'(Reuters) - Robin Williams was suffering from the early stages of Parkinson's disease along with severe depression at the time of his apparent suicide, his widow said on Thursday, drawing public attention to the correlation between the diseases.

Although the gifted comedian had spoken before about his depression, Parkinson's experts have noted how the incurable and debilitating nervous system disorder that causes tremors and slowness of movement also affects people emotionally.'

Robin Williams' death highlights Parkinson's-depression link | Reuters

This explains a lot for me.

Btw - I am not trying to hijack the other Robin Williams thread. But I thought this news warranted a separate thread,