High-order brain interactions in ketamine during rest and task: A double-blinded cross-over design using portable EEG.

In a double-blinded cross-over design, 30 adults (mean age = 25.57, SD = 3.74; all male) were administered racemic ketamine and compared against saline infusion as a control. Both task-driven (auditory oddball paradigm) and resting-state EEG were recorded. HOI were computed using advanced multivariate information theory tools, allowing us to quantify nonlinear statistical dependencies between all possible electrode combinations. Results: Ketamine increased redundancy in brain dynamics, most significantly in the alpha frequency band. Redundancy was more evident during the resting state, associated with a shift in conscious states towards more dissociative tendencies. Furthermore, in the task-driven context (auditory oddball), the impact of ketamine on redundancy was more significant for predictable (standard stimuli) compared to deviant ones. Finally, associations were observed between ketamine's HOI and experiences of derealization. Conclusions: Ketamine appears to increase redundancy and genuine HOI across metrics, suggesting these effects correlate with consciousness alterations towards dissociation. HOI represents an innovative method to combine all signal spatial interactions obtained from low-density dry EEG in drug interventions, as it is the only approach that exploits all possible combinations from different electrodes. This research emphasizes the potential of complexity measures coupled with portable EEG devices in monitoring shifts in consciousness, especially when paired with low-density configurations, paving the way for better understanding and monitoring of pharmacological-induced changes.

Neuroscience from the comfort of your home: Repeated, self-administered wireless dry EEG measures brain function with high fidelity.

Recent advances have enabled the creation of wireless, "dry" electroencephalography (EEG) recording systems, and easy-to-use engaging tasks, that can be operated repeatedly by naïve users, unsupervised in the home. Here, we evaluated the validity of dry-EEG, cognitive task gamification, and unsupervised home-based recordings used in combination. Two separate cohorts of participants-older and younger adults-collected data at home over several weeks using a wireless dry EEG system interfaced with a tablet for task presentation. Older adults (n = 50; 25 females; mean age = 67.8 years) collected data over a 6-week period. Younger male adults (n = 30; mean age = 25.6 years) collected data over a 4-week period. All participants were asked to complete gamified versions of a visual Oddball task and Flanker task 5-7 days per week. Usability of the EEG system was evaluated via participant adherence, percentage of sessions successfully completed, and quantitative feedback using the System Usability Scale. In total, 1,449 EEG sessions from older adults (mean = 28.9; SD = 6.64) and 684 sessions from younger adults (mean = 22.87; SD = 1.92) were collected. Older adults successfully completed 93% of sessions requested and reported a mean usability score of 84.5. Younger adults successfully completed 96% of sessions and reported a mean usability score of 88.3. Characteristic event-related potential (ERP) components-the P300 and error-related negativity-were observed in the Oddball and Flanker tasks, respectively. Using a conservative threshold for inclusion of artifact-free data, 50% of trials were rejected per at-home session. Aggregation of ERPs across sessions (2-4, depending on task) resulted in grand average signal quality with similar Standard Measurement Error values to those of single-session wet EEG data collected by experts in a laboratory setting from a young adult sample. Our results indicate that easy-to-use task-driven EEG can enable large-scale investigations in cognitive neuroscience. In future, this approach may be useful in clinical applications such as screening and tracking of treatment response.

Age and sex related differences in orthostatic cerebral oxygenation: Findings from 2764 older adults in the Irish Longitudinal Study on Ageing (TILDA).

