Following a single haloperidol challenge in normal subjects, they found a significant decrease in cortical metabolism with sparing of the basal ganglia. These metabolic alterations extended beyond the target regions of dopaminergic projections. Using the same experimental strategy in unmedicated schizophrenic patients, the researchers found that drug treatment responders and treatment non-responders show very different patterns of metabolic response to a neuroleptic challenge. Overall, only the non-responsive patients showed decreased metabolism after challenge in all brain regions except the striatum, a finding consistent with results observed in normal male subjects. The study demonstrated individual differences in the brain's neurochemical adaptation to blockade and showed that these may be linked to treatment response.
Further studies using magnetic resonance imaging are in progress.