Cortical thickness moderates intraindividual variability in prefrontal cortex activation patterns of older adults during walking.

OBJECTIVE: Increased intraindividual variability (IIV) in behavioral and cognitive performance is a risk factor for adverse outcomes but research concerning hemodynamic signal IIV is limited. Cortical thinning occurs during aging and is associated with cognitive decline. Dual-task walking (DTW) performance in older adults has been related to cognition and neural integrity. We examined the hypothesis that reduced cortical thickness would be associated with greater increases in IIV in prefrontal cortex oxygenated hemoglobin (HbO2) from single tasks to DTW in healthy older adults while adjusting for behavioral performance. METHOD: Participants were 55 healthy community-dwelling older adults (mean age = 74.84, standard deviation (SD) = 4.97). Structural MRI was used to quantify cortical thickness. Functional near-infrared spectroscopy (fNIRS) was used to assess changes in prefrontal cortex HbO2 during walking. HbO2 IIV was operationalized as the SD of HbO2 observations assessed during the first 30 seconds of each task. Linear mixed models were used to examine the moderation effect of cortical thickness throughout the cortex on HbO2 IIV across task conditions. RESULTS: Analyses revealed that thinner cortex in several regions was associated with greater increases in HbO2 IIV from the single tasks to DTW (ps < .02). CONCLUSIONS: Consistent with neural inefficiency, reduced cortical thickness in the PFC and throughout the cerebral cortex was associated with increases in HbO2 IIV from the single tasks to DTW without behavioral benefit. Reduced cortical thickness and greater IIV of prefrontal cortex HbO2 during DTW may be further investigated as risk factors for developing mobility impairments in aging.

Frontal-striatal tract integrity and depression in older adults with and without multiple sclerosis.

OBJECTIVE: Lower white matter integrity of frontal-subcortical circuitry has been associated with late-life depression in normally aging older adults and with the presence of multiple sclerosis (MS). Frontal-striatal white matter tracts involved in executive, cognitive, emotion, and motor function may underlie depression in older adults with MS. The present study examined the association between depression score and frontal-striatal white matter integrity in older adults with MS and controls. METHODS: Older adults with MS (OAMS) (n = 67, mean age = 64.55 ± 3.89) and controls (n = 74, mean age = 69.04 ± 6.32) underwent brain MRI, cognitive assessment, psychological, and motoric testing. Depression was assessed through the 30-item Geriatric Depression Scale. Fractional anisotropy (FA) was extracted from two bilateral tracts: dorsolateral prefrontal cortex to putamen nucleus (DLPFC-pn) and dorsolateral prefrontal cortex to caudate nucleus (DLPFC-cn). RESULTS: OAMS reported significantly worse (i.e., higher) depression symptoms (ß = .357, p < .001) compared to healthy controls. Adjusted moderation analyses revealed, via group by FA interactions, significantly stronger associations between FA of the left DLPFC-pn tract and total depression (B = - 61.70, p = .011) among OAMS compared to controls. Conditional effects revealed that lower FA of the left DLPFC-pn was significantly associated with worse (i.e., higher) depression symptoms (b = - 38.0, p = .028) only among OAMS. The other three tracts were not significant in moderation models. CONCLUSIONS: We provided first evidence that lower white matter integrity of the left DLPFC-pn tract was related to worse depression in older adults with MS.

Depressive Symptoms are Associated with Decline Over Time in Verbal Fluency Performance in Female but Not Male Community-Dwelling Older Adults.

OBJECTIVE: The current study was designed to examine associations between depressive symptoms and longitudinal declines in category and letter fluency performance in a gender-stratified sample of older adults. METHOD: Participants were community-residing older adults (females: n = 289; males: n = 233) followed annually (2011-2018) as part of a cohort study conducted at Albert Einstein College of Medicine in New York. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). Standard forms assessed category and letter fluency performance. Participants were dementia-free during study enrollment. RESULTS: The presence of baseline depressive symptoms suggestive of subclinical depression was associated with a worse longitudinal decline in category fluency performance in female but not male participants. These associations remained significant when excluding participants with prevalent and incident mild cognitive impairment and incident dementia. Irrespective of gender, letter fluency performance did not decline over time and was not influenced by the presence of depressive symptoms. DISCUSSION: The present study's results can aid in identification of older adults who may be at greater risk for cognitive decline, and add to the limited literature examining the influence of gender on longitudinal associations between depressive symptoms and verbal fluency performance.