AIMS: Cerebral hypoperfusion is implicated in the pathogenesis of associations between orthostatic hypotension and adverse outcome such as falls, cognitive impairment, depression, and mortality. Although the blood pressure response to orthostasis has been well studied there is a lack of information on orthostatic cerebrovascular responses in older populations. METHODS AND RESULTS: We measured cerebral hemodynamics, utilizing near infrared spectroscopy, coupled with peripheral blood pressure during an active stand in a large population of well-phenotyped older adults (N = 2764). Multi-level mixed effect models were utilized to investigate associations with age and sex, as well as confounders including anti-hypertensive medications. Normative cerebral oxygenation responses were also modelled utilizing generalized additive models for location, scale, and shape (GAMLSS). Older age groups experienced larger initial drops in oxygenation and a slower recovery, and responses also differed by sex. The drop after standing ranged from -1.85 % (95 % confidence interval (CI): -2.02 to -1.68) in the males aged 54-59 years vs -1.15 % (95 % CI: -1.31 to -1.00) in females aged 54-59 years, to -2.67 % (95 % CI: -3.01 to -2.33) in males aged ≥ 80 years vs -1.97 % (95 % CI: -2.32 to -1.62) females aged ≥ 80 years. Reduced oxygenation levels were also evident in those taking anti-hypertensive medications. CONCLUSION: Cerebral autoregulation is impaired with age, particularly in older women and those taking anti-hypertensives. SBP during the stand explained some of the age gradient in the late recovery stage of the stand for the oldest age group. Reported orthostatic symptoms did not correlate with hypoperfusion. Therefore, measures of orthostatic cerebral flow should be assessed in addition to peripheral BP in older patients irrespective of symptoms. Further studies are required to investigate the relationship between NIRS measurements and clinical outcomes such as falls, cognitive impairment and depression.

Feasibility of Repeated Assessment of Cognitive Function in Older Adults Using a Wireless, Mobile, Dry-EEG Headset and Tablet-Based Games.

Access to affordable, objective and scalable biomarkers of brain function is needed to transform the healthcare burden of neuropsychiatric and neurodegenerative disease. Electroencephalography (EEG) recordings, both resting and in combination with targeted cognitive tasks, have demonstrated utility in tracking disease state and therapy response in a range of conditions from schizophrenia to Alzheimer's disease. But conventional methods of recording this data involve burdensome clinic visits, and behavioural tasks that are not effective in frequent repeated use. This paper aims to evaluate the technical and human-factors feasibility of gathering large-scale EEG using novel technology in the home environment with healthy adult users. In a large field study, 89 healthy adults aged 40-79 years volunteered to use the system at home for 12 weeks, 5 times/week, for 30 min/session. A 16-channel, dry-sensor, portable wireless headset recorded EEG while users played gamified cognitive and passive tasks through a tablet application, including tests of decision making, executive function and memory. Data was uploaded to cloud servers and remotely monitored via web-based dashboards. Seventy-eight participants completed the study, and high levels of adherence were maintained throughout across all age groups, with mean compliance over the 12-week period of 82% (4.1 sessions per week). Reported ease of use was also high with mean System Usability Scale scores of 78.7. Behavioural response measures (reaction time and accuracy) and EEG components elicited by gamified stimuli (P300, ERN, Pe and changes in power spectral density) were extracted from the data collected in home, across a wide range of ages, including older adult participants. Findings replicated well-known patterns of age-related change and demonstrated the feasibility of using low-burden, large-scale, longitudinal EEG measurement in community-based cohorts. This technology enables clinically relevant data to be recorded outside the lab/clinic, from which metrics underlying cognitive ageing could be extracted, opening the door to potential new ways of developing digital cognitive biomarkers for disorders affecting the brain.

Discrepancies in self-reported and actigraphy-based sleep duration are associated with self-reported insomnia symptoms in community-dwelling older adults.

