Age-specific differences of dual n-back training

Age-related decline in executive functions can be decisive in performing everyday tasks autonomously. Working memory (WM) is closely related to executive functions, and training of WM has yielded evidence toward cognitive plasticity in older adults. The training effects often transfer to untrained tasks and functions. These effects have mostly been shown in processes such as WM and attention, whereas studies investigating transfer to executive functions have been scarce. We trained older adults aged 57–73 years in a WM training task that was reported to be effective in producing transfer in young adults. The training intervention consisted of a dual n-back task including independently processed auditory and visual n-back tasks. We investigated transfer to tasks engaging executive functions, and compared the effects in older adults to those reported in young adults. We found that both training groups improved in the training task. Although the training effect in older adults was smaller than the training effect in young adults, the older adults still showed a notable improvement so that after training they performed on the same level as young adults without training. The older adults also showed transfer to an untrained WM updating task, a result that was in accordance with the findings in young adults; other transfer effects in older adults were lacking. We conclude that although transfer effects were scarce, the present study provides encouraging evidence toward the possibilities to compensate for age-related decline in executive functions by a WM training intervention.     

Proverb interpretation changes in aging

Recent investigations have emphasized the involvement of fronto-subcortical networks to proverb comprehension. Although the prefrontal cortex is thought to be affected by normal aging, relatively little work has been carried out to investigate potential effects of aging on proverb comprehension. In the present investigation participants in three age groups were assessed on a proverb comprehension task and a range of executive function tasks. The older group showed impairment in selecting correct interpretations from alternatives. They also showed executive function deficits, as reflected by reduced working memory and deficient set shifting and inhibition abilities. The findings of the present investigation showed proverb comprehension deficits in normal aging which appeared to be related to reduced executive skills.     

Executive process training in young and old adults

There is a growing body of research on the modifiability of executive functions in different stages of life. Previous studies demonstrate robust training effects but limited transfer in younger and particularly in older adults. The aim of the present study was to investigate whether a theoretically derived intervention for executive functioning, addressing several basic processes (updating, shifting, and inhibition), can induce transfer effects in early and late adulthood. Fifty-nine healthy adults, 29 young and 30 older adults, were randomly assigned to either training or no-contact control groups. The training groups received 15 sessions of executive process training for about 45 min/session during 5 weeks. A test battery including a criterion task and near, intermediate, and far transfer tasks was administered before and after training. Results showed pronounced age-equivalent gains on the criterion task. Near transfer was seen to non-trained updating and inhibition tasks for the young and older trained participants. However, only the young adults showed intermediate transfer to two complex working memory tasks. No far transfer effects were seen for either age group. These findings provide additional evidence for age-related constraints in the ability to generalize acquired executive skills, and specifically show that training of multiple executive processes is not sufficient to foster transfer beyond the very near in older adults.     

Age differences in executive functioning across the lifespan: the role of verbalization in task preparation

Age-related changes in executive functioning across the lifespan were assessed in children (mean age=9.4 years), younger adults (mean age=21.5 years), and older adults (mean age=65.3 years). Executive functioning was investigated with a task-switching paradigm that permits the separation of two control components: to select and to switch between task sets. The specific aims of this study were (a) to determine developmental functions in both control components across the lifespan; and (b) to examine whether age-related changes in these components are influenced by verbal prompts during task preparation. The results revealed an inverted u-shaped developmental function for the ability to select between task sets but not for the ability to switch between task sets. In contrast to younger adults and children, older adults generally benefited from verbalizations during task preparation. Children, but not older adults, showed a facilitation of task execution when verbal prompts were task-compatible. Conversely, older adults, but not children, showed stronger interference when verbal prompts are task-incompatible. Our findings suggest that inner speech in an important modulator of developmental changes in executive functioning across the lifespan.     

