When Robin Williams took his life in August 2014, he was reportedly suffering from depression. But in an interview on KTLA-TV in Los Angeles, his widow, Susan Williams, said it wasn’t depression that drove him to suicide. Nor was it a recurrence of alcohol or drug addiction, as some had speculated. Instead, she said, it was a disease called Lewy body dementia (LBD).

LBD is the most common form of progressive dementia besides Alzheimer’s disease, but relatively few people are familiar with it.

The Oscar Award-winning comedian had been diagnosed with Parkinson’s disease, but he was at peace with that, according to his widow. Nonetheless, he and his wife “were living in a nightmare” in the months before his death, Susan Williams said in the interview. Robin Williams was aware he was losing his mind, and that’s what drove him to suicide, she told reporters. When the emergency team was unable to revive him, she told reporters, “I got to tell him, 'I forgive you with all my heart. You're the bravest man I've ever known.’”

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An autopsy stated that Williams’ brain showed “diffuse Lewy body dementia.”

The diagnosis has stirred up interest in and coverage of “this frequently misdiagnosed condition,” according to the Lewy Body Dementia Association (LBDA). That organization cautioned that the autopsy findings did not mean Williams had already developed dementia.

“The use of the term dementia in the neuropathology report should not be inferred to mean that dementia was observed during life,” said Dennis Dickson, MD, of the Mayo Clinic in Jacksonville, Florida, in a news release. Dickson is a member of the LBDA Scientific Advisory Council.

Dickson reviewed the autopsy and coroner’s report “Mr. Williams was given a clinical diagnosis of PD and treated for motor symptoms,” he noted. “The report confirms he experienced depression, anxiety and paranoia, which may occur in either Parkinson's disease or dementia with Lewy bodies.”

What is Lewy body dementia?

Like Alzheimer’s disease, Lewy body dementia causes confusion, memory loss, reduced attention span and problems with mood and movement. The name comes from protein deposits in the brain that build up in nerve cells in clumps known as “Lewy bodies” and "muck up the ability for the brain to transmit signals," James Leverenz, MD of the Cleveland Clinic, told reporters.

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According to the Mayo Clinic, symptoms of the disease include:

  • Hallucinations that often involve people or animals who are not there. You may see, smell or hear things that are not there or have conversations with people who have died. You may also feel anxious or paranoid.
  • Problems with movement. As in Parkinson’s disease, you may have tremors, muscle rigidity, slow movements or a shuffling walk.
  • Problems with normal body function. The diseases affects the cells that regulate pulse, blood pressure, digestion and sweating, so you may have bowel issues or problems with falls and dizziness.
  • Difficulty thinking, with reduced attention, confusion and eventual memory loss. You may feel unusual drowsiness, sit and stare into space for long periods or have trouble expressing yourself (“disorganized speech.”)
  • Depression. It’s common to experience this as the illness progresses.

No one is sure what causes Lewy body dementia, but it may be related to Parkinson’s or Alzheimer’s disease, which may co-exist with the illness. You’re more likely to get it if you’re over 60, male or have a family history of the disease, according to the Mayo Clinic.

There is no cure for Lewy body dementia at this time. If you are diagnosed with the disease, a doctor may prescribe cholinesterase inhibitors, which can boost the level of neurotransmitters (chemical messengers) in the brain and improve thinking and memory. Your doctor may also prescribe Parkinson’s disease medications, which can help ease muscle rigidity and tremors.

As for Robin Williams, he will live forever as the brilliant, tortured, frenetic genius of comedy.

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Diana is an award-winning writer and editor with more than 20 years' experience in magazine, video, book and digital journalism, with a specialty in health coverage. She was a longtime writer and news editor at the Center for Investigative Reporting; has written for publications from the Washington Post to the Times of London syndicate; and has served as a senior and/or consulting editor at Time Inc. Health, Hippocrates, HealthDay News Service and Reporting on Health. She was also editor in chief of Consumer Health Interactive, a national health and medical web site, and has reported on finance for Blueshift Research and PBS Frontline. Before joining SafeBee, she was editor of Bioenergy Connection, a national magazine about bioenergy at UC Berkeley. Her favorite safety tip: Wear a bike helmet.