Cerebral blood flow velocity decreases during cognitive stimulation in Huntington's disease

Objective: To examine whether activation of cerebral blood flow velocity du ring cognitive stimulation, as measured by transcranial Doppler ultrasonogr aphy (TCD), is altered in patients with Huntington's Disease (HD). Backgrou nd: Previous research suggests that resting cerebral blood flow in symptoma tic and asymptomatic HD patients is reduced from expected premorbid levels. The effects of cognitive activation on this relative hypoperfusion in HD h as not been studied extensively. Methods: We measured TCD flow velocity dur ing rest and cognitive testing with the Porteus Maze Test and the Trails Te st in 12 normal control subjects and 10 gene-positive HD patients. Percent change (i.e., flow during testing/resting) of flow velocity in the anterior and middle cerebral arteries were compared between groups. Correlations am ong percent flow velocity change, a disability rating scale, and cognitive test scores were calculated. Results: In control subjects, anterior cerebra l artery flow velocity and middle cerebral artery velocity increased during cognitive testing (p = 0.001). HD patients showed a smaller blood flow vel ocity increase in the anterior cerebral arteries during the Porteus Maze Te st (p < 0.001) and the Trails Test, Part B (p < 0.001). In the left anterio r cerebral artery, flow velocity fell an average of 4.2% below resting base line levels during the Porteus Maze Test, and 1.2% below resting levels dur ing the Trails Test. The magnitude of the cerebral blood flow velocity chan ges in the anterior cerebral artery correlated with a number of cognitive t est scores and with a rating scale of functional disability. In addition, l ogistic regression was able to discriminate the KD patients from the contro l group based on blood flow velocity changes (p = 0.0025). When HD patients were divided into more (i.e., HD with chorea; n = 4) and less impaired (i. e., without chorea; n = 6) groups, both showed significant decreases in lef t anterior cerebral artery flow velocity during visual spatial executive co gnition testing compared with control subjects. Conclusions: These results suggest that activation of visual spatial executive functions cause decreas ed flow velocity in the anterior cerebral artery, but not the middle cerebr al artery, in HD patients. These changes are related to test performance an d functional capabilities.