OBJECTIVES: To establish agreement between self-reported and actigraphy-based total sleep time (TST). To determine the impact of self-reported sleep problems on these measurements. DESIGN: Cross-sectional study using data from Wave 3 of The Irish Longitudinal Study on Ageing (2014-2015). PARTICIPANTS: Community-dwelling older adults, aged ≥50 years, with self-reported sleep information and ≥4 days of actigraphy-based TST (n = 1520). MEASUREMENT: Self-reported total sleep time, daytime sleepiness, insomnia symptoms (trouble falling asleep, trouble waking too early) measured during a structured self-interview. Actigraphy-based total TST was collected using GENEactiv wrist-worn accelerometers. Demographic characteristics and health information were controlled for. Analyses included descriptive statistics, reliability and agreement analysis using paired t-tests, intra-class correlations and Bland-Altman analysis. Linear regression was used to model associations with measurement discrepancies. RESULTS: Participants reported that they slept 7.0 hours (SD: 1.4, Range: 2.0-13.0 hours) on average, compared to 7.7 hours (SD: 1.2 hours, Range: 3.0-13.0 hours) recorded by accelerometry. Trouble falling asleep or waking too early "most of the time" were associated with under-reporting of sleep by 2.3, and 2.2 hours respectively. Agreement between measurements had an intra-class correlation of 0.18 and wide 95% limits of agreement (-3.90 to 2.55 hours). Under-reporting of sleep was independently associated with insomnia symptoms. CONCLUSION: The agreement between self-reported and actigraphy-based TST in community dwelling older adults was low. Self-reported insomnia symptoms were independently associated with under-reporting of sleep. Studies seeking to measure sleep duration should consider inclusion of questions measuring experience of insomnia symptoms to account for potential influence on measurements.

Associations between cognitive function, actigraphy-based and self-reported sleep in older community-dwelling adults: Findings from the Irish Longitudinal Study on Ageing.

OBJECTIVE: Cognitive impairment is prevalent in older ages. Associations with sleep are well established; however, ambiguity remains in which sleep characteristics contribute to this impairment. We examined cross-sectional associations between both self-reported and actigraphy-based sleep and cognitive performance across a number of domains in community-dwelling older adults. METHODS: 1520 participants aged 50 and older with self-reported and actigraphy-based total sleep time (TST) (≤5, 6, 7-8, 9 and ≥10 h) and self-reported sleep problems were analysed. Cognitive function was assessed using the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), verbal fluency, immediate and delayed recall memory, colour trails tests, and choice reaction tests (CRT). Associations between sleep and cognition were modelled using linear and negative binomial regression. RESULTS: Negative associations were found between ≥10 h of self-reported TST and MoCA error rate (incidence rate ratio [IRR] = 1.42; 95% confidence interval [CI] = 1.18, 1.71; p < 0.001); verbal fluency (beta [B] = -2.32 words; 95% CI = -4.00, -0.65; p < 0.01); and delayed recall (B = -0.91 words; 95% CI = -1.58, -0.25; p < 0.05) compared to 7-8 h. Significant associations with actigraphy-based TST were limited to MoCA error rate in ≤5 h (IRR = 1.22; 95% CI = 1.02, 1.45; p < 0.05) compared to 7-8 h. Higher numbers of sleep problems were associated with slower performance in CRT cognitive response time (IRR = 1.02; 95% CI = 1.00, 104; p < 0.05) and total response time (IRR = 1.02; 95% CI = 1.00, 1.04; p < 0.05). CONCLUSIONS: Self-reported long sleep duration was consistently associated with worse cognitive performance across multiple domains. Marginal associations between cognition and both actigraphy-based sleep and self-reported sleep problems were also apparent. These results further affirm poor sleep as a risk factor for cognitive impairment.

Objective Sleep Duration in Older Adults: Results From The Irish Longitudinal Study on Ageing.

