Robin Williams‘ widow is opening up about the last months of the actor’s life in which he struggled with a neurological condition called Lewy body disease (LBD) that fundamentally altered his personality and behavior.

“The massive proliferation of Lewy bodies throughout his brain had done so much damage to neurons and neurotransmitters that in effect, you could say he had chemical warfare in his brain,” Susan Schneider Williams wrote for the scientific journal “Neurology.”

She recounts how Williams began experiencing a range of seemingly unrelated physical issues like stomach pain, insomnia and urinary troubles around October 2013.

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“I knew his normal reactions when it came to fear and anxiety,” she wrote. “What would follow was markedly out of character for him. His fear and anxiety skyrocketed to a point that was alarming…Not until after Robin left us would I discover that a sudden and prolonged spike in fear and anxiety can be an early indication of LBD.”

Over the next 10 months, bouts of paranoia and anxiety became more and more consistent, with doctors unable to determine a root cause for the sudden changes.

–no amount of intelligence or love could hold it back.”

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Then, on Aug. 11, 2014, Williams took his own life at his home in Tiburon, California. His sudden death sent shockwaves throughout the world.

The autopsy revealed that Williams was suffering from a particularly severe case of LBD. “One professional stated, ‘It was as if he had cancer throughout every organ of his body,'” Schneider Williams wrote. “The key problem seemed to be that no one could correctly interpret Robin’s symptoms in time.”