Évaluation du statut neuropsychiatrique chez les patients schizophrènes après l'arrêt du traitement antipsychotique

Objectives: Schizophrenia and related psychoses are chronic brain disorders whose prognosis is often poor and whose pathophysiology remains obscure. Neuroimaging technologies such as PET (positron emission tomography), fMRI (functional magnetic resonance imaging), DTI (diffusion tensor imaging) and MRSI (magnetic resonance spectroscopic imaging) offer opportunities to elucidate the pathophysiology by studying brain function in living research subjects. The use of these techniques to study psychotic disorders is severely limited, however, by a critical methodological confound: antipsychotic treatment. The purpose of this protocol is to admit research subjects with schizophrenia and other related disorders to the Clinical Center, carefully evaluate their neuropsychiatric status, and discontinue psychotropic medications for a brief period so research subjects can be studied without the confound of antipsychotic treatment. Study Population: 700 participants The study will include research subjects with schizophrenia. Study Design: There are several phases to this protocol. The first phase is the Screening Evaluation and Stabilization Phase and includes gathering historical data, structured diagnostic interviews, general physical and laboratory assessments, basic physiological monitoring, neuropsychological testing, limited collection of blood and urine samples, and serial behavioral ratings. In the second phase (Coded Medication Phase), research subjects will receive blinded compounds that will contain inactive placebo or active antipsychotic administered in a crossover fashion. Patients and unit clinical nursing staff evaluating and caring for the patient will be blind to arm status. Each arm normally lasts 4 to 6 weeks. The total duration of this phase is 8 to 12 weeks. During the Coded Medication Phase, research subjects are enrolled in a series of neuroimaging and other approved studies designed to elucidate the neurobiology of these disorders. These include studies using neuropsychological testing, MEG, PET, fMRI, DTI, and MRSI. The antipsychotic free period is essential to distinguish the effects of illness versus medication. Outcome Measures: Parameters under investigation include traits that are candidate phenotypes for genetic studies and state-dependent aspects of brain function. The combined use of many neuroimaging modalities will allow us to look at the functional relationship between a variety of brain abnormalities hypothesized to play a role in schizophrenia. These include hippocampal neurochemical abnormalities, deficits in prefrontal cortical activation, and dysregulation of subcortical dopamine in a single research subject.