Cognitive function in peripheral autonomic disorders

Postprandial Hypotension and Impaired Postprandial Sustained and Selective Attention in Older Inpatients: Is There a Link?

OBJECTIVES

The study aimed to investigate the prevalence of postprandial hypotension (PPH) in older inpatients, to verify the overall postprandial behavior of blood pressure and attentional performances, and to explore the overall associations between blood pressure (including PPH) and attentional performances. Eventually, we aimed to investigate differences on PPH, blood pressure values and attentional performances based on the subjects' frailty status.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

A sample of older inpatients at the Geriatric Unit of the University Hospital of Messina (Italy).

METHODS

Basal, preprandial, and postprandial blood pressures (75 minutes after the meal) were measured for each patient; PPH was detected according to its empirical definition. Global cognitive functioning, and sustained and selective attention were assessed; a 46-item Frailty Index was calculated.

RESULTS

The sample consisted of 112 inpatients (54 females), with a mean age of 80.9 years. The prevalence of PPH was 30.4%; in the postprandial window, a reduction in blood pressure between 10 and 20 mm Hg and a reduction of >20 mm Hg were reported by 27.1% and 29.9% of inpatients, respectively. In the postprandial evaluation, sustained and selective attention markedly decreased. No significant associations were found between PPH occurrence and the postprandial dip of attentional performances, and no significant cognitive differences were found between inpatients with and without PPH. On the other hand, reduced postprandial attentional performances were associated especially with preprandial lower systolic and diastolic blood pressure values. Ultimately, no significant differences in PPH occurrence were found between frail and nonfrail inpatients; frail inpatients significantly exhibited also an overall lower cognitive functioning.

CONCLUSIONS AND IMPLICATIONS

In our sample, PPH and impaired postprandial attentional performances were not associated, even though this association deserves further investigation. In hospitalized older adults, the accurate management of blood pressure levels appears relevant, because we evidenced that low blood pressure (especially preprandial) was associated with poor attentional functioning. Although the plausible occurrence of several interfering and confounder factors was observed in an acute care setting, we consider that the screening of attentional functioning among hospitalized older patients could be helpful.

Diagnosis and treatment of orthostatic hypotension

Orthostatic hypotension is an unusually large decrease in blood pressure on standing that increases the risk of adverse outcomes even when asymptomatic. Improvements in haemodynamic profiling with continuous blood pressure measurements have uncovered four major subtypes: initial orthostatic hypotension, delayed blood pressure recovery, classic orthostatic hypotension, and delayed orthostatic hypotension. Clinical presentations are varied and range from cognitive slowing with hypotensive unawareness or unexplained falls to classic presyncope and syncope. Establishing whether symptoms are due to orthostatic hypotension requires careful history taking, a thorough physical examination, and supine and upright blood pressure measurements. Management and prognosis vary according to the underlying cause, with the main distinction being whether orthostatic hypotension is neurogenic or non-neurogenic. Neurogenic orthostatic hypotension might be the earliest clinical manifestation of Parkinson's disease or related synucleinopathies, and often coincides with supine hypertension. The emerging variety of clinical presentations advocates a stepwise, individualised, and primarily non-pharmacological approach to the management of orthostatic hypotension. Such an approach could include the cessation of blood pressure lowering drugs, adoption of lifestyle measures (eg, counterpressure manoeuvres), and treatment with pharmacological agents in selected cases.

Cognitive profile in idiopathic autonomic failure: relation with white matter hyperintensities and neurofilament levels

OBJECTIVE

To disclose the nature of cognitive deficits in a cohort of patients with idiopathic autonomic failure (IAF) by exploring the relation among cognitive functions, cardiovascular autonomic failure (AF) and clinical progression to another α-synucleinopathy (phenoconversion).

