In a recent interview with People, Susan Williams, widow of the late Robin Williams, revealed details about his death that until now, was said to be suicide due to extreme depression. In her interview, Susan said, "It was not depression that killed Robin."

She shared that what took her husband's life was actually a brain disease called Diffuse Lewy Body Dementia (DLB) and as she put it, "Depression was one of let's call it 50 symptoms and it was a small one."

The disease is said to be frequently misdiagnosed, with Susan stating that "you don't know exactly what you're looking at". Some of its signs and symptoms include heightened levels of anxiety, delusions and impaired movement. But what makes it even more difficult to diagnose is the fact that the symptoms vary from case to case.

Dr. James E Galvin Director of the Leon and Toby Cooperman Center for Alzheimer Disease and Memory Disorders at the Marcus Neuroscience Institute in Boca Raton, Florida, said about DLB, "Patients can have different presentations -- some patients start off with memory and thinking problems, particularly in their visual-perceptive abilities. Others start off with movement problems: slowed movements, unsteady walking, falls."

"Still others have changes in their behavior: anxiety and depression with a loss of interest in things around them (apathy) and may start to experience visual hallucinations (usually small people or animals) or have false beliefs (delusions) such as their loved ones being replaced by imposters," he continued.

According to Alzheimers.org, DLB symptoms depend on where the Lewy Bodies are located in the brain. Those that are located at the base are likely to be linked with movement, while those in the outer layers are more cognitive and a re linked with mental abilities.

Symptoms of the disease are usually subtle but gradually worsens until they cause problems with daily living. As in Robin Williams's case, there are also those that experience depression.

A progressive disease, later stages of DLB worsens symptoms over time, until eventually, extensive nursing care will be needed.

Robin's symptoms have gradually worsened in the months leading up to his death as well, but Susan says she doesn't blame the doctors for not diagnosing her late husband properly. She said, I know now the doctors, the whole team was doing exactly the right things. It's just that this disease was faster than us and bigger than us. We would have gotten there eventually."

Learn more about DLB here.