Two grown men turn into tantrum-throwing children One brother giggles constantly while the other loves playing with toy trainsImage Credit: SuppliedMatthew, 39, and Michael Clark, 42 (right)Published: 00:00 May 3, 2012 IANS SMALLMEDIUMLARGELondon: Two Britons seem to be ageing in reverse after contracting a bizarre condition which is rapidly making them behave like children.The brothers — Matthew, 39, and Michael Clark, 42 (right) — contracted terminal leukodystrophy last year. It usually only affects newborns and despite having jobs both now behave much like toddlers, The Sun reported.Michael, an ex-Royal Air Force regiment member, is now thought to have a mental age of 10 and giggles constantly while his elder brother Matthew, a factory worker, behaves like a small child. Both throw tantrums.Their parents Anthony, 63, and Christine Clark, 61, are devastated. Anthony, from Lincoln, Lincolnshire county, said: "It is a devastating disease. Both of them are very childlike now. Matthew went out the other day and bought himself a train set and a Mr Potato Head."Michael's symptoms turned more apparent as he was evicted for not looking after himself. "Matthew was fired from his job as a factory worker," said the father.The parents have now abandoned their plans to retire to Spain as they have to look after Michael and Matthew, the grown ups turned children.