I'm Who?

Undercover police officer Bob Arctor begins cracking up following long-term use of Substance D. By the time his boss interviews him on the subject, Arctor is hallucinating, exhibiting false memories of a family he never had, and suffering from a growing state of anxiety. Also, immersed for too long in the double life of an undercover cop, he fails to recognize his own name.

Example of:
Sanity Slippage