Memory flexibility training for autobiographical memory as an intervention for maintaining social and mental well-being in older adults

Autobiographical memory specificity (AMS) reduces with increasing age and is associated with depression, social problem-solving and functional limitations. However, ability to switch between general and specific, as well as between positive and negative retrieval, may be more important for the strategic use of autobiographical information in everyday life. Ability to switch between retrieval modes is likely to rely on aspects of executive function. We propose that age-related deficits in cognitive flexibility impair AMS, but the “positivity effect” protects positively valenced memories from impaired specificity. A training programme to improve the ability to flexibly retrieve different types of memories in depressed adults (MemFlex) was examined in non-depressed older adults to determine effects on AMS, valence and the executive functions underlying cognitive flexibility. Thirty-nine participants aged 70+ (MemFlex, n?=?20; control, n?=?19) took part. AMS and the inhibition aspect of executive function improved in both groups, suggesting these abilities are amenable to change, although not differentially affected by this type of training. Lower baseline inhibition scores correlated with increased negative, but not positive AMS, suggesting that positive AMS is an automatic process in older adults. Changes in AMS correlated with changes in social problem-solving, emphasising the usefulness of AMs in a social environment.     

A bilingual advantage for episodic memory in older adults

The ability to remember events—referred to as episodic memory—is typically subject to decline in older adulthood. Episodic memory decline has been attributed in part to less successful executive functioning, which may hinder an older adult's ability to implement controlled encoding and retrieval processes. Since bilingual older adults often show more successful executive functioning than monolinguals, they may be better able to maintain episodic memory. To examine this hypothesis, we compared bilingual and monolingual older adults on a picture scene recall task (assessing episodic memory) and a Simon task (assessing executive functioning). Bilinguals exhibited better episodic memory than their monolingual peers, recalling significantly more items overall. Within the bilingual group, earlier second language acquisition and more years speaking two languages were associated with better recall. Bilinguals also demonstrated higher executive functioning, and there was evidence that level of executive functioning was related to memory performance. Results indicate that extensive practice controlling two languages may benefit episodic memory in older adults.     

The effects of adult aging and induced positive and negative mood on planning

Changes in executive functions have been found in older adults and also in young adults experiencing positive or negative mood states. The current study investigated the hypothesis that older adults would show greater executive function impairment following mood induction than young adults. Ninety-six participants (half aged 19-37, half aged 53-80) completed a neutral, positive, or negative mood induction procedure, followed by the Tower of London planning task. Significant interactions were found between age and mood such that older adults showed greater planning impairment than young adults in both the positive and negative mood conditions. Emotionally salient events occurring before testing may interfere with executive function in older adults.     

Effects of interactive physical-activity video-game training on physical and cognitive function in older adults

The purpose of the present study was to assess the potential of exergame training based on physically simulated sport play as a mode of physical activity that could have cognitive benefits for older adults. If exergame play has the cognitive benefits of conventional physical activity and also has the intrinsic attractiveness of video games, then it might be a very effective way to induce desirable lifestyle changes in older adults. To examine this issue, the authors developed an active video game training program using a pretest-training-posttest design comparing an experimental group (24 × 1 hr of training) with a control group without treatment. Participants completed a battery of neuropsychological tests, assessing executive control, visuospatial functions, and processing speed, to measure the cognitive impact of the program. They were also given a battery of functional fitness tests to measure the physical impact of the program. The trainees improved significantly in measures of game performance. They also improved significantly more than the control participants in measures of physical function and cognitive measures of executive control and processing speed, but not on visuospatial measures. It was encouraging to observe that, engagement in physically simulated sport games yielded benefits to cognitive and physical skills that are directly involved in functional abilities older adults need in everyday living (e.g., Hultsch, Hertzog, Small, & Dixon, 1999).     

Self-reference enhances relational memory in young and older adults

The present study investigated the influence of self-reference on two kinds of relational memory, internal source memory and associative memory, in young and older adults. Participants encoded object–location word pairs using the strategies of imagination and sentence generation, either with reference to themselves or to a famous other (i.e., George Clooney or Oprah Winfrey). Both young and older adults showed memory benefits in the self-reference conditions compared to other-reference conditions on both tests, and the self-referential effects in older adults were not limited by low memory or executive functioning. These results suggest that self-reference can benefit relational memory in older adults relatively independently of basic memory and executive functions.     

Resolving conflicting social categories: the role of age-related executive ability

We investigated the effect of age-related decline in executive ability on the application of emergent features to incongruent social category conjunctions (e.g., male midwife). When forming an impression of an incongruent conjunction, older adults used more emergent attributes (attributes associated exclusively with the category conjunction and not the constituents), relative to younger adults. Moreover, this relationship was mediated by a reduction in inhibitory ability (measured using a Stroop task) and processing speed (measured using a Digit Symbol Substitution Test, DSST). These findings are consistent with the notion that executive ability is pivotal in understanding social functioning in older adults. We discuss the implications of these findings for the continuing development of models outlining the processes and stages involved in perceiving social category conjunctions.     

