Recollection and Familiarity in Healthy Adult Ageing and its Correlates with Frontal Lobe and Medial Temporal Lobe Function

The current study examined the effect of healthy ageing on recollection and familiarity in a picture recognition memory task, using the receiver operating characteristic (ROC) procedure, in healthy younger (n=20) and older adults (n=20). Recollection and familiarity estimates were calculated using the Yonelinas procedure (Yonelinas, Kroll, Dobbins, Lazzara, & Knight, 1998). No age effects for recollection were found. However, older adults had impaired familiarity. This contradicts previous research. Older adults were also impaired on recognition memory performance with fewer hits and more false alarms than younger adults. The frontal lobes and the medial temporal lobes are believed to be involved in recollection and familiarity. However, very few studies have investigated this in healthy younger and older adults using neuropsychological test batteries, and seen whether performance on these batteries was related to recollection and familiarity. The current study also examined this. On neuropsychological tests, older adults were impaired on tasks that tapped the medial temporal lobes (People and Shapes subtests of Doors and People) and dorsolateral prefrontal lobe (digit span total only), but not on the individual dorsolateral prefrontal tasks (digit span forwards and backwards) or the ventromedial prefrontal tasks (faux pas). However, older adults had significantly lower years of education and when this was controlled; they were only impaired on correct rejections and familiarity. It was found that in younger adults better performance on the shapes test was correlated with increased familiarity, while in older adults better performance on the shapes test was correlated with increased recollection. Recollection and familiarity did not correlate with any of the other neuropsychological measures. The findings suggest that the medial temporal lobe may be differentially involved in the recognition processes depending on age, with involvement only for familiarity in younger adults, and recollection only for older adults