METHODS

We retrospectively identified all patients with a clinical diagnosis of IAF who underwent a comprehensive neuropsychological evaluation, clinical examination and cardiovascular autonomic tests from the IAF-BO cohort. Brain magnetic resonance imaging (MRI) studies and cerebrospinal fluid (CSF) analysis, including neurofilament light chain (NfL), Alzheimer disease core biomarkers, and α-synuclein seeding activity were further evaluated when available. Correlations among cognitive functions, clinical features, cardiovascular AF, cerebral white matter hyperintensities (WMH) load, and CSF biomarkers were estimated using Spearman correlation coefficient.

RESULTS

Thirteen out of 30 (43%) patients with IAF displayed cognitive deficits (CI) mainly concerning executive functioning. Seven out of 30 (23%) met the criteria for mild cognitive impairment (MCI). The diagnosis of CI and MCI was not associated with phenoconversion or autonomic function parameters, including duration and severity of neurogenic orthostatic hypotension, presence and severity of supine hypertension, and nocturnal dipper profile. Twenty patients underwent a brain MRI and CSF analysis. MCI was related to WMH load (r = 0.549) and NfL levels (r = 0.656), while autonomic function parameters were not associated with either WMH or NfL levels.

INTERPRETATION

Cardiovascular AF and phenoconversion, underlying the spreading of neurodegeneration to the central nervous system, were not independent drivers of cognitive dysfunction in IAF. We identified WMH load and NfL levels as potential biomarkers of the neural network disruption associated with cognitive impairment in patients with IAF.

Neurogenic Orthostatic Hypotension: State of the Art and Therapeutic Strategies

Neurogenic orthostatic hypotension (nOH) is a subtype of orthostatic hypotension in which patients have impaired regulation of standing blood pressure due to autonomic dysfunction. Several primary and secondary causes of this disease exist. Patients may present with an array of symptoms making diagnosis difficult. This review article addresses the epidemiology, pathophysiology, causes, clinical features, and management of nOH. We highlight various pharmacological and non-pharmacological approaches to treatment, and review the recent guidelines and our approach to nOH.

Neurogenic orthostatic hypotension impairs information processing speed and attention

Neurogenic orthostatic hypotension (NOH) is characterized by a drop in systolic blood pressure (SBP) ≥20 mmHg or diastolic blood pressure (DBP) ≥10 mmHg within three minutes of upright posture. NOH is common in the elderly population. This group of individuals is at an increased risk for deficits in multiple cognitive domains such as information processing speed (IPS) and attention. The objective of the current study was to investigate the change in IPS and attention during head-up tilt (HUT) in patients with NOH compared to controls. Cognitive function was assessed in the supine and HUT positions using the symbol digit modalities test (SDMT) which assesses IPS and the Stroop Test which measures attention. 40 participants completed the study, 20 controls (age 64.50 ± 9.25) and 20 NOH patients (age 69.55 ± 7.43) with associated conditions of Parkinson's disease (n = 11), multiple systems atrophy (n = 3), early Lewy body dementia (n = 1) and idiopathic NOH (n = 5). NOH patients had no difference in IPS between supine (43.20 ± 15.26) and HUT (42.90 ± 14.33; p = .77). Controls had significantly faster IPS in the HUT position (69.90 ± 12.02) compared to supine (63.55 ± 9.96; p < .001). NOH patients had significantly slower IPS in both the supine and HUT position compared to controls (p < .001). Attention in the HUT position was significantly worse in NOH patients (-14.86 ± 8.96) compared to controls (-8.68 ± 7.13; p = .029). During HUT, NOH patients experienced a significant decrease in mean SBP by -64.11 ± 18.96 from baseline, whereas controls only had a mean decrease of -5.69 ± 7.65. It is evident that NOH patients have impaired IPS and attention compared to controls and likely plays an important role in the morbidity of these individuals.

The Trail Making test: a study of its ability to predict falls in the acute neurological in-patient population

Objective:

To determine whether tests of cognitive function and patient-reported outcome measures of motor function can be used to create a machine learning-based predictive tool for falls.

Design:

Prospective cohort study.

