ADHD: What is Rejection Sensitive Dysphoria?

Rejection Sensitive Dysphoria is a symptom of ADHD not listed in the DSM-5 and is considered as a form of emotional dysregulation. It is extremely common (around 95% of ADHDers experience it) in both children and adults with ADHD, but as there is still very little research it is unclear whether it is a trait exclusive to people with ADHD.