Caudate volume and symptoms of apathy in older adults with multiple sclerosis.

BACKGROUND: Apathy is common in multiple sclerosis (MS) and neurological disease, but its presence and underlying brain mechanisms in older adults with MS (OAMS) have not been evaluated. OBJECTIVE: Examine apathy and its association with caudate nuclei volume in OAMS and controls. We hypothesized that compared to controls, OAMS would demonstrate: a) greater apathy; b) stronger associations between apathy and caudate nuclei volumes. METHODS: OAMS (n = 67, mean age = 64.55 ± 3.89) and controls (n = 74, mean age = 69.04 ± 6.32) underwent brain MRI, cognitive assessment, psychological, and motoric testing. Apathy was assessed through the apathy subscale of the 30-item Geriatric Depression Scale. RESULTS: OAMS reported greater apathy compared to controls (ß = 0.281, p = 0.004). Adjusted moderation analyses revealed a significantly stronger association between caudate volume and apathy (left: B = -1.156, p = 0.039, right: B = -1.163, p = 0.040) among OAMS compared to controls. Conditional effects revealed that in adjusted models, lower volume of both the left (b = -0.882, p = 0.037) and right (b = -0.891, p = 0.038) caudate nuclei was significantly associated with greater apathy only among OAMS. CONCLUSION: Caudate nuclei, which are susceptible to adverse MS effects and implicated in mediating cognitive and motor function, may influence the presence and severity of apathy in OAMS.

Presence and Persistence of Perceived Subjective Cognitive Complaints and Incident Mild Cognitive Impairments Among Community-Residing Older Adults.

OBJECTIVES: To examine whether Subjective Cognitive Complaints (SCCs) predicted incident mild cognitive impairment (MCI). DESIGN: Prospective Study. SETTING: Central Control of Mobility and Aging (CCMA), a cohort study of community-residing older adults. PARTICIPANTS: Participants were dementia-free community-residing older adults. MEASUREMENTS: SCCs were assessed at the baseline and via bi-monthly structured phone interviews during the first year using the Ascertain Dementia 8 (AD8). Nonpersistent status required one or two SCCs endorsements and Persistent status required three or more SCCs endorsements. Outcome, presence of mild cognitive impairments (MCI) was determined by established case conference diagnostic procedures. Participants were followed annually. Generalized estimating equations (GEE), logistic model type, were used to determine the odds of developing MCI during follow-up. SCCs served as the three-level predictor (no/nonpersistent/persistent) and cognitive status (MCI versus normal) as the binary outcome. Analyses were adjusted for age, sex, education, race, health status, depressive symptoms, and global cognition. RESULTS: The sample (n=454; mean age=75.67 ± 6.43; %female=55.3) included 245 participants who reported no SCCs, 156 who reported 1-2 SCCs, and 53 who reported 3 or more SCCs. Sixty-eight participants developed MCI during follow-up. Results showed that compared to no SCCs, persistent SCCs, and nonpersistent SCCs were significantly associated with increased odds of developing MCI during follow-up. CONCLUSIONS: The presence of SCCs regardless of their persistence was associated with increased odds of developing MCI even when adjusting for objectively-assessed cognitive performance.

Gray matter volume and within-task verbal fluency performance among older adults.

The current study examined the relationship between gray matter volume (GMV) and rate of word generation over the course of three consecutive 20-sec intervals in 60-sec letter and category verbal fluency (VF) tasks. Attenuated rate of within-person word generation in VF provides incremental information beyond total scores and predicts increased risk of incident Mild Cognitive Impairment (MCI). No studies to date, however, have determined the structural neural substrates underlying word generation rate in VF. Participants were 70 community-residing adults ≥ 65 years, who completed the letter and category VF tasks and a 3 T structural MRI scan. Linear mixed effects models (LMEMs) were used to determine the moderating effect of GMV on word generation rate. Whole brain voxel-wise LMEMs, adjusted for age, gender, education, Wide-Range Achievement Test - reading subtest score (WRAT3), and global health score, were run using permutation methods to correct for multiple comparisons. Lower GMV, primarily in frontal regions (superior frontal, rostral middle frontal, frontal pole, medial orbitofrontal, and pars orbitalis), were related to attenuated word generation rate, especially for letter VF. We propose that lower frontal GMV underlies inefficient executive word search processes reflected by attenuated word generation slope in letter VF amongst older adults.