Setting:

Tertiary neurological and neurosurgical center.

Subjects:

In all, 337 in-patients receiving neurosurgical, neurological, or neurorehabilitation-based care.

Main Measures:

Binary (Y/N) for falling during the in-patient episode, the Trail Making Test (a measure of attention and executive function) and the Walk-12 (a patient-reported measure of physical function).

Results:

The principal outcome was a fall during the in-patient stay ( n = 54). The Trail test was identified as the best predictor of falls. Moreover, addition of other variables, did not improve the prediction (Wilcoxon signed-rank P < 0.001). Classical linear statistical modeling methods were then compared with more recent machine learning based strategies, for example, random forests, neural networks, support vector machines. The random forest was the best modeling strategy when utilizing just the Trail Making Test data (Wilcoxon signed-rank P < 0.001) with 68% (± 7.7) sensitivity, and 90% (± 2.3) specificity.

Conclusion:

This study identifies a simple yet powerful machine learning (Random Forest) based predictive model for an in-patient neurological population, utilizing a single neuropsychological test of cognitive function, the Trail Making test.

Orthostatic hypotension associated with executive dysfunction in mild cognitive impairment

INTRODUCTION

Midlife hypertension is associated with dementia in longitudinal studies while chronic hypotension in the elderly is associated with dementia onset. Orthostatic hypotension could influence cognitive performance in the elderly. The objective of this study was to assess the relationship between orthostatic hypotension and cognitive functions.

METHODS

Consecutive participants with complete neuropsychological evaluation from a Memory Clinic were included. Orthostatic hypotension (OH) was defined by a fall≥20/10mmHg systolic/diastolic pressure. Participants were classified into one of 3 groups: 1) subjective cognitive impairment (SCI), 2) mild cognitive impairment (MCI), and 3) dementia. Neuropsychological tests were analyzed for patients with and without OH.

RESULTS

One hundred and twenty participants were included, of which 16 (13%) were classified as SCI, 42 (35%) as MCI, and 63 (52%) with dementia. Prevalence of OH was 0% for the SCI group, 26% (n=11) for the MCI group, and 38% (n=24) for the dementia group. Age, sex, education, and brief cognitive test scores (MMSE & MoCA) were not different between groups with or without OH. In the MCI group, OH was associated with lower cognitive performance in several executive functions tests: visual working memory (p<0.001), processing speed (p=0.006), Stroop flexibility (p=0.030) and Trail-Making Test part B (p=0.024). There was no difference in episodic memory performance. OH was associated with a diagnosis of hypertension and the use of antihypertensive medication. No differences were observed in vascular brain injury between groups with and without OH.

CONCLUSIONS

This study found that orthostatic hypotension prevalence is correlated to severity of cognitive deficits in a Memory Clinic. In MCI, OH is associated with lower performance in executive functions. OH could represent an under-recognized correlate of cognitive performance.

The recommendations of a consensus panel for the screening, diagnosis, and treatment of neurogenic orthostatic hypotension and associated supine hypertension

Neurogenic orthostatic hypotension (nOH) is common in patients with neurodegenerative disorders such as Parkinson’s disease, multiple system atrophy, pure autonomic failure, dementia with Lewy bodies, and peripheral neuropathies including amyloid or diabetic neuropathy. Due to the frequency of nOH in the aging population, clinicians need to be well informed about its diagnosis and management. To date, studies of nOH have used different outcome measures and various methods of diagnosis, thereby preventing the generation of evidence-based guidelines to direct clinicians towards ‘best practices’ when treating patients with nOH and associated supine hypertension. To address these issues, the American Autonomic Society and the National Parkinson Foundation initiated a project to develop a statement of recommendations beginning with a consensus panel meeting in Boston on November 7, 2015, with continued communications and contributions to the recommendations through October of 2016. This paper summarizes the panel members’ discussions held during the initial meeting along with continued deliberations among the panel members and provides essential recommendations based upon best available evidence as well as expert opinion for the (1) screening, (2) diagnosis, (3) treatment of nOH, and (4) diagnosis and treatment of associated supine hypertension.

