CLONIDINE INFUSION INCREASES UPTAKE OF TC-99M-EXAMETAZIME IN ANTERIORCINGULATE CORTEX IN KORSAKOFF PSYCHOSIS

The effects upon regional brain function of infusing either saline or clonidine (1.5 mug/kg) has been examined-in 18 patients with alcoholic Korsakoff's psychosis using Tc-99m-hexamethylpropyleneamineoxime (Tc- 99m-HMPAO or Tc-99m-Exametazime) and Single Photon Emission Tomography (SPET or SPECT). The hypothesis tested was that frontal lobe function would be increased by adrenoceptor stimulation. This was confirmed by an increase in the uptake of Tc-99m-Exametazime into anterior cingula te regions of the frontal lobes. Patients were scanned before and afte r saline or clonidine infusion during performance of a verbal fluency task. There was a significantly increased performance of verbal fluenc y in patients given clonidine. This effect was variable and could not be unequivocably distinguished from increases in performance in the sa line treated group. Nevertheless, the increase in neuropsychological p erformance was also correlated with increased function in left dorsola teral frontal cortex within the clonidine treated group. An explorator y examination of other brain areas suggested that relative increases i n posterior cingulate cortex and changes in the symmetry of function w ithin the thalamus may also be produced by acute infusion of clonidine in Korsakoff patients. The findings support the idea that adrenergic mechanisms may modulate cognitive performance by actions on attentiona l systems within the brain. These appear to be located primarily withi n limbic cortex. It is, of course, notable that this can occur in pati ents with profound and disabling amnesia.