<prompt> A 44 year old man presents with fears that his mathematical abilities have been slowly sucked out of his brain for the last four years. He believes an alien force disguised as a human being is responsible. To avoid contact with this being, he has isolated himself in a room in a boarding house. He has left his wife and children. After ten years teaching math at a local high, he resigned about 3 years ago. He suppos himself by collecting cans. His effect is blunted. His appearance is disheveled,unshaven and unwashed.Which of the following is least suggestive of a schizophrenic disorder in this man?Delusional systemFour-year history of symptomsAge of onsetDecrease in level of functioning  <response>: Schizophrenia usually develops in young adulthood.The mean age of the first psychotic break is in the early twenties for men. Of men with schizophrenia, 9 of 10 have developed the disorder by age 30.Women tend to develop the disorder at an older age. Developing the disorder at age 40 is unusual. Ref: Nurnberger, Jr. J.I. 2008. Chapter 3. Psychiatric Genetics. In M.H. Ebe, P.T. Loosen, B. Nurcombe, J.F. Leckman Eds, CURRENT Diagnosis Treatment: Psychiatry, 2e. 