Perseverative error in schizophrenia: correlation with cortical blood flow by SPECT.

INTRODUCTION: Perseverative error (PE) is a core symptom of schizophrenia which has been proposed as a phenotypic marker of the illness. Moreover, hypofrontality observed in functional neuroimaging studies while executing a cognitive task has also been suggested as a characteristic sign of schizophrenia. We propose combining symptom and sign to demonstrate the existence of a regional cortical blood flow (RCBF) pattern associated to PE that might constitute a biological marker of schizophrenia. MATERIAL AND METHOD: We used Single Photon Emission Computerized Tomography (SPECT), to study the RCBF associated to PE and to correct response (CR), during the execution of the Wisconsin Card Sorting Test (WCST), of 18 patients with schizophrenia and 13 controls. We focused on five well-defined bilateral brain regions, using the RCBF of the same regions at rest as a baseline. RESULTS: Patients made more PE than controls in the WCST. Among patients, we observed a correlation between PEs and right occipital RCBF. Among controls, we found a negative correlation between PEs and left temporal cortex RCBF and a positive correlation between CRs and left frontobasal and overall left frontal cortexes RCBF. CONCLUSIONS: The severity of PE is associated to higher right parietal-occipital activity in patients with schizophrenia. CR in the WCST are associated to higher left frontal activity in controls but not in patients. Probably, there is a RCBF redistribution pattern related to the typical perseveration of schizophrenia which might constitute a phenotypic marker of the illness observable by functional neuroimaging techniques.

Estudio del flujo sanguíneo cerebral regional (FSCr) mediante SPECT, en reposo y activación con el test de Clasificación de Tarjetas de Wisconsin (WCST), en pacientes con esquizofrenia sin tratamiento o tratados con neurolépticos atípicos / Regional cerebral blood flow SECT study, at rest and during Wisconsin Card Sorting Test (WCST) performance, in schizophrenia naive patients or treated with atypical neuroleptics

Introducción. Corroborar la hipótesis de la hipofrontalidad en la esquizofrenia y estudiar la posible relación existente entre los síntomas positivos y negativos (medidos con la Escala de síndromes positivos y negativos, PANSS) y el flujo sanguíneo cerebral regional (FSCr), tanto en reposo como en activación mediante el Wisconsin Card Sorting Test (WCST). Métodos. Comparamos el FSCr de un grupo de controles (n = 18) con el de un grupo de pacientes con esquizofrenia (n = 21) mediante tomografía computarizada por emisión de fotón único (SPECT). Resultados. En el grupo control los índices de FSC frontal izquierdo en reposo y activación y derecho en activación son significativamente superiores a los de los pacientes. Únicamente en los controles el índice frontal derecho experimenta un incremento significativo como resultado de la activación. El FSC occipital derecho en activación se incrementa significativamente sólo en los pacientes. Observamos una correlación positiva significativa entre las puntuaciones de la PANSS-P y el índice frontal izquierdo en reposo. Síntomas aislados de la PANSS-N como dificultad en el pensamiento abstracto (N5) y falta de espontaneidad y fluidez en la conversación (N6) se asocian a hipoperfusión frontal en reposo. El embotamiento afectivo (N1) se asocia a hipoperfusión frontal izquierda en activación. Conclusiones. Nuestros datos apoyan la hipótesis de la hipofrontalidad, tanto en reposo como en activación, es decir, entendida como la incapacidad de los pacientes con esquizofrenia para incrementar el FSC frontal durante la ejecución del WCST (activación). Los síntomas positivos de la esquizofrenia se asocian a hiperperfusión frontal izquierda

Introduction. To corroborate the hypothesis of hypofrontality in schizophrenia and to study the relationship between positive/negative symptoms (measured by the positive and negative syndrome scale [PANSS]) and regional cortical blood flow (rCBF), both at rest and during the Wisconsin Card Sorting Test (WCST) performance (activation). Methods. We compared a control group (n = 18) to a group of patients with schizophrenia (n = 21) in terms of rCBF, measured by single photon emission computed tomography (SPECT). Results. We found significantly higher left-frontal- CBF (during the WCST performance and at rest) and right-frontal-CBF (only at rest) in control subjects. Only the control group showed a right-frontal-CBF increase during activation. Only the patients group showed a significant right-occipital-CBF increase during the activation. We observed a positive significant correlation between the PANSS-P score and the left- frontal index at rest. Some negative symptoms such as difficulty in abstract thinking (N5) and lack of spontaneity and flow of conversation (N6) are associated to low frontal blood flow at rest. Affective blunting (N1) is associated to low left-frontal blood flow during activation. Conclusions. Our data support the hypothesis of hypofrontality, at rest and during activation, which means the incapacity of schizophrenic patients to increase the frontal CBF while performing the WCST (activation). Schizophrenia positive symptoms are associated to high left-frontal blood flow