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Altered dopaminergic function and negative symptoms in drug-free patients with schizophrenia. [123I]-iodobenzamide
M B Knable1, M F Egan, A Heinz
1Clinical Disorder Branch, National Institute of Mental Health, Washington, DC 20032, USA.
Background:
Previous in vivo studies of schizophrenia with dopamine D2 receptor radioligands have yielded contradictory results. No prior study has used multiple scans to examine within-subject clinical change.
Method:
Twenty-one patients were studied with [123I]-iodobenzamide single photon emission computed tomography about two weeks after neuroleptic withdrawal. Thirteen of the 21 completed a second scan about four weeks after neuroleptic withdrawal. Sixteen controls were scanned for comparison.
Results:
There was no significant difference between groups in [123I]-iodobenzamide uptake at either scanning session. No significant correlations with demographic variables (age, illness duration, drug-free period), or clinical ratings (positive and negative symptoms, movement disorder) were observed at either scanning session. There was a significant correlation between change in [123I]-iodobenzamide uptake and change in negative symptom ratings for the subjects who underwent two scans (r = 0.72, P < 0.05).
Conclusions:
Worsening of negative symptoms may be associated with increased availability of striatal D2 receptors, perhaps because of decreased concentrations of endogenous dopamine.