Modeling the development of cognitive reserve in children: A residual index approach.

OBJECTIVE: To model cognitive reserve (CR) longitudinally in a neurodiverse pediatric sample using a residual index approach, and to test the criterion and construct validity of this index. METHOD: Participants were N = 115 children aged 9.5-13 years at baseline (MAge = 10.48 years, SDAge = 0.61), and n = 43 (37.4%) met criteria for ADHD. The CR index represented variance in Matrix Reasoning scores from the WASI that was unexplained by MRI-based brain variables (bilateral hippocampal volumes, total gray matter volumes, and total white matter hypointensity volumes) or demographics (age and sex). RESULTS: At baseline, the CR index predicted math computation ability (estimate = 0.50, SE = 0.07, p < .001), and word reading ability (estimate = 0.26, SE = 0.10, p = .012). Longitudinally, change in CR over time was not associated with change in math computation ability (estimate = -0.02, SE = 0.03, p < .513), but did predict change in word reading ability (estimate = 0.10, SE = 0.03, p < .001). Change in CR was also found to moderate the relationship between change in word reading ability and white matter hypointensity volume (estimate = 0.10, SE = 0.05, p = .045). CONCLUSIONS: Evidence for the criterion validity of this CR index is encouraging, but somewhat mixed, while construct validity was evidenced through interaction between CR, brain, and word reading ability. Future research would benefit from optimization of the CR index through careful selection of brain variables for a pediatric sample.

Assessing Emotion Regulation across Asian and Western Cultures: Psychometric Properties of Three Common Scales across Singaporean and Australian Samples.

Given the differences in emotion regulation across cultures, it is paramount to ensure that measures of emotion regulation measure the same construct and that conceptualizations of emotion regulation are valid across cultures. Therefore, the present study assessed the measurement invariance (alongside other psychometric properties) of three popular emotion regulation questionnaires, the Emotion Regulation Questionnaire (ERQ), Difficulties in Emotion Regulation Scale (DERS), and the Perth Emotion Regulation Competency Inventory (PERCI), across 434 Singaporeans and 489 Australians. Our study showed that all three questionnaires were measurement invariant, had excellent internal consistency, and relatively good concurrent validity with psychopathology and alexithymia across our Singaporean and Australian sample, justifying their use in comparing Asian and Western cultures. Our findings suggest that measures of emotion regulation have utility across both individualistic and collectivistic cultures. Our findings supports the use of these measures in cross-cultural research and provides support for the utility for personality assessments across cultures.

Tau and amyloid biomarkers modify the degree to which cognitive reserve and brain reserve predict cognitive decline.

OBJECTIVE: Brain reserve, cognitive reserve, and education are thought to protect against late-life cognitive decline, but these variables have not been directly compared to one another in the same model, using future cognitive and functional decline as outcomes. We sought to determine whether the influence of these protective factors on executive function (EF) and daily function decline was dependent upon Alzheimer's disease (AD) pathology severity, as measured by the total tau to beta-amyloid (T-τ/Aß1-42) ratio in cerebrospinal fluid (CSF). METHOD: Participants were 1201 older adult volunteers in the Alzheimer's Disease Neuroimaging Initiative (ADNI) study. Brain reserve was defined using a composite index of structural brain volumes (total brain matter, hippocampus, and white matter hyperintensity). Cognitive reserve was defined as the variance in episodic memory performance not explained by brain integrity and demographics. RESULTS: At higher levels of T-τ/Aß1-42, brain and cognitive reserve predicted slower decline in EF. Only brain reserve attenuated decline at lower levels of T-τ/Aß1-42. Education had no independent association with cognitive decline. CONCLUSIONS: These results point to a hierarchy of protection against aging- and disease-associated cognitive decline. When pathology is low, only structural brain integrity predicts rate of future EF decline. The ability of cognitive reserve to predict future EF decline becomes stronger as CSF biomarker evidence of AD increases. Although education is typically thought of as a proxy for cognitive reserve, it did not show any protective effects on cognition after accounting for brain integrity and the residual cognitive reserve index.

Loneliness and objective social isolation are differentially associated with anomalous perceptions in community-dwelling older adults.

