Late-onset schizophrenia and late paraphrenia.

The term "late-onset schizophrenia" was first coined by Manfred Bleuler (1943) to describe a form of schizophrenia with an onset between the ages of 40 and 60. This concept has been adopted by German psychiatry. Until recently, British and American psychiatrists had little interest in this patient group. However, they often used the term "late-onset schizophrenia" interchangeably with late paraphrenia or as a generic term for both these diseases, even though the concept of late paraphrenia is quite different from that of late-onset schizophrenia. Late paraphrenia is a British concept that includes all delusional disorders starting after age 60. This confusion of terms and concepts is even more important now, because recent neuroimaging and neuropsychological studies suggest that an organic substrate probably exists in most cases of late paraphrenia, while only minor organic abnormalities can be found in late-onset schizophrenia. We believe it is of utmost importance to establish a clear boundary between late-onset schizophrenia and other delusional disorders in middle and old age, because the confusion in terminology and concepts is a serious impediment to comparative international research.