Structural Correlates of Overt Sentence Reading in Mild Cognitive Impairment and Mild-to-Moderate Alzheimer's Disease.

BACKGROUND: Overt sentence reading in mild cognitive impairment (MCI) and mild-tomoderate Alzheimer's disease (AD) has been associated with slowness of speech, characterized by a higher number of pauses, shorter speech units and slower speech rate and attributed to reduced working memory/ attention and language capacity. OBJECTIVE: This preliminary case-control study investigates whether the temporal organization of speech is associated with the volume of brain regions involved in overt sentence reading and explores the discriminative ability of temporal speech parameters and standard volumetric MRI measures for the classification of MCI and AD. METHODS: Individuals with MCI, mild-to-moderate AD, and healthy controls (HC) had a structural MRI scan and read aloud sentences varying in cognitive-linguistic demand (length). The association between speech features and regional brain volumes was examined by linear mixed-effect modeling. Genetic programming was used to explore the discriminative ability of temporal and MRI features. RESULTS: Longer sentences, slower speech rate, and a higher number of pauses and shorter interpausal units were associated with reduced volumes of the reading network. Speech-based classifiers performed similarly to the MRI-based classifiers for MCI-HC (67% vs. 68%) and slightly better for AD-HC (80% vs. 64%) and AD-MCI (82% vs. 59%). Adding the speech features to the MRI features slightly improved the performance of MRI-based classification for AD-HC and MCI-HC but not HC-MCI. CONCLUSION: The temporal organization of speech in overt sentence reading reflects underlying volume reductions. It may represent a sensitive marker for early assessment of structural changes and cognitive- linguistic deficits associated with healthy aging, MCI, and AD.

Cognitive and Structural Correlates of Conversational Speech Timing in Mild Cognitive Impairment and Mild-to-Moderate Alzheimer's Disease: Relevance for Early Detection Approaches.

Background: Increasing efforts have focused on the establishment of novel biomarkers for the early detection of Alzheimer's disease (AD) and prediction of Mild Cognitive Impairment (MCI)-to-AD conversion. Behavioral changes over the course of healthy ageing, at disease onset and during disease progression, have been recently put forward as promising markers for the detection of MCI and AD. The present study examines whether the temporal characteristics of speech in a collaborative referencing task are associated with cognitive function and the volumes of brain regions involved in speech production and known to be reduced in MCI and AD pathology. We then explore the discriminative ability of the temporal speech measures for the classification of MCI and AD. Method: Individuals with MCI, mild-to-moderate AD and healthy controls (HCs) underwent a structural MRI scan and a battery of neuropsychological tests. They also engaged in a collaborative referencing task with a caregiver. The associations between the conversational speech timing features, cognitive function (domain-specific) and regional brain volumes were examined by means of linear mixed-effect modeling. Genetic programming was used to explore the discriminative ability of the conversational speech features. Results: MCI and mild-to-moderate AD are characterized by a general slowness of speech, attributed to slower speech rate and slower turn-taking in conversational settings. The speech characteristics appear to be reflective of episodic, lexico-semantic, executive functioning and visuospatial deficits and underlying volume reductions in frontal, temporal and cerebellar areas. Conclusion: The implementation of conversational speech timing-based technologies in clinical and community settings may provide additional markers for the early detection of cognitive deficits and structural changes associated with MCI and AD.

Rehabilitation of emergent awareness of errors post traumatic brain injury: A pilot intervention.