INTRODUCTION: Anomalous perceptions are characterised by the subjective experience of a range of distorted and/or hallucinatory percepts. Whilst considerable attention has been paid to the neurocognitive processes contributing to anomalous perceptions amongst older adults, less is known about the social factors (e.g. social isolation, loneliness). Furthermore, it is unknown whether loneliness and social isolation are associated with different types of anomalous perceptions, including anomalous body-centred self-experiences and anomalous external experiences. METHODS: This study examined the cross-sectional relationships between loneliness, objective social isolation, and anomalous perceptions in a sample of community-dwelling older adults (N = 242, Mage = 71.87 ± 7.73, range = 52-91, 67.8% female) using structural equation modelling. RESULTS: Higher levels of loneliness were associated with more anomalous body-centred self-experiences and anomalous external experiences. Those reporting more loneliness also reported higher levels of anxiety and depression; however, the relationship between loneliness and anomalous perceptions was not mediated by these factors. Social disconnection from a religious group was associated with more anomalous external experiences and being married/living with a partner was associated with more anomalous body-centred self-experiences. CONCLUSIONS: These findings suggest that loneliness and social isolation have differential associations with anomalous perceptions in older adults and provide additional evidence that attending to loneliness in older adults is important.

Alexithymia as a risk factor for poor emotional outcomes in adults with acquired brain injury.

Emotional disorders are pervasive in the acquired brain injury (ABI) population, adversely affecting quality of life and rehabilitation. This study aimed to explore the unique associative effects of alexithymia as measured by the Perth Alexithymia Questionnaire (PAQ; i.e., difficulty identifying positive/negative feelings, difficulty describing positive/negative feelings, and externally orientated thinking), on emotional outcomes as measured by the Depression Anxiety Stress Scale-21 (DASS-21) and Mayo-Portland Adaptability Inventory (MPAI-4) Adjustment index, in 83 adults with ABI. The addition of alexithymia to hierarchical multiple regression models (controlling for demographic, injury-related, and functional outcome variables) yielded statistically significant changes in R2 for all emotional outcome measures (i.e., Depression, Anxiety, Stress, and Adjustment). Difficulty identifying negative feelings was found to be a significant unique predictor of Depression (ß = .43 p = <.001), Anxiety (ß = .40, p <.001), Stress (ß = .49, p <.001), and Adjustment (ß = .26, p = .001). Externally oriented thinking was found to be a significant unique predictor of Adjustment (ß = -.15, p = .033). These findings strengthen the argument that alexithymia, especially difficulties identifying negative feelings, may be an important risk factor for psychological distress in ABI and should be considered during early rehabilitation.

Assessing Alexithymia across Asian and Western Cultures: Psychometric Properties of the Perth Alexithymia Questionnaire and Toronto Alexithymia Scale-20 in Singaporean and Australian Samples.

Alexithymia refers to difficulties identifying feelings (DIF), describing feelings (DDF), and externally orientated thinking (EOT). Originally conceptualized by American psychiatrists, some researchers have since questioned the validity and application of this construct in Asian cultures. However, to date, there is little empirical work formally assessing the invariance of alexithymia across Asian and Western cultures. The present study aimed to help address this gap, by examining the psychometric properties and measurement invariance of two alexithymia measures, the Perth Alexithymia Questionnaire (PAQ) and Toronto Alexithymia Scale-20 (TAS-20), across samples from Singapore (n = 434) or Australia (n = 489). The same theoretically congruent factor structure was supported across both samples; this structure was fully invariant across samples for the PAQ, and partially invariant for the TAS-20. Both measures had good internal consistency and concurrent validity across samples, except the TAS-20 EOT subscale which had low internal consistency and factor loadings in both samples. The Singaporean sample reported higher DIF and DDF for positive emotions than the Australian sample. Overall, our results support the cross-cultural validity and application of the alexithymia construct. The PAQ and TAS-20 both appear to have good utility in this respect, though the PAQ may provide a more detailed facet-level profile.

Apathy and Depression as Predictors of Activities of Daily Living Following Stroke and Traumatic Brain Injuries in Adults: A Meta-Analysis.

