Correlation between Scores for Dementia and Counts of ‘Senile Plaques’ in Cerebral Grey Matter of Elderly Subjects

Abstract

SMALL, discrete masses of argyrophilic particles, with a mean diameter of 50–60µ, were first seen in the cerebral cortex by Blocq and Marinesco¹ and named “senile plaques” by Simchowicz², who discovered large numbers of these lesions in cases of senile dementia. Since they may be present in the normal old person³ and no close relationship between intensity of plaque formation and clinical changes was found by some workers⁴, their relevance for senile dementia—the extreme form of intellectual decay of old age—has often been called into question. More recently Corsellis⁵ has demonstrated a reasonably good correlation between clinical diagnosis and neuropathological changes in post-mortem studies of aged mental hospital patients. But the nature and extent of the relationship between plaque formation and mental deterioration in old age remained uncertain. An attempt has been made to shed further light on this problem by enquiries in a series of patients, aged 60 years and more, admitted with psychiatric or physical illness to mental and geriatric hospitals and subsequently studied at post-mortem. The aim was to carry out a quantitative assessment of the severity of dementia in individual subjects during life and to ascertain whether this bore any relationship with mean plaque counts in cerebral grey matter. At this stage of the enquiry cases with gross cerebrovascular lesions were excluded as there was no available technique for making a quantitative estimate of their extent. The degree of dementia was expressed in quantitative form by carrying out the two following assessments.