Impaired awareness of errors is common following traumatic brain injury (TBI) and can be a barrier to successful rehabilitation. The objective of this study was to develop and evaluate a computer-based intervention programme aimed at improving error awareness in individuals with TBI. A further aim was to explore its effects on metacognitive awareness and variability of performance. Participants were 11 individuals with TBI and impaired error awareness who performed a sustained attention task twice-weekly for four weeks. The intervention consisted of audio-visual feedback-on-errors during the sustained attention task. Six participants received audio-visual feedback-on-error, five did not receive feedback. Emergent and metacognitive awareness were measured pre- and post-intervention. Between-groups comparisons of emergent awareness from pre- to post-intervention showed that audio-visual feedback-on-error improved emergent awareness compared to no feedback-on-error. Some changes in metacognitive awareness of executive behaviours as a result of feedback were observed. Audio-visual feedback-on-error improved emergent awareness in individuals with TBI following a four-week/eight-session intervention. This improvement was not observed in the no-feedback group. This pilot intervention is not a stand-alone treatment but it has potential to be usefully incorporated into cognitive or clinical rehabilitation programmes to improve emergent awareness.

Neuropolypathology as a result of severe traumatic brain injury?

A history of brain trauma has long been acknowledged as increasing an individual's risk of developing dementia in later life. The underlying mechanisms that belie this pre-disposition are, however, very poorly understood. Here, we report a clinical-neuropathological correlation of a man who presented at the age of 66 with a progressive complex atypical dementia with early and prominent neurobehavioral symptoms. His neurological condition continued to decline up to his death at the age of 74. During the compilation of his clinical history, it was established that the subject had experienced a single severe traumatic brain injury (TBI) aged 12 years in 1954 resulting in loss of consciousness, hospitalization, and coma for a number of days after which he was deemed to have recovered. Following post-mortem neuropathological analysis, numerous distinct neuropathologies were observed in various brain regions and these included i) widespread Braak stage VI neurofibrillary tangle formation, ii) widespread α-synuclein positive Lewy bodies and Lewy neurites and iii) diffuse amyloid plaques and severe cerebral amyloid angiopathy (CAA). Added to this, a comprehensive analysis of blood-brain barrier (BBB) integrity, known to be disrupted during and after TBI, showed iv) distinct BBB breakdown with extravasated IgG and activated microglia present. This report represents an interesting documented case of neuropolypathology that may be associated with prior history of severe TBI. We propose one testable theory that a history of brain trauma may be a potential trigger for late onset dementia due to damage and unresolved functioning of the cerebral microvasculature.
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Changes in Speech Chunking in Reading Aloud is a Marker of Mild Cognitive Impairment and Mild-to-Moderate Alzheimer's Disease.

BACKGROUND: Speech and Language Impairments, generally attributed to lexico-semantic deficits, have been documented in Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD). This study investigates the temporal organisation of speech (reflective of speech production planning) in reading aloud in relation to cognitive impairment, particularly working memory and attention deficits in MCI and AD. The discriminative ability of temporal features extracted from a newly designed read speech task is also evaluated for the detection of MCI and AD. METHOD: Sixteen patients with MCI, eighteen patients with mild-to-moderate AD and thirty-six healthy controls (HC) underwent a battery of neuropsychological tests and read a set of sentences varying in cognitive load, probed by manipulating sentence length and syntactic complexity. RESULTS: Our results show that Mild-to-Moderate AD is associated with a general slowness of speech, attributed to a higher number of speech chunks, silent pauses and dysfluences, and slower speech and articulation rates. Speech chunking in the context of high cognitive-linguistic demand appears to be an informative marker of MCI, specifically related to early deficits in working memory and attention. In addition, Linear Discriminant Analysis shows the ROC AUCs (Areas Under the Receiver Operating Characteristic Curves) of identifying MCI vs. HC, MCI vs. AD and AD vs. HC using these speech characteristics are 0.75, 0.90 and 0.94 respectively. CONCLUSION: The implementation of connected speech-based technologies in clinical and community settings may provide additional information for the early detection of MCI and AD.

Semantic and Phonemic Verbal Fluency Discrepancy in Mild Cognitive Impairment: Potential Predictor of Progression to Alzheimer's Disease.

