Neural correlates of observation of disgusting images in subjects with first episode psychosis and post-traumatic stress disorder

The aim of this study was to analyze neural responses to disgusting images in individuals with first episode psychosis and post-traumatic stress disorder (PTSD). Although anhedonia is a common symptom in both disorders we expected that they would be associated with different neurophysiological abnormalities and patterns of activation. We recruited three groups of participants: 13 individuals with first episode psychosis, 10 individuals with PTSD who had survived the April 2009 L Aquila earthquake and 25 healthy controls matched for age and education. All individuals participated in a functional imaging experiment in which they watched six alternating blocks of disgusting and scrambled images whilst undergoing scanning with a General Electric 1.5T whole-body scanner. We estimated individuals' beta-weights, extracting 22 clusters corresponding to 22 significant areas. Findings were consistent with other neuroimaging studies; the active areas (i.e. amygdala, insula, inferior and medial frontal gyrus) have consistently been associated with emotional experiences. Statistical analysis revealed important group differences in intensity and direction (positive or negative) of signal from baseline during disgusting condition. Although these results are preliminary they show that functional neuroimaging techniques may make a valuable contribution to differential diagnosis of first episode psychosis and PTSD.