Old Man-One Year Puppy Syndrome
The psychological syndrome of having two alternating personalities, one of whom is an energetic, exuberant personality of almost childlike naivety, and the other being a uncommunicative, curmudgeonly, anti-social personality. The afflicted person will often alternate between these two personalities relatively frequently and without apparently one personality affecting the other, such that care should be taken that you haven't actually misdiagnosed two twins with distinct personalities.
Patient zero, diagnostic-wise, was believed to be a recluse in South Wales whose only significant contact was said to be his local postman and his dog. His interests were only reported to include playing the piano, throwing magnets in elevators, complaining about the rate of inflation and the state of his internet connection. He was reported by neighbours to watch old videos of Fred Dibnah all day long at unsociable levels of noise. Artistically he supposedly painted pictures of bizarre or surreal scenes, for example chickens stuck behind a wall, abstract pictures of formless people being uppercutted with a boxing glove, and magnets with crossing field lines (it is speculated what the apparent fascination with magnets was). Politically he was said to be very right wing, and visitors reported being uncomfortable with the videos that were played in the background when they were there (it is assumed for their political content). Whether any of this behaviour was consequent of his syndrome, or related to the causes of, or indeed completely unrelated to his syndrome is not known due to the scarcity of sufferers, estimated to constitute only approximately 0.0001% of the population.
No known treatment.