TARDIVE-DYSKINESIA AND ASSOCIATED COGNITIVE DISORDERS - A CONVERGENT NEUROPSYCHOLOGICAL AND NEUROPHYSIOLOGICAL APPROACH

This study sought to assess whether tardive dyskinesia (TD) related differentially to two types of cognitive functioning in schizophrenia. Thirteen schizophrenics with severe formal thought disorders (+ FTD) were matched for age, sex, education, chronicity, dosage, hospital care, with 13 schizophrenics selected for absence of or minimal formal thought disorders (- FTD). TD and neuroleptic dosage were analyzed in relation to cognitive and motor tests of the Luria- Nebraska (L-N) battery and to attentional evoked potentials (EPs). EPs were recorded at electrodes Fz, Cz, and Pz, in a dichotic signal detection task (oddball paradigm), during attention and inattention conditions. Group differences on attentional EPs replicated published results with flatter and smaller positive waves in + FTD patients and larger late negative waves (FzN4-N7) in - FTD patients. Controlling for dosage, the following were the best groups discriminators. + FTD schizophrenics presented more severe dyskinesia in the orofacial area and poorer verbal scores on L-N. Severe TD correlated with smaller N1 amplitudes. + FTDs also presented distinct attentional EP deficits with abnormally small P3a, a correlate of deficient categorization and orienting. Neuroleptic dosage was not directly correlated to any single motor or cognitive measure, nor to TD indices. The hypothesis of a differential association of TD with distinct attentional/cognitive disorders was generally supported. © 1993 Academic Press, Inc.