OBJECTIVES: To assess the utility of verbal fluency discrepancy scores in predicting progression to Alzheimer's disease (AD) in a cohort of individuals with mild cognitive impairment (MCI). DESIGN: Case control. SETTING: Cases identified from new referrals to a memory clinic and controls identified from The Irish Longitudinal Study on Ageing. PARTICIPANTS: Of 308 individuals with MCI at baseline identified from consecutive referrals to a memory clinic and compared at with age-, sex-, and education-matched controls (n=302), 161 completed 2 years of follow-up or progressed to AD during the study period. MEASUREMENTS: Verbal fluency discrepancy (semantic-phonemic fluency) scores at baseline were calculated for each participant. Each case was followed with repeated neuropsychological measurements, and multidisciplinary consensus diagnosis was recorded. RESULTS: Mean discrepancy score for those who progressed to AD (2.7) was significantly lower than for those who retained a MCI diagnosis (4.8) and normal controls (7.7) (p<.001). Logistic regression revealed that, for each unit decrease in discrepancy score at baseline, the odds of progressing to AD were 9% greater. (Exp(B) = 1.09, p=.02) CONCLUSION: Individuals with MCI have less of a semantic advantage than those without MCI. Those with MCI presenting with a phonemic advantage at initial assessment warrant close follow-up and a high index of suspicion for progression to AD.

Supplemental Retinal Carotenoids Enhance Memory in Healthy Individuals with Low Levels of Macular Pigment in A Randomized, Double-Blind, Placebo-Controlled Clinical Trial.

BACKGROUND: There is a biologically plausible rationale whereby the dietary carotenoids lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ), which are collectively referred to as macular pigment (MP) in the central retina (macula), support the maintenance of cognition via their antioxidant and anti-inflammatory properties. OBJECTIVE: To investigate the impact of supplemental L, Z, and MZ on memory, executive function, and verbal fluency among healthy individuals with low MP levels. METHODS: In this double-blind, placebo-controlled, randomized clinical trial, subjects (n = 91; mean±SD age = 45.42±12.40; % male = 51.6) consumed a daily formulation of 10 mg L, 10 mg MZ, and 2 mg Z (n = 45) or placebo (n = 46) for 12 months. Cognitive domains assessed included verbal and visual learning, immediate and delayed memory, executive function, and verbal fluency. MP and serum carotenoid concentrations of L, Z, and MZ were also measured. RESULTS: Following 12-month supplementation, individuals in the active group exhibited statistically significant improvements in memory when compared to the placebo group (paired associated learning [PAL] memory score [rANOVA, p = 0.009]; PAL errors [rANOVA, p = 0.017]). Furthermore, the observed reduction in the number of errors made in the PAL task among those in the intervention group was positively and significantly related to observed increases in MP volume (p = 0.005) and observed increases in serum concentrations of L (p = 0.009). CONCLUSION: This randomized, double-blind, placebo-controlled clinical trial demonstrates a memory-enhancing effect of daily supplementation with L, Z, and MZ in healthy subjects with low MP at baseline. The implications of these findings for intellectual performance throughout life, and for risk of cognitive decline in later life, warrant further study.

The Frontal Assessment Battery: Normative Performance in a Large Sample of Older Community-Dwelling Hospital Outpatient or General Practitioner Attenders.

BACKGROUND: The Frontal Assessment Battery (FAB) is a short battery designed to assess frontal executive functioning, but data for interpretation of performance are limited. OBJECTIVES: The Trinity, Ulster, Department of Agriculture (TUDA) study provided the opportunity to derive performance data from a large sample of community-dwelling hospital outpatient or general practitioner (GP) attenders. METHODS: Normative analysis based on 2508 TUDA participants meeting these criteria: Mini-Mental State Examination (MMSE) >26/30, not depressed (Center for Epidemiologic Studies Depression <16) or anxious (Hospital Anxiety and Depression Scale <8), no history of stroke, or transient ischemic attack. Correlation and regression analyses were used to evaluate the effects of age, education, gender, and general cognition (MMSE). Norms for FAB were created stratified by age and education, using overlapping midpoint ranges of 10 years with a 3-year interval from age 60 to 97. RESULTS: Age and education accounted for 9.6% of variance in FAB score ( r2 = .096) with no significant effect of gender. The FAB and MMSE were modestly correlated ( r = .29, P < .01) with MMSE increasing the model's total explained variance in FAB score from 9.6% to 14%. CONCLUSION: This is the largest study to date to create normative data for the FAB. Age and education had the most significant impact on FAB performance, which was largely independent of global cognition (MMSE). These data may be of benefit in interpreting FAB performance in individuals with similar demographic/health status characteristics in hospital outpatient or GP settings.