Diabetes and Cognitive Impairment

Both type 1 (T1DM) and type 2 diabetes mellitus (T2DM) have been associated with reduced performance on multiple domains of cognitive function and with evidence of abnormal structural and functional brain magnetic resonance imaging (MRI). Cognitive deficits may occur at the very earliest stages of diabetes and are further exacerbated by the metabolic syndrome. The duration of diabetes and glycemic control may have an impact on the type and severity of cognitive impairment, but as yet we cannot predict who is at greatest risk of developing cognitive impairment. The pathophysiology of cognitive impairment is multifactorial, although dysfunction in each interconnecting pathway ultimately leads to discordance in metabolic signaling. The pathophysiology includes defects in insulin signaling, autonomic function, neuroinflammatory pathways, mitochondrial (Mt) metabolism, the sirtuin-peroxisome proliferator-activated receptor-gamma co-activator 1α (SIRT-PGC-1α) axis, and Tau signaling. Several promising therapies have been identified in pre-clinical studies, but remain to be validated in clinical trials.

Orthostatic Changes in Blood Pressure and Cognitive Status in the Elderly

We studied a cohort of 1408 older subjects to explore whether postural changes in blood pressure (BP; defined as orthostatic hypo- or hypertension) can predict the onset of cognitive deterioration. Orthostatic hypotension was defined as a drop of 20 mm Hg in systolic or 10 mm Hg in diastolic BP and orthostatic hypertension as a rise of 20 mm Hg in systolic BP. Orthostatic BP values were grouped into quintiles for secondary analyses. Two cognitive assessments were considered: (1) cognitive impairment, that is, Mini-Mental State Examination scores ≤24/30, and (2) cognitive decline (CD), that is, a 3-point decrease in Mini-Mental State Examination score from the baseline to the follow-up. At the baseline, the prevalence of orthostatic hypotension and hypertension was 18.3% and 10.9%, respectively. At the follow-up (4.4±1.2 years), 286 participants were found cognitively impaired and 138 had a CD. Using logistic regression analysis adjusted for potential baseline confounders, participants with orthostatic hypertension were at significantly higher risk of CD (odds ratio =1.50; 95% confidence intervals =1.26–1.78). Neither orthostatic hypotension nor orthostatic hypertension raised the risk of developing a cognitive impairment. Using quintiles of orthostatic BP values, we found that both decreases and increases in systolic and diastolic BP raised the risk of CD, but not of cognitive impairment. In conclusion, we found that orthostatic hypertension predicts the onset of CD, but not of cognitive impairment in the elderly, whereas orthostatic hypotension predicts neither of these conditions. Further studies are needed to confirm our findings.

Potential Interactions between the Autonomic Nervous System and Higher Level Functions in Neurological and Neuropsychiatric Conditions

The autonomic nervous system (ANS) maintains the internal homeostasis by continuously interacting with other brain structures. Its failure is commonly observed in many neurological and neuropsychiatric disorders, including neurodegenerative and vascular brain diseases, spinal cord injury, and peripheral neuropathies. Despite the different underlying pathophysiological mechanisms, ANS failure associates with various forms of higher level dysfunctions, and may also negatively impact on patients’ clinical outcome. In this review, we will discuss potential relationships between ANS and higher level dysfunctions in a selection of neurological and neuropsychiatric disorders. In particular, we will focus on the effect of a documented fall in blood pressure fulfilling the criteria for orthostatic hypotension and/or autonomic-reflex impairment on cognitive performances. Some evidence supports the hypothesis that cardiovascular autonomic failure may play a negative prognostic role in most neurological disorders. Despite a clear causal relationship between ANS involvement and higher level dysfunctions that is still controversial, this might have implications for neuro-rehabilitation strategies aimed at improving patients’ clinical outcome.