Relationship between orthostatic hypotension and cognitive impairment in the elderly

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Abstract

Background and purpose

To determine the relationship between orthostatic hypotension (OH) and cognitive function in elderly subjects with memory complaints.

Methods

We studied the association between cognitive function and OH in 495 consecutive elderly outpatients attending a memory centre. Blood pressure (BP) was measured in a sitting and standing position. We examined cognitive function using a validated comprehensive battery of neuropsychological tests, the cognitive efficiency profile (CEP) assessing the main cognitive areas. Subjects were classified into 4 categories according to their cognitive status: normal cognitive function, mild cognitive impairment (MCI), Alzheimer's disease (AD) or vascular dementia (VaD).

Results

In this population, 76 ± 8 years of age (women 72%), 18% had normal cognitive function, 28% had MCI, 47% AD, and 7% VaD. Hypertension was observed in 74% of patients. OH was present in 14% of subjects (n = 69). After adjustment for age, education level, systolic BP, diastolic BP, weight, and antihypertensive drugs, subjects with OH had worse cognitive function than those without OH (CEP score 50 ± 24 vs 56 ± 22, p < 0.05). Moreover, a significant relationship was observed between OH and cognitive status (normal cognitive function, MCI, AD, or VaD). OH was present in 22% in VaD subjects, 15% in AD subjects, 12% in MCI subjects and 4% in normal control subjects (p < 0.01 for overall test).

Conclusion

Our results showed an association between OH and cognitive impairment and emphasize the need for longitudinal studies designed to evaluate the nature of the relationship between OH and cognitive decline.

Introduction

Dementia represents one of the main neurological disorders leading to loss of autonomy in the elderly. Considering this major public health issue, therapeutic and preventive strategies must be found. In the past decade several studies have implicated hypertension as a risk factor not only for vascular dementia (VaD) but also for degenerative dementia such as Alzheimer's disease (AD) [1], [2], [3]. Postural change in blood pressure (BP) increases with advancing age [4]. The prevalence of orthostatic hypotension (OH) in the elderly population ranges from 4% to 33%, depending on comorbidities and the definition of OH [5]. Arterial aging and age-related changes in the autonomic nervous system are involved in the hemodynamic response to orthostatic challenge in the elderly [6]. A decline in baroreceptor sensitivity, reduced sympathetic nervous system activation with the uncoupling of beta-adrenergic receptors to orthostatic challenge, a diminished vasomotor response to sympathetic nervous system activation, and a decline in the vestibulosympathetic reflex with aging all play a role in the onset of OH in the elderly [7]. With aging, there is a progressive reshape of cerebral autoregulation from a sigmoid curve to a straight line. This implies that any abrupt change in BP will result in a rapid and significant change in cerebral blood flow (CBF) [6]. Few studies, to date, have examined the relationship between OH and cognitive decline and their results have been contradictory [8], [9], [10]. The aim of this study was to examine the association between OH and cognitive function in elderly people.

Section snippets

Methods and study population

The study group was part of a cohort of elderly subjects with complaints of memory loss attending a geriatric memory clinic. We included 495 consecutive elderly outpatients from this cohort. Patients with major depressive states, psychiatric deficits, confusion, or types of dementia other than AD and VaD were excluded. All the subjects gave written informed consent for their participation in the study which was approved by the local ethics committee.

Statistical analysis

Results in the tables and text are expressed as mean ± standard deviation (SD) and as mean ± standard error (SE) in figures. A chi-square test was used for the group comparisons of qualitative variables and an analysis of variance (ANOVA) was performed for quantitative variables. An analysis of covariance (ANCOVA) was used to compare CEP scores between groups including confounding variables as covariates. A multivariate regression analysis was used to assess the relationship between OH and

Results

The population included 495 subjects, mean age 76 ± 8 years and 72% were female. Prevalence of OH was 14% (n = 69/495). Hypertension (SBP and/or DBP  140/90 mm Hg and/or use of antihypertensive drug) was seen in 74% of patients (n = 366/495) with mean values of SBP/DBP (143 ± 24/79 ± 13 mm Hg). Antihypertensive therapy was used by 55% of people of the overall sample (n = 272/495). Diabetes mellitus was present in 7% of the patients (n = 35/495) and hyperlipidemia in 36% (n = 178/495).

Table 1 shows the baseline

Discussion

We demonstrated a significant association between OH and cognitive function in elderly subjects. Our cross-sectional data revealed that in this cohort, subjects with OH showed poorer cognitive function. This relationship was independent of age, education level, seated SBP/DBP, weight and antihypertensive drugs. Interestingly, OH was associated not only with VaD but also of AD.

The prevalence of OH that we showed in this cohort is in agreement with other studies performed in an elderly ambulatory

Acknowledgments

The authors are grateful to the patients and their relatives for cooperating in this research study.

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      Symptomatic OH has a substantial impact on quality of life due to lightheadedness, blurred vision, leg buckling, and syncope that may predispose patients to falls and resultant physical trauma. Additionally, OH is associated with adverse clinical outcomes, such as increased mortality in middle-aged adults, and higher rates of myocardial infarction, heart failure, atrial fibrillation, cerebrovascular events, and cognitive decline in the elderly (Verwoert et al., 2008; Rose et al., 2006; Ricci et al., 2015b; Mehrabian et al., 2010). The short- and long-term health complications associated with OH make it a common cause of hospitalization, especially among elderly patients, incurring a significant economic burden on the health care system (Shibao et al., 2007).

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