Cross-sectional associations between 24-hour time-use composition, grey matter volume and cognitive function in healthy older adults.

BACKGROUND: Increasing physical activity (PA) is an effective strategy to slow reductions in cortical volume and maintain cognitive function in older adulthood. However, PA does not exist in isolation, but coexists with sleep and sedentary behaviour to make up the 24-hour day. We investigated how the balance of all three behaviours (24-hour time-use composition) is associated with grey matter volume in healthy older adults, and whether grey matter volume influences the relationship between 24-hour time-use composition and cognitive function. METHODS: This cross-sectional study included 378 older adults (65.6 ± 3.0 years old, 123 male) from the ACTIVate study across two Australian sites (Adelaide and Newcastle). Time-use composition was captured using 7-day accelerometry, and T1-weighted magnetic resonance imaging was used to measure grey matter volume both globally and across regions of interest (ROI: frontal lobe, temporal lobe, hippocampi, and lateral ventricles). Pairwise correlations were used to explore univariate associations between time-use variables, grey matter volumes and cognitive outcomes. Compositional data analysis linear regression models were used to quantify associations between ROI volumes and time-use composition, and explore potential associations between the interaction between ROI volumes and time-use composition with cognitive outcomes. RESULTS: After adjusting for covariates (age, sex, education), there were no significant associations between time-use composition and any volumetric outcomes. There were significant interactions between time-use composition and frontal lobe volume for long-term memory (p = 0.018) and executive function (p = 0.018), and between time-use composition and total grey matter volume for executive function (p = 0.028). Spending more time in moderate-vigorous PA was associated with better long-term memory scores, but only for those with smaller frontal lobe volume (below the sample mean). Conversely, spending more time in sleep and less time in sedentary behaviour was associated with better executive function in those with smaller total grey matter volume. CONCLUSIONS: Although 24-hour time use was not associated with total or regional grey matter independently, total grey matter and frontal lobe grey matter volume moderated the relationship between time-use composition and several cognitive outcomes. Future studies should investigate these relationships longitudinally to assess whether changes in time-use composition correspond to changes in grey matter volume and cognition.

Metaplastic neuromodulation via transcranial direct current stimulation has no effect on corticospinal excitability and neuromuscular fatigue.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation tool with potential for managing neuromuscular fatigue, possibly due to alterations in corticospinal excitability. However, inconsistencies in intra- and inter- individual variability responsiveness to tDCS limit its clinical use. Emerging evidence suggests harnessing homeostatic metaplasticity induced via tDCS may reduce variability and boost its outcomes, yet little is known regarding its influence on neuromuscular fatigue in healthy adults. We explored whether cathodal tDCS (ctDCS) prior to exercise combined with anodal tDCS (atDCS) could augment corticospinal excitability and attenuate neuromuscular fatigue. 15 young healthy adults (6 males, 22 ± 4 years) participated in four pseudo-randomised neuromodulation sessions: sham stimulation prior and during exercise, sham stimulation prior and atDCS during exercise, ctDCS prior and atDCS during exercise, ctDCS prior and sham stimulation during exercise. The exercise constituted an intermittent maximal voluntary contraction (MVC) of the right first dorsal interosseous (FDI) for 10 min. Neuromuscular fatigue was quantified as an attenuation in MVC force, while motor evoked potential (MEP) amplitude provided an assessment of corticospinal excitability. MEP amplitude increased during the fatiguing exercise, whilst across time, force decreased. There were no differences in MEP amplitudes or force between neuromodulation sessions. These outcomes highlight the ambiguity of harnessing metaplasticity to ameliorate neuromuscular fatigue in young healthy individuals.

Prevalence and characteristics of preoperative patients with depression.

