The case of a 39 year old in-patient with a paranoid syndrome is presented. During the course of examination, a vitamin B12 deficiency as well as a hypothyreosis were found, which seemed to have a common cause in an autoimmune disease. The paranoid symptoms disappeared completely under treatment with vitamin B12 and thyroid hormones. Moreover, the neuropsychological deficit improved markedly. The relationship between psychiatric symptoms and organic disease, and also the differential diagnosis, is discussed.
