What is the Difference Between Lewy Body Dementia & Alzheimer’s?
I recently learned of a friend’s Lewy body dementia diagnosis. This prompted me to dust off and finish a blog post I started some time ago. Lewy body dementia, after all, accounts for as much as 15% of dementia cases.
Robin Williams Death Caused By Lewy Body Dementia
On August 11, 2014 I heard on the radio that Robin Williams had committed suicide.
I fell in love with Robin’s rowdy, insane style of comedy immediately when I first saw him on an episode of Happy Days. That was probably 1970. After that I followed his career closely. Dead Poet Society is still one of my favorite movies — not just one of my favorite Robin Williams’ movies.
Early reports indicated that Robin took his life because of depression. He was, in fact, struggling with depression before his death. However, we later learned that Lewy body dementia probably caused that depression. As we will see, depression is a common symptom of this disease.
A few months before his death Williams learned of a Parkinson’s disease diagnosis. He started experiencing physical symptoms including Parkinsonism late in the previous year. Symptoms of dementia, including paranoia, increased following the diagnosis.
An autopsy following his death (I think Robin would appreciate the humor there) revealed that he more likely had dementia with Lewy bodies.
What is Lewy Body Dementia?
Lewy body dementia is, in fact, the second or third most common cause of dementia, depending on who you ask. According to the Lewy Body Dementia Association the disease, “affects an estimated 1.4 million individuals and their families in the United States.”
Like Alzheimer’s disease, age is the greatest risk factor for Lewy body dementia. Otherwise, we know very little about the causes, risk factors, or lifestyles that may be associated with Lewy body dementia. One way that Lewy body dementia differs from Alzheimer’s is that more men are affected than women.
Lewy body dementia is not the same as Alzheimer’s
Lewy body dementia is like Alzheimer’s disease in several ways. Deposits of mis-folded protein damage brain cells in much the same way as do the plaques and tangles of Alzheimer’s disease. Dr Friedrich Lewy first described “spherical…neuronal inclusions” he found post mortem in the brain of a Parkinson’s patient. Coincidentally, this happened shortly after Dr. Alzheimer presented his findings describing the plaques and tangles that are now hallmarks of Alzheimer’s disease.
In both conditions neuronal damage continues over time, accounting for the progressive nature of the diseases. As with Alzheimer’s, no one knows if Lewy bodies are the cause or an effect of the disease.
Lewy body dementia and Alzheimer’s disease share many symptoms, but the two diseases are also very different. Alzheimer’s disease progresses through the brains of its victims in a very predictable way. It begins in the area of the hippocampus. By the time it is done almost every part of the brain has lost significant mass. The order in which different areas are affected is essentially the same in everyone. You can read more about how Alzheimer’s affects the brain in The Alzheimer’s Brain.
Lewy bodies, on the other hand, affect the brain in two entirely different ways and cause two related but different conditions, dementia with Lewy bodies (DLB) and Parkinson’s disease dementia. The two eventually have similar symptoms, but the symptoms do not appear in the same order. This is due to the fact that the misfolded protein begins to accumulate in different parts of the brain. Generally speaking, Parkinson’s disease affects the body first, Dementia with Lewy Bodies affects the brain first.