Joaquin Phoenix's creepy laugh in “Joker” is shedding light on a real-life medical disorder.
In the film that shattered box office records over the weekend, Phoenix’s sinister character explains he has a condition that causes him to laugh uncontrollably.
It's called pseudobulbar affect, also known as PBA, and it's a neurological condition characterized by uncontrollable laughing and/or crying outbursts. The documentary “Beyond Laughter and Tears: A Journey of Hope” features people who have PBA.