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.

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.

A concept for extending the applicability of constraint-induced movement therapy through motor cortex activity feedback using a neural prosthesis.

This paper describes a concept for the extension of constraint-induced movement therapy (CIMT) through the use of feedback of primary motor cortex activity. CIMT requires residual movement to act as a source of feedback to the patient, thus preventing its application to those with no perceptible movement. It is proposed in this paper that it is possible to provide feedback of the motor cortex effort to the patient by measurement with near infrared spectroscopy (NIRS). Significant changes in such effort may be used to drive rehabilitative robotic actuators, for example. This may provide a possible avenue for extending CIMT to patients hitherto excluded as a result of severity of condition. In support of such a paradigm, this paper details the current status of CIMT and related attempts to extend rehabilitation therapy through the application of technology. An introduction to the relevant haemodynamics is given including a description of the basic technology behind a suitable NIRS system. An illustration of the proposed therapy is described using a simple NIRS system driving a robotic arm during simple upper-limb unilateral isometric contraction exercises with healthy subjects.