Postural Control in the Elderly
Postural Control in the Elderly
This study will examine loss of balance in the elderly. Falls due to balance problems are a
 major health issue in older people, often resulting in bone fractures and other bodily
 injuries, and functional decline. In addition, the fear of falling leads some elderly people
 to restrict their movements and social activities, causing depressed moods and decreased
 enjoyment of life. Risk factors for falling in the elderly include some standing positions in
 which older people usually experience balance problems, such as leaning forward or backward.
 This study will examine these unstable positions and the brain mechanisms associated with
 loss of balance in the elderly.

 Normal volunteers between 20 and 90 years of age may be eligible for this study. Candidates
 must be in good health, with no difficulties in performing activities of daily living, and
 must be able to walk for at least 400 meters (1/4 mile). They will be screened with a medical
 history, physical examination, and blood tests.

 Participants will undergo the following three experiments:

 -  Movement task: The subject stands on a platform with markers placed at different parts
 of the body to record body movements. A cap with electrodes (metal disks) is placed on
 the head for electrocardiographic (EEG) recording of the electrical activity of the
 brain (brain waves) during the experiment. The positions of the feet on the platform are
 measured. While standing on the platform, the subject leans forward and backward as far
 as possible without losing balance. (Subjects are secured in a safety harness to prevent
 actual falls.) The task is repeated 5 times. The experiment lasts up to 2 hours.

 -  Postural response task: This study is identical to the first, except that the subject
 does not voluntarily lean forward and backward, but is pushed with a device to cause
 forward and backward movements. The experiment lasts 1 to 2 hours.

 -  Perceptual task: The subject sits in front of a computer screen and watches the postural
 movements of a human body model in forward and backward directions. When the subject
 recognizes an unstable position in the movements, he or she presses a computer mouse. An
 EEG records brain activity during the task, which lasts up to 2 hours.
A number of studies have explored the role of visual, vestibular and somatosensory systems in
 the control of upright posture. However, the cortical control of postural stability, in
 general, and the role of higher cognitive function in assessment of postural stability, in
 specific, has been less studied. It is well established that certain features of postural
 control change during the advancing years of life so that the stability of posture can be a
 problem in the elderly. However, neural mechanisms of postural stability that decline with
 age and make older adults more prone to falling have not been identified specifically. To
 characterize specific causes of falling in the elderly in problematic, because human posture
 is a product of an extremely complex dynamical system and like any other physical activity
 undergoes dramatic changes in organization throughout the life-span. In our previous research
 we showed the existence of specialized neural detectors that are embodied in spatiotemporal
 patterns of brain activiation (Slobounov et al., 200) capable of discrimination the unstable
 postures in dynamic situations. We propose that these neural detectors may deteriorate with
 aging, which result in difficulty to (a) initiate compensatory postural adjustments when
 balance is in danger, and (b) to discriminate relevant from irrelevant information in control
 of upright posture. This can be documented via changes in behavioral correlates of postural
 control and spatiotemporal patterns of the brain activation as a function of advanced age.
 Accordingly, the purpose of this study is to investigate the age-related cortical control of
 postural stability combining electroencephalography and postural control measures. This will
 be done when a subject physically approaches the postural stability boundary and when a
 subject solves a cognitive task identifying unstable postures in dynamic situations.
INCLUSION CRITERIA:

 Subjects will be enrolled in this balance study if they are within the range of 20-90 years
 old;

 in good health;

 report no difficulties or need for help in performing self-care or instrumental activities
 of daily living;

 and are able to walk for at least 400 meters.

 EXCLUSION CRITERIA:

 We will be unable to study people who have substantial congitive impairment based on mental
 status screening tests;

 history of cardiovascular disease (including angina, myocardial infarction, congestive
 heart failure, cerebro-vascular disease);

 cancer;

 neurological diseases;

 birth defects;

 kidney or liver disease;

 gastrointestinal (G.I.) disease;

 musculo-skeletal disorder (if they cause pathological weakness and/or chronic pain);

 important sensory deficits and any conditions that precludes them from being tested with
 standard neurophyschological tests.

 Pregnant women will be excluded from this study.

 In addition, the following criteria are considered as markers of pathological conditions
 and are used as exclusion criteria for study enrollment:

 1. HIV virus infection;

 2. WBC greater than 12,000 ML;

 3. Platelets less than 100,000 or greater than 600,000/ML;

 4. Hemoglobin less than 11 gr/dl unless higher level can be ascribed to Gilbert's
 disease;

 5. Abnormal level of SGOT and SGPT and alkaline phosphetase twice the norm serum
 concentration;

 6. Corrected calcium less than 8.5 or 10.7 mg/dl;

 7. Albumin less than 3.4 g/dl;

 8. Shortness of breath while performing normal activities of daily living, such as
 walking or climbing stairs;

 9. evidence or history of cancer;

 10. absolute need for long term treatment with antibiotics, corticosteroids,
 immunosuppressors, H2 blockers and pain medications;

 11. any severe psychiatric condition such as subjects with Axis I psychiatric diagnosis;

 12. any condition that may preclude informed consent.