Preservation of the Semantic Verbal Fluency Advantage in a Large Population-Based Sample: Normative Data from the TILDA Study.

OBJECTIVES: It is widely believed that phonemic fluency is more difficult than naming exemplars from a semantic category. Normative data in this regard are scarce, and there is considerable disagreement in the literature regarding the pattern in normal ageing and neurodegenerative conditions. Our objective was to provide normative data for semantic phonemic discrepancy scores from a large sample of older adults. METHODS: A total of 5780 community-dwelling older adults were included in this prospective, longitudinal study. Discrepancy scores were calculated by subtracting phonemic fluency score from semantic fluency score for each participant. Quantile regression was used to estimate normative values stratified for age. RESULTS: Subjects did better on testing of semantic fluency. The average discrepancy score was 9.18±6.89 words, (range, -20 to 37; n=5780). At the fiftieth percentile, those in their fifth decade produced 10 more "animals" than "letter F" words. Subjects scored one word less per decade, with an average of seven more "animal" words produced by those in their eighth decade. CONCLUSIONS: Our study is the first to provide normative data and confirms that, for animal versus letter F fluency, the semantic advantage persists into later life in a population-based sample of community-dwelling older adults. Given that a majority of clinical samples have confirmed a reverse of this pattern in Alzheimer's dementia (i.e., loss of semantic advantage in Alzheimer's disease, yielding a phonemic advantage), our findings support the clinical utility of brief fluency tests and encourage further research into their use in diagnosis and prediction of progression to dementia.

Clarifying the associations between anxiety, depression and fatigue following stroke.

Both psychological distress and fatigue are common post stroke. Although there is recognition that the phenomena are related, the nature of the relationship is unclear.Cross-sectional study of 98 independently functioning participants within 2 years of stroke. Significant relationships were observed between fatigue and general anxiety, health-related anxiety and stroke-specific anxiety (r range from .31 to .37). In the final regression model, depression, pain and stroke-specific anxiety were significant, accounting for 32 per cent of the variance in fatigue scores (p < .001). The findings provide insight into the importance of anxiety-related factors post stroke, their relevance to our understanding of post-stroke fatigue and their implications for post-stroke intervention.

Strengths and Limitations of the MoCA for Assessing Cognitive Functioning: Findings From a Large Representative Sample of Irish Older Adults.

BACKGROUND: The Montreal Cognitive Assessment (MoCA) is a very widely used test for mild cognitive impairment. Differing recommendations have been made regarding its utility in providing a profile of performance across several cognitive domains. OBJECTIVES: To examine the factor structure of the MoCA in a nationally representative population study of older Irish adults and evaluate its utility in providing domain-specific information. METHODS: A cross-sectional analysis of wave 1 data from the Irish Longitudinal Study on Ageing was undertaken. Data from a subset of 2342 participants assessed using the MoCA were analyzed using both confirmatory factor analytic (CFA) and exploratory factor analytic (EFA) methods. RESULTS: Mean age was 72.64 (range 65 to 98), 53% female. The CFA provided evidence of adequate overall model fit for a previously proposed 6-factor model. In contrast, EFA yielded a 3-factor solution and test items cross-loaded onto a number of factors with no clear pattern of underlying cognitive domains. Using EFA to explore the 6-factor model yielded good fit, but again test items cross-loaded onto a number of factors with no clear pattern evident. CONCLUSION: Lack of concordance between the CFA and EFA findings demonstrates that the correspondence between individual tests and their assumed cognitive domains is not robust, reflecting at least in part a current lack of consensus on how core cognitive constructs are defined and on what subcomponents can be subsumed under different cognitive domains. The MoCA should not be viewed as a substitute for more in-depth neuropsychological assessment when domain-specific information is required.

