Vanessa Taler

Measuring the impact of exercise on cognitive aging: methodological issues

Physical exercise and fitness have been proposed as potential factors that promote healthy cognitive aging. Support for this hypothesis has come from cross sectional, longitudinal, and intervention studies. In the present review, we discuss several methodological problems that limit the conclusions of many studies. The lack of consensus on how to retrospectively measure exercise intensity is a major difficulty for all studies that attempt to estimate lifelong impact of exercise on cognitive performance in older adults. Intervention studies have a much better capacity to establish causality, but still suffer from difficulties arising from inadequate control groups and the choice and modality of administration of cognitive measures. We argue that, while the association between exercise and preserved cognition during aging is clearly demonstrated, the specific hypothesis that physical exercise is a cause of healthy cognitive aging has yet to be validated. A number of factors could mediate the exercise-cognition association, including depression, and social or cognitive stimulation. The complex interactions among these 3 factors and the potential impact of exercise on cognition remain to be systematically studied. At this time, the best prescription for lifestyle interventions for healthy cognitive aging would be sustained physical, social, and mental activities. What remains unknown is which type of activity might be most useful, and whether everyone benefits similarly from the same interventions.

Executive function and bilingualism in young and older adults

Research suggests that being bilingual results in advantages on executive control processes and disadvantages on language tasks relative to monolinguals. Furthermore, the executive function advantage is thought to be larger in older than younger adults, suggesting that bilingualism may buffer against age-related changes in executive function. However, there are potential confounds in some of the previous research, as well as inconsistencies in the literature. The goal of the current investigation was to examine the presence of a bilingual advantage in executive control and a bilingual disadvantage on language tasks in the same sample of young and older monolingual anglophones, monolingual francophones, and French/English bilinguals. Participants completed a series of executive function tasks, including a Stroop task, a Simon task, a sustained attention to response task (SART), the Wisconsin Card Sort Test (WCST), and the digit span subtest of the Wechsler Adult Intelligence Scale, and language tasks, including the Boston Naming Test (BNT), and category and letter fluency. The results do not demonstrate an unequivocal advantage for bilinguals on executive function tasks and raise questions about the reliability, robustness and/or specificity of previous findings. The results also did not demonstrate a disadvantage for bilinguals on language tasks. Rather, they suggest that there may be an influence of the language environment. It is concluded that additional research is required to fully characterize any language group differences in both executive function and language tasks.

Comprehension of Grammatical and Emotional Prosody Is Impaired in Alzheimer's Disease

Previous research has demonstrated impairment in comprehension of emotional prosody in individuals diagnosed with Alzheimers disease (AD). The present pilot study further explored the prosodic processing impairment in AD, aiming to extend our knowledge to encompass both grammatical and emotional prosody processing. As expected, impairments were seen in emotional prosody. AD individuals were also found to be impaired in detecting sentence modality, suggesting that impairments in affective prosody processing in AD may be ascribed to a more general prosodic processing impairment, specifically in comprehending prosodic information signaled across the sentence level. AD participants were at a very mild stage of the disease, suggesting that prosody impairments occur early in the disease course.

The Montreal Cognitive Assessment (MoCA) in geriatric rehabilitation: psychometric properties and association with rehabilitation outcomes

BACKGROUND Cognitive status has been reported to be an important predictor of rehabilitation outcome. The Montreal Cognitive Assessment (MoCA) was designed to overcome some of the limitations of established cognitive screening tools such as the Mini-Mental State Examination (MMSE). The purpose of this study is to evaluate the psychometric characteristics of the MoCA as a screening tool in a geriatric rehabilitation program and its ability to predict rehabilitation outcome. METHODS Forty-seven geriatric rehabilitation program patients participated in the study. Assessments of each patients functional (Functional Independence Measure) and cognitive status (MMSE and MoCA) were performed. Information on discharge destinations were obtained and rehabilitation efficacy and efficiency scores were calculated. RESULTS Significant correlations were found between the MoCA and other cognitive status measures. Cognitive status at admission and successful rehabilitation were also associated. Defining rehabilitation success on the basis of relative functional efficacy (an indicator that includes the patients potential for improvement), the sensitivity and specificity of the MoCA were 80% and 30% respectively. The attention subscale of the MoCA was also uniquely predictive of rehabilitation success. The attention subscale (cutoff 5/6) of the MoCA had a sensitivity of 40% and specificity of 90%, as did the MMSE. CONCLUSIONS As a cognitive screening tool, the MoCA appears to have acceptable psychometric properties. Results suggest that the MoCA can have a considerable advantage over the MMSE in sensitivity and equivalence in specificity using both total and attention scale scores. The MoCA may be a more useful measure for detecting cognitive impairment and predicting rehabilitation outcome in this population.

