Contributions of clinical neuropsychology to the study of schizophrenia

Article Abstract:

Clinical neuropsychology has often focused on the symptoms associated with clear-cut brain damage, resulting from traumatic accidents, surgery, battle wounds, and the like. The field has also attended to syndromes like aphasia, or defective language function, in which the symptoms are limited to a particular set of functions and may be studied with a fair degree of objectivity. Now, neuropsychology is turning its attention to the elucidation of hypotheses about schizophrenia, a broad class of psychotic mental disorders covering a bewildering array of behaviors and symptoms. While traditionally the goal of the neuropsychologist has been to ascribe functions to brain structures, no region of the brain is consistently found to be damaged in schizophrenics. A better approach to schizophrenia may be the examination of brain systems, rather than brain structures, to determine if groups of functionally related structures are performing in an inappropriate fashion. Attention functions are extensively damaged in schizophrenia, and have been studied for many years. Unfortunately, it remains unclear whether the attention dysfunctions are fundamental to the psychotic process, or whether they are simply a consequence of a psychosis which arises in other brain systems. Executive functions allow a person to respond appropriately to actions and events in the environment. Schizophrenics have abnormal executive functions, and careful neuropsychological testing reveals differences between schizophrenics and other psychotic disorders in this regard. There is some indication that some subtypes of schizophrenia may be associated with the way executive functions are assigned to different sides of the brain, but these indications must be interpreted cautiously. Studies of motor systems have showed motor slowing, but studies on handedness have yielded conflicting results and more sensitive assessment methods must be applied. The visual and spatial systems in schizophrenics have been studied, but the results are inconclusive. One possibility is that there is much heterogeneity among the visuospatial systems of schizophrenics. Affect, which is the outward indication of a person's feelings or emotions, is often inappropriate in schizophrenics, and evidence points to an inability to properly generate affect rather than an inability to experience the appropriate underlying emotions. Studies of language systems in schizophrenics provide no evidence of impairment of basic language functions, and the observed deficits in semantic content and discourse may well be a result of executive and attentional deficits, rather than a problem with the linguistic process itself.

Physiological aspects, Mental illness, Mental disorders

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Relation of neuroleptic and anticholinergic medication to cognitive functions in schizophrenia

Article Abstract:

Despite the importance of obtaining accurate data on the relation of drugs to cognitive performance, both in normal and schizophrenic individuals, such data are notoriously difficult to obtain. Patient populations are generally not selected at random, and often represent a chronic, hospitalized population rather than recent-onset cases. Such patients are already being medicated; their participation in a study requires a "wash-out" period. Unfortunately, some individuals may be so adversely affected by the cessation of medication that they cannot be used in the research. There are also ethical questions, and physicians are appropriately reluctant to remove from a patient a medication believed to be effective. Nonetheless, it is possible to conduct such studies, and neuroleptic drugs, which alter the state of consciousness of the patient, seem to affect some cognitive processes and not others. Neuroleptics appear to normalize the disordered thinking and attention deficit associated with schizophrenia, and the degree of normalization correlates well with clinical improvement. There are, however, some forms of disordered thinking and attention deficit that are not affected by these drugs, including residual-thought pathology and eye-movement dysfunction. The authors believe that deficits not amenable to neuroleptic treatment may be regarded as trait markers for schizophrenia or the tendency to its development. Although it is currently difficult to perform the studies which would clarify the effects of medication on schizophrenic patients, it is still possible to design and carry out some studies which will add to our understanding of the development and treatment of this disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Methods, Evaluation, Drug therapy, Antipsychotic drugs, Antipsychotic agents, Neuropsychological tests

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Forward and backward visual masking of contour by light in positive- and negative-symptom schizophrenia

Article Abstract:

The Andreasen scale enables classification of schizophrenic patients to positive- and negative-symptom groups and helps a study of the visual marking phenomena in these patients. This scale suggests the absence of any variations between schizophrenic patients and controls in forward masking of contour by light. Backward masking is enhanced in negative-symptom patients, as implied by their longer thresholds of target duration, while the positive-symptom patients do not exhibit any such differences.

Analysis, Visual perception

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