Criminal Minds2005

Derek Morgan:
He said his parents had been replaced.

Emily Prentiss:
He just sounds delusional.

Dr. Spencer Reid:
You know, he might have Capgras syndrome. It's a delusional disorder in which one believes that their friends and loved ones have been replaced by imposters.

Derek Morgan:
Sort of like Invasion of the Body Snatchers.

Dr. Spencer Reid:
It typically involves only one sense, such as sight. Basically, the neural connection between the visual cortex and the emotional center of the brain becomes severed, so that looking at a loved one doesn't elicit the same emotional response one would expect.

Aaron Hotchner:
So, you think they're an imposter.

Dr. Spencer Reid:
And the interesting thing is that the auditory connection remains intact, so that if they were to hear a loved one speak and not see them, they'd think that they were real.