BACKGROUND: Within the perioperative period, depression-related diagnoses are associated with postoperative complications. We developed a perioperative depression screening programme to assess disease prevalence and feasibility for intervention. METHODS: Adult patients in multiple surgical departments at a single academic centre were screened for depression via the electronic health record patient portal or preoperative anaesthesia clinic before surgery, using the Patient Health Questionnaire (PHQ)-2 and -8. We utilised a broad method, screening all patients, and a focused method, only screening patients with a history of depression. Logistic regression was used to identify characteristics associated with clinically significant depression (PHQ-8 ≥10). Symptomatic patients were administered a brief psychoeducational intervention and referred for mental health services. RESULTS: A total of 3735 patients were identified by the broad and focused screens, of whom 2940 (79%) returned PHQ-2 data and were included in analysis. The broad screen (N=1216) found 46 (4%) patients who reported symptoms of moderate or greater severity. The focused screen (N=1724) found 242 (14%) patients with symptoms of moderate or greater severity and over all higher rates of depression across the symptom severity scale. Using the total screened pool, logistic regression identified a history of depression as the strongest associated patient characteristic variable but this did not capture most cases. Finally, we found that 66% of patients who were contacted about mental health services accepted referrals or sought outside care. CONCLUSIONS: At least 4% of preoperative patients have clinically significant symptoms of depression, most of whom do not have a chart history of depression.

A scoping review of resting-state brain functional alterations in Type 2 diabetes.

Resting-state functional magnetic resonance imaging (rs-fMRI) has been actively used in the last decade to investigate brain functional connectivity alterations in Type 2 Diabetes Mellitus (T2DM) to understand the neuropathophysiology of T2DM in cognitive degeneration. Given the emergence of new analysis techniques, this scoping review aims to map the rs-fMRI analysis techniques that have been applied in the literature and reports the latest rs-fMRI findings that have not been covered in previous reviews. Graph theory, the contemporary rs-fMRI analysis, has been used to demonstrate altered brain topological organisations in people with T2DM, which included altered degree centrality, functional connectivity strength, the small-world architecture and network-based statistics. These alterations were correlated with T2DM patients' cognitive performances. Graph theory also contributes to identify unbiased seeds for seed-based analysis. The expanding rs-fMRI analytical approaches continue to provide new evidence that helps to understand the mechanisms of T2DM-related cognitive degeneration.

The association between reallocations of time and health using compositional data analysis: a systematic scoping review with an interactive data exploration interface.

BACKGROUND: How time is allocated influences health. However, any increase in time allocated to one behaviour must be offset by a decrease in others. Recently, studies have used compositional data analysis (CoDA) to estimate the associations with health when reallocating time between different behaviours. The aim of this scoping review was to provide an overview of studies that have used CoDA to model how reallocating time between different time-use components is associated with health. METHODS: A systematic search of four electronic databases (MEDLINE, Embase, Scopus, SPORTDiscus) was conducted in October 2022. Studies were eligible if they used CoDA to examine the associations of time reallocations and health. Reallocations were considered between movement behaviours (sedentary behaviour (SB), light physical activity (LPA), moderate-to-vigorous physical activity (MVPA)) or various activities of daily living (screen time, work, household chores etc.). The review considered all populations, including clinical populations, as well as all health-related outcomes. RESULTS: One hundred and three studies were included. Adiposity was the most commonly studied health outcome (n = 41). Most studies (n = 75) reported reallocations amongst daily sleep, SB, LPA and MVPA. While other studies reported reallocations amongst sub-compositions of these (work MVPA vs. leisure MVPA), activity types determined by recall (screen time, household chores, passive transport etc.) or bouted behaviours (short vs. long bouts of SB). In general, when considering cross-sectional results, reallocating time to MVPA from any behaviour(s) was favourably associated with health and reallocating time away from MVPA to any behaviour(s) was unfavourably associated with health. Some beneficial associations were seen when reallocating time from SB to both LPA and sleep; however, the strength of the association was much lower than for any reallocations involving MVPA. However, there were many null findings. Notably, most of the longitudinal studies found no associations between reallocations of time and health. Some evidence also suggested the context of behaviours was important, with reallocations of leisure time toward MVPA having a stronger favourable association for health than reallocating work time towards MVPA. CONCLUSIONS: Evidence suggests that reallocating time towards MVPA from any behaviour(s) has the strongest favourable association with health, and reallocating time away from MVPA toward any behaviour(s) has the strongest unfavourable association with health. Future studies should use longitudinal and experimental study designs, and for a wider range of outcomes.

Mixed-methods evaluation of Daily Moves, a community-based physical activity program for older adults.

