July 27, 2011

The Parkinson's Connection to Cognitive Impairment and Dementia

This subject -- cognitive impairment and dementia -- scares me the most, particularly if my Parkinson's increases the likelihood I'll encounter these conditions later. (Sometimes -- please tell me why I just walked up the stairs to the second floor -- I think the future is now.)

I was interested in an article in the summer 2011 supplement to Johns Hopkins Medicine's ongoing report on Memory Disorders. It's written by Jason Brandt, director of John Hopkins division of medical psychology.

This opening comment grabbed my attention: "Although Parkinson's disease is a neurological disorder affecting movement, it is also associated with a sometimes disabling, often overlooked psychological condition known as cognitive impairment. This impairment can affect your memory and attention span as well as your ability to plan and organize. Many patients already have some degree of cognitive impairment when first diagnosed. As the disease advances, the ability to recognize people and objects and communicate with others becomes increasingly difficult, especially in the later stages."

An unwelcome wrap-up followed: "Some experts believe that nearly all patients will ultimately develop some degree of cognitive impairment."

Here's more:

Dr. Brandt adds that while many Parkinson's Disease patients complain of cognitive problems, not all will develop dementia.

What's My Risk?
Brandt clarifies that 30 to 40% of people with Parkinson's will develop cognitive impairments severe enough to interfere with their daily functioning. And when he talks about impairment, it's in the context of the virtual universality of mental slowing that accompanies aging. OK, then. Some friends and family members might say a bit more mental slowness might be just the ticket for this hyperactive, shoot-from-the-hip guy.

Brandt offer this analogy: It's like "a ten-year-old desktop computer that still works but has a very slow central processor."


Dopamine and Levodopa Don't Impact Mental Functioning  
The depletion of dopamine in the brain is responsible for the motor problems characteristic of Parkinson's. But the primary medication used to treat this condition -- levodopa -- doesn't help with the cognitive problems associated with Parkinson's. The decline in mental functioning appears to be unrelated to the depletion of dopamine.

Dr. Brandt indicates that other symptoms of Parkinson's are also "dopamine-unresponsive." This list includes the severe depression, gait disorders, falling and posture problems.

What Specific Mental Functions Are Impacted
Cognitive problems associated with Parkinson's are marked by slowness of thought, forgetfulness, impaired decision-making and reasoning, and reduced multi-tasking ability. People with Parkinson's often become overwhelmed by too many tasks. And they may lose control or erupt in anger when frustrated.

People with Parkinson's have impaired processing speed (that ten-year-old computer again), which makes it difficult for them to score well on attention and memory tests, during which they're bombarded with information.

Early Signs
Probably the earliest signs of impairment are problems with multi-tasking and changes in judgement, reasoning, and problem solving. These changes in executive function are very common and often provide the first clue that someone with Parkinson's is starting to experience some cognitive decline.

Can PD-Related Dementia and Cognitive Impairment Be Treated?
So far, no therapies exist to modify the progress of dementia. Maintaining a regular, structured routine can help.

Anti-psychotic drugs are commonly prescribed to treat disruptive behavior associated with Parkinson's and dementia. But they can be tricky.

Results from a number of other studies suggest that exercise might retard the progress of dementia.

Bottom Line: After a closer look, this report isn't as depressing as I'd first thought.

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