Observations on the brains of demented old people

Abstract

The brains from 50 cases of proven dementia in old age were examined and various features objectively assessed, and compared with similar features in a group of non-demented (controls) old people. Statistically significant differences were found in the two groups in relation to cortical atrophy, ventricular dilatation, senile plaque formation, Alzheimer's neurofibrillary change, granulo-vacuolar degeneration and the quantity of cerebral softening. Seventy per cent of the cases showed more changes of senile or ischaemic type than any control, and in 90% the changes found were probably sufficient to allocate the cases to a specific diagnostic category. 50% were considered to be cases of senile dementia, showing the histological features of Alzheimer's disease, the majority with no or small ischaemic lesions. By contrast only 12% appeared to be definitely and solely produced by cerebral softening (arteriosclerotic dementia) although a further 5% were probably of this origin. Mixed cases, with the pathological features of senile and arteriosclerotic disease, accounted for 8% with certainty, and probably for a further 10%, though the evidence in these latter cases was less certain. One case of Wernicke's encephalopathy was seen and 1 was possibly of traumatic origin. Five cases (10%) were not classified on pathological grounds, but in only 2 of these were no significant lesions found and 1 of these may have been mentally subnormal from birth. Striking sex differences in the incidence of the major lesions was found in the series. Thus 15 of the 16 females were, on pathological grounds, cases of senile dementia, whereas only 10 of the 34 males showed only this type of pathology, and in the males, arteriosclerosis probably caused, or contributed to the dementia in 50%. The age incidence of the cases of arteriosclerotic dementia was significantly less than the cases of senile dementia, or the cases of mixed senile or arteriosclerotic dementia. Arteriosclerotic dementia is almost certainly over-diagnosed clinically.