BACKGROUND: Although the health benefits of physical activity are well documented, most older adults are not sufficiently active. There is a need to explore approaches to physical activity promotion amongst older adults that meet the personal preferences and needs of participants, and that can be implemented on a large scale in community-based settings. The current study evaluates Daily Moves, a community-based physical activity program for older adults living in Adelaide, Australia.  METHODS: The Daily Moves program, which ran almost entirely during the COVID-19 pandemic, provided participants with personalized plans and information about suitable physical activity promoting activities available in their local area. This study used an explanatory sequential mixed-methods approach to evaluate associations between participation in the Daily Moves program and physical activity engagement, physical function and psychosocial wellbeing, and to explore the experiences of Daily Moves participants through qualitative interviews, with a particular focus on the impact of the COVID-19 pandemic on program participation and enjoyment. RESULTS: The research evaluation included 69 older adults (mean age at baseline = 73.9 ± 5.6 years; 19 male). Following Daily Moves, participants reported an increase in self-report physical activity levels (mean increase = 1.8 days, p < 0.001), improvements on several measures of physical function (left grip strength (mean increase = 1.8 kg, p < 0.001); right grip strength (mean increase = 1.3 kg, p = 0.03); Timed Up and Go (mean decrease = 1.3 s, p < 0.001)), and no significant changes in measures of psychosocial wellbeing. Qualitative interviews revealed that participants valued the supportive and flexible nature of Daily Moves, and that they felt connected with staff and other participants despite the onset of the pandemic. CONCLUSIONS: This evaluation demonstrates that physical activity programs embedded within the community can provide flexible and tailored recommendations to participants, and that this approach can promote positive change in important indicators of health in older adults.

Differential effects of aging and physical activity on corticospinal excitability of upper and lower limb muscles.

Corticospinal tract excitability can be altered by age, physical activity (PA), and possibly sex, but whether these effects differ between upper and lower limb muscles is unknown. We determined the influence of age, PA, and sex on corticospinal excitability of an upper limb and a lower limb muscle during submaximal contractions by comparing stimulus-response curves of motor evoked potentials (MEPs). Transcranial magnetic stimulation (TMS) was used to evoke stimulus-response curves in active muscles by incrementally increasing the stimulator intensity from below the active motor threshold (AMT) until a plateau in MEP amplitudes was achieved. Stimulus-response curves were analyzed from the first dorsal interosseous (FDI) of 30 young (23.9 ± 3.8 yr) and 33 older (72.6 ± 5.6 yr) men and women and the vastus lateralis (VL) of 13 young (23.2 ± 2.2 yr) and 25 older (72.7 ± 5.5 yr) men and women. Corticospinal excitability was determined by fitting the curves with a four-parameter sigmoidal curve and calculating the maximal slope (slopemax). PA was assessed with triaxial accelerometry, and participants were dichotomized into high-PA (>10,000 steps/day, n = 15) or low-PA (<10,000 steps/day, n = 43) groups. Young adults had larger FDI MEP amplitudes (% maximum amplitude of compound muscle action potential) at higher TMS intensities (120-150% AMT) and greater slopemax than older adults (P < 0.05), with no differences between high- and low-PA groups (P > 0.05). VL MEP amplitudes and slopemax, however, were lower in the high-PA than low-PA participants, with no age or sex differences. These data suggest that aging and PA, but not sex, differentially influence the excitability of the corticospinal tracts projecting to muscles of the upper compared with the lower limb. NEW & NOTEWORTHY Excitability of the corticospinal tract projecting to the first dorsal interosseous assessed with transcranial magnetic stimulation was reduced with age but independent of regular physical activity (steps/day) and sex of the individual. In contrast, corticospinal excitability of the vastus lateralis was not affected by age but was reduced in individuals achieving more than the physical activity recommendations of 10,000 steps/day. Aging and activity differentially affect corticospinal excitability of upper and lower limb muscles.

Submaximal Exercise-Based Equations to Predict Maximal Oxygen Uptake in Older Adults: A Systematic Review.