Differential relationships of somatic and cognitive anxiety with measures of processing speed in older adults

Research suggests a reciprocal relationship between late-life anxiety and cognition, particularly attention and executive functions. Whereas evidence supports a conceptual distinction between cognitive and somatic dimensions of anxiety, their differential relationship with cognitive outcomes has not been examined, particularly on tests of attention/executive functions that rely on processing speed. Study goals were threefold: (a) to describe levels of overall, cognitive, and somatic anxiety in a sample of older adults without dementia, (b) to determine if overall anxiety is associated with performance on select measures of attention/executive functions that rely on processing speed, and (c) to determine if a differential relationship exists between cognitive and somatic anxiety and cognitive performance. Participants were 368 community-dwelling older adults. Results showed that elevated levels of somatic, but not cognitive anxiety were associated with poorer performance across measures. Findings suggest that the nature of anxiety symptoms may have important implications for cognitive performance in older adults.     

Ageing, remembering, and executive function

This study was designed to investigate the relationship between executive functions and the age-related decline in episodic memory through the states-of-awareness approach. Following the presentation of a word list, a group of younger adults and a group of older adults undertook a recognition test in which they classified their responses according to the Remember-Know-Guess procedure (Gardiner & Richardson-Klavehn, 2000). In order to operationalise the executive function hypothesis, we investigated three specific executive functions (updating, shifting, and inhibition of a prepotent response) described in Miyake et al.'s (2000) theoretical model, and a complex executive task. The results revealed that fewer "R" responses were made during the recognition test by the older than the younger group, whereas there was no difference between the groups in the number of "K" responses. In addition, correlations indicated that remembering depended on executive function measures, whereas knowing did not. The hierarchical regression analyses showed that controlling for executive function, and particularly for the 2-back test, largely removed the age-related variance in remembering. These findings support the notion that executive dysfunction, and specifically updating decline, plays a central role in age-related memory loss.     

How older adults use cognition in sentence-final word recognition

This study examined the effects of executive control and working memory on older adults’ sentence-final word recognition. The question we addressed was the importance of executive functions to this process and how it is modulated by the predictability of the speech material. To this end, we tested 173 neurologically intact adult native English speakers aged 55–84 years. Participants were given a sentence-final word recognition test in which sentential context was manipulated and sentences were presented in different levels of babble, and multiple tests of executive functioning assessing inhibition, shifting, and efficient access to long-term memory, as well as working memory. Using a generalized linear mixed model, we found that better inhibition was associated with higher accuracy in word recognition, while increased age and greater hearing loss were associated with poorer performance. Findings are discussed in the framework of semantic control and are interpreted as supporting a theoretical view of executive control which emphasizes functional diversity among executive components.     

Do young and older adults rely on different processes in source memory tasks? A neuropsychological study

Source memory has consistently been associated with prefrontal function in both normal and clinical populations. Nevertheless, the exact contribution of this brain region to source memory remains uncertain, and evidence suggests that processes used by young and older adults may differ. The authors explored the extent to which scores on composite measures of neuropsychological tests of frontal and medial temporal function differentially predicted the performance of young and older adults on source memory tasks. Results indicated that a frontal composite measure, consistently associated with source memory performance in older adults, was unrelated to source memory in young adults, although it was sensitive to a demanding working memory task. The memory composite score, however, predicted performance in the young group. In addition, item and source memory were correlated in young but not older people. Findings are discussed in terms of age-related differences in working memory and executive functions, and differential binding processes necessary for item and source memory. The requirement to integrate item and source information at encoding appears to place greater demands on executive or working memory processes in older adults than in younger adults.     

Bilingualism, aging, and cognitive control: evidence from the Simon task

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.     

Differences in the functional neuroanatomy of inhibitory control across the adult life span

Inhibitory control, the ability to suppress irrelevant or interfering stimuli, is a fundamental cognitive function that deteriorates during aging, but little is understood about the bases of decline. Thus, we used event-related functional magnetic resonance imaging (fMRI) to study inhibitory control in healthy adults aged 18 to 78. Activation during "successful inhibition" occurred predominantly in right prefrontal and parietal regions and was more extensive, bilaterally and prefrontally, in the older groups. Presupplementary motor area was also more active in poorer inhibitory performers. Therefore, older adults activate areas that are comparable to those activated by young adults during inhibition, as well as additional regions. The results are consistent with a compensatory interpretation and extend the aging neuroimaging literature into the cognitive domain of inhibition.     

