FMRI, antipsychotics and schizophrenia. Influence of different antipsychotics on BOLD-signal

In the last decade, functional Magnetic Resonance Imaging (FMRI) has been increasingly used to investigate the neurobiology of schizophrenia. This technique relies on changes in the blood-oxygen-level-dependent (BOLD) - signal, which changes in response to neural activity. Many FMRI studies on schizophrenia have examined medicated patients, but little is known about the effects of antipsychotic medication on the BOLD-signal. In this review we investigated to what extent studies in patients with schizophrenia (SC), who were treated with different antipsychotics, could give insight in the effects of antipsychotics on the BOLD-signal. A PubMed search was performed using the search items "schizophrenia", "FMRI", "antipsychotics" and "schizophrenia", "BOLD", "antipsychotics". Only articles in which there were at least two groups of patients with different treatments or in which patients were scanned twice with different treatments were selected. 18 articles, published between 1999 and 2009, fulfilled these criteria. Paradigms and results of these studies were compared regarding differences induced by the administered antipsychotics. This analysis showed no general effect of antipsychotics on the BOLD-signal. However, there is some evidence that the extent of blockade of the dopamine (DA) D(2) receptor does influence the BOLD-signal. Higher affinity to the dopamine D2 receptor, as expressed by a higher/lower inhibition constant (Ki) seems to cause a decrease in BOLD-signal.