Physical reserve: construct development and predictive utility.

BACKGROUND: Physical reserve (PR) refers to one's ability to maintain physical functioning despite age, illness, or injury. The measurement and predictive utility of PR, however, are not well established. AIMS: We quantified PR using a residual measurement approach by extracting standardized residuals from gait speed, while accounting for demographic and clinical/disease variables, and used it to predict fall-risk. METHODS: Participants (n = 510; age ≥ 70ys) were enrolled in a longitudinal study. Falls were assessed annually (in-person) and bimonthly (via structured telephone interview). RESULTS: General Estimating Equations (GEE) revealed that higher baseline PR was associated with reduced odds of reporting falls over repeated assessments in the total sample, and incident falls among those without fall's history. The protective effect of PR against fall risk remained significant when adjusting for multiple demographic and medical confounders. DISCUSSION/CONCLUSION: We propose a novel framework to assessing PR and demonstrate that higher PR is protective against fall-risk in older adults.

Asthma history influences gait performance and associated prefrontal cortex activation patterns in older adults.

Walking and cognition are interrelated due to dependence on shared brain regions that include the prefrontal cortex (PFC). Limited literature indicates that asthma is associated with poor mobility in older adults but the mechanisms underlying this relationship are unknown. Therefore, we tested the hypothesis that asthma history was associated with poor gait performance due to limited attention resources and neural inefficiency. Participants, older adults age ≥ 65 years reporting positive (n = 36) and negative (n = 36) history of asthma, walked under single and dual-task conditions with a functional near-infrared-spectroscopy (fNIRS) sensor placed on their forehead to assess task-related changes in PFC oxygenated hemoglobin (HbO2). Results showed that positive asthma history was associated with slower gait and higher fNIRS-derived HbO2 under dual-task walking. These findings suggest that limited attention resources and neural inefficiency underlie the association between asthma and poor walking performance in older adults.

Recurrent but not single report of fear of falling predicts cognitive decline in community-residing older adults.

OBJECTIVES: Literature regarding the association of fear of falling (FOF), a common concern in aging, and cognition is scarce. Moreover, whether frequency of FOF endorsement influences age-related cognitive decline has not been reported. Here we determined whether FOF status (no FOF, single-report FOF, recurrent FOF), predicted decline in global cognitive function (GCF), memory, and attention/executive functions. METHODS: Participants were community-residing older adults (n = 421; mean age = 76.29 ± 6.48; %female = 56.06). FOF was assessed bimonthly through yes/no responses to "do you have a fear of falling?" during the first year of the study. Recurrent status required two or more FOF endorsements. GCF was assessed using Repeatable Battery for the Assessment of Neuropsychological Status (RBANS); composite scores were used to assess memory as well as attention/executive functions. Cognitive measures were administered annually for up to six years. RESULTS: Stratification of the cohort by FOF status showed that 81 participants reported recurrent FOF, 60 participants endorsed FOF once and 280 participants reported no FOF. Linear mixed effects models revealed that compared to no FOF, recurrent FOF was associated with worse declines in GCF (estimate=-0.03, p=.006), memory (estimate=-0.04, p=.012) and attention/executive functions (estimate=-0.04, p=.006). Comparisons between single-report FOF and no FOF, however, were not significant. CONCLUSIONS: These findings demonstrate that recurrent but not single-report FOF is a risk factor for cognitive decline in community-residing older adults.

The Effects of Perceived Pain in the Past Month on Prefrontal Cortex Activation Patterns Assessed During Cognitive and Motor Performances in Older Adults.

