Neural correlates of blunted affect in patients with schizophrenia : an fMRI study

Abstract

Objectives: Blunted affect may be associated with motor and social dysfunction in schizophrenia. This study was designed to investigate the neurobiological basis of blunted affect in patients with schizophrenia specifically in limbic regions and brain regions related to motor and social functioning.Methods: Fifteen patients with schizophrenia and 16 healthy controls were asked to reproduce facial expressions during functional magnetic resonance imaging (fMRI) scanning for three conditions: happy, sad and unmeaningful facial movement (UFM) conditions. Blunted affect was rated using the affective flattening subscale of the Scale for the Assessment of Negative Symptoms (SANS AF). Facial expressions were videotaped and rated using the Facial Expression Coding System (FACES). Results: Compared to healthy controls, the patient group was impaired for all expressive variables. The patient group exhibited decreased activity in the left premotor cortex, right superior parietal lobule, left insula and right cerebellum compared to the control group during the expression of happy and sad emotion relative to UFM condition. The percent signal change in the left premotor cortex was correlated with total facial expression score rated by FACES in the patient group. After controlling for facial movements, the patient group showed decreased activity in the right dorsolateral prefrontal cortex (DLPFC), right supplementary motor area, left motor cortex, right superior parietal lobule, left insula and right cerebellum compared to the control group during the expression of happy and sad emotion relative to UFM condition. The percent signal change in the left insula was correlated with the SANS AF score. The percent signal changes in the right DLPFC and right cerebellum were correlated with the Social Anhedonia Scale score.Discussion: These findings suggest that motor coordination problem may affect blunted affect in patients with schizophrenia. This study also provides evidence that blunted affect in schizophrenia may be influenced by the functional disturbance of the interconnected networks including the insula. In addition, the association of decreased activities in the DLPFC and cerebellum with increased social anhedonia found in this study suggests possible involvement of altered cortico-cerebellar circuit in social anhedonia in patients with schizophrenia.