MR and genetics in schizophrenia: focus on auditory hallucinations.

Although many structural and functional abnormalities have been related to schizophrenia, until now, no single biological marker has been of diagnostic clinical utility. One way to obtain more valid findings is to focus on the symptoms instead of the syndrome. Auditory hallucinations (AHs) are one of the most frequent and reliable symptoms of psychosis. We present a review of our main findings, using a multidisciplinary approach, on auditory hallucinations. Firstly, by applying a new auditory emotional paradigm specific for psychosis, we found an enhanced activation of limbic and frontal brain areas in response to emotional words in these patients. Secondly, in a voxel-based morphometric study, we obtained a significant decreased gray matter concentration in the insula (bilateral), superior temporal gyrus (bilateral), and amygdala (left) in patients compared to healthy subjects. This gray matter loss was directly related to the intensity of AH. Thirdly, using a new method for looking at areas of coincidence between gray matter loss and functional activation, large coinciding brain clusters were found in the left and right middle temporal and superior temporal gyri. Finally, we summarized our main findings from our studies of the molecular genetics of auditory hallucinations. Taking these data together, an integrative model to explain the neurobiological basis of this psychotic symptom is presented.