A qualitative study of the experience of psychological distress post-stroke.

There is little qualitative data on the emotional effect of stroke upon which to base hypotheses for psychological interventions. We used Interpretative Phenomenological Analysis of semi-structured interviews with 10 individuals in the clinical range for psychological distress on the Hospital Anxiety and Depression Scale to explore their experiences of psychological distress. Three super-ordinate themes (the fear of stroke, loss of self and sense of isolation and aloneness) emerged. Processes involving a lack of acceptance and self-compassion underlined these themes. Internal isolation was found as a great problem. These themes may indicate targets for directed psychological interventions in people following stroke.

Cognitive Function and Its Relationship with Macular Pigment Optical Density and Serum Concentrations of its Constituent Carotenoids.

BACKGROUND: Macular pigment (MP) levels correlate with brain concentrations of lutein (L) and zeaxanthin (Z), and have also been shown to correlate with cognitive performance in the young and elderly. OBJECTIVE: To investigate the relationship between MP, serum concentrations of L and Z, and cognitive function in subjects free of retinal disease with low MP (Group 1, n = 105) and in subjects with AMD (Group 2, n = 121). METHODS: MP was measured using customized heterochromatic flicker photometry and dual-wavelength autofluorescence; cognitive function was assessed using a battery of validated cognition tests; serum L and Z concentrations were determined by HPLC. RESULTS: Significant correlations were evident between MP and various measures of cognitive function in both groups (r = -0.273 to 0.261, p≤0.05, for all). Both serum L and Z concentrations correlated significantly (r = 0.187, p≤0.05 and r = 0.197, p≤0.05, respectively) with semantic (animal) fluency cognitive scores in Group 2 (the AMD study group), while serum L concentrations also correlated significantly with Verbal Recognition Memory learning slope scores in the AMD study group (r = 0.200, p = 0.031). Most of the correlations with MP, but not serum L or Z, remained significant after controlling for age, gender, diet, and education level. CONCLUSION: MP offers potential as a non-invasive clinical biomarker of cognitive health, and appears more successful in this role than serum concentrations of L or Z.

Orthostatic Blood Pressure Behavior in People with Mild Cognitive Impairment Predicts Conversion to Dementia.

OBJECTIVES: To compare the patterns of blood pressure (BP) behavior during orthostasis in individuals with mild cognitive impairment (MCI) with those of controls and to investigate whether orthostatic BP behavior differs between individuals with MCI who convert to dementia and those who do not. DESIGN: Longitudinal study with 3 years of follow-up. SETTING: Memory clinic in Dublin, Ireland, between 2007 and 2012. PARTICIPANTS: Community-dwelling individuals with MCI (n = 150) and controls (n = 75). MEASUREMENTS: Orthostatic BP was examined using the active standing test with a beat-to-beat continuous BP monitoring device in addition to neuropsychological testing. Hazard ratios (HRs) from parametric survival models were used to determine whether conversion to dementia was independently associated with baseline orthostatic BP variables. RESULTS: Individuals with MCI were more likely than controls to have a systolic BP (SBP) deficit of greater than 30% 30 seconds after standing (P = .01). Thirty percent of participants with MCI (n = 43) converted to dementia within the 3-year follow-up period. Individuals with MCI with a SBP deficit greater than 30% 30 seconds after standing were twice as likely to convert to dementia as those without the deficit (HR = 2.77, 95% confidence interval = 1.02-7.50). CONCLUSION: Human beings have evolved an elaborate neurological control system to maintain cerebral perfusion during orthostatic challenge. In people with MCI, this response is impaired and renders them twice as likely to convert to dementia.

