DECREASED BENZODIAZEPINE RECEPTOR-BINDING IN MACHADO-JOSEPH-DISEASE

Benzodiazepine receptor binding was assessed in four Japanese men with Machado-Joseph disease. Methods: The distribution of benzodiazepine r eceptors was measured by radionuclide imaging (SPECT) after intravenou s administration of I-123-iomazenil (Ro 16-0154), Results: SPECT demon strated decreased binding throughout the cerebral cortex and cerebellu m in all patients. Binding potential (receptor concentration x affinit y) was diffusely decreased in cerebral cortex, thalamus, striatum and cerebellum compared with control subjects, suggesting that GABAergic f unction may be decreased globally in these patients. Cerebral blood fl ow was largely normal, and no cerebral cortical atrophy was evident on MRI, Conclusion: Iodine-123-iomazenil SPECT may become a potent metho d for detecting impairment of the cerebral cortex even before brain pe rfusion SPECT or MRI can reveal early abnormalities.