OBJECTIVE: Pain is prevalent and functionally impactful in older adults. The prefrontal cortex is involved in pain perception, attentional control, and cortical control of locomotion. Although pain is a known moderator of attentional capacity, its moderating effect on cortical control of locomotion has not been assessed. This study aimed to examine the effects of subjective pain on changes in functional near-infrared spectroscopy-derived measurements of oxygenated hemoglobin (HbO2), gait velocity, and cognitive accuracy from single- to dual-task walking conditions among older adults. SUBJECTS: The sample consisted of 383 healthy older adults (55% female). METHODS: Participants completed two single tasks (Single-Task-Walk [STW] and Cognitive Interference [Alpha]) and the Dual-Task-Walk (DTW), during which participants performed the two single tasks simultaneously. The Medical Outcomes Study Pain Severity Scale and Pain Effects Scale were used to assess pain severity and interference. ProtoKinetics Movement Analysis Software was used to assess gait velocity and rate of correct letter generation to assess cognitive accuracy. Functional Near-Infrared Spectroscopy (fNIRS) was used to assess HbO2 during active walking. RESULTS: Linear mixed-effects models revealed that HbO2 increased from single- to dual-task conditions. Perceived pain presence was associated with an attenuated increase in HbO2 from Alpha to DTW. Among those with pain, worse pain severity was associated with an attenuated increase in HbO2 from STW to DTW. Pain interference did not moderate the increase in HbO2 from single to dual tasks. Pain did not have a moderating effect on behavioral outcomes. CONCLUSIONS: Task-related changes in the hemodynamic response in the prefrontal cortex during walking may be a sensitive marker of the effects of subjective pain on brain function in healthy older adults.

Independent associations of apathy and depressive symptoms with perceived social support in healthy older adults.

OBJECTIVE: Apathy symptoms are common in healthy older adults and may manifest independently of depressive symptoms. Perceived social support is considered a protective factor against adverse health outcomes in aging. We investigated the differential associations of apathy and depressive symptoms with perceived social support in older adults. METHOD: The sample (n = 295) included community dwelling healthy older adults. Apathy was assessed with the Apathy Evaluation Scale, depression with the Geriatric Depression Scale, and perceived social support with the Medical Outcomes Study-Social Support Survey. RESULTS: Fully adjusted multiple linear regression revealed that, when jointly modeled as predictors, both apathy (standardized ß= -0.214 p<.05) and depressive symptoms (standardized ß= -0.157 p<.05) had significant negative associations with perceived social support. DISCUSSION: We provide the first evidence that apathy and depressive symptoms have independent associations with perceived social support in older adults.

Predicting change in perceived social support in late life: The role of personality and gender.

OBJECTIVES: Perceived social support (PSS) has a uniquely beneficial effect on physical and mental health in older adults, yet relatively little is known about patterns of change in PSS during late life. The purpose of this study was to identify risk factors related to individual-level change in PSS, with a focus on personality (specifically Neuroticism and Extraversion) and gender as primary variables of interest. METHOD: The study sample consisted of 409 community-dwelling, healthy older adults (56.5% female) who were followed annually for up to five years. Personality traits were analyzed independently and as combined Neuroticism-Extraversion quadrants. Linear mixed effect models (LMEM) and Cox proportional hazards regression were used to examine continuous change and incidence of decline in PSS, respectively. Analyses were conducted for the entire sample and in stratified models in order to explore the potential moderating effect of gender. RESULTS: Personality was identified as a significant predictor of PSS change, including personality quadrants and High Neuroticism alone. Stratified models revealed significant gender differences, with High Neuroticism-Low Extraversion and High Neuroticism alone consistently linked to PSS decline in males, while Low Neuroticism-Low Extraversion was linked to PSS decline in females. CONCLUSION: Patterns in LMEM and Cox model results suggest that PSS decline in males is likely associated with High Neuroticism, while PSS decline in females may be associated instead with Low Extraversion. Future clinical implications include earlier identification of individuals who are at risk for decreased social support, and its related impact on health.

Multi-modal neuroimaging of dual-task walking: Structural MRI and fNIRS analysis reveals prefrontal grey matter volume moderation of brain activation in older adults.

