 -- Robin Williams had a common but difficult to diagnose condition known as Lewy Body Dementia and this may have contributed to his decision to commit suicide last August, according to documents included in his autopsy report.

The coroner in San Rafael, California, released its autopsy report as well as a pathology report from the University of California San Francisco documenting the comedian's condition.

All people with LBD have dementia, and sometimes appear confused and disoriented and exhibit unusual behavior, said Angela Taylor, the director of programming for the Lewy Body Dementia Association. According to the coroner’s report, Williams had been acting strangely before his death. He is said to have kept several watches in a sock and was very concerned about keeping the watches safe.

“The dementia usually leads to significant cognitive impairment that interferes with everyday life,” Taylor said, adding that people with LBD often struggle with tasks like eating, staying clean and paying bills.

People with LBD tend to experience extremely graphic hallucinations that are visual but can also include smells and sounds, Taylor said. Many with the diagnosis have Lilliputian hallucinations populated by small people or creatures. They usually don’t find these frightening, just very real, she said.

While difficult to distinguish from Parkinson’s disease – which Williams also had -- LBD isn’t rare, Taylor said. It’s one of the most common forms of dementia and affects more than 1.4 million people in the U.S. according to the association’s latest statistics.

Like Williams, many people who have LBD are initially diagnosed with Parkinson’s. As the diseases progress they begin to show LBD symptoms including trouble sleeping and the vivid hallucinations. Hunched posture, rigid muscles, a shuffling walk and trouble initiating movement, are similar for both conditions. Some are also diagnosed with Alzheimer’s or a psychiatric disorder.

Despite how common LBD seems to be, doctors have difficulty making the correct diagnosis, Taylor said. In the early stages, cognitive function fluctuates and people who have it may be able to pull themselves together for periods of time, Taylor explained.

“If you didn’t know them you may not realize anything is wrong,” she said.

The diagnosis is often confirmed after death when looking through a microscope reveals Lewy Bodies, tiny protein deposits on the nerve cells of the brain. The autopsy of Williams’ brain showed Lewy Bodies as well as other brain changes that are the hallmarks of Alzheimer’s and Parkinson’s, according to the report.

Medical experts can’t say for sure whether LBD contributed to William’s suicide. He also suffered from clinical depression and had a history of drug and alcohol abuse, though he had no drugs or alcohol in his system when he died, according to the autopsy report.

“Though his death is terribly sad it’s a good opportunity to inform people about this disease and the importance of early diagnosis,” Taylor said.