Just found in an article from Lawrence Journal-World:

Studies have found that while negative words register with a depressed person’s brain, positive words are dismissed.

“If we give people sentences to read — like ‘I am a loser’, ‘I am a winner’, and ‘I am a wagon’ — it’s obvious that wagon is nonsense,” Atchley said. “But a depressed person’s brain responds to wagon the same way it responds to winner.”

“That’s because both words — winner and wagon — are unexpected”, said Steve Ilardi, a KU psychology professor who’s partnering with Atchley on the project.

“If you read a sentence like ‘This pizza is too hot to cry’, the word ‘cry’ would trigger a telltale brain-wave pattern that says ‘I wasn’t expecting that”, Ilardi said.

…

“So if a depressed person reads a sentence ‘I am a success’, the word ‘success’ triggers a brain-wave pattern showing the patient doesn’t see himself that way at all”, Ilardi said. “If the person isn’t depressed, the brain-wave reaction will be just the opposite”.

No shit…