By Brandon Pollock PhD, ACSM-EP-C
Parkinson’s disease (PD) is frequently accompanied by declines in cognitive function, such as memory loss, impaired thinking, and decreased intellect. The underlying cause of cognitive dysfunction in PD is unclear, and because of the complexity of the disease, cognitive declines could be caused by many things. The spread of Lewy bodies (abnormal proteins that develop inside nerve cells) to the brain is one well-supported theory believed to result in cognitive dysfunction in PD. However, more recent observations contrast this hypothesis and suggest that impairments in cognitive function in PD may actually result from reduced cerebral blood flow.
When a healthy individual stands up, gravity causes blood to pool in their legs. Because there is now less blood circulating back to their heart, this, in turn, decreases their blood pressure. Normally, special cells known as baroreceptors located near the heart and neck vessels sense this drop in blood pressure and signal the heart to beat faster and pump more blood, which stabilizes blood pressure.
Parkinson’s disease and orthostatic hypotension
These cells also cause blood vessels to narrow, which increases resistance to blood flow and increases blood pressure. As a result of interruptions in the body's natural process of counteracting low blood pressure, orthostatic hypotension (an abnormal decrease in blood pressure that occurs upon standing) is highly prevalent in PD. The primary symptom of orthostatic hypotension is feeling lightheaded or dizzy when you stand up after sitting or lying down.
Research has begun to explore a possible association between orthostatic hypotension and cognitive dysfunction in Parkinson’s disease patients. Investigations have reported altered cerebral blood flow responses in PD, suggesting that cerebral autoregulation is impaired. Other investigations have also indicated degeneration of cerebral vessels in Parkinson’s disease, supporting a possible role for reduced blood flow in the neuronal degeneration process of Parkinson’s disease.
What could this mean?
So what could this mean? Well, if cognitive dysfunction in PD is caused by orthostatic hypotension or reduced cerebral blood flow, this would emphasize the need for PD individuals to perform the regular physical activity. Cardiovascular exercise increases plasma volume and is usually associated with improved orthostatic tolerance. Exercise also activates something known as the muscle pump, which helps squeeze pooled blood out of the lower extremities and up towards the head. If cognitive dysfunction in PD is a result of impaired cerebral blood flow, it is possible that exercise activities which alleviate orthostatic hypotension may also improve cognitive function in PD.
Currently, there are no specifically designed therapies for treating orthostatic hypotension in Parkinson’s disease, only strategies which may be helpful for increasing venous return are:
- Wearing peripheral stockings and abdominal bandages.
- Performing basic physical counter-maneuvers such as leg crossing, squatting, bending forward, and tiptoeing.
- Drinking plenty of water.
- Proper diet and salt intake.
Exercise may improve symptoms
Cognitive dysfunction and orthostatic hypotension are two of the most common symptoms of PD. Symptoms of PD vary widely from individual to individual, however, if you are diagnosed with PD and frequently experience symptoms of cognitive dysfunction, it is possible that exercise may help improve your symptoms simply by increasing blood to your head!
Regular physical activity can also help improve your balance and coordination and enhance your overall quality of life. The association between cognitive dysfunction and orthostatic hypotension is currently a hot topic of research in PD. Together these results indicate a possible association between orthostatic hypotension and cognitive dysfunction in PD and highlight the need for further research exploring the topic.
* Always consult your doctor before beginning any exercise program.
**For examples of other variations/exercises look under Multimedia-VDF Exercise Tip
***Listen to our podcast show discussing living with Parkinson's Disease
Living with Parkinson's Disease
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Article’s Resource
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Yang, D. Pavlovic, H. Waldvogel, M. Dragunow, B. Synek, C. Turner, R. Faull, and J. Guan, ‘String Vessel Formation Is Increased in the Brain of Parkinson Disease', J Parkinsons Dis (2015).