The NEIL Memory Research Unit: psychosocial, biological, physiological and lifestyle factors associated with healthy ageing: study protocol.

BACKGROUND: Population ageing is a global phenomenon that has characterised demographic trends during the 20th and 21st century. The rapid growth in the proportion of older adults in the population, and resultant increase in the incidence of age-related cognitive decline, dementia and Alzheimer's disease, brings significant social, economic and healthcare challenges. Decline in cognitive abilities represents the most profound threat to active and healthy ageing. Current evidence suggests that a significant proportion of cases of age-related cognitive decline and dementia may be preventable through the modification of risk factors including education, depressive symptomology, physical activity, social engagement and participation in cognitively stimulating activities. The NEIL Memory Research Unit cohort study was established to investigate factors related to brain health and the maintenance of cognitive function. METHODS: A cohort of 1000 normally ageing adults aged 50 years and over are being recruited to participate in comprehensive assessments at baseline, and at follow-up once every 2 years. The assessment protocol comprises a comprehensive neuropsychological battery, some basic physical measures, psychosocial scales, questionnaire measures related to a range of health, lifestyle and behavioural factors, and a measure of resting state activity using electroencephalography (EEG). DISCUSSION: The NEIL Memory Research Unit cohort study will address key questions about brain health and cognitive ageing in the population aged 50+, with a particular emphasis on the influence of potentially modifiable factors on cognitive outcomes. Analyses will be conducted with a focus on factors involved in the maintenance of cognitive function among older adults, and therefore will have the potential to contribute significant knowledge related to key questions within the field of cognitive ageing, and to inform the development of public health interventions aimed at preventing cognitive decline and promoting active and healthy ageing.

The impact of supplemental macular carotenoids in Alzheimer's disease: a randomized clinical trial.

BACKGROUND: Patients with Alzheimer's disease (AD) exhibit significantly less macular pigment (MP) and poorer vision when compared to control subjects. OBJECTIVE: To investigate supplementation with the macular carotenoids on MP, vision, and cognitive function in patients with AD versus controls. METHODS: A randomized, double-blind clinical trial with placebo and active arms. 31 AD patients and 31 age-similar control subjects were supplemented for six months with either Macushield (10 mg meso-zeaxanthin [MZ]; 10 mg lutein [L]; 2 mg zeaxanthin [Z]) or placebo (sunflower oil). MP was measured using dual-wavelength autofluorescence (Heidelberg Spectralis®). Serum L, Z, and MZ were quantified by high performance liquid chromatography. Visual function was assessed by best corrected visual acuity and contrast sensitivity (CS). Cognitive function was assessed using a battery of cognition tests, including the Cambridge Neuropsychological Test Automated Battery (CANTAB)). RESULTS: Subjects on the active supplement (for both AD and non-AD controls) exhibited statistically significant improvement in serum concentrations of L, Z, MZ, and MP (p < 0.001, for all) and also CS at (p = 0.039). Also, for subjects on the active supplement, paired samples t-tests exhibited four significant results (from five spatial frequencies tested) in the AD group, and two for the non-AD group, and all indicating improvements in CS. We found no significant changes in any of the cognitive function outcome variables measured (p > 0.05, for all). CONCLUSION: Supplementation with the macular carotenoids (MZ, Z, and L) benefits patients with AD, in terms of clinically meaningful improvements in visual function and in terms of MP augmentation.

Cognitive function in the prefrailty and frailty syndrome.