OBJECTIVE: This study assessed the distribution and correlates of objective sleep duration in the older population in Ireland. DESIGN: Cross-sectional study using population-derived data from wave 3 of The Irish Longitudinal Study on Ageing. SETTING: Community-dwelling adults. PARTICIPANTS: Adults, aged 50 years and older, who wore an accelerometer for at least 4 days (N = 1533). MEASUREMENTS: Sleep was measured for at least 4 days in 1533 participants using a GENEActiv wrist-worn accelerometer device. Sleep parameters included total sleep time (TST) and self-reported sleep problems. TST was categorized as short and long sleep duration using US National Sleep Foundation guidelines. Linear and multinomial logistic regression models assessed sociodemographic, health, and behavioral correlates of sleep duration. RESULTS: Mean TST for the sample was 463 minutes (SD = 72.6 minutes). Of participants, 13.9% and 16.5% measured short and long sleep duration, respectively. TST decreased as sleep problems increased, as did durations recorded in summer compared to winter recordings. Advancing age was associated with longer sleep, as was antidepressant use. Retired/unemployed participants recorded longer TST and were more likely to record long sleep compared to employed participants. Fair/poor self-rated health and separated/divorced participants were more likely to record short sleep. Those reporting moderate or high physical activity were less likely to record short or long sleep, respectively, compared to those reporting low physical activity. Participants reporting a limiting disability were less likely to record long sleep. CONCLUSION: Average TST was within recommended guidelines; however, a significant subset of older adults recorded sleep duration outside of the guidelines. Independent demographic and health correlates of suboptimal sleep were identified, many of which are modifiable. Patients and clinicians should be aware of factors potentially influencing sleep patterns. Longitudinal analyses to confirm directionality of relationships with potential risk factors are warranted. J Am Geriatr Soc 68:120-128, 2019.

Age and sex differences in frontal lobe cerebral oxygenation in older adults-Normative values using novel, scalable technology: Findings from the Irish Longitudinal Study on Ageing (TILDA).

AIMS: Near-infrared spectroscopy (NIRS) is a non-invasive, easy to apply, optical technology for measuring cerebral blood oxygenation, but there is lack of comprehensive population data to aid interpretation and clinical use. Given the importance of cerebral perfusion in the context of evolving guideline recommendations for more aggressive lowering of blood pressure (BP) in hypertension, even in the oldest old, understanding of normative NIRS values is timely. We estimated normative values of cerebral oxygenation measured by NIRS in a large community-dwelling population sample of adults aged > = 50 years (n = 3110). We hypothesized that measurements would be attenuated by cardiovascular risk factors. METHODS: Data from Wave 3 of The Irish Longitudinal Study on Ageing (TILDA) was utilized. Frontal lobe cerebral oxygenation was continuously measured via a Portalite, while participants rested in the supine position. Beat-to-beat BP was measured simultaneously. Normative data was modelled using generalized additive models for location, scale, and shape (GAMLSS). Multivariate linear regressions were used to examine associations with cardiovascular risk factors. RESULTS: All three measures of NIRS (TSI, O2Hb and HHb) declined with increasing age. O2Hb and HHb were significantly lower in males than females. Increased smoking, excess alcohol intake, a higher waist-hip ratio, diabetes, angina, congestive heart failure, transient ischemic attack and total cardiovascular disease burden were all associated with decreased cerebral oxygenation. CONCLUSION: We present for the first time, normative resting-state NIRS reference data from a large population, which contributes to clinical interpretation of NIRS and advances the use of NIRS as a standard clinical tool.

Impact of Standing Speed on the Peripheral and Central Hemodynamic Response to Orthostasis: Evidence From the Irish Longitudinal Study on Ageing.

Assessment of the cerebrovascular and cardiovascular response to standing has prognostic value for a range of outcomes in the older adult population. Studies generally attempt to control for standing speed differences by asking participants to stand in a specified time but little is known about the range of transition times observed. This study aimed to characterize how standing speed associates with cardiovascular and cerebrovascular measures following transition from supine to standing. Continuous cerebral oxygenation, heart rate, systolic and diastolic blood pressure were monitored for 3 minutes after transitioning from supine to standing. An algorithm was used to calculate the time taken to transition from existing Finometer data (from the height correction unit). Linear mixed-effects models were used to assess the influence of transition time on each of the signals while adjusting for covariates. Transition time ranged from 2 to 27 s with 17% of participants taking >10 s to stand. Faster transition was associated with a more extreme decrease 10 s after standing but improved recovery at 20 s for cerebral oxygenation and blood pressure. Standing faster was associated with an elevated heart rate on initiation of stand and a quicker recovery 10 to 20 s after standing. The speed of transitioning from supine to standing position is associated with cardiovascular and cerebrovascular response in the early period after standing (<40 s). Care should be taken in the interpretation of findings which may be confounded by standing speed and statistical adjustment for standing time should be applied where appropriate.

