Higher physical fitness levels are associated with less language decline in healthy ageing

Effects of increasing fitness through exercise training on language comprehension in monolingual and bilingual older adults: a randomized controlled trial

Exercise training has been proposed to counteract age-related cognitive decline through improvements in cardiorespiratory fitness (CRF hypothesis). Research has focused on cognitive domains like attention and processing speed, and one cross-sectional study reported a positive relationship between CRF and language production in older adults. In a randomized controlled trial, we investigated whether these benefits could extend to language comprehension in healthy older adults, and whether bilinguals, for whom language processing is more costly, would exhibit greater benefits than monolinguals. Eighty older English monolinguals and 80 older Norwegian-English bilinguals were randomized into either a 6-month exercise training group or into a passive control group. We assessed CRF (VO2peak) and language comprehension (reaction times to spoken word monitoring) in first (L1, all participants) and second language (L2, bilinguals only), before and after the intervention. We found that monolinguals in the exercise group (compared to the control group) were faster in comprehension following the intervention. Moreover, this effect was mediated by exercise-induced increases in VO2peak, supporting the CRF hypothesis. This extends previous cross-sectional research and establishes a causal link between exercise training and speeded comprehension in older monolinguals. However, despite inducing increased VO2peak, exercise training did not affect bilingual (L1 or L2) comprehension, and bilinguals in both groups were slower after the intervention period. Exploratory analyses suggested that this slowing may be driven by participants with low L2 proficiency, but further research is needed to examine whether bilingual language processing is in fact unaffected by exercise training and its consequent improvements in CRF.

Exercise and Protection from Age-Related Cognitive Decline

In this chapter, we review the cross-sectional evidence in healthy human subjects for physical activity and cardiorespiratory fitness to offer neuroprotection and moderate cognitive decline in older age. The role of exercise training on cognition in healthy older adults and those diagnosed with mild cognitive impairment (MCI) is also discussed, including the evidence from neuroimaging studies that document changes to brain structure and function after a period of exercise training and improved fitness. Finally, in reference to animal models, the potential neurophysiological mechanisms for physical activity and exercise to impact human brain health are highlighted.

Episodic memory and aging: Benefits of physical activity depend on the executive resources required for the task

Physical activity has beneficial effects on executive functions and episodic memory, two processes affected by aging. These benefits seem to depend on the type of memory task, but only a few studies have evaluated them despite their importance in understanding aging. This study aimed to confirm that the benefits of physical activity on episodic memory in older adults vary according to the executive resources required by the memory task, comparing free recall and cued recall. Thirty-seven young adults and 37 older adults performed two memory tasks and an updating task. The two groups had a similar level of physical activity over the preceding 12 months, assessed by a questionnaire. Both the memory and the updating tasks were performed better by the younger than the older adults. A similar cueing effect was observed in the two groups. Physical activity was positively correlated with updating and free recall, but not with cued-recall, and only in older adults. Regression analyses indicated that physical activity accounted for 24% of the variance in free recall in older adults. Updating did not predict free recall (ns) when physical activity was entered in the analysis. The present results show that the benefits of physical activity vary with age and episodic memory task. Only free-recall performance, which relies on updating, seems to depend on physical activity, suggesting that the executive resources required for the task play an important role in the effect of physical activity on memory performance. This should be investigated in greater depth in subsequent studies.

How the healthy ageing brain supports semantic binding during language comprehension

Semantic binding refers to constructing complex meaning based on elementary building blocks. Using electroencephalography (EEG), we investigated the age-related changes in modulations of oscillatory brain activity supporting lexical retrieval and semantic binding. Young and older adult participants were visually presented two-word phrases, which for the first word revealed a lexical retrieval signature (e.g., swift vs. swrfeq) and for the second word revealed a semantic binding signature (e.g., horse in a semantic binding "swift horse" vs. no binding "swrfeq horse" context). The oscillatory brain activity associated with lexical retrieval as well as semantic binding significantly differed between healthy older and young adults. Specifically for lexical retrieval, we found that different age groups exhibited opposite patterns of theta and alpha modulation, which as a combined picture suggest that lexical retrieval is associated with different and delayed signatures in older compared with young adults. For semantic binding, in young adults, we found a signature in the low-beta range centred around the target word onset (i.e., a smaller low-beta increase for binding relative to no binding), whereas in healthy older adults, we found an opposite binding signature about ~500 ms later in the low- and high-beta range (i.e., a smaller low- and high-beta decrease for binding relative to no binding). The novel finding of a different and delayed oscillatory signature for semantic binding in healthy older adults reflects that the integration of word meaning into the semantic context takes longer and relies on different mechanisms in healthy older compared with young adults.

Modelling Modifiable Predictors of Age-Related Cognitive Decline: Exercise, Aortic Stiffness, and the Importance of Physical Fitness

BACKGROUND

Previous modelling found that fitness and aortic stiffness both independently predicted spatial working memory (SWM) performance in older people. There is also evidence that greater engagement in moderate intensity exercise contributes to better cognitive performance, potentially working through improving fitness and aortic stiffness.

OBJECTIVE

To investigate the effect of exercise on the previously established relationships between fitness, aortic stiffness, and SWM, and whether these associations differ between older adults of higher and lower fitness.

METHODS

One hundred and two residents of independent living facilities, aged 60-90 (M = 77.5, SD = 6.9) participated in the study. Measures included computerized cognitive assessment, the Six-Minute Walk fitness test, the CHAMPS physical activity questionnaire, and aortic pulse wave analysis. Multiple structural equation models were used to test hypotheses.

RESULTS

Overall, exercise levels had a small additional effect in predicting SWM, working exclusively through fitness, although this was only true for those of lower than average fitness. Additionally, it was found that while fitness was the most important factor in predicting SWM in those of lower fitness, aortic stiffness was the strongest predictor in those of higher fitness.

CONCLUSION

Fitness and aortic stiffness are strong predictors of cognition in older people, and greater engagement in exercise predicted better cognition in those who were of lower fitness. Fitter older people may benefit more from interventions which target aortic stiffness in order to preserve cognitive performance as they age, while those who are less fit may benefit most from improving fitness first, including through increased physical activity.

Healthy Aging and Sentence Production: Disrupted Lexical Access in the Context of Intact Syntactic Planning

Healthy aging does not affect all features of language processing equally. In this study, we investigated the effects of aging on different processes involved in fluent sentence production, a complex task that requires the successful execution and coordination of multiple processes. In Experiment 1, we investigated age-related effects on the speed of syntax selection using a syntactic priming paradigm. Both young and older adults produced target sentences quicker following syntactically related primes compared to unrelated primes, indicating that syntactic facilitation effects are preserved with age. In Experiment 2, we investigated age-related effects in syntactic planning and lexical retrieval using a planning scope paradigm: participants described moving picture displays designed to elicit sentences with either initial coordinate or simple noun phrases and, on half of the trials, the second picture was previewed. Without preview, both age groups were slower to initiate sentences with larger coordinate phrases, suggesting a similar phrasal planning scope. However, age-related differences did emerge relating to the preview manipulation: while young adults displayed speed benefits of preview in both phrase conditions, older adults only displayed speed preview benefits within the initial phrase (coordinate condition). Moreover, preview outside the initial phrase (simple condition) caused older adults to become significantly more error-prone. Thus, while syntactic planning scope appears unaffected by aging, older adults do appear to encounter problems with managing the activation and integration of lexical items into syntactic structures. Taken together, our findings indicate that healthy aging disrupts the lexical, but not the syntactic, processes involved in sentence production.