Loss of Striatal [ 76 Br]Bromospiperone Binding Sites Demonstrated by Positron Tomography in Progressive Supranuclear Palsy

Using positron tomography and ⁷⁶Br-labeled bromospiperone, a neuroleptic drug with high affinity for the dopamine (DA) receptors, we have estimated the specific binding of the radiotracer to striatal DA receptors in seven patients suffering from progressive supranuclear palsy. Compared with age- and sex-matched control subjects, we found a significant (p < 0.02) decrease of the striatum–cerebellum uptake ratio in progressive supranuclear palsy patients, suggesting loss of striatal DA receptors. This in vivo study confirms recent postmortem data on progressive supranuclear palsy patients and provides an explanation for the lack of benefit from l-DOPA and DA agonists in this condition, despite reduced nigrostriatal dopaminergic function.