Lapses of intention and performance variability reveal age-related increases in fluctuations of executive control

We examine the hypothesis that the efficiency of executive control processes is less stable over time in older than younger adults. An age-related decrease in the efficiency of executive control should result in an increase in performance variability in task conditions requiring the recruitment of executive control processes and not in task conditions requiring minimal involvement of executive control. Performance variability was similar for younger and older adults in task conditions requiring minimal executive control and greater for older than younger adults in task conditions requiring executive control. These and other data are consistent with the proposal that aging is associated with a decrease in the stability of executive control over time.     

The role of executive functioning in CBT: a pilot study with anxious older adults

Cognitive behavior therapy (CBT) is an effective treatment for late life anxiety and depression. The successful use of CBT is assumed to rely on cognitive skills known as executive functions (EF; e.g., hypothesis generation, allocation of attention, self-monitoring) governed by the prefrontal cortex. Because older adults sometimes have executive deficits as a consequence of normal aging, EF may be a mediator of CBT outcome in older samples. The current pilot study tested the hypothesis that older adults with executive deficits (as measured by neuropsychological tests) would show decreased therapeutic benefit from CBT for generalized anxiety disorder, as compared to a group with intact EF. Results indicated differential response to CBT within the dysfunction group depending on the stability (and possibly, the etiology) of executive deficits from pre- to posttreatment. Those whose EF scores remained low from pre- to posttreatment did not respond to CBT, while those whose scores improved responded quite well, similar to an Intact EF group. Results indicate that some, but not all, older adults with executive dysfunction show decreased benefit from CBT, and are consistent with the assumption that executive skills are important for the successful use of CBT. However, some participants may show improvement on both mood and cognitive skills during treatment, which is discussed further.     

The relationship between executive function and fine motor control in young and older adults

The present study examined the relationship between executive function (EF) and fine motor control in young and older healthy adults. Participants completed 3 measures of executive function; a spatial working memory (SWM) task, the Stockings of Cambridge task (planning), and the Intra-Dimensional Extra-Dimensional Set-Shift task (set-shifting). Fine motor control was assessed using 3 subtests of the Purdue Pegboard (unimanual, bimanual, sequencing). For the younger adults, there were no significant correlations between measures of EF and fine motor control. For the older adults, all EFs significantly correlated with all measures of fine motor control. Three separate regressions examined whether planning, SWM and set-shifting independently predicted unimanual, bimanual, and sequencing scores for the older adults. Planning was the primary predictor of performance on all three Purdue subtests. A multiple-groups mediation model examined whether planning predicted fine motor control scores independent of participants’ age, suggesting that preservation of planning ability may support fine motor control in older adults. Planning remained a significant predictor of unimanual performance in the older age group, but not bimanual or sequencing performance. The findings are discussed in terms of compensation theory, whereby planning is a key compensatory resource for fine motor control in older adults.     

Tai Chi exercise training enhances executive function and fluid intelligence of healthy older adults: Cross-sectional and longitudinal evidence

Executive function and fluid intelligence are two of the crucial frontal lobe functions susceptible to aging. Tai Chi as a mind-body exercise has been proposed for preventing cognitive aging. However, whether Tai Chi has similar effects on multiple components of executive functions in older adults remains underspecified. Moreover, it is not currently known whether Tai Chi exercise training improvements in lower-order executive functions are able to explain improvements in higher-order fluid intelligence. Study 1 included a cross-sectional design based on a large sample of healthy older adults (55–79 years old). Modeling results showed that experience of Tai Chi training exerted significantly positive effects on fluid intelligence, inhibition and updating after controlling for age and education. Both inhibition and updating mediated effects of Tai Chi on fluid intelligence. Study 2 carried out a 12-month Tai Chi training intervention on a novice group and an experienced group of older adults. Results indicated that only the novices exhibited significant improvements in inhibition and fluid intelligence. In addition, improvements in fluid intelligence were no longer significant after controlling for improvements in inhibition. These results shed lights on the mechanism by which mind-body training enhances intelligence.