Article

In Vivo D2 Dopamine Receptor Density in Psychotic and Nonpsychotic Patients With Bipolar Disorder

Department of Psychiatry, Johns Hopkins University, Baltimore, Md, USA.
Archives of General Psychiatry (Impact Factor: 13.75). 06/1995; 52(6):471-7. DOI: 10.1001/archpsyc.1995.03950180057008
Source: PubMed

ABSTRACT A prior positron emission tomographic study from The Johns Hopkins University, Baltimore, Md, using N-methylspiperone labeled with carbon 11 reported elevated basal ganglia D2 dopamine receptor density (Bmax) values in neuroleptic-naive schizophrenic patients compared with controls. We have now extended these studies to include patients with bipolar disorder.
Patients with bipolar disorder (n = 14) either had never received neuroleptic medication or had been neuroleptic-free for more than 6 months, and they met DSM-III criteria for currently symptomatic affective disorder. Patients with bipolar disorder were compared with matched schizophrenic patients and normal controls. All received two positron emission tomographic scans, the second of which was preceded by oral administration of haloperidol lactate, to permit the calculation of D2 dopamine receptor Bmax.
Diagnostic groups differed in Bmax by analysis of variance (P < .0001); post hoc tests showed higher Bmax values for psychotic patients with bipolar disorder and schizophrenic patients compared with normal controls and for schizophrenic patients and psychotic patients with bipolar disorder compared with nonpsychotic patients with bipolar disorder. Among patients with bipolar disorder, Bmax values correlated significantly with the severity of psychotic symptoms (r = .63) on the Present State Examination but not with the severity of nonpsychotic mood symptoms.
We conclude that, like schizophrenic patients, patients with psychotic bipolar disorder have elevations of D2 dopamine receptor Bmax values and that such elevations in affective disorder are more closely associated with the presence of psychosis than with mood abnormality. Elevations in dopamine receptor values thus may occur in psychiatric states that are characterized by psychotic symptoms rather than being specific to schizophrenia.

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    • "These findings suggest that individuals with BD I exhibit abnormal functioning in both cortical and subcortical regions, and that although patients may perform comparably to controls on certain behavioral tasks, they also harness different regions of the brain to compensate for hypoactive activity in regions of the brain typically used to complete such tasks. PET studies on dopamine have found that dopamine D1 receptor binding potentials are reduced in the frontal cortex but not in the caudate nucleus (Suhara et al., 1992; Wong et al., 1985), whereas D2 receptor density was found to be higher in patients with psychosis (Pearlson et al., 1995). Another study by Zubieta and colleagues (2000) found increased thalamic and brain stem concentrations of central vesicular monoamine transporter protein (VMAT2), which is a marker of monoaminergic activity. "
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