Subjective and Objective Memory Changes in Old Age across Five Years.

Typically, subjective memory assessments (be it in form of single items or questionnaires) in old age only weakly correlate with the performance in objective memory tests at cross-section. It thus appears as if individual differences in subjective memory assessments hardly reflect individual differences in memory in old age. A shortcoming of cross-sectional studies, however, is that subjective assessments may rely on different individual standards, which are not taken into account. One solution to this problem has been to investigate subjective and objective memory longitudinally, thereby focusing on individual differences in intraindividual changes. Results from studies using this approach have been mixed, with some studies showing a significantly stronger relation between changes than between levels, and other studies showing no such significant difference. Using data from the Zurich Longitudinal Study on Cognitive Aging (n=236), we find that 5-year changes in subjective assessments of memory capacity and memory changes correlate with objective memory changes of 0.54 and -0.44, respectively. These correlations are significantly stronger than at cross-section. After controlling for age, depressive affect, and subjective health at the first measurement occasion, correlations are slightly attenuated, but the basic findings remain the same.