OBJECTIVE: To evaluate and discuss the accuracy of submaximal exercise-based equations to predict maximum oxygen uptake (V˙o2max), validated using direct gas analysis, in older apparently healthy adults. DATA SOURCES: Studies were identified by searching 5 electronic databases and manually scanning reference lists of included articles from the respective inception of each database through April 2015. STUDY SELECTION: Studies were included if they used at least 1 submaximal exercise-based variable in the prediction, the actual V˙o2max was directly measured using a gas analysis device, and if participants were apparently healthy older adults (mean age ≥65y). Eligible studies were required to report at least 1 validity statistic (eg, Pearson product-moment correlation [r]) and either a predicted and measured V˙o2max value or a directional significant difference between the measured and predicted V˙o2max values. No limits were placed on year of publication, but only full-text, published articles in the English language were included. DATA EXTRACTION: Nine articles and 13 equations were retained from the systematic search strategy. If the same prediction equation was used across multiple trials, data from the most accurate trial were reported. DATA SYNTHESIS: Submaximal equations predicted directly measured V˙o2max with a moderate to strong correlation strength (r range, 0.4-0.9). Predicted V˙o2max significantly differed from directly measured in 2 of the 13 equations. The preferred mode of ergometry was walking or running (7 equations); a stepping protocol was the most accurate (R(2)=0.9, not significant between predicted and measured V˙o2max). CONCLUSIONS: Factors to consider when choosing a submaximal exercise-based equation are the accuracy of the equation, the population tested, the mode of ergometry, the equipment availability, and the time needed to conduct familiarization sessions.

Patterning of physiological and affective responses in older active adults during a maximal graded exercise test and self-selected exercise.

PURPOSE: The American College of Sports Medicine has highlighted the importance of considering the physiological and affective responses to exercise when setting exercise intensity. Here, we examined the relationship between exercise intensity and physiological and affective responses in active older adults. METHOD: Eighteen participants (60-74 years; 64.4 ± 3.9; 8 women) completed a maximal graded exercise test (GXT) on a treadmill. Since time to exhaustion in the GXT differed between participants, heart rate (HR), oxygen consumption (VO2), affective valence (affect) and rating of perceived exertion (RPE) were expressed relative to the individually determined ventilatory threshold (%atVT). RESULT: During the GXT, VO2, HR and RPE increased linearly (all P < 0.01). Affect declined initially (but remained positive) (P = 0.03), stabilised around VT (still positive) (P > 0.05) and became negative towards the end of the test (P < 0.01). In a subsequent session, participants completed a 20-min bout of self-selected exercise (at a preferred intensity). Initially, participants chose to exercise below VT (88.2 ± 17.4 %VO2atVT); however, the intensity was adjusted to work at, or above VT (107.7 ± 19.9 %VO2atVT) after 10 min (P < 0.001), whilst affect remained positive. CONCLUSION: Together, these findings indicate that exercise around VT, whether administered during an exercise test, or self-selected by the participant, is likely to result in positive affective responses in older adults.

A perceptually-regulated exercise test predicts peak oxygen uptake in older active adults.

Peak oxygen uptake (VO2peak) is reliably predicted in young and middle-aged adults using a submaximal perceptually-regulated exercise test (PRET). It is unknown whether older adults can use a PRET to accurately predict VO2peak. In this study, the validity of a treadmill-based PRET to predict VO2peak was assessed in 24 participants (65.2 ± 3.9 years, 11 males). The PRET required a change in speed or incline corresponding to ratings of perceived exertion (RPE) 9, 11, 13, and 15. Extrapolation of submaximal VO2 from the PRET to RPE endpoints 19 and 20 and age-predicted HRmax were compared with measured VO2peak. The VO2 extrapolated to both RPE19 and 20 over-predicted VO2peak (p < .001). However, extrapolating VO2 to age-predicted HRmax accurately predicted VO2peak (r = .84). Results indicate older adults can use a PRET to predict VO2peak by extrapolating VO2 from submaximal intensities to an age-predicted HRmax.

The influence of a single bout of aerobic exercise on short-interval intracortical excitability.

Regular physical activity can have positive effects on brain function and plasticity. Indeed, there is some limited evidence that even a single bout of exercise may promote plasticity within the cortex. However, the mechanisms by which exercise acutely promotes plasticity are not clear. To further explore the effects of acute exercise on cortical function, we examined whether a single bout of exercise was associated with changes in cortical excitability and inhibition. Using standard techniques, cortical stimulus-response curves [90% resting motor threshold (RMT)-150% RMT] were investigated in nine subjects (four females, 31.1 ± 11.7 years) and short-interval intracortical inhibition (SICI) [interstimulus interval 2 ms and 3 ms, conditioning intensities of 80% active motor threshold (AMT) and 90% AMT] in 13 subjects (six females, 28.4 ± 5.1 years) before and at 0 and 15 min following 30 min of ergometer cycling at low-moderate or moderate-high intensity. There were no changes in cortical excitability following exercise but less SICI at both 0 and 15 min post-exercise (F [2, 24] = 7.7, P = 0.003). These findings show that a short period of exercise can transiently reduce SICI. Such a change in inhibition after exercise may contribute to the development of a cortical environment that would be more optimal for plasticity and may partially explain previous findings of enhanced neuroplasticity following low-intensity exercise.

