Does Parkinson's Cause Dementia and Alzheimer's

Cognitive impairment, Dementia, and Alzheimer’s.  In 1817, when James Parkinson first described the “shaking palsy” he said that, “the senses and intellect were uninjured.” While he was correct in many of his assertions, Dr. Parkinson missed the mark with this one. Statistics show that throughout the course of the disease 90% of people with PD will experience some form of very mild to acute cognitive change beyond what is normal for their age. Up to 50% will suffer from mild cognitive impairment and 40% will suffer from dementia but not all people with PD will experience them. Mild cognitive impairment does not affect one's ability to carry out activities of daily living whereas dementia refers to a person that has multiple cognitive problems that significantly impact activities of daily life and has trouble retrieving memories. Alzheimer's is the inability to encode new memories. PD researchers now believe that mild cognitive changes may be present even before diagnosis. Dementia usually develops many years after the initial onset of PD and is more common with advanced disease. Many people with PD fear cognitive impairment, dementia, and Alzheimer's more than the physical symptoms of the disease because they are seen as the end of meaningful life, loss of independence, and loss of self.

What is cognition? Cognition is a general term that refers to the mental abilities we use to process information and apply knowledge. These mental processes allow us to perform daily functions such as paying attention, solving problems, communicating, remembering, and how to perform certain tasks. When people talk about cognition, they often focus on memory but memory is only one aspect of cognition. Rather, the study of cognition recognizes "cognitive domains" which reflect different types of cognitive processes. Parkinson’s typically affects three main cognitive areas: Executive functioning which includes concentration and attention, multitasking, reasoning, problem solving, and complex planning; Language which includes difficulty finding the right word or feeling tongue-tied; Memory which involves trouble retrieving memories that have already been encoded. And then there is bradyphrenia, meaning slow brain, a cognitive impairment common to Parkinson’s. Slowing of the brains processing speed is especially noticeable when switching from one task to another. So be patient with people with PD, we may need a little extra time.

The causes of cognitive impairment in PD are not fully understood but are believed to be related to the same causes of PD motor symptoms namely the death of nerve cells which result in changes in brain chemistry. Psychological problems like depression and anxiety and some medications can also affect cognition.

Can cognitive impairment be prevented? Regular physical exercise, whether aerobic, resistance or balance activity is believed to reduce the risk of dementia, including Alzheimer’s, by as much as 50%. A review of academic studies by researchers at the University of Edinburgh states that more than three quarters of cognitive decline is accounted for by lifestyle and other environmental factors including level of education. The review also states that physical exercise is the most effective way to ward off cognitive decline in healthy older people and reduce the risk of dementia and Alzheimer’s. Exercise may turn out to be the best medicine available for PD.

How does exercise protect against dementia? The brain’s hippocampus and prefrontal cortex play critical roles in memory formation and complex thinking and are responsive to physical exercise. Their deterioration is a predictor for Alzheimer’s disease. Higher fitness levels correlate with an increase in size of the hippocampus and the prefrontal cortex. This means that exercise can help our brains continue to grow and head off cognitive decline.

The golden rules for reducing the risk of cognitive decline, dementia and Alzheimer’s:

1 Exercise regularly.

2 Maintain an active mind. 

3 Eat healthy and maintain a healthy weight.

4 Don't drink too much alcohol.

5 Don’t smoke.

6 Maintain a healthy blood pressure.

7 Be socially active. (I find that I am the sharpest and least aware of my PD when I am socially engaged with other people.)

The things that make our brain healthy are also good for the heart and overall health as well as the brain. It is, forgive me, a no brainer so just do them if you are  concerned about your health.

Can you tell if you are cognitively impaired? Sometimes. You can be painfully aware or not have clue and there’s the rub. You may not have enough awareness left to be able to know. Your partner, care giver, or friends may be more aware than you are so doctors often include information from a spouse or care giver in making a determination. The real question is do you have a cognitive problem that affects your daily life. You can be evaluated by a doctor and there are several tests available online. The Montreal Cognitive Assessment (MoCA) was created to identify people with mild cognitive impairment from normal elderly adults. It looks at the following cognitive domains: attention and concentration, executive functions, memory, language, visuoconstructional skills, conceptual thinking, calculations, and orientation. It takes five minutes and can be found online.