Comparison of Childhood, Adolescent, and Adult Schizophrenias: Etiologic Significance of Intellectual Functioning

Introduction  Although the diagnosis of schizophrenia is applied to all ages, from the infant to the aged, there is increasing recognition that schizophrenia is not a single clinical entity but, rather, a descriptive term that reflects a variety of abnormalities.^* Accurate delineation of these abnormalities (or the group of schizophrenias in Bleuler’s terminology¹¹) is of major importance for the detection of basic defects and their ultimate prevention.One approach to delineating the factors associated with mental illness is the study of age of onset. Landis and Bolles⁴⁹ have remarked that “the most important single determining fact that we can know about mental disease is the age of the patient or the age distribution of a group of patients. If these data are available, one can make fairly accurate estimates of the beginning of the different diagnostic types of mental disease, the relative proportion of