Dissociable age and memory relationships with hippocampal subfield volumes in vivo:Data from the Irish Longitudinal Study on Ageing (TILDA).

The heterogeneous specialisation of hippocampal subfields across memory functions has been widely shown in animal models. Yet, few in vivo studies in humans have explored correspondence between hippocampal subfield anatomy and memory performance in ageing. Here, we used a well-validated automated MR segmentation protocol to measure hippocampal subfield volumes in 436 non-demented adults aged 50+. We explored relationships between hippocampal subfield volume and verbal episodic memory, as indexed by word list recall at immediate presentation and following delay. In separate multilevel models for each task, we tested linearity and non-linearity of associations between recall performance and subfield volume. Fully-adjusted models revealed that immediate and delayed recall were both associated with cubic fits with respect to volume of subfields CA1, CA2/3, CA4, molecular layer, and granule cell layer of dentate gyrus; moreover, these effects were partly dissociable from quadratic age trends, observed for subiculum, molecular layer, hippocampal tail, and CA1. Furthermore, analyses of semantic fluency data revealed little evidence of robust associations with hippocampal subfield volumes. Our results show that specific hippocampal subfields manifest associations with memory encoding and retrieval performance in non-demented older adults; these effects are partly dissociable from age-related atrophy, and from retrieval of well-consolidated semantic categories.

The association between frontal lobe perfusion and depressive symptoms in later life.

BACKGROUND: Deficits in frontal lobe perfusion have been demonstrated in late-life depression; however, studies to date have generally involved small numbers, used neuroimaging rather than bedside testing and have not controlled for important covariates.AimsWe aimed to examine the association between depressive symptoms and frontal lobe perfusion during standing, in a large cohort of community-dwelling older people. METHOD: Participants aged ≥50 years underwent continuous measurement of orthostatic blood pressure by finometry, and frontal lobe perfusion by near-infrared spectroscopy. Depressive symptoms were assessed by the eight-item Centre for Epidemiological Studies Depression Scale. Real-time frontal lobe cerebral oxygenation was measured by the Portalite System, detecting changes in frontal lobe perfusion and reporting a tissue saturation index score. RESULTS: Almost 8% (209 out of 2616) had clinically significant depressive symptoms. Multilevel models demonstrated a significantly lower tissue saturation index in participants with depressive symptoms at both 60 and 90 s post-stand, with coefficients of -0.43 (95% CI -0.63 to -0.22) and -0.37 (95% CI -0.57 to -0.16), respectively. Controlling for relevant covariates did not significantly attenuate these associations. After addition of systolic blood pressure this association was no longer significant, suggesting lower blood pressure may modify this relationship. CONCLUSIONS: This study demonstrates that lower frontal lobe perfusion, related to lower values of baseline systolic blood pressure, is associated with clinically significant depressive symptoms in a cohort of community-dwelling older people. Given the recognised longitudinal association between lower blood pressure and depression in older people, this may represent a potential therapeutic target for prevention of incident depression.Declaration of interestNone.

Cortical covariance networks in ageing: Cross-sectional data from the Irish Longitudinal Study on Ageing (TILDA).