It has been well established over the last two decades that walking is not merely an automatic, motoric activity; it also utilizes executive function circuits, which play an increasingly important role in walking for older people and those with mobility and cognitive deficits. Dual-task walking, such as walking while performing a cognitive task, is a necessary skill for everyday functioning, and has been shown to activate prefrontal lobe areas in healthy older people. Another well-established point in healthy aging is the loss of grey matter, and in particular loss of frontal lobe grey matter volume. However, the relationship between increased frontal lobe activity during dual-task walking and loss of frontal grey matter in healthy aging remains unknown. In the current study, we combined oxygenated hemoglobin (HbO2) data from functional near-infrared spectroscopy (fNIRS), taken during dual-task walking, with structural MRI volumetrics in a cohort of healthy older subjects to identify this relationship. We studied fifty-five relatively healthy, older participants (≥65 years) during two separate sessions: fNIRS to measure HbO2 changes between single-task (i.e., normal walking) and dual-task walking-while-talking, and high-resolution, structural MRI to measure frontal lobe grey matter volumes. Linear mixed effects modeling was utilized to determine the moderation effect of grey matter volume on the change in prefrontal oxygenated hemoglobin between the two walking tasks, while controlling for covariates including task performance. We found a highly significant interaction effect between frontal grey matter volume and task on HbO2 levels (p < 0.0001). Specifically, increased HbO2 levels during dual-task compared to single-task walking were associated with reduced frontal grey matter volume. Regional analysis identified bilateral superior and rostral middle gyri as the primary areas driving these results. The findings provide support for the concept of neural inefficiency: in the absence of behavioral gains, grey matter loss in relatively healthy, older individuals leads to over-activation of frontal lobe during a cognitively demanding walking task with established clinical and predictive utility.

The effect of polypharmacy on prefrontal cortex activation during single and dual task walking in community dwelling older adults.

INTRODUCTION: Polypharmacy, defined as the use of 5 or more medications is associated with multiple adverse outcomes in older adults, including falls and slow gait velocity. However, the relationship between polypharmacy and cortical control of locomotion has not been reported. The purpose of this study was to examine the relationship between polypharmacy and activation patterns in the prefrontal cortex (PFC), a brain region involved in higher order control of locomotion during attention-demanding conditions. METHODS: Using Functional Near Infrared Spectroscopy (fNIRS) to quantify PFC oxygenated hemoglobin (HbO2) levels, we performed a cross sectional analysis of 325 community dwelling adults age ≥65 years, and examined HbO2 levels during single tasks (Single-Task-Walk (STW), (talking, cognitive interference (Alpha)) and Dual-Task Walk (DTW)). RESULTS: The prevalence of polypharmacy was 33% (n = 104) amongst the 325 participants (mean age 76.4 ± 6.7 years, 56% women). Among the 221 participants with no polypharmacy there was an increase in HbO2 levels from STW to DTW (estimate = -0.625; p = <0.001) and from Alpha to DTW (estimate=-0.079; p = 0.031). Polypharmacy status, however, moderated the change in HbO2 levels comparing the two single tasks to the dual-task walking condition. Specifically, the presence of polypharmacy was associated with an attenuated increase in HbO2 levels from STW to DTW (estimate = 0.149; p = 0.027) and with a decline in HbO2 levels from Alpha to DTW (estimate = 0.169; p = 0.009) after adjustments for potential confounders including medical comorbidities and the use of high-risk medications. CONCLUSION: The results of this study further support the need for clinicians to reduce polypharmacy in older adults, given its significant association with the PFC hemodynamic response during attention-demanding locomotion.

Gender-stratified analyses reveal longitudinal associations between social support and cognitive decline in older men.

Objectives: Research has extensively examined the relationship between social support and health outcomes in older adults. Little is known, however, about the longitudinal associations between distinct dimensions of perceived social support and incident cognitive decline. The current longitudinal study examined whether dimensions of perceived social support were associated with increased risk of cognitive decline, and if the relationship differed by gender. Methods: 493 community-residing non-demented older adults were assessed for baseline social support via the Medical Outcomes Study-Social Support Survey (MOS-SSS). Incident cognitive impairment was determined using a 1 standard deviation below age and education adjusted total score on the Repeatable Battery for the Assessment of Neuropsychological Status Cox proportional-hazard models were used to analyze incident risk of cognitive impairment. Results: Higher perceived support, overall and in specific domains, at baseline was associated with increased risk of incident cognitive impairment. Further gender-stratified analyses revealed that higher perceived support at baseline was associated with increased risk of incident cognitive impairment only among males. Conclusion: Contrary to previous research, results from this longitudinal study suggest that perceived support might be an important risk factor for cognitive decline, notably in males, and should be integrated into multifactorial risk assessment and intervention procedures.