Rural Environments and Community Health (REACH): a randomised controlled trial protocol for an online walking intervention in rural adults.

BACKGROUND: Rural Australian adults are continually shown to be insufficiently active with higher prevalence of lifestyle-related diseases associated with physical inactivity compared to urban adults. This may, partly, be attributable to the challenges associated with implementing community-based physical activity programs in rural communities. There is a need for broadly accessible physical activity programs specifically tailored to the unique attributes of rural communities. The aim of the Rural Environments And Community Health (REACH) study is to evaluate the effectiveness of an online-delivered physical activity intervention for increasing regular walking among adults living in rural areas of South Australia. METHODS/DESIGN: This is a randomised controlled trial. The intervention is 12-weeks with a 12-month follow-up. Participants will be insufficiently active, aged 18 to 70 years and randomly assigned to either Control or Intervention group. Participants receive a pedometer, but only the Intervention group will receive access to the purpose built REACH website where they will report steps taken, affect and ratings of perceived exertion during daily walking. These variables will be used to establish individualised step goals for increasing walking. Control participants will receive a paper diary to record their variables and generic incremental step goals.The primary outcome measures are time spent in sedentary, light and moderate-to-vigorous intensity physical activity, measured by accelerometry. Secondary outcomes include 1) health measures (anthropometric and physiological), 2) psychological well-being, 3) diet quality, and 4) correlates of physical activity (exercise self-efficacy and physical activity environments). Measures will be collected at baseline, post-intervention, 6-month and 12-month follow-up. DISCUSSION: This protocol describes the implementation of a trial testing the effectiveness of an online resource designed to assist rural Australians to become more physically active. The outcomes of this study will guide the efforts of health promotion professionals by providing evidence for a relatively inexpensive, widely accessible and effective method for increasing physical activity that can be utilized by anyone with access to the internet. Findings may indicate future directions for the implementation of physical activity and other health related interventions in rural communities. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTR12614000927628 (registered 28 August 2014).

Understanding farmers' barriers to health and mental health-related help-seeking: The development, factor structure, and reliability of the Farmer Help-Seeking Scale.

PURPOSE: The aim of this research was to develop a contextually and culturally appropriate scale to assess farmers' barriers to health-related help-seeking. METHODS: An initial pool of items was developed from the academic literature and input from an expert panel of farmers, rural academics, and rural clinicians. A draft 32-item questionnaire was then developed and sent to farmers registered with FARMbase, which is an Australian national farmer database. FINDINGS: Two hundred and seventy-four farmers completed the draft questionnaire (93.7% male, 73.7% aged 56-75 years). An exploratory factor analysis identified 6 factors; "Health Issues are a Low Priority," "Concerns about Stigma," "Structural Health System Barriers," "Minimization and Normalization," "Communication Barriers," and "Continuity of Care.". Test-retest reliability was examined with a further 10 farmers (90% male, Mean age = 57, SD = 5.91), who completed the questionnaire twice (at 2- to 3-week intervals). Results indicated moderate-good test-retest reliability. CONCLUSIONS: The resulting 24-item Farmer Help-Seeking Scale provides a measure of help-seeking that is specifically designed to capture the unique context, culture, and attitudes that can interfere with farmers' help-seeking, and inform the development of strategies to increase health-service utilization in this at-risk group.

Age-related changes in responsiveness to non-invasive brain stimulation neuroplasticity paradigms: A systematic review with meta-analysis.

