Séverine Fay

Aging and self-reported internal and external memory strategy uses: The role of executive functioning

The aim of this study was to investigate the effect of advanced age on self-reported internal and external memory strategy uses, and whether this effect can be predicted by executive functioning. A sample of 194 participants aged 21 to 80 divided into three age groups (21-40, 41-60, 61-80) completed the two strategy scales of the Metamemory in Adulthood (MIA) questionnaire, differentiating between internal and external everyday memory strategy uses, and three tests of executive functioning. The results showed that: (1) the use of external memory strategies increased with age, whereas use of internal memory strategy decreased; (2) executive functioning appeared to be related only to internal strategies, the participants who reported the greatest use of internal strategies having the highest executive level; and (3) executive functioning accounted for a sizeable proportion of the age-related variance in internal strategy use. These findings suggest that older adults preferentially use external memory strategies to cope with everyday memory impairment due to aging. They also support the view that the age-related decrease in the implementation of internal memory strategies can be explained by the executive hypothesis of cognitive aging. This result parallels those observed using objective laboratory memory strategy measures and then supports the validity of self-reported memory strategy questionnaire.

Ageing affects brain activity in highly educated older adults: An ERP study using a word-stem priming task

In this event-related evoked potentials (ERP) study, the neural correlates of a group of highly educated older adults were compared with those of a group of young adults while performing a word-stem completion priming task under semantic and lexical encoding conditions. The results revealed that both age groups exhibited robust priming. The older participants showed better performance than the young adults. Both groups exhibited ERP repetition effects at posterior sites, but only the older adults showed additional frontal activity. The results suggest that highly performing older adults compensate for their lower level of parieto-occipital functioning, reflected by smaller P300 amplitude at posterior sites, by recruiting frontal sites as a mode of brain adaptation.

Aging and implementation of encoding strategies in the generation of rhymes: The role of executive functions.

This experiment examines whether the age-related decrease in the generation effect of rhymes is mediated by executive functioning. Young and elderly adults read and generated pairs of rhyming words for subsequent recall. Participants were also administered neuropsychological tests (executive and mnemonic functions). Results showed that elderly adults performed less well on the neuropsychological tests and benefited less than the younger participants from the generation effect. Hierarchical regression analyses revealed that the executive functions composite score was correlated with the generation effect and that it accounted for a large proportion of the age-related variance of the size of this measure. This finding supports the view that the age-related decrement in strategic encoding implementation is due to a decrease of executive functioning.

Ageing and organisation strategies in free recall: The role of cognitive flexibility

The first goal of this experiment was to examine the effect of age on recall and clustering across three successive trials. Sixty-two young (age 20–40 years) and 62 elderly (age 60–80 years) adults learnt a categorised word list for subsequent recall. A clustering index was computed to assess organisational strategy. Results showed that elderly adults performed less well on the recall test and forgot more words across trials. They also indicated that their clustering index was lower than that of younger adults but increased more across trials. Clustering was only associated with the recall scores for the younger adults. Participants were also administered cognitive tests (cognitive flexibility, cognitive speed, and categorical fluency) to explore the possible mediators of memory and organisational strategy performances. Younger adults performed better on all these tests. Statistical analyses revealed that the variable most closely associated with clustering was cognitive flexibility. This finding supports the view that the age-related decrement in strategic organisation is due to a decrease in cognitive flexibility.

Protective role of educational level on episodic memory aging: An event-related potential study

The aim of the present experiment was to investigate whether educational level could modulate the effect of aging on episodic memory and on the electrophysiological correlates of retrieval success. Participants were divided into four groups based on age (young vs. older) and educational level (high vs. low), with 14 participants in each group. Event-related potentials (ERP) were recorded while participants performed a word-stem cued-recall task. Age-related memory deficits were greater for the less educated individuals. Age differences in the ERP old/new effects were also modulated by the level of education. This study demonstrated that the effects of age on episodic memory and ERP correlates of retrieval success are smaller in participants with high educational levels than those with lower levels. These findings provide support for the reserve hypothesis and highlight the need to consider individual differences when studying cognitive and cerebral changes in aging.

