Declining cognition has been associated with detrimental consequences such as decline in independence and reduced quality of life. If we can understand the nature of the decline, we may be able to reduce the detrimental consequences. It seems that with increasing age we remember the general detail of the stimuli, rather than the specific details. Recall of general information but failure to identify the specific instances previously known or studied is termed gist error, and this is seen to be indicative of age related change in memory. Previous studies have compared younger vs older age groups; meaning that the time course of these changes has not been established. We used three age groups in a trial move to examine whether age related change might start earlier than recognized from previous studies. Sixty-six participants aged 18 to 86 years completed computerised tasks assessing non-verbal and verbal gist recognition. Older adults recognised correctly fewer target stimuli than the young old and middle old cohorts on the non-verbal gist task. They also were significantly more likely to identify critical semantic lures related to the target (“general”) than the other two age groups. In addition, on the verbal gist task, both middle and older adults recognised (incorrectly) more semantically related items than did the younger cohorts. These results are consistent and suggest that older adults are more likely to remember the general idea of stimuli (gist). However, older adults were able to recognize (recognized) more target stimuli than the young adults on the verbal task. This indicates probable dissociation between verbal and non-verbal representations and suggests cognitive decline is modular and related to specific functional decline, and is not generalized over all functions. The results also suggest that cognitive decline begins in early adulthood, rather than at the later spectrum of aging. These findings have implications for potential behavioural and pharmacological intervention.
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