Ageing is associated with widespread alterations to the brain's anatomy and to attendant cortical networks. Yet, few studies to date have indexed anatomical covariance network differences within the age distribution of older adulthood, despite known phenotypic variation. Here, we explored cortical anatomical covariance networks in middle and older age cross-sectionally, using a large sample of community-dwelling older adults from the Irish Longitudinal Study on Ageing (TILDA). We assayed age-related anatomical changes via cortical thickness. Moreover, we explored age-related alterations in small-world and global properties of cortical thickness covariance networks, by targeting analyses towards the elder (ages 75-88; n = 88) and younger (ages 52-64; n = 95) sample members. Age, sex, and chronic disease-adjusted vertex-wise analyses revealed robust reductions in cortical thickness with age. Graph theoretical analyses of cortical thickness covariance networks revealed significantly lower betweenness centrality (i.e., network hub status) at left inferior parietal cortex in the eldest participant group as compared to the youngest. Furthermore, indices of small-worldness revealed greater lambda (i.e., less effective integration) across the right hemisphere of the eldest participant group versus the youngest. Our results are interpreted in the context of mechanisms of cortical atrophy in ageing, functional network organisation, and cognition in ageing.

Machine Learning EEG to Predict Cognitive Functioning and Processing Speed Over a 2-Year Period in Multiple Sclerosis Patients and Controls.

Event-related potentials (ERPs) show promise to be objective indicators of cognitive functioning. The aim of the study was to examine if ERPs recorded during an oddball task would predict cognitive functioning and information processing speed in Multiple Sclerosis (MS) patients and controls at the individual level. Seventy-eight participants (35 MS patients, 43 healthy age-matched controls) completed visual and auditory 2- and 3-stimulus oddball tasks with 128-channel EEG, and a neuropsychological battery, at baseline (month 0) and at Months 13 and 26. ERPs from 0 to 700 ms and across the whole scalp were transformed into 1728 individual spatio-temporal datapoints per participant. A machine learning method that included penalized linear regression used the entire spatio-temporal ERP to predict composite scores of both cognitive functioning and processing speed at baseline (month 0), and months 13 and 26. The results showed ERPs during the visual oddball tasks could predict cognitive functioning and information processing speed at baseline and a year later in a sample of MS patients and healthy controls. In contrast, ERPs during auditory tasks were not predictive of cognitive performance. These objective neurophysiological indicators of cognitive functioning and processing speed, and machine learning methods that can interrogate high-dimensional data, show promise in outcome prediction.

Speed of Heart Rate Recovery in Response to Orthostatic Challenge.

RATIONALE: Speed of heart rate recovery (HRR) may serve as an important biomarker of aging and mortality. OBJECTIVE: To examine whether the speed of HRR after an orthostatic maneuver (ie, active stand from supine position) predicts mortality. METHODS AND RESULTS: A longitudinal cohort study involving a nationally representative sample of community-dwelling older individuals aged ≥50 years. A total of 4475 participants completed an active stand at baseline as part of a detailed clinic-based cardiovascular assessment. Beat-to-beat heart rate and blood pressure responses to standing were measured during a 2-minute window using a finometer and binned in 10-s intervals. We modeled HRR to the stand by age group, cardiovascular disease burden, and mortality status using a random effects model. Mortality status during a mean follow-up duration of 4.3 years served as the primary end point (n=138). Speed of HRR in the immediate 20 s after standing was a strong predictor of mortality. A 1-bpm slower HRR between 10 and 20 s after standing increased the hazard of mortality by 6% controlling for established risk factors. A clear dose-response relationship was evident. Sixty-nine participants in the slowest HRR quartile died during the observation period compared with 14 participants in the fastest HRR quartile. Participants in the slowest recovery quartile were 2.3× more likely to die compared with those in the fastest recovery quartile. CONCLUSIONS: Speed of orthostatic HRR predicts mortality and may aid clinical decision making. Attenuated orthostatic HRR may reflect dysregulation of the parasympathetic branch of the autonomic nervous system.

Delayed P100-Like Latencies in Multiple Sclerosis: A Preliminary Investigation Using Visual Evoked Spread Spectrum Analysis.

