Cortical dopamine in relation to negative symptoms and cognitive dysfunction in schizophrenia
03 / 2012 - unknown
Schizophrenia is a chronic, severely disabling psychiatric disorder characterized by positive/psychotic symptoms, negative symptoms (e.g. reduced motivation) and cognitive dysfunction (e.g. memory deficits). The positive symptoms are associated with a hyperdopaminergic dysregulation in the striatum of the brain and are treated with antipsychotics. However, the cognitive and negative symptoms are not related to this finding and remain very difficult to treat. One important theory hypothesizes that the cognitive and negative symptoms are related to hypodopaminergic dysfunction in the cortex, which may drive the hyperdopaminergic function of the striatum. Evidence for the cortical hypodopaminergia has never been obtained though. A tracer that is recently well-validated for measurement of cortical dopamine transmission now provides a unique opportunity. Therefore, this study aims to demonstrate that cortical dopamine transmission is decreased in schizophrenia and that this correlates with the cognitive and negative symptoms. In 20 drug-naïve schizophrenic patients and 20 healthy controls, we will measure cortical dopamine transmission and striatal dopamine synthesis capacity using state-of-the-art positron emission tomography (PET) imaging. Furthermore, cognitive function and negative and positive symptoms will be assessed. Confirmation of the hypothesis can provide a breakthrough in the understanding and treatment possibilities of cognitive and negative symptoms in schizophrenia.