ERP measures of semantic richness: the case of multiple senses.

Semantic richness refers to the amount of semantic information that a lexical item possesses. An important measure of semantic richness is the number of related senses that a word has (e.g., TABLE meaning a piece of furniture, a table of contents, to lay aside for future discussion, etc.). We measured electrophysiological response to lexical items with many and few related senses in monolingual English-speaking young adults. Participants performed lexical decision on each item. Overall, high-sense words elicited shorter response latencies and smaller N400 amplitudes than low-sense words. These results constitute further evidence of the importance of semantic richness in lexical processing, and provide evidence that processing of multiple related senses begins as early as 200 milliseconds after stimulus onset.

The Role of Semantic Diversity in Word Recognition across Aging and Bilingualism.

Frequency effects are pervasive in studies of language, with higher frequency words being recognized faster than lower frequency words. However, the exact nature of frequency effects has recently been questioned, with some studies finding that contextual information provides a better fit to lexical decision and naming data than word frequency (Adelman et al., 2006). Recent work has cemented the importance of these results by demonstrating that a measure of the semantic diversity of the contexts that a word occurs in provides a powerful measure to account for variability in word recognition latency (Johns et al., 2012, 2015; Jones et al., 2012). The goal of the current study is to extend this measure to examine bilingualism and aging, where multiple theories use frequency of occurrence of linguistic constructs as central to accounting for empirical results (Gollan et al., 2008; Ramscar et al., 2014). A lexical decision experiment was conducted with four groups of subjects: younger and older monolinguals and bilinguals. Consistent with past results, a semantic diversity variable accounted for the greatest amount of variance in the latency data. In addition, the pattern of fits of semantic diversity across multiple corpora suggests that bilinguals and older adults are more sensitive to semantic diversity information than younger monolinguals.

Performance on the Boston Naming Test in Bilinguals

OBJECTIVES We examined performance on the Boston Naming Test (BNT) in older and younger adults who were monolingual English or French speakers, or bilingual speakers of English and French (n=215). METHODS Monolingual participants completed the task in their native language, and bilingual participants completed the task in English, French, and bilingual (either-language) administrations. RESULTS Overall, younger and older monolingual French speakers performed worse than other groups; bilingual participants performed worst in the French administration and approximately two-thirds of bilingual participants performed better when responses were accepted in either language. Surprisingly, however, a subset of bilinguals performed worse when responses were accepted in either language as compared to their maximum score achieved in either English or French. This either-language disadvantage does not appear to be associated with the degree of balanced bilingualism, but instead appears to be related to overall naming abilities. Differential item analysis comparing language groups and the different administrations identified several items that displayed uniform and/or non-uniform differential item functioning (DIF). CONCLUSIONS The BNT does not elicit equivalent performance in English and French, even when assessing naming performance in monolingual French speakers using the French version of the test. Scores were lower in French overall, and several items exhibited DIF. We recommend caution in interpreting performance on these items in bilingual speakers. Finally, not all bilinguals benefit from an either-language administration of the BNT.

The bilingual advantage: Elusive but worth the effort?

