Robin Williams died by suicide primarily due to the complex interplay of severe mental health challenges and a devastating neurological disease called Lewy body dementia (LBD). Although he had a lifelong battle with depression and anxiety, the discovery after his death showed that LBD, which causes severe symptoms like paranoia, insomnia, memory loss, and hallucinations, was the critical factor that led to his decision to end his life. This disease created unbearable psychological distress, exacerbating his pre-existing depression and anxiety. Additionally, Williams faced other challenges such as past substance abuse, relationship problems, financial issues, and the emotional impact of his declining health. Despite these factors, LBD's severe neurological impact was described by his widow as "chemical warfare in his brain," profoundly affecting his cognition and mood, contributing directly to his tragic suicide by asphyxiation in 2014.

Mental Health and Neurological Condition

• Williams had long-standing depression and anxiety, which were significant but not the sole cause.
• He was diagnosed posthumously with diffuse Lewy body dementia, a disease with symptoms overlapping Parkinson’s disease but more severe cognitive and psychiatric effects.
• Symptoms included paranoia, hallucinations, restlessness, and memory loss, which led Williams to feel he was "losing his mind".

Other Contributing Factors

• He struggled with substance abuse in the past and had achieved sobriety but returned briefly to rehab in 2014.
• Relationship and financial problems added emotional and psychological stress.
• His health issues, including heart surgery and the stress of a cancelled TV show, worsened his mental health.

Circumstances of Death

• Williams died at home by hanging, with no evidence of overdose.
• The coroner’s report noted asphyxiation as the cause of death consistent with suicide.
• The discovery of LBD after death helped clarify that neurological disease, more than depression alone, was a pivotal factor.

In summary, Robin Williams' suicide was caused by a severe combination of mental health struggles compounded critically by the neurological damage of Lewy body dementia, a condition that profoundly impacted his brain function and emotional well-being, leading to his tragic death.