Effects of depth-of-processing and ageing on word-stem and word-fragment implicit memory tasks: Test of the lexical-processing hypothesis

The joint effects of depth-of-processing and age on repetition priming in implicit memory tests of word-fragment completion (WFC) and word-stem completion (WSC) were investigated. The experiment consisted of three study tasks (perceptual, lexical, and semantic) and four memory conditions: implicit (WSC and WFC) and explicit (WS cued recall and WF cued recall). In the WSC condition, semantic and lexical study processing produced equal priming, both superior to the perceptual study processing, whereas the WFC test showed equal priming for these three study conditions. This finding provides clear evidence, consistent with the lexical-processing hypothesis, that depth-of-processing in WSC priming reflects a lexical rather than a semantic process. It also provides support for the view that WSC and WFC involve different processes. However, there was no evidence of an age effect on either of these two implicit tasks. The data also revealed an overall significant effect of age and depth-of-processing, and an interaction between these variables on explicit cued recall tasks, indicating that older adults benefited less than younger ones from a deep encoding condition.

The effect of age on word-stem cued recall: A behavioral and electrophysiological study

The present study investigated the effects of aging on behavioral cued-recall performance and on the neural correlates of explicit memory using event-related potentials (ERPs) under shallow and deep encoding conditions. At test, participants were required to complete old and new three-letter word stems using the letters as retrieval cues. The main results were as follows: (1) older participants exhibited the same level of explicit memory as young adults with the same high level of education. Moreover older adults benefited as much as young ones from deep processing at encoding; (2) brain activity at frontal sites showed that the shallow old/new effect developed and ended earlier for older than young adults. In contrast, the deep old/new effect started later for older than for young adults and was sustained up to 1000 ms in both age groups. Moreover, the results suggest that the frontal old/new effect was bilateral but greater over the right than the left electrode sites from 600 ms onward; (3) there were no differences at parietal sites between age groups: the old/new effect developed from 400 ms under both encoding conditions and was sustained up to 1000 ms under the deep condition but ended earlier (800 ms) under the shallow condition. These ERP results indicate significant age-related changes in brain activity associated with the voluntary retrieval of previously encoded information, in spite of similar behavioral performance of young and older adults.

Episodic memory and organizational strategy in free recall in unipolar depression: The role of cognitive support and executive functions

Executive functioning and memory impairment have been demonstrated in adults with depression. Executive functions and memory are related, mainly when the memory tasks require controlled processes (attentional resource demanding processes)—that is, when a low cognitive support (external aid) is provided. A cross-sectional study was carried out on 45 participants: 21 with depression, and 24 healthy controls matched for age, verbal ability, education level, and anxiety score. Cognitive support was manipulated by providing a categorized word list at encoding, presented either clustered (high cognitive support) or randomized (low cognitive support) to both depressed and healthy adults. The number of words recalled was calculated, and an index of clustering was computed to assess organizational strategies. Participants were also administered cognitive tests (executive functions, cognitive speed, and categorical fluency) to explore the mediators of organizational strategies. Depressed participants had greater difficulty recalling and organizing the words, but the differences between the two groups were reduced for both measures when high cognitive support was provided at encoding. Healthy adults performed better on all cognitive tests. Statistical analyses revealed that in the depressed group, executive functions were the only variable associated with clustering and only when low cognitive support was provided. These findings support the view that the decrement in executive function due to depression may lead to impairment in organization when this mnemonic strategy has to be self-initiated.

Two hemispheres for better memory in old age: Role of executive functioning

This experiment explored the functional significance of age-related hemispheric asymmetry reduction associated with episodic memory and the cognitive mechanisms that mediate this brain pattern. ERPs were recorded while young and older adults performed a word-stem cued-recall task. Results confirmed that the parietal old/new effect was of larger latency and reduced magnitude and less lateralized in the older group than the young group. Correlational and regression analyses indicated that the degree of laterality of brain activity determines the accuracy of memory performance and mediates age-related differences in memory performance among older participants. They also confirmed a cascade model in which the individual level of executive functioning of older adults mediates age-related differences in the degree of lateralization of brain activity, which in turn mediates age-related differences in memory performance.

Does the greater involvement of executive control in memory with age act as a compensatory mechanism

Recent behavioural and imaging data have shown that memory functioning seems to rely more on executive functions and on the prefrontal cortex (PFC) in older than in young adults. Using a behavioural approach, our objective was to confirm the hypothesis that young and older adults present different patterns of correlation between episodic memory performance and executive functioning. We report three studies comparing the correlations of young and older adults in a broad range of episodic memory and executive function tasks. The results indicated that memory and executive performance were consistently and significantly correlated in older but not in younger adults. Regression analyses confirmed that age-related differences in episodic memory performance could be explained by individual differences in executive functioning. The results are consistent with the view that memory functioning in aging is accompanied by a shift from automatic to controlled forms of processing. They also generalise the executive hypothesis of episodic memory aging and are in line with the idea that executive functions act as a compensatory mechanism against age-related memory decline.