Apathy and depression are common sequelae of acquired brain injury (ABI). Apathy is a syndrome characterized by diminished motivation and purposeful behaviours. Depression is a mood disorder featuring sadness, worthlessness, anhedonia and suicidal ideation. Both are associated negatively with activities of daily living (ADL), the skills required to fulfil basic and complex physical needs. However, the current literature's results are inconsistent and based on relatively small sample sizes. Furthermore, the unique and combined effects of apathy and depression as predictors of ADL have not yet been estimated. This is important, as both may have implications for planning rehabilitation after an ABI. Consequently, we aimed to estimate the association between apathy, depression and ADL in the stroke and traumatic brain injured population via meta-analysis and meta-analytic path-analysis. Based on the meta-analyses (N = 1,166 to N = 1,389), we estimated the following statistically significant bivariate effects: depression and apathy (r = .53, 95% CI: .42/.63), depression and ADL (r = -.27, 95% CI: -.43/-.11), apathy and ADL (r = -.41, 95% CI: -.51/-.31). A meta-analytic mediation model found that depression had a significant indirect effect onto ADL (ß = -.17, 95% CI: -.26/-.09), while apathy had a significant direct effect (ß = -.34, 95% CI: -.48/-.19) onto ADL (model R2 = .16). We interpreted the results to suggest that apathy and depression may impact adversely on engagement with ADL in people with ABI, although the potential influence of depression on ADL may occur primarily through its influence on apathy. Thus, greater focus on apathy by practitioners may be merited in cases with ABI.

The Effect of Self-Paced Exercise Intensity and Cardiorespiratory Fitness on Frontal Grey Matter Volume in Cognitively Normal Older Adults: A Randomised Controlled Trial.

OBJECTIVE: Exercise has been found to be important in maintaining neurocognitive health. However, the effect of exercise intensity level remains relatively underexplored. Thus, to test the hypothesis that self-paced high-intensity exercise and cardiorespiratory fitness (peak aerobic capacity; VO2peak) increase grey matter (GM) volume, we examined the effect of a 6-month exercise intervention on frontal lobe GM regions that support the executive functions in older adults. METHODS: Ninety-eight cognitively normal participants (age = 69.06 ± 5.2 years; n = 54 female) were randomised into either a self-paced high- or moderate-intensity cycle-based exercise intervention group, or a no-intervention control group. Participants underwent magnetic resonance imaging and fitness assessment pre-intervention, immediately post-intervention, and 12-months post-intervention. RESULTS: The intervention was found to increase fitness in the exercise groups, as compared with the control group (F = 9.88, p = <0.001). Changes in pre-to-post-intervention fitness were associated with increased volume in the right frontal lobe (ß = 0.29, p = 0.036, r = 0.27), right supplementary motor area (ß = 0.30, p = 0.031, r = 0.29), and both right (ß = 0.32, p = 0.034, r = 0.30) and left gyrus rectus (ß = 0.30, p = 0.037, r = 0.29) for intervention, but not control participants. No differences in volume were observed across groups. CONCLUSIONS: At an aggregate level, six months of self-paced high- or moderate-intensity exercise did not increase frontal GM volume. However, experimentally-induced changes in individual cardiorespiratory fitness was positively associated with frontal GM volume in our sample of older adults. These results provide evidence of individual variability in exercise-induced fitness on brain structure.

The Prevalence and Characteristics of Alexithymia in Adults Following Brain Injury: A Meta-Analysis.