The effect of diabetes on prefrontal cortex activation patterns during active walking in older adults.

BACKGROUND: Gait alterations were documented in diabetic patients. However, the effect of diabetes on cortical control of gait has not been reported. We evaluated the effect of diabetes on prefrontal cortex (PFC) Oxygenated Hemoglobin (HbO2) levels during active walking in older adults. METHODS: Of the total sample (n = 315; mean age = 76.84 ±â€¯6.71ys; % female = 56.5) 43 participants (13.7%) had diabetes. The experimental paradigm consisted of two single tasks: Normal-Walk (NW); and Cognitive Interference (Alpha); and one dual-task condition consisting of the two single tasks, Walk-While-Talk (WWT). Functional Near-Infrared-Spectroscopy (fNIRS) was used to quantify PFC HbO2 levels. RESULTS: Older adults without diabetes showed higher PFC HbO2 levels in WWT compared to both NW and Alpha. HbO2 levels during NW were not different between the two groups. Consistent with Neural Inefficiency, older adults with diabetes exhibited higher HbO2 levels during Alpha while performing significantly worse than those without diabetes. Moreover, the presence of diabetes was associated with attenuated HbO2 levels during WWT. This pattern is consistent with Capacity Limitations suggesting a failure to recruit brain resources vis-à-vis the more cognitively challenging WWT condition. CONCLUSIONS: A distinct functional neural signature of diabetes was established during active and attention demanding walking among older adults without overt neurological disease.

Stress and gender effects on prefrontal cortex oxygenation levels assessed during single and dual-task walking conditions.

The ability to walk is critical for functional independence and wellbeing. The pre-frontal cortex (PFC) plays a key role in cognitive control of locomotion, notably under attention-demanding conditions. Factors that influence brain responses to cognitive demands of locomotion, however, are poorly understood. Herein, we evaluated the individual and combined effects of gender and perceived stress on stride velocity and PFC Oxygenated Hemoglobin (HbO2 ) assessed during single and dual-task walking conditions. The experimental paradigm included Normal Walk (NW); Cognitive Interference (Alpha); and Walk-While-Talk (WWT) tasks. An instrumented walkway was used to assess stride velocity in NW and WWT conditions. Functional Near-Infrared-Spectroscopy (fNIRS) was used to quantify PFC HbO2 levels during NW, Alpha and WWT. Perceived task-related stress was evaluated with a single 11-point scale item. Participants were community residing older adults (age = 76.8 ± 6.7 years; %female = 56). Results revealed that higher perceived stress was associated with greater decline in stride velocity from single to dual-task conditions among men. Three-way interactions revealed that gender moderated the effect of perceived stress on changes in HbO2 levels comparing WWT to NW and Alpha. Attenuation in the increase in HbO2 levels, in high compared to low perceived stress levels, from the two single task conditions to WWT was observed only in men. Thus, older men may be more vulnerable to the effect of perceived stress on the change in PFC oxygenation levels across walking conditions that vary in terms of cognitive demands. These findings confer important implications for assessment and treatment of individuals at risk of mobility impairments.

Mild Cognitive Impairments Moderate the Effect of Time on Verbal Fluency Performance.

OBJECTIVES: Mild cognitive impairments (MCI) is a transitional state in aging associated with increased risk of incident dementia. The current study investigated whether MCI status moderated the effect of time on word generation during verbal fluency tasks. Specifically, the objective was to determine whether MCI status had differential effects on initial automatic or latter more effortful retrieval processes of fluency tasks. METHODS: Participants were community residing older adults enrolled in a longitudinal cohort study. Of the 408 participants, 353 were normal (age=76.06±6.61; %female=57.8) and 55 were diagnosed with MCI (age=78.62±7.00; %female=52.7). Phonemic and category fluency were each administered for 60 s, but performance was recorded at three consecutive 20-s intervals (0-20 s [T1], 21-40 s [T2], 41-60 s [T3]. Separate linear mixed effects models for each fluency task were used to determine the effects of group, time, and their interaction on word generation. RESULTS: In both fluency tasks, word generation declined as a function of time. Individuals with MCI generated fewer words compared to controls during the first 20 s of phonemic (beta=-1.56; p<.001; d=0.28) and category fluency (beta=-1.85; p<.001; d=0.37). Group by time interactions revealed that individuals with MCI demonstrated attenuated declines in word generation from the first to the second and third time intervals of both phonemic ([T1 vs. T2] beta=2.17, p=.001; d=0.41; [T1 vs. T3]beta=2.28, p=.001; d=0.45) and category ([T1 vs. T2] beta= 2.22, p=.002; d=0.50; [T1 vs. T3]beta=3.16, p<.001; d=0.71) fluency. CONCLUSIONS: Early automatic retrieval processes in verbal fluency tasks are compromised in MCI. (JINS, 2017, 23, 44-55).