Conduction along the optic nerve is often slowed in multiple sclerosis (MS). This is typically assessed by measuring the latency of the P100 component of the Visual Evoked Potential (VEP) using electroencephalography. The Visual Evoked Spread Spectrum Analysis (VESPA) method, which involves modulating the contrast of a continuous visual stimulus over time, can produce a visually evoked response analogous to the P100 but with a higher signal-to-noise ratio and potentially higher sensitivity to individual differences in comparison to the VEP. The main objective of the study was to conduct a preliminary investigation into the utility of the VESPA method for probing and monitoring visual dysfunction in multiple sclerosis. The latencies and amplitudes of the P100-like VESPA component were compared between healthy controls and multiple sclerosis patients, and multiple sclerosis subgroups. The P100-like VESPA component activations were examined at baseline and over a 3-year period. The study included 43 multiple sclerosis patients (23 relapsing-remitting MS, 20 secondary-progressive MS) and 42 healthy controls who completed the VESPA at baseline. The follow-up sessions were conducted 12 months after baseline with 24 MS patients (15 relapsing-remitting MS, 9 secondary-progressive MS) and 23 controls, and again at 24 months post-baseline with 19 MS patients (13 relapsing-remitting MS, 6 secondary-progressive MS) and 14 controls. The results showed P100-like VESPA latencies to be delayed in multiple sclerosis compared to healthy controls over the 24-month period. Secondary-progressive MS patients had most pronounced delay in P100-like VESPA latency relative to relapsing-remitting MS and controls. There were no longitudinal P100-like VESPA response differences. These findings suggest that the VESPA method is a reproducible electrophysiological method that may have potential utility in the assessment of visual dysfunction in multiple sclerosis.

Social Disadvantage and Social Isolation Are Associated With a Higher Resting Heart Rate: Evidence From The Irish Longitudinal Study on Ageing.

OBJECTIVES: A high resting heart rate (RHR) represents a major risk factor for cardiovascular disease and individuals from poorer backgrounds have a higher RHR compared with their more advantaged peers. This study investigates the pathways through which low socioeconomic status (SES) contributes to a higher RHR. METHOD: The sample involved data for 4,888 respondents who were participating in the first wave of The Irish Longitudinal Study on Ageing. Respondents completed a detailed interview at home and underwent a 5-min baseline electrocardiograph recording as part of a clinic-based health assessment. SES was indexed using household income. RESULTS: The mean difference in RHR between those at polarized ends of the income distribution was 2.80 beats per minute (bpm) (95% CI = 1.54, 4.06; p < .001), with the magnitude of the socioeconomic differential being greater for men (4.15 bpm; 95% CI = 2.18, 6.12; p < .001) compared with women (1.57 bpm; 95% CI = 0.04, 3.10; p < .05). Psychosocial factors including social network size and loneliness accounted for a sizeable proportion of the socioeconomic differential in RHR, particularly among men. DISCUSSION: The finding that poorer people have a higher RHR reinforces the need for additional research exploring the pathways through which social inequalities are translated into biological inequalities.

Age-related normative changes in phasic orthostatic blood pressure in a large population study: findings from The Irish Longitudinal Study on Ageing (TILDA).

BACKGROUND: In this report, we provide the first normative reference data and prevalence estimates of impaired orthostatic blood pressure (BP) stabilization, initial orthostatic hypotension, and orthostatic hypotension based on beat-to-beat blood pressure methods in a population-representative sample. METHODS AND RESULTS: Participants were recruited from a nationally representative cohort study (≥50 years). Beat-to-beat systolic BP, diastolic BP, and heart rate records were analyzed among those who underwent an active stand test (n=4475). Normograms were estimated by use of generalized additive models for location, shape, and scale with Box-Cox power exponential distribution. Prevalence estimates of impaired BP stabilization, initial orthostatic hypotension, and orthostatic hypotension are reported. Orthostatic BP responses in adults aged 50 to 59 years stabilized within 30 seconds of standing, with older groups taking 30 seconds or longer. The total prevalence of impaired BP stabilization was 15.6% (95% confidence interval [CI], 14.1%-17.1%), increasing with age to 41.2% (95% CI, 30.0%-52.4%) in people ≥80 years old. Initial orthostatic hypotension occurred in 32.9% (95% CI, 31.2%-34.6%) of the population aged ≥50 years, with no age gradient evident. The prevalence of orthostatic hypotension was 6.9% (95% CI, 5.9%-7.8%) in the total population, increasing to 18.5% (95% CI, 9.0%-28.0%) in those aged ≥80 years old. CONCLUSIONS: Significant age-related differences exist in the time course of postural BP responses, with abnormal responses taking longer than 30 seconds to stabilize. Impaired BP stabilization is more common as we age, affecting more than two-fifths of the population aged ≥80 years, and may play a future role in the management of falls and syncope.