Alexithymia is the inability to identify and describe one's own emotions. Some research suggests that organic alexithymia may occur after acquired brain injury (ABI). However, the results in the literature are inconsistent, when comparisons are made against healthy controls. Furthermore, a precise estimate of alexithymia prevalence in the ABI population has not yet been reported. Consequently, this meta-analysis aimed to estimate the prevalence and characteristics of alexithymia in ABI, as measured by the Toronto Alexithymia Scale-20 (TAS-20). Based on 22 unique ABI samples, a series of random-effects meta-analyses estimated moderate to large positive effect sizes (i.e., greater alexithymia in ABI samples) for the TAS-20 total scale (Hedges' g = 1.00, 95% CI [0.75, 1.35]), as well as the subscales: difficulty identifying feelings (Hedges' g = 0.92, 95% CI [0.66, 1.17]), difficulty describing feelings (Hedges' g = 0.69, 95% CI [0.50, 0.87]) and externally oriented thinking (Hedges' g = 0.75, 95% CI [0.64, 0.85]). Furthermore, a meta-regression identified a larger effect size (TAS-20 total scale score) for traumatic brain injury (TBI) samples, in comparison to non-TBI samples. Finally, the prevalence of clinically significant levels of alexithymia (TAS-20 total scale ≥ 68.4; i.e., two SDs above the general population mean) in ABI patients was estimated at 15.2%. We interpreted the results to suggest that ABI may have a substantial negative impact on affective processing abilities and, thus, comprehensive assessment of emotional functioning deficits following ABI should be considered by practitioners.

Androgen receptor CAG repeat length as a moderator of the relationship between free testosterone levels and cognition.

Age-related decrease in testosterone levels is a potential risk factor for cognitive decline in older men. However, observational studies and clinical trials have reported inconsistent results on the effects of testosterone on individual cognitive domains. Null findings may be attributed to factors that studies have yet to consider. In particular, individual variations in polyglutamine (CAG) length in the androgen receptor (AR) gene could alter androgenic activity in brain regions associated with cognitive processes including memory and executive functions. However, the role of AR CAG repeat length as a moderator of the relationship between testosterone levels and cognition has not been investigated. Therefore, we aimed to examine the relationship between baseline calculated free testosterone (cFT) levels, change in cFT levels over 18 months and CAG repeat length on cognitive performance in memory, executive function, language, attention and processing speed domains. These relationships were examined in 304 cognitively normal older male participants of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Ageing. In the attention and processing speed domain, a short CAG repeat length appears to exacerbate the effects of low baseline cFT levels that are also lower than expected at follow-up. These results highlight that individual variations in AR CAG repeat length should be considered in future studies and clinical trials that examine the complex relationship between testosterone and cognition.

A Randomized Controlled Trial of High-Intensity Exercise and Executive Functioning in Cognitively Normal Older Adults.

BACKGROUND: There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function. METHODS: Ninety-nine cognitively normal participants (age = 69.10 ± 5.2 years; n = 54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO2peak. RESULTS: First, the exercise intervention was found to increase cardiorespiratory fitness (VO2peak) in the intervention groups, in comparison to the control group (F =10.40, p≤0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis of change scores, cardiorespiratory fitness was found to associate positively with the executive function (EF) subdomains of Updating/Working Memory (ß = 0.37, p = 0.01, r = 0.34) and Verbal Generativity (ß = 0.30, p = 0.03, r = 0.28) for intervention, but not control participants. CONCLUSION: At the aggregate level, the authors failed to find evidence that 6-months of high-intensity aerobic exercise improves EF in older adults. However, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in Updating/ Working Memory and Verbal Generativity.

Sleep Mediates Age-Related Executive Function for Older Adults with Limited Cognitive Reserve.

OBJECTIVE: Sleep quantity and quality are associated with executive function (EF) in experimental studies, and in individuals with sleep disorders. With advancing age, sleep quantity and quality decline, as does the ability to perform EF tasks, suggesting that sleep disruption may contribute to age-related EF declines. This cross-sectional cohort study tested the hypothesis that poorer sleep quality (i.e., the frequency and duration of awakenings) and/or quantity may partly account for age-related EF deficits. METHOD: Community-dwelling older adults (N = 184) completed actigraphic sleep monitoring then a range of EF tasks. Two EF factors were extracted using exploratory structural equation modeling. Sleep variables did not mediate the relationship between age and EF factors. Post hoc moderated mediation analyses were conducted to test whether cognitive reserve compensates for sleep-related EF deficits, using years of education as a proxy measure of cognitive reserve. RESULTS: We found a significant interaction between cognitive reserve and the number and frequency of awakenings, explaining a small (approximately 3%), but significant amount of variance in EF. Specifically, in individuals with fewer than 11 years of education, greater sleep disturbance was associated with poorer EF, but sleep did not impact EF in those with more education. There was no association between age and sleep quantity. CONCLUSIONS: This study highlights the role of cognitive reserve in the sleep-EF relationship, suggesting individuals with greater cognitive reserve may be able to counter the impact of disturbed sleep on EF. Therefore, improving sleep may confer some protection against EF deficits in vulnerable older adults.