Development and Validation of the State-Trait Inventory of Cognitive Fatigue in Community-Dwelling Older Adults.

OBJECTIVE: To develop and validate a subjective measure of cognitive fatigue-the State-Trait Inventory of Cognitive Fatigue-in community-dwelling older adults. DESIGN: Scale development and test construction. SETTING: Community-dwelling older adults enrolled in a longitudinal cohort aging study. PARTICIPANTS: Participants (N=175) were healthy, English-speaking, community-dwelling adults, age ≥65 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: State-Trait Inventory of Cognitive Fatigue total, cognitive fatigue, motivation, mental effort, and boredom summation scores for both state and trait forms. RESULTS: Principal component analysis yielded the expected 4 components for both state and trait forms: cognitive fatigue, mental effort, motivation, and boredom. All components had good reliability. There was good convergent validity as measured by the strong positive relation between cognitive fatigue and a subjective measure of general fatigue, even after controlling for depressive symptoms. Greater subjective cognitive fatigue was associated with worse performance on measures thought to be more sensitive to aspects of executive functioning. CONCLUSIONS: This study developed and established the psychometric properties of a new instrument for the subjective measurement of cognitive fatigue for use in community-dwelling older adults. The State-Trait Inventory of Cognitive Fatigue's relatively brief administration time (<10min; mean, 5.6±2.9) and strong psychometric properties support its utility in both research and clinical settings. Future studies should establish the psychometric properties of this scale in other populations and examine its predictive utility for relevant clinical outcomes.

Frontal brain activation changes due to dual-tasking under partial body weight support conditions in older adults with multiple sclerosis.

BACKGROUND: Gait impairments present while dual-tasking in older adults with multiple sclerosis (MS) have been associated with an increased risk of falls. Prior studies have examined prefrontal cortex (PFC) activity using functional near infrared spectroscopy (fNIRS) while dual-tasking in older adults with and without cognitive impairment. While the benefits of partial body weight support (PBWS) on gait have been clearly outlined in the literature, the potential use of PBWS to improve the ability to dual task in older adults with and without MS has not been examined. The aim of this study was to examine the effects of PBWS on the PFC activation while dual-tasking in older adults with and without MS. METHODS: Ten individuals with MS (mean 56.2 ± 5.1 yrs., 8 females) and 12 healthy older adults (HOA) (mean 63.1 ± 4.4 yrs., 9 females) participated in this study. PFC activation (i.e., oxygenated hemoglobin-HbO2) was measured using fNIRS. Assessments were done under two treadmill walking conditions: no body weight support (NBWS) and PBWS. Under each condition, participants were asked to walk at a comfortable speed (W) or walk and talk (WT). Linear mixed models were used to test for differences between cohorts, conditions, and tasks. RESULTS: HbO2 levels differed significantly between task (p < .001), cohort (p < .001), and BWS (p = .02). HbO2 levels increased under higher cognitive demands (i.e., W vs WT), in individuals with MS, and under different conditions (i.e., NBWS vs PBWS). Post-hoc analysis demonstrated a significant difference between cohorts during the WT and NBWS condition (p = .05). When examining the relative change in HbO2 levels during each task, a significant interaction between task, BWS, and cohort across time was observed (p < 0.01). While HOA increased PFC activation across time, MS exhibited a maintenance of PFC activation patterns during the WT under PBWS condition. CONCLUSIONS: This study establishes the potential impact of PBWS on PFC activation patterns under dual-tasking conditions and sheds light on the ability for PBWS to be used as a therapeutic tool in individuals with neurological conditions to decrease cognitive demands while dual-tasking and thus decrease the risk of falls.