Definition and Overview
Aging is a physiological process that causes structural and functional changes in the autonomic nervous system. As age increases, changes occur in both the sympathetic nervous system and the parasympathetic nervous system, but the direction and speed are different.
Major autonomic changes due to aging include decreased heart rate variability (HRV), decreased baroreflex sensitivity, increased frequency of orthostatic hypotension, impaired thermoregulation, and abnormal bladder function.
These autonomic aging changes are an important clinical problem in geriatric medicine as they are associated with increased risk of cardiovascular disease, falls, decline in cognitive function, and poor quality of life.
Cause/Pathophysiology
The mechanisms of autonomic nervous system changes due to aging are multilayered.
Neuroanatomical changes include decreased autonomic ganglion neurons, decreased myelination and nerve conduction velocity, and altered function of central autonomic control structures (hypothalamus, brainstem NTS, medulla, etc.).
Receptor and signal transduction changes include decreased cardiac beta-adrenergic receptor responsiveness. This reduces maximum heart rate and the ability to increase cardiac output.
The effects of underlying diseases include diseases common in the elderly, such as high blood pressure, diabetes, Parkinson's disease, and amyloidosis, which cause additional damage to the autonomic nervous system.
A paradoxical increase in sympathetic nerve activity is also a characteristic of aging. Resting blood norepinephrine concentrations increase in the elderly, which is associated with hypersympathetic response and increased cardiovascular risk.
symptoms
The prevalence of orthostatic hypotension in people over 65 years of age is approximately 20%. It is defined as a decrease in systolic blood pressure of 20 mmHg or more or diastolic blood pressure of 10 mmHg or more within 3 minutes of standing, and causes dizziness, fainting, falls, and blurred vision.
Postprandial hypotension is also common in the elderly and is characterized by a decrease in blood pressure due to increased intestinal blood flow after a meal.
Decreased heart rate variability reflects decreased cardiovascular reserve and reduced cardiovascular response to acute stress.
Heat regulation disorders include reduced sweating and decreased skin vasodilation response, making people vulnerable to heat.
Abnormal bladder function increases frequent urination, nocturia, and urge incontinence.
diagnosis
Assessment of autonomic function in the elderly is done through the autonomic function test (AFT) battery.
The tilt table test evaluates orthostatic hypotension and syncope. Heart rate variability test (HRV analysis) is a non-invasive test using electrocardiogram, which evaluates parasympathetic function through time domain and frequency domain analysis.
It includes the Valsalva maneuver, cold blood pressure response, and sweat secretion tests (QSART, TST). 24-hour ambulatory blood pressure monitoring (ABPM) is used to evaluate blood pressure variability between day and night.
Treatment and Management
The key to managing autonomic function in the elderly is as follows.
Regular aerobic exercise is effective as a non-pharmacological treatment. Exercise helps increase HRV, improve baroreceptor reflex sensitivity, and improve symptoms of orthostatic hypotension. Drinking enough water (preventing orthostatic hypotension), managing your posture before and after meals, and wearing compression stockings are also helpful.
Polypharmacy review is important to review and adjust medications that may cause orthostatic hypotension, fever side effects, and heart rate dysregulation (alpha blockers, diuretics, anticholinergics, tricyclic antidepressants, etc.).
As drug treatment, fludrocortisone, midodrine, etc. can be used for orthostatic hypotension, but in the elderly, caution is required regarding side effects and should be used under a specialist's prescription.
prognosis
Deterioration of autonomic function due to aging is a physiological process, but its rate varies greatly depending on lifestyle habits, underlying diseases, and genetic factors. There is evidence that the rate of decline in autonomic function can be slowed through regular exercise, a healthy diet, and risk factor management.
The main goal of geriatric medicine is to reduce clinical complications (falls, fractures, syncope) related to autonomic function in the elderly through management of orthostatic hypotension, prevention of falls, and elimination of polypharmacy.
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This information is provided for medical educational purposes and is not a substitute for individual medical care or treatment. If you have any symptoms, be sure to seek professional advice. Inquiries: Osang Neurosurgery 1599-5453 | osns.co.kr