Improving Prospective Memory Performance in Community-dwelling Older Adults: Goal Management Training and Implementation Intentions.

Aim: The present study tested a compensatory executive intervention for prospective memory (goal management training) for the first time in older adults. Prospective memory (the ability to remember and execute a task in the future) declines with age, with significant implications for older adults' activities of daily living and quality of life. Prospective memory interventions have focused primarily on the retrospective component of prospective memory (e.g., implementation intentions). However, executive dysfunction is also implicated in age-related prospective memory decline.Methods: Community-dwelling older adults were randomly allocated to receive goal management training, implementation intentions or no intervention. Prospective memory was assessed before and after the intervention with a well-validated laboratory-based prospective memory measure. Results: Contrary to predictions, neither goal management training nor implementation intentions were successful at improving prospective memory in healthy older adults. Participants who received goal management training were more likely to have difficulty comprehending the intervention. Post-hoc analyses suggested implementation intentions improved prospective memory specifically for participants with poorer baseline prospective memory. Conclusions: These results represent important cautionary findings about the possible limitations of goal management training to improve prospective memory in older adults. Future research should also consider the role of baseline prospective memory ability in affecting response to compensatory intervention.

Metacognitive knowledge and functional outcomes in adults with acquired brain injury: A meta-analysis.

Pronounced difficulties in functional outcomes often follow acquired brain injury (ABI), and may be due, in part, to deficits in metacognitive knowledge (being unaware of one's cognitive strengths and limitations). A meta-analytic review of the literature investigating the relationship between metacognitive knowledge and functional outcomes in ABI is timely, particularly given the presence of apparently inconsistent findings. Twenty-two articles revealed two distinct methods of measuring metacognitive knowledge: (1) absolute (the degree of inaccurate self-appraisal regardless of whether the error tends towards under- or over-confident estimations) and (2) relative (the degree and the direction of the inaccuracy) discrepancy. Separate meta-analyses were conducted for absolute and relative discrepancy studies to assess the relationship between metacognitive knowledge and functional outcomes (affect-related quality of life, family and community integration, and work outcomes). The pattern of results found suggested that better metacognitive knowledge is related to better overall functional outcomes, but the relationship may differ depending on the outcome domain. These findings generally support the importance of focusing on metacognitive knowledge to improve outcomes following ABI. Nonetheless, the relatively small effect sizes observed suggest that other predictors of functional outcome should be investigated, including other subdomains of metacognition.

A Meta-Analysis of Neuropsychological Predictors of Outcome Following Stroke and Other Non-Traumatic Acquired Brain Injuries in Adults.

A number of cognitive abilities have been reported to predict outcome following a non-traumatic acquired brain injury (ABI) in adults. However, the results are inconsistent. Furthermore, the unique and combined capacity of these cognitive abilities to predict ABI outcome has not been evaluated. Consequently, we employed meta-analysis and multiple regression to evaluate the capacity of various neuropsychological domains to predict two separate outcome variables in adults: (1) activities of daily living; and (2) quality of life. Based on the activities of daily living meta-analysis (N = 2384), we estimated the following significant bivariate effects: memory (r = .31, 95% CI: .20/.41]), language (r = .33, 95% CI:.26/.40), attention (r = .38, 95% CI: .30/.46]), executive functions (r = .29, 95% CI: .19/.39]), and visuospatial abilities (r = .41, 95% CI: .34/ .48). Based on the quality of life meta-analysis (N = 1037), we estimated the following significant bivariate effects: memory (r = .12, 95% CI: .03/.20]), language (r = .19, 95% CI: .06/ .32), attention (r = .30, 95% CI: .16/.44]), executive functions (r = .24, 95% CI: .12/.37) and visuospatial/constructional abilities (r = .30, 95% CI: .14/.46). Meta-analytic structural equation modelling (metaSEM) identified two significant, unique predictors of activities of daily living, attention and visuospatial abilities, and the model accounted for 21% of the variance (multiple R2 = .21, 95%CI: .16/.26). For the corresponding quality of life metaSEM, no statistically significant unique predictors were identified, however, a significant multiple correlation was observed, multiple R2 = .11 (95%CI: 04/.18). We conclude that practitioners may be able to predict, with some degree of accuracy, functional outcome following a stroke and other non-traumatic ABI in adults. We also provide some critical commentary on the nature and quality of the measures used in this area of research to represent the cognitive dimensions of interest.

