Decreased density of GABA-A receptors in the left sensorimotor cortex in akinetic catatonia: investigation of in vivo benzodiazepine receptor binding.

OBJECTIVES: Catatonia is a psychomotor syndrome with concomittant akinesia and anxiety which both respond almost immediately to benzodiazepines such as lorazepam. The benzodiazepine receptor distribution was therefore investigated in akinetic catatonia with single photon emission tomography (SPECT) using iodine-123-iomazenil ((123) I Iomazenil).
METHODS: Ten akinetic catatonic patients, 10 psychiatric controls (similar age, sex, medication, and underlying psychiatric diagnosis but without catatonic syndrome), and 20 healthy controls were investigated with SPECT 2 hours after injection of (123) I Iomazenil. To exclude potential effects of cerebral perfusion (r-CBF) r-CBF was additionally investigated with Tc-99mECD SPECT.
RESULTS: Catatonic patients showed significantly lower iomazenil binding and altered right-left relations in the left sensorimotor cortex compared with psychiatric (p<0.001) and healthy (p<0.001) controls. In addition, there was significantly lower r-CBF in the right lower prefrontal and parietal cortex in catatonia whereas in the left sensorimotor cortex no differences in r-CBF between groups were found. Catatonic motor and affective symptoms showed significant correlations (p<0.05) with benzodiazepine binding in the left sensorimotor cortex as well as with right parietal r-CBF.
CONCLUSIONS: Reduced iomazenil binding suggests decreased density of GABA-A receptors in the left sensorimotor cortex in akinetic catatonia. In addition to reduced GABA-A receptor density in the left sensorimotor cortex the parietal cortex seems to be involved in pathophysiology of catatonic symptoms. It is concluded that, considering results from correlation analyses, both emotional and motor symptoms in catatonia seem to be closely related to left sensorimotor and right parietal alterations.