On the Morphological Changes of Locus Caeruleus in the Senile Human Brain

Abstract

Locus caeruleus is a brainstem nucleus which consists of melanin-containing nerve cells and recently it is reported that the number of nerve cells decreased markedly in the elderly persons (Brody, 1976).
In this report, we investigated the locus caeruleus of the aged human brains, with or without degenerative diseases, on the following changes: nerve cell number, neurofibrillary change, Lewy body, and further, on the relationship with hypertension and cerebral bleeding.
The results were as follows:
1) Number of nerve cells: The number of nerve cells was counted on the cross section of the middle part of locus caeruleus in the upper pons. The mean value of the numbers from 60 cases of the aged persons over 60 years without degenerative diseases was fewer than that of 12 younger cases, and a statistically significant decrease was observed in the over 90 year- old persons.
2) Neurofibrillary tangles and Lewy bodies: Neurofibrillary change was observed in 10-20% of 60-90 year- old persons and 100% in over 100 year-old ones. Lewy bodies were observed in 33% of the over 90 year- old persons. In the cases showing Lewy bodies, the number of nerve cells was prominently decreased.
3) Degenerative diseases: Marked decrease of nerve cells of locus caeruleus was observed in the cases of Parkinson's disease, multiple system atrophy and senile dementia. On the other hand, 2 cases of progressive supranuclear palsy showed no decrease of the number.
4) Hypertension and cerebral bleeding: No correlation of nerve cell number and hypertension or cerebral bleeding was found. However, Lewy bodies were observed frequently in the cases without hypertension or cerebral bleeding.
These findings suggest that the neurons of locus caeruleus are strongly affected in old age and various senile degenerative diseases. As the result of it, various autonomic dysfunction, including sleep disturbance, can appear in the aged persons.