Minimal influence of age, education, and gender on episodic memory functioning in very old age: a population-based study of nonagenarians.

The purpose of this study was to assess the relative importance of age, gender, and education on episodic memory functioning in a population-based sample of healthy individuals, between 90 and 100 years of age. A total of 80 persons completed a face recognition task, immediate and delayed word recall, object recall, and the Mini-Mental State Examination. Utilizing regression analyses, it was found that the demographic variables explained only 3-8% of the variation in cognitive performance. Age had a negative effect only on object recall, where increasing age was associated with decreasing performance. Level of education was positively related to delayed word recall and MMSE score, whereas gender had no effect whatsoever. It was suggested that demographic variables may lose some of their importance as predictors of memory performance in very old age. This may result from selective survival effects that become particularly pronounced when participants are rigorously screened for health.