Most diagnostic studies with multivoxel pattern analysis (MVPA) have been based on structural imaging and some have obtained classification check details accuracies around 90% (Table 3). Although at such levels of accuracy, MVPA analysis of structural scans may in principle aid clinical diagnosis, accurately classifying psychiatric disease in patients suffering manifest clinical symptoms is perhaps not the greatest challenge of psychiatry. A real clinical benefit might be derived from the early detection of cases at high risk and the prediction of natural history

and treatment outcome. Koutsouleris et al. (2009) tested patients with prodromal symptoms of schizophrenia and obtained classification accuracies over 80% with whole-brain gray matter patterns between controls, early and late psychosis-risk states, as well as prediction of conversion to psychotic

disorder. The effectiveness of medication in preventing psychiatric disease even in psychologically well-defined high-risk groups (such as prodromal patients for schizophrenia or MCI for AD) is still not proven, and a better prediction of conversion risk through imaging would greatly aid clinical trials aimed at developing drugs that could be administered prophylactically in individuals with the highest risk. The prediction accuracies obtained this website by Koutsouleris et al. (2009) were in the upper range of those reported for purely clinical predictors (Klosterkötter et al., 2011), but a formal evaluation whether imaging biomarkers provide added value to clinical and psychometric predictors of psychosis is still lacking. Gray matter

volumetry is not the only parameter that has been utilized for such diagnostic and predictive purposes. Using DTI, Ingalhalikar et al. (2010) obtained high classification accuracy for schizophrenia in adults and for ASD in children. Similarly, Rathi et al. (2010) applied this method for early detection of first episode psychosis in schizophrenia. fMRI has also been used, particularly in depression, both during the resting state (Craddock et al., 2009) and during presentation of emotional facial expressions (Fu et al., 2008). Although the classification accuracy of MVPA techniques has been high in several studies, they may not reveal much about the underlying neurobiology of Levetiracetam the disorder. The mutual dependence of signal from different voxels often prevents simple neuroanatomical interpretations. However, the feature maps may provide some indication of which neuroanatomical correlates are particularly relevant for the diagnosis in question. For example, the patients with fragile X syndrome (FXS) showed a distinctive pattern of volume increases (basal ganglia) and decreases (frontal lobe) (Hoeft et al., 2008), and the late prodromal group showed relative gray matter decrease in many cortical areas but also increases in other areas including the thalamus (Koutsouleris et al.