Post-traumatic stress
Post-traumatic stress disorder was a psychological condition, caused by suffering a traumatic experience and being unable to cope with it. Symptoms included becoming anxious, prone to physical illness or increasingly withdrawn. The Fifth Doctor hypothesised that Nyssa was suffering from post-traumatic stress disorder as a result of Adric's death. (PROSE: Empire of Death)
Professor Geoffrey Thynne specialised in post-traumatic stress. (PROSE: The Touch of the Nurazh)
Quell suffered from post-traumatic stress following his time as a soldier. While working as the captain of the Orient Express, this mental affliction was identified by the Foretold, leading it to target and kill him as the weakest remaining passenger. (TV: Mummy on the Orient Express)