Effects of Testosterone Supplementation on Separate Cognitive Domains in Cognitively Healthy Older Men: A Meta-analysis of Current Randomized Clinical Trials.

BACKGROUND: An increasing body of literature suggests a positive, neuroprotective effect for testosterone on cognition in older men. However, randomized clinical trials (RCTs) examining the effects of testosterone supplementation (TS) on cognitive function have been inconclusive. OBJECTIVE: To investigate the potential for TS to prevent cognitive decline in otherwise cognitively healthy older men, by examining the differential effects of TS on cognitively healthy older men in RCTs. METHODS: Comprehensive search of electronic databases, conference proceedings, and grey literature from 1990 to 2018 was performed to identify RCTs examining the effects of TS on cognition before and after supplementation, in cognitively healthy individuals. RESULTS: A final sample of 14 eligible RCTs met inclusion criteria. Using pooled random effects expressed as Hedge's g, comparison of placebo versus treatment groups pre- and postsupplementation showed improvements in the treatment group in executive function (g (11) = 0.14, 95% confidence interval [CI]: 0.03-0.26, z = 0.56, p = 0.011). However, it was noted that two studies in our sample did not report a significant increase in mean serum total testosterone (TT) levels in the treatment group after supplementation. Following exclusion of these studies, analysis indicated improvement in the treatment group for the overall cognitive composite (g (11) = 0.18, 95% CI: 0.02-0.33, z = 2.18), psychomotor speed (g (3) = 0.22, 95% CI: 0.01-0.43, z = 2.07) and executive function (g (9) = 0.15, 95% CI: 0.03-0.28, z = 2.35). No significant differences were noted for the global cognition, attention, verbal memory, visuospatial ability or visuospatial memory domains. CONCLUSION: Overall, our findings support the potential for TS as a preventative measure against cognitive decline, although the effect sizes were small. These findings warrant further observational studies and clinical trials of good methodological quality, to elucidate the effect of TS on cognition.

Subjective memory complaints predict baseline but not future cognitive function over three years: results from the Western Australia Memory Study.

ABSTRACTBackground:This study investigated the characteristics of subjective memory complaints (SMCs) and their association with current and future cognitive functions. METHODS: A cohort of 209 community-dwelling individuals without dementia aged 47-90 years old was recruited for this 3-year study. Participants underwent neuropsychological and clinical assessments annually. Participants were divided into SMCs and non-memory complainers (NMCs) using a single question at baseline and a memory complaints questionnaire following baseline, to evaluate differential patterns of complaints. In addition, comprehensive assessment of memory complaints was undertaken to evaluate whether severity and consistency of complaints differentially predicted cognitive function. RESULTS: SMC and NMC individuals were significantly different on various features of SMCs. Greater overall severity (but not consistency) of complaints was significantly associated with current and future cognitive functioning. CONCLUSIONS: SMC individuals present distinctive features of memory complaints as compared to NMCs. Further, the severity of complaints was a significant predictor of future cognition. However, SMC did not significantly predict change over time in this sample. These findings warrant further research into the specific features of SMCs that may portend subsequent neuropathological and cognitive changes when screening individuals at increased future risk of dementia.

Higher Cardiorespiratory Fitness Is Associated With Better Verbal Generativity in Community-Dwelling Older Adults.