OBJECTIVES: We aimed to summarise and critically appraise the available evidence for the effect of age on responsiveness to non-invasive brain stimulation (NBS) paradigms delivered to the primary motor cortex. METHODS: Four databases (Medline, Embase, PsycINFO and Scopus) were searched from inception to February 7, 2023. Studies investigating age group comparisons and associations between age and neuroplasticity induction from NBS paradigms were included. Only studies delivering neuroplasticity paradigms to the primary motor cortex and responses measured via motor-evoked potentials (MEPs) in healthy adults were considered. RESULTS: 39 studies, encompassing 40 experiments and eight NBS paradigms were included: paired associative stimulation (PAS; n = 12), repetitive transcranial magnetic stimulation (rTMS; n = 2), intermittent theta burst stimulation (iTBS; n = 8), continuous theta burst stimulation (cTBS; n = 7), transcranial direct and alternating current stimulation ((tDCS; n = 7; tACS; n = 2)), quadripulse stimulation (QPS; n = 1) and i-wave periodic transcranial magnetic stimulation (iTMS; n = 1). Pooled findings from PAS paradigms suggested older adults have reduced post-paradigm responses, although there was considerable heterogeneity. Mixed results were observed across all other NBS paradigms and post-paradigm timepoints. CONCLUSIONS/SIGNIFICANCE: Whilst age-dependent reduction in corticospinal excitability is possible, there is extensive inter- and intra-individual variability both within and between studies, making it difficult to draw meaningful conclusions from pooled analyses.

Weakness Thresholds Are Differentially Linked to Cognitive Function by Obesity Status in Older Americans.

Background: Weakness can be operationalized with several thresholds, which in turn, could impact associations with cognitive impairment when considering obesity status. Objective: We examined the associations of absolute, normalized, and collective weakness thresholds on future cognitive impairment by obesity status in older adults. Methods: We performed a secondary data analysis on the 2006-2018 waves of the Health and Retirement Study. A spring-type dynamometer collected handgrip strength (HGS). Males were categorized weak if their HGS was <35.5-kg (absolute), <0.45-kg/kg (body mass normalized), or <1.05-kg/kg/m2 (body mass index (BMI) normalized), while females were defined as weak if their HGS was <20.0-kg, <0.337-kg/kg, or <0.79-kg/kg/m2. The modified Telephone Interview of Cognitive Status examined cognitive function. Persons scoring ≤10 had a cognitive impairment. Obesity was categorized as BMI ≥30 kg/m2. Results: We included 7,532 and 3,584 persons aged ≥65-years living without and with obesity, respectively. Those without obesity but beneath the absolute weakness threshold had 1.54 (95% confidence interval (CI): 1.24-1.91) greater odds for future cognitive impairment. Persons with obesity and beneath each threshold also had greater odds for future cognitive impairment: 1.89 (95% CI: 1.28-2.78) for absolute, 2.17 (95% CI: 1.02-4.62) for body mass normalized, and 1.75 (95% CI: 1.10-2.80) for BMI normalized. Older Americans without obesity but underneath all the weakness thresholds had 1.32 (95% CI: 1.00-1.74) greater odds for impairment in cognitive function, while persons with obesity had 2.76 (95% CI: 1.29-5.93) greater odds. Conclusions: There should be consideration for how body size and different weakness thresholds may influence future cognitive outcomes.

Physiological evidence consistent with reduced neuroplasticity in human adolescents born preterm.

Preterm-born children commonly experience motor, cognitive, and learning difficulties that may be accompanied by altered brain microstructure, connectivity, and neurochemistry. However, the mechanisms linking the altered neurophysiology with the behavioral outcomes are unknown. Here we provide the first physiological evidence that human adolescents born preterm at or before 37 weeks of completed gestation have a significantly reduced capacity for cortical neuroplasticity, the key overall mechanism underlying learning and memory. We examined motor cortex neuroplasticity in three groups of adolescents who were born after gestations of ≤32 completed weeks (early preterm), 33-37 weeks (late preterm), and 38-41 weeks (term) using a noninvasive transcranial magnetic brain stimulation technique to induce long-term depression (LTD)-like neuroplasticity. Compared with term-born adolescents, both early and late preterm adolescents had reduced LTD-like neuroplasticity in response to brain stimulation that was also associated with low salivary cortisol levels. We also compared neuroplasticity in term-born adolescents with that in term-born young adults, finding that the motor cortex retains a relatively enhanced neuroplastic capacity in adolescence. These findings provide a possible mechanistic link between the altered brain physiology of preterm birth and the subsequent associated behavioral deficits, particularly in learning and memory. They also suggest that altered hypothalamic-pituitary-adrenal axis function due to preterm birth may be a significant modulator of this altered neuroplasticity. This latter finding may offer options in the development of possible therapeutic interventions.

