Temporary Chronological Displacement Deterioration

Temporary Chronological Displacement Deterioration,(or TCDD for short), was the condition which gave sufferers short term memory loss after travelling in time.

After being touched by a Weeping Angel, and sent back to 1511 from 2015, Gabby was told by the Doctor that she was suffering from this condition after she told him that she could not remember the specifics of their meeting at the Sistine Chapel. (AUDIO: Fallen Angels)