Objectives: To examine the associations between physical activity duration and intensity, cardiorespiratory fitness, and executive function in older adults. Methods: Data from 99 cognitively normal adults (age = 69.10 ± 5.1 years; n = 54 females) were used in the current study. Physical activity (intensity and duration) was measured with the International Physical Activity Questionnaire, and fitness was measured by analysis of maximal aerobic capacity, VO2peak. Executive function was measured comprehensively, including measures of Shifting, Updating, Inhibition, Generativity, and Nonverbal Reasoning. Results: Higher levels of cardiorespiratory fitness were associated with better performance on Generativity (B = .55; 95% confidence interval [.15, .97]). No significant associations were found between self-reported physical activity intensity/duration and executive functions. Discussion: To our knowledge, this study is the first to identify an association between fitness and Generativity. Associations between physical activity duration and intensity and executive function requires further study, using objective physical activity measures and longitudinal observations.

Neuropsychological Predictors of Outcome Following Traumatic Brain Injury in Adults: a Meta-Analysis.

Several neuropsychological dimensions are correlated with functional outcome (e.g., ability to return to family and community roles) following traumatic brain injury (TBI). Commonly investigated neuropsychological dimensions include verbal memory, visuo-spatial construction, set-shifting, generativity, and processing speed. Unfortunately, small sample sizes across relevant studies have contributed to inconsistent results. Furthermore, no studies have concurrently measured all of the candidate neuropsychological predictors, most of which are known to be inter-correlated. Thus, the unique predictive effects associated with the candidate predictors in TBI recovery have never been investigated. Consequently, this study used both meta-analysis and multiple regression to statistically evaluate neuropsychological candidate predictors across two outcome variables (1) the Glasgow Outcome Scale-Extended (GOS-E) and (2) the Disability Rating Scale (DRS). Seven studies met inclusion criteria. Based on the meta-analyses, the following neuropsychological dimensions were found to be correlated with the GOS-E: immediate verbal memory (r = .43, 95% CI [.27, .58]), delayed verbal memory (r = .43, 95% CI [.21, .61]), visuo-spatial construction (r = .29, 95% CI [.15, .53]), set-shifting (r = -.31, 95% CI [-.45, -.15], and generativity (r = .44, 95% CI [.32, .54]). By contrast, only one neuropsychological dimension was found to be significantly related to the DRS (generativity: r = -.21, 95% CI [-.39, -.01]). Multiple regression on the GOS-E relevant meta-analytically derived correlation matrix determined that all neuropsychological dimensions were significant predictors of the GOS-E (multiple R 2 = .31) with the exception of immediate verbal memory or learning. However, due to analytic characteristics, these findings must be interpreted with caution. Results were consistent with the need to consider multiple neuropsychological abilities in recovery and rehabilitation following TBI.

Enhancing Cognitive Functioning in Healthly Older Adults: a Systematic Review of the Clinical Significance of Commercially Available Computerized Cognitive Training in Preventing Cognitive Decline.

Successfully assisting older adults to maintain or improve cognitive function, particularly when they are dealing with neurodegenerative disorders such as Alzheimer's disease (AD), remains a major challenge. Cognitive training may stimulate neuroplasticity thereby increasing cognitive and brain reserve. Commercial brain training programs are computerized, readily-available, easy-to-administer and adaptive but often lack supportive data and their clinical validation literature has not been previously reviewed. Therefore, in this review, we report the characteristics of commercially available brain training programs, critically assess the number and quality of studies evaluating the empirical evidence of these programs for promoting brain health in healthy older adults, and discuss underlying causal mechanisms. We searched PubMed, Google Scholar and each program's website for relevant studies reporting the effects of computerized cognitive training on cognitively healthy older adults. The evidence for each program was assessed via the number and quality (PEDro score) of studies, including Randomized Control Trials (RCTs). Programs with clinical studies were subsequently classified as possessing Level I, II or III evidence. Out of 18 identified programs, 7 programs were investigated in 26 studies including follow-ups. Two programs were identified as possessing Level I evidence, three programs demonstrated Level II evidence and an additional two programs demonstrated Level III evidence. Overall, studies showed generally high methodological quality (average PEDro score = 7.05). Although caution must be taken regarding any potential bias due to selective reporting, current evidence supports that at least some commercially available computerized brain training products can assist in promoting healthy brain aging.