Resting EEG power spectra across middle to late life: associations with age, cognition, APOE-ɛ4 carriage, and cardiometabolic burden.

We investigated how resting electroencephalography (EEG) measures are associated with risk factors for late-life cognitive impairment and dementia, including age, apolipoprotein E ɛ4 (APOE-ɛ4) carriage, and cardiometabolic burden. Resting EEG was recorded from 86 adults (50-80 years of age). Participants additionally completed the Addenbrooke's Cognitive Examination (ACE) III and had blood drawn to assess APOE-ɛ4 carriage status and cardiometabolic burden. EEG power spectra were decomposed into sources of periodic and aperiodic activity to derive measures of aperiodic component slope and alpha (7-14 Hz) and beta (15-30 Hz) peak power and peak frequency. Alpha and beta peak power measures were corrected for aperiodic activity. The aperiodic component slope was correlated with ACE-III scores but not age. Alpha peak frequency decreased with age. Individuals with higher cardiometabolic burden had lower alpha peak frequencies and lower beta peak power. APOE-ɛ4 carriers had lower beta peak frequencies. Our findings suggest that the slope of the aperiodic component of resting EEG power spectra is more closely associated with measures of cognitive performance rather than chronological age in older adults.

The Role of Different Weakness Cut-Points for Future Cognitive Impairment in Older Americans.

OBJECTIVES: New absolute and normalized handgrip strength (HGS) cut-points may not yield similar predictive value for cognitive performance. We sought to determine the associations of (1) each absolute and normalized weakness cut-point, and (2) compounding weakness on future cognitive impairment in older Americans. DESIGN: Longitudinal panel. SETTING AND PARTICIPANTS: The analytic sample included 11,116 participants aged ≥65 years from the 2006 to 2018 waves of the Health and Retirement Study. Participants from the Health and Retirement Study completed detailed interviews that included physical measures and core interviews. METHODS: The modified Telephone Interview of Cognitive Status assessed cognitive function and persons scoring <11 were classified as having a cognitive impairment. A handgrip dynamometer measured HGS. Men were considered weak if their HGS was <35.5 kg (absolute), <0.45 kg/kg (body mass normalized), or <1.05 kg (body mass index normalized), whereas women were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg. Compounding weakness included those below 1, 2, or all 3 cut-points. Generalized estimating equations quantified the associations. RESULTS: Persons considered weak under the absolute cut-point had 1.62 (95% CI 1.34-1.96) greater odds for future cognitive impairment, but no significant associations were observed for those classified as weak under the body mass [odds ratio (OR) 1.12, CI 0.91-1.36] and body mass index normalized (OR 1.17, CI 0.95-1.43) cut-points. Older Americans below all 3 weakness cut-points had 1.47 (CI 1.15-1.88) greater odds for future cognitive impairment, but no significant associations were found for persons classified as weak under 1 (OR 1.08, CI 0.83-1.42) or 2 (OR 1.19, CI 0.91-1.55) cut-points. CONCLUSIONS AND IMPLICATIONS: Our findings suggest that each weakness cut-point has differential prognostic value for future cognitive impairment, and aggregating weakness cut-points may improve their predictive utility. Consideration should be given to how weakness categories are uniquely linked to cognitive function.

Do age-related differences in aperiodic neural activity explain differences in resting EEG alpha?

Alpha-band oscillatory activity in human electroencephalography (EEG) becomes slower and lower in amplitude with advanced age. However, the influence of aperiodic activity on these measures has received little consideration. We investigated whether age-related differences in aperiodic activity explains differences in resting EEG peak alpha frequency and power. We assessed aperiodic activity in 85 younger and 92 older adults by fitting the 1/f-like background activity evident in EEG power spectra using the spectral parameterization ("specparam") algorithm. Across the scalp, the aperiodic exponent and offset were smaller in older compared to younger participants, reflecting a flatter 1/f-like slope and a downward broadband shift in power spectra with age. After correcting for aperiodic activity, peak alpha frequency remained slower in older adults; however, peak alpha power no longer differed statistically between age groups. The large sample size utilized in this study, as well as the depth of analysis, provides further evidence that the aperiodic component of the resting EEG signal is altered with aging and should be considered when investigating neural oscillatory activity.