Altered patterns of regional cerebral blood flow in patients with Huntington's disease: A SPECT study during rest and cognitive or motor activation

Previous research using functional transcranial Doppler sonography showed t hat blood flow velocity in the anterior cerebral artery is significantly le ss in patients with Huntington's disease (HD) than in healthy volunteers wh ile they are completing mazes. The current research used SPECT to study reg ional cerebral blood flow (rCBF) in patients with HD during rest and maze t esting. Methods. Seven patients with HD and 9 healthy volunteers were injec ted twice with 0.96-1.15 GBq Tc-99m-labeled hexamethylpropylene amine oxime . During the 10 min after injection, subjects either solved mazes or rested with their eyes open while looking at a modified maze. After SPECT, count density was obtained from If brain regions and corrected for decay and inje cted dose. Two types of data generated from this experiment, including abso lute regional counts per pixel in the regions of interest and count density computed as a percentage of activity in the lateral cerebellum, were compa red between groups. Results. During rest, the absolute regional count densi ty was greater in the HD brains than in the healthy brains (P < 0.001). Cou nt density was typically between 8% and 13% higher in the HD group than in the healthy group, The single exception was the caudate density, for which the 2 groups had similar values. No significant differences in absolute reg ional count density were observed between groups during maze testing. When rCBF was calculated as a percentage of cerebellar rCBF, analysis of covaria nce found decreases in HD caudate density (P < 0.001) and orbital frontal c ortex density (P < 0.005) during maze testing. Changes in rCBF in the cauda te nucleus predicted gene status (P = 0.0007) and correlated with time to c omplete the mazes (P < 0.05). Conclusion. Patients with HD showed an increa se in resting rCBF for all brain regions measured except the caudate nucleu s. When rCBF was calculated as a percentage of cerebellar blood flow, rCBF in the striatum and orbital cortex in patients with HD was less during maze testing than during rest. Although the cause of these rCBF changes ih HD p atients is unclear, nitric oxide synthase, a regulator of vasomotor activit y, may be involved.