Sleep duration and disturbance are associated with orthostatic heart rate recovery: Findings from the Irish Longitudinal Study on Ageing.

OBJECTIVE: To examine a novel measurement of autonomic innervation, the early heart rate response to orthostasis, in relation to sleep duration and disturbance (actigraphy-based and self-reported) in healthy older adults. DESIGN: Cross-sectional analyses of a nationally representative prospective cohort study, the Irish Longitudinal Study on Ageing (TILDA). PARTICIPANTS: Nine hundred sixty community-dwelling adults aged 50 and over (mean age 65.6 ± 8.1; 53% women). MEASUREMENT: Orthostatic heart rate response was measured during an active stand test. Beat-to-beat heart rate was monitored over 3 minutes using noninvasive digital photoplethysmography. Mean values at each 10-second time point after standing were generated and differences from baseline at each time point were used for analysis. Actigraphy-based sleep measures were extracted from wrist-worn GENEactiv devices; self-reported sleep measures using interview questions. RESULTS: Linear mixed-effects regression analyses, with inclusion of a large number of confounders, show that self-reported sleep duration and actigraphy-based sleep duration and disturbance were associated with altered orthostatic heart rate response, particularly within the first 20 seconds poststanding. Self-reported short sleep (ß = -0.06; 95% confidence interval [CI]: -0.11, -0.01) and long sleep (ß = -0.15; 95% CI: -0.24, -0.05) and actigraphy-based short sleep (ß = -0.08; 95% CI: -0.14, -0.01) were characterized by a smaller increase at 10 seconds (p < .01). Actigraphy-based short sleep (ß = 0.15; 95% CI: 0.08, 0.22) and sleep disturbance (ß = 0.04; 95% CI: 0.02, 0.06) were associated with a slower return toward baseline at 20 seconds (p < .001). CONCLUSIONS: Our findings suggest sympathetic dysregulation, impaired vagal reactivation, and/or decreased baroreceptor sensitivity in the presence of shortened or disturbed sleep.

Association between speech rate measures and cognitive function in people with relapsing and progressive multiple sclerosis.

Background: Cognitive impairments are well-documented in multiple sclerosis (MS), while speech impairments are often overlooked despite their significant effect on quality of life. For effective clinical management of multisystem conditions such as MS, consideration should be given to the interaction between deficits in multiple domains, such as speech and cognition. To evaluate speech rate measures of spontaneous and read speech, in people with MS and to examine the link between speech and cognition. Methods: Forty-five people with MS and 25 controls underwent an extensive cognitive battery, including executive functioning, information processing and memory tasks, and completed two speech tasks: a reading task and a picture description task, from which speech rate measures were derived. Results: The progressive MS cohort had reduced articulation (p < 0.04) and speech rate (p < 0.02) compared to controls and those with relapsing MS. Regression models also revealed information processing speed accounted for 18% to 30% of the variance of spontaneous speech rate measures, and 27% of read speech. Executive functioning accounted for a further 10% of the variance of speech rate in those with MS. Conclusions: The present study suggests that speech production is contingent on cognitive ability, with information processing speed and executive functioning linked with speech timing patterns.

Hemodynamic and structural brain measures in high and low sedentary older adults.

Due to its cardiovascular effects sedentary behaviour might impact cerebrovascular function in the long term, affecting cerebrovascular regulatory mechanisms and perfusion levels. Consequently this could underly potential structural brain abnormalities associated with cognitive decline. We therefore assessed the association between sedentary behaviour and brain measures of cerebrovascular perfusion and structural abnormalities in community-dwelling older adults. Using accelerometery (GENEActiv) data from The Irish Longitudinal Study on Ageing (TILDA) we categorised individuals by low- and high-sedentary behaviour (≤8 vs >8 hours/day). We examined prefrontal haemoglobin oxygenation levels using Near-Infrared Spectroscopy during rest and after an orthostatic challenge in 718 individuals (66 ± 8 years, 52% female). Global grey matter cerebral blood flow, total grey and white matter volume, total and subfield hippocampal volumes, cortical thickness, and white matter hyperintensities were measured using arterial spin labelling, T1, and FLAIR MRI in 86 individuals (72 ± 6 years, 55% female). While no differences in prefrontal or global cerebral hemodynamics were found between groups, high-sedentary individuals showed lower hippocampal volumes and increased white matter hyperintensities compared to their low-sedentary counterparts. Since these structural cerebral abnormalities are associated with cognitive decline and Alzheimer's disease, future work exploring the causal pathways underlying these differences is needed.