The eugeria study of cognitive ageing: Who are the ‘normal’ elderly?

A cross‐sectional study of the cognitive performance of 575 normal elderly persons suggests considerable heterogeneity at each age level. While a number of cognitive functions (articulation, reading, semantic matching, comprehension of syntax and implicit memory) showed no difference with age, explicit memory, and other linguistic and visuospatial capacities, were significantly poorer, especially over 80 years. Within this normal population an ‘unstable’ subgroup showing significant deterioration in everyday performance according to an informant questionnaire was found to differ significantly on cognitive testing from elderly persons who had remained stable over this period. The ‘unstable’ group was also found to have a higher prevalence of depressive symptomatology and depressive illness. The question is raised as to whether ‘instability’ over time may be a very early indicator of subclinical pathology. The importance of taking such a group into account in the interpretation of studies of cognitive functioning and senile dementia is also discussed.