Neuropsychological Assessment of Schizophrenia Versus Brain Damage

The previous 10 years of research comparing neuropsychological test performances of adults diagnosed as schizophrenic with adults diagnosed as brain damaged is reviewed. Current concepts and criteria for classifying and sub-classifying patients in terms of brain damage and schizophrenia are presented. Right hemisphere, left hemisphere, and diffusely brain-damaged patients and paranoid, reactive, and process schizophrenics may differ in neuropsychological test performances. However, not all differences among these groups are well substantiated or well understood. Few studies were found that reported consistently using the most valid criteria in forming schizophrenic and brain damaged samples. Furthermore, only a small proportion of studies included appropriate controls for age, IQ or education, length of hospitalizaton, and drug effects.Canter's Background Interference Procedure and DeWolfe's Wechsler Adult Intelligence Scale sign approach have been found to discriminate well between schizophrenic and brain-damaged groups after replicated investigation of these procedures. The Halstead-Reitan Battery provided discriminatory power equivalent to, but not superior to, many single measures. However, the use of inadequate criteria appears to have resulted in an imposed ceiling (70 to 75 per cent accuracy) on the discriminatory power of psychological tests. Recommendations for future research include: a) the use of more valid criteria for brain damage (i.e., computerized tomographic scan) and more valid and standardized assessment of schizophrenia (i.e., Inpatient Multidimensional Psychiatric Rating Scale) in classifying subjects; b) evaluating all subjects using both neurological and psychopathological criteria; c) reporting percentages of hits, false negatives, and false positives; and d) increased comparisons among schizophrenic and brain-damaged subclassifications.