OBJECTIVES: To explore the relationship between cognitive function and frailty. DESIGN: A cross-sectional study using data from Wave 1 of The Irish Longitudinal Study on Ageing, a population representative study of adults aged 50 and older in the Republic of Ireland. SETTING: Community-dwelling adults completed a home- or health center-based nurse-led assessment. PARTICIPANTS: Individuals aged 50 and older without a history of stroke, Parkinson's disease, or severe cognitive impairment (Mini-Mental State Examination (MMSE) score <18) and not taking antidepressants (N = 4,649). MEASUREMENTS: A cognitive battery including MMSE, Montreal Cognitive Assessment, Color Trails Test, Cambridge Mental Disorders of the Elderly Examination memory and executive function subtests, 10-word recall, Sustained Attention to Response Task, and choice reaction time was used to generate composite scores of cognitive domains. Frailty was assessed according to weakness, slowness, exhaustion, low physical activity, and weight loss. RESULTS: After full adjustment, cognitive function across all domains except self-rated memory and processing speed was significantly worse in prefrail and frail participants (P < .05) than in those who were robust. Weakness and walking speed were most consistently linked to poorer cognition, whereas low activity and weight loss were not independently associated with any cognitive domain. Exhaustion was associated with global cognition (B = -0.18 ± 0.06), with some evidence of links to objectively measured and self-rated memory. CONCLUSION: Cognitive function is worse across multiple cognitive domains in prefrail and frail individuals aged 50 and older than in those who are robust, although the absolute differences are small after adjusting for confounding factors.

Cognitive function is associated with impaired heart rate variability in ageing adults: the Irish longitudinal study on ageing wave one results.

OBJECTIVE: To examine the independent association between heart rate variability (HRV) and cognitive performance, in a nationally representative population study of older adults. METHODS: Cross-sectional analysis of wave 1 data from the Irish longitudinal study on ageing (TILDA) was performed. A subset of 4,763 participants who underwent ECG recording during resting and paced breathing periods were used for the analysis. HRV indices were divided into quintiles for comparison of values and cognitive performance was defined using the Montreal cognitive assessment (MOCA) score. Multivariate linear regression was used to model the association between cognition and different quintiles of each HRV index, after adjustment for covariates. RESULTS: The mean age was 61.7 ± 8.3 years and 2,618 (55 %) were female. Lower quintiles of SDNN (P = 0.01-paced), LF (P = 0.001-paced), and LF:HF ratio (P = 0.049-paced) were significantly associated with lower MOCA scores (during both recording periods), independent of confounders. Sub-domains of MOCA responsible for the relationship were predominantly memory recall and language. INTERPRETATION: Reduced HRV is significantly associated with lower cognitive performance at a population level in people aged 50 and older. This further strengthens the relationship between autonomic dysfunction and cognitive disorders.

Normative values of cognitive and physical function in older adults: findings from the Irish Longitudinal Study on Ageing.

OBJECTIVES: To provide normative values of tests of cognitive and physical function based on a large sample representative of the population of Ireland aged 50 and older. DESIGN: Data were used from the first wave of The Irish Longitudinal Study on Ageing (TILDA), a prospective cohort study that includes a comprehensive health assessment. SETTING: Health assessment was undertaken at one of two dedicated health assessment centers or in the study participant's home if travel was not practicable. PARTICIPANTS: Five thousand eight hundred ninety-seven members of a nationally representative sample of the community-living population of Ireland aged 50 and older. Those with severe cognitive impairment, dementia, or Parkinson's disease were excluded. MEASUREMENTS: Measurements included height and weight, normal walking speed, Timed Up-and-Go, handgrip strength, Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Color Trails Test, and bone mineral density. Normative values were estimated using generalized additive models for location shape and scale (GAMLSS) and are presented as percentiles, means, and standard deviations. RESULTS: Generalized additive models for location shape and scale fit the observed data well for each measure, leading to reliable estimates of normative values. Performance on all tasks decreased with age. Educational attainment was a strong determinant of performance on all cognitive tests. Tests of walking speed were dependent on height. Distribution of body mass index did not change with age, owing to simultaneous declines in weight and height. CONCLUSION: Normative values were found for tests of many aspects of cognitive and physical function based on a representative sample of the general older Irish population.