Changes in resting connectivity with age: a simultaneous electroencephalogram and functional magnetic resonance imaging investigation.

Resting fluctuations in the blood oxygenation level-dependent signal have attracted considerable interest for their sensitivity to pathological brain processes. However, these analyses are susceptible to confound by nonneural physiological factors such as vasculature, breathing, and head movement which is a concern when investigating elderly or pathological groups. Here, we used simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) (EEG/fMRI) to constrain the analysis of resting state networks (RSNs) and identify aging differences. Four of 26 RSNs showed fMRI and EEG/fMRI group differences; anterior default-mode network, left frontal-parietal network, bilateral middle frontal, and postcentral gyri. Seven RSNs showed only EEG/fMRI differences suggesting the combination of these 2 methods might be more sensitive to age-related neural changes than fMRI alone. Five RSNs showed only fMRI differences and might reflect nonneural group differences. Activity within some EEG/fMRI RSNs was better explained by neuropsychological measures (Mini Mental State Examination and Stroop) than age. These results support previous studies suggesting that age-related changes in specific RSNs are neural in origin, and show that changes in some RSNs relate better to elderly cognition than age.

Only low frequency event-related EEG activity is compromised in multiple sclerosis: insights from an independent component clustering analysis.

Cognitive impairment (CI), often examined with neuropsychological tests such as the Paced Auditory Serial Addition Test (PASAT), affects approximately 65% of multiple sclerosis (MS) patients. The P3b event-related potential (ERP), evoked when an infrequent target stimulus is presented, indexes cognitive function and is typically compared across subjects' scalp electroencephalography (EEG) data. However, the clustering of independent components (ICs) is superior to scalp-based EEG methods because it can accommodate the spatiotemporal overlap inherent in scalp EEG data. Event-related spectral perturbations (ERSPs; event-related mean power spectral changes) and inter-trial coherence (ITCs; event-related consistency of spectral phase) reveal a more comprehensive overview of EEG activity. Ninety-five subjects (56 MS patients, 39 controls) completed visual and auditory two-stimulus P3b event-related potential tasks and the PASAT. MS patients were also divided into CI and non-CI groups (n = 18 in each) based on PASAT scores. Data were recorded from 128-scalp EEG channels and 4 IC clusters in the visual, and 5 IC clusters in the auditory, modality were identified. In general, MS patients had significantly reduced ERSP theta power versus controls, and a similar pattern was observed for CI vs. non-CI MS patients. The ITC measures were also significantly different in the theta band for some clusters. The finding that MS patients had reduced P3b task-related theta power in both modalities is a reflection of compromised connectivity, likely due to demyelination, that may have disrupted early processes essential to P3b generation, such as orientating and signal detection. However, for posterior sources, MS patients had a greater decrease in alpha power, normally associated with enhanced cognitive function, which may reflect a compensatory mechanism in response to the compromised early cognitive processing.

Motion P3 demonstrates neural nature of motion ERPs.

The technical challenges of recording electroencephalographic (EEG) data during motion are considerable, but would enable the possibility of investigating neural function associated with balance, motor function and motion perception. The challenges include finding a reliable method of motion stimulus reproduction, removing artifacts, and ensuring that the recordings retain sufficient EEG signal for proper interpretation. This study details the use of the P3 waveform to validate the concept of motion-based EEG data, and discusses some potential future uses in experimental and clinical settings.