Brain imaging research on subjective responses to psychotropic drugs

OBJECTIVE: Neuroimaging studies on subjective responses to psychotropic drugs in humans were reviewed to examine progress in the field and identify gaps in knowledge. METHOD: An exhaustive search of computerized databases identified two categories of in vivo imaging studies: i) correlates of negative(dysphoric) subjective responses to neuroleptic use in schizophrenia, and ii) research on positive (euphoric) subjective responses, mostly from substance abuse population. RESULTS: Research has been largely confined to neurochemical imaging of dopamine in the striatal complex, confirming earlier speculations that impaired or deficient dopaminergic function is associated with dysphoric responses, and enhanced activity is associated with euphoric or pleasurable responses. Cerebral blood flow, regional metabolic rate and glucose utilization studies provided preliminary clues to the putative neuroanatomical sites. CONCLUSION: Neuroimaging techniques added credibility to the study of subjective responses; however, further studies are required to identify the underlying anatomical and neurochemical interactions in order to enhance their applied value.