These data form the basis for the hypothesis that PDE10A inhibitors will have potential for the treatment of neuropsychiatric disorders in humans that are correlated with striatal hypofunction such as schizophrenia, obsessive-compulsive disorders, Parkinson’s disease, and Huntington’s disease, and make PDE10A an interesting target for diagnostic and therapeutic monitoring by non-invasive imaging techniques such as positron emission tomography (PET). Here, PDE10A is linked to Parkinson disease.