The notion of a bilingual advantage in cognitive function is an attractive hypothesis that has clearly garnered significant interest from the scientific community. Beyond simply implying that the ability to communicate in more than one language in a relatively proficient way over many years leads to advantages in cognition, it suggests that training in one domain, i.e., language, results in advantages in a domain-general faculty, i.e., general executive control. Beyond this, and not discussed in detail in by Paap, Johnson, and Sawi (2015), the bilingual advantage has been purported to confer advantages as people age and experience changes in cognitive function (e.g., Bialystok, Craik, Klein, & Viswanathan, 2004; Gold, Kim, Johnson, Kryscio, & Smith, 2013; Luk, Bialystok, Craik, & Grady, 2011). Furthermore, some research suggests that merely being bilingual can result in a delay in the onset of Alzheimers disease symptoms (e.g., Bialystok, Craik, Binns, Ossher, & Freedman, 2014; Bialystok, Craik, & Freedman, 2007; but see Chertkow et al., 2010; Crane et al., 2010; Zahodne, Schofield, Farrell, Stern, & Manly, 2014 for alternate findings). It is exciting to think that something as natural as language could have such dramatic effects on cognitive functioning over the course of the lifespan, and potentially buffer against age-related cognitive decline. It is not surprising that many researchers have pursued this hypothesis in an attempt to understand its magnitude and mechanism(s). Paap et al. provide an extensive review of the published findings, and conclude that current evidence does not support thehypothesisof a cognitiveadvantage forbilinguals.Weagree that theeffects of bilingualismmayhavebeenoverstated in the literature, although we believe that there are indeed undeniable differences between monolinguals and bilinguals. What remains unclear is whether these differences lead to measurable changes in domain-general executive function and, if so, under what circumstances. One important consideration with respect to the failure to find behavioural advantages in executive control for bilinguals is that much of the research uses samples of young adults, who are at the peak of their cognitive functioning. However, it is probable that differencesemergemostclearly incaseswherecognitive functioning is sub-optimal, suchas inolderadultswhomaybeexperiencing age-related cognitive declines. That is, when cognition is suboptimal there is room for bilingualism to exert an effect, whereas in young adults there is no room for improvement because they are at the height of cognitive function. A second major issue raised in the target article relates to brain-based evidence that ostensibly supports an advantage for bilinguals in the absence of behavioural evidence. Paap et al. point out that “reorganization to accommodate bilingualism does not logically need to result in more efficient performance” (p. 29). We agree that behavioural advantages are required in order to ascertain that a brain-based difference represents a true advantage. However, brain-based differences, even in the absence of behavioural advantages, remain an interesting and important area of study. Even in the absence of behavioural differences, any observed differences in measures of brain structure or function suggest that bilinguals and monolinguals are performing the same tasks differently, despite arriving at the same endpoint. This speaks to language-induced brain plasticity and suggests a possible source of cognitive differences later in the lifespan. In addition, advances in cognitive neuroscience methods that are potentially more sensitive and/or of higher resolution (e.g., resting-state functional connectivity, global and local efficiency measures) may prove useful in further elucidating

Cognitive measures in the Canadian Longitudinal Study on Aging

Abstract Objective: We describe the implementation of cognitive measures within the Canadian Longitudinal Study on Aging (CLSA), a nationwide, epidemiological study of aging, and relate CLSA Tracking cohort data (n over 20,000) to previous studies using these measures.Method: CLSA participants (aged 45–85, n over 50,000) provided demographic, social, physical/clinical, psychological, economic, and health service utilization information relevant to health and aging through telephone interviews (Tracking cohort, n over 20,000) or in-person (i.e. Comprehensive cohort, n over 30,000) in both official languages (i.e. English, French). Cognitive measures included: the Rey Auditory Verbal Learning Test (RAVLT) – Trial 1 and five-minute delayed recall; Animal Fluency (AF), the Mental Alternation Test (MAT) (both cohorts); Controlled Oral Word Association Test, Stroop Test, Prospective Memory Test, and Choice reaction times (Comprehensive Cohort).Results: Performance on the RAVLT Trial 1 and AF were very similar to comparable groups studied previously; CLSA sample sizes were far larger. Within the CLSA Tracking cohort, main effects of age and language were observed for all cognitive measures except RAVLT delayed recall. Interaction effects (language × age) were observed for AF.Conclusion: This preliminary examination of the CLSA Tracking cognitive measures lends support to their use in large studies of aging. The CLSA has the potential to provide the ‘best’ comparison data for adult Canadians generated to date and may also be applicable more broadly. Future studies examining relations among the psychological, biological, health, lifestyle, and social measures within the CLSA will make unique contributions to understanding aging.

Alterations in resting-state activity relate to performance in a verbal recognition task.

In the brain, resting-state activity refers to non-random patterns of intrinsic activity occurring when participants are not actively engaged in a task. We monitored resting-state activity using electroencephalogram (EEG) both before and after a verbal recognition task. We show a strong positive correlation between accuracy in verbal recognition and pre-task resting-state alpha power at posterior sites. We further characterized this effect by examining resting-state post-task activity. We found marked alterations in resting-state alpha power when comparing pre- and post-task periods, with more pronounced alterations in participants that attained higher task accuracy. These findings support a dynamical view of cognitive processes where patterns of ongoing brain activity can facilitate –or interfere– with optimal task performance.