Robin Williams' Parkinson's Diagnosis May Have Led to Dementia

Patient Expert

We all were aghast and saddened by the news about Robin Williams' death. While the speculation about the reasons behind his fatal decision continued during the week, the announcement by his wife that he was in the early stages of Parkinson's disease helped provide some clarity.

Approximately 1 million Americans have been diagnosed with Parkinson's disease. This number include boxer Muhammad Ali, actor Michael J. Fox, former attorney general Janet Reno, journalist Michael Kinsley and former NBA star Brian Grant. The condition is caused when certain neurons in the brain malfunction and then die. This situation leads the brain to stop producing dopamine which regulates movement. While symptoms may vary, the most common symptom of this disease is depression, which has been found in about 60 percent of the people who are diagnosed. Other common symptoms include tremors and vocal spasms.

So why am I talking about Parkinson's disease on this particular site? It turns out that between 50-80 percent of people with this disease may develop dementia. While some people who have Parkinson's disease may develop Alzheimer's disease, they also may develop a different form of dementia, which is known as Parkinson's disease dementia. This type of dementia affects the brain through abnormal microscopic deposits that are made up of a protein widely found in the brain called alpha-synuclein. The deposits are known as Lewy bodies, which are also a hallmark of another kind of dementia known as dementia with Lewy bodies.   Researchers currently believe that Parkinson's dementia and dementia with Lewy bodies are actually different expressions of the brain's difficulty processing alpha-synuclein.

The person with Parkinson's disease dementia may experience cognitive decline on several levels. "In addition to forgetfulness, thought processes can be slowed, with long lags before answering a question and with slowed processing of ideas," the Parkinson's Disease Foundation reports. "There can be difficulty concentrating and in particular a lack of drive or initiative, with caregivers complaining that a person with Parkinson's has become more passive. Visuospatial processing can be impaired: this can lead to difficulties with everyday tasks such as driving, dressing or even inserting a hearing aid." Other symptoms of this type of dementia include:

  • Difficulty with judgment
  • Muffled speech
  • Hallucinations
  • Delusions and paranoia
  • Depression
  • Irritability
  • Anxiety
  • Sleep disturbances

In addition, some people with Parkinson's may develop several types of dementia, which is called dementia-multifactorial. Thus, they can have a combination of dementia with Lewy bodies, Parkinson's disease dementia and Alzheimer's disease, which involves plaques and tangles. After looking at studies based on a number of autopsies, researchers currently believe that dementia-multifactorial is more common than previously thought.

There isn't a test that conclusively determines whether a person has developed Parkinson's disease dementia. Currently, guidelines for marking a diagnosis are as follows:

  • Parkinson's disease dementia is diagnosed when a person is originally diagnosed with Parkinson's based on movement symptoms. They then develop dementia symptoms a year or more after Parkinson's was diagnosed.
  • A diagnosis of dementia with Lewy bodies is made when a person's symptoms are consistently showing that dementia with Lewy bodies developed first. This diagnosis also is made when dementia symptoms and movement symptoms are both present at the time of the diagnosis. Finally, this diagnosis also may be made when movement symptoms develop within a year after a diagnosis of dementia with Lewy bodies has been made.

Knowing the extent of what Robin Williams may have been facing in the future health-wise helps provides some additional context for his battle with depression. He not only had to think about his Parkinson's disease, but also the possibility that he might develop one or several forms of dementia.That prospect can make the future seem very bleak, indeed.

Primary Sources for This Sharepost:

Alzheimer's Association. (2011). Mixed dementia.

Alzheimer's Association. (ND). Parkinson's disease dementia.

Diamond, D. (2014). Why Parkinson's disease is so scary: No cause, no cure. But it's not a killer. Forbes.

Parkinson's Disease Foundation. (2003). Coping with dementia; Advice for caregivers.