The Joker on Instagram: "Joaquin Phoenix based his laugh on “videos of people suffering from pathological laughter,” also known as Pseudobulbar affect (PBA). This is a real disorder which causes the patient to suffer from uncontrollable laughter attacks in response to tense or stressful situations. These attacks can stop the normal flux of oxygen to the brain or lungs, causing hypoxia or even asphyxia.  “Joker” (2019) Dir. Todd Phillips."

Uni Medical care on Instagram: "Pseudobulbar affect is a rare neurological disorder that causes excessive and disproportionate laughter. The patient with this disorder suffers from constant laughter that may occur at inappropriate times, whether the situations are sad or neutral. The person may laugh even in situations that do not call for laughter, such as while sleeping or while performing daily activities. This disorder can cause social and professional problems for the patient as he may face