine structure was identical to that of typical PBs in the cerebral cortex. In conclusion, PB formation may play an important role in neuronal decrease in the LC of PB-positive cases, whereas the LC may not be affected in PB-negative cases. In this respect, Pick's disease with PB formation appears distinct from that without PB formation.