Normal cognitive aging compromises the ability to form and retrieve associations among features of a memory episode. One indicator of this age-related deficit is older adults' difficulty in detecting and correctly rejecting new associations of familiar items. Comparing 28 younger and 30 older adults on a continuous recognition task with word pairs, we found that older adults whose activation patterns deviate less from the average pattern of younger adults while detecting repaired associations show the following: (1) higher overall memory and fewer false recognitions; (2) stronger functional connectivity of prefrontal regions with middle temporal and parahippocampal gyrus; and (3) higher recall and strategic categorical clustering in an independently assessed free recall task. Deviations from the average young-adult network reflected underactivation of frontoparietal regions instead of overactivation of regions not activated by younger adults. We conclude that maintenance of youth-like task-relevant activation patterns is critical for preserving memory functions in later adulthood.
Normal cognitive aging is associated with a decline in the ability to form and retrieve associations among different features of an episode (Old and Naveh-Benjamin, 2008 and Shing et al., 2010). This general trend of declining associative memory is accompanied by massive individual differences in rates of decline (Ghisletta et al., 2012, Lindenberger and Ghisletta, 2009 and Persson et al., 2012). As a result, associative memory is preserved in some older individuals, but not in others (Fandakova et al., 2012). Little is known about the mechanisms driving this heterogeneity (Barulli and Stern, 2013 and Nyberg et al., 2012). The general goal of this study is to examine the degree to which individual differences in neural activation and connectivity are related to individual differences in associative memory and false remembering in later adulthood.
Evidence is accumulating that age-related memory deficits are especially pronounced when individuals are required to remember specific contextual details instead of isolated items (Naveh-Benjamin, 2000 and Spencer and Raz, 1995). For example, when investigating memory for word pairs in 278 adults (18–85 years), Bender et al. (2010) found that older participants were not only less likely to correctly endorse studied word pairs but were also more likely to falsely endorse repaired associations in which the original words were studied in different configurations (see also Shing et al., 2008). In fact, a direct comparison of the two effects revealed a stronger association between age and false endorsement of repaired associations than between age and failure to recognize intact associations. At the same time, this study revealed a considerable amount of variability among individuals of the same age. For example, in the group of 60- to 80-year-olds, some individuals were almost perfect in correctly detecting repaired associations whereas others wrongly endorsed repaired associations in more than 70% of the cases (see Fig. 1, Bender et al., 2010). This observation is in line with longitudinal observations, indicating increasing heterogeneity of cognitive functions with advancing adult age (de Frias et al., 2007, Ghisletta et al., 2012 and Lindenberger and Ghisletta, 2009). Given the notable difficulties of older adults to detect repaired associations of familiar features, the specific goal of this study was to characterize the neural mechanisms underlying heterogeneity in older adults' tendency to falsely recognize associations they have not encountered before. This topic is of great importance for everyday life because it may result in greater susceptibility to misinformation (Jacoby and Rhodes, 2006).
