GAD1 and schizophrenia: Our findings extend other evidence of GABAergic dysfunction, such as reduced levels of GAD67 in the frontal cortex (Fung et al. 2010; Volk et al. 2000), to identify a particular sub-class of GABAergic interneuron, parvalbumin-positive interneurons, as being affected in schizophrenia, although they do not exclude other sub-types also being involved.