On Some Involutional Changes in the Hippocampal Region of the Elderaly Brains

With Special Reference to Age, Sex and Dementia

Abstract

The incidence and quantity of some senile involutional changes in the hippocampal region of the brain was examined in 146 consecutive autopsy cases, with special reference to age, sex and dementia. The subjects, ranging in age at death between 50 and 92 with the mean 73.3 years, had been admitted to the Department of Geriatrics, University of Tokyo Hospital and Harunaso Hospital for chiefly physical diseases (cerebral infarction in 40 patients, myocardial infarction 10, malignant neoplams 24, etc.; unequivocal senile dementia in only 5).
The hippocampus and adjacent areas (dentate, parahippocampal, and medial occipito-temporal gyri) of the left hemisphere were prepared into slices of 6μ-thickness after formalin fixation and paraffin embedding, and number of Alzheimer's neurofibrillary changes (NF), senile plaques (SP), the and vessels involved into amyloid angiopathy (AA) was counted respectively over the whole specimen through thioflavine T fluorescence microscopy.
(1) Relation of age and sex to the incidence and quantity of NF, SP and AA.
The incidence of each change generally rose with age (NF: 29% in 6th decade of age, 59% in 7th, 81% in 8th, and 91% in 9th and above, SP: 12%, 22%, 44%, 56%, and AA: 0%, 7%, 24% 23%, respectively) In each age decade females were usually more frequently affected than males, though the differences were not significant in these small numbers of cases.
Quantity of NF, SP and AA was expressed as total counts over the whole specimen of 6μ-thickness, which ranged from 0 to 1, 550 in NF, from 0 to 1, 480 in SP, and from 0 to 330 in AA. When number of each change was graded into 4 levels (0, 1-10, 11-100 and 101-), the occurrence of levels of 11-100 and 101-increased with age both in NF and SP, indicating the age-related increase of NF and SP. The increase of AA was less prominent.
(2) Quantitative correlation among NF, SP and AA.
Approximate positive correlations in quantity were noted among NF, SP and AA, most markedly between NF and SP, followed by SP and AA, and finally NF and AA.
(3) Relationship between the quantity of NF, SP and AA and dementia.
Of the subjects examined there were 55 patients whose intellectual capacities had been well-preserved until death (non-demented group), and 61 patients with various degree of dementia (demented group). There was significant difference in the incidence disitribution of the quantity of NF and SP between these two groups (compared after matching age and sex). The comparison of the incidence distribution between severely demented and less severely demented patients, however, revealed no significant difference in the quantity of NF and SP. There was thus a significant difference in the quantity of NF and SP in the hippocampal region between elderly demented and non-demented patients, but no definite correlation was found between the quantity of these changes and the severity of dementia, with the exception of AA.