Intrusive memories in post-traumatic stress disorder (PTSD) are a part of re-experiencing trauma. They can take the form of flashbacks, nightmares, and other types of involuntary emotional recall.

Intrusive thoughts are a symptom of obsessive-compulsive disorder (OCD), a mental health condition in which a person experiences involuntary obsessions and compulsions that may cause distress.

In conversation, print, and social media, people have been using the terms "intrusive thoughts" and "unwanted intrusive thoughts" to refer to a wide range of thoughts, feelings, and images that enter ...