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

Objective: To examine whether activation of cerebral blood flow velocity during cognitive stimulation, as measured by transcranial Doppler ultrasonography (TCD), is altered in patients with Huntington's Disease (HD). Background: Previous research suggests that resting cerebral blood flow in symptomatic and asymptomatic HD patients is reduced from expected premorbid levels. The effects of cognitive activation on this relative hypoperfusion in HD has not been studied extensively. Methods: We measured TCD flow velocity during rest and cognitive testing with the Porteus Maze Test and the Trails Test 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 among percent flow velocity change, a disability rating scale, and cognitive test scores were calculated. Results: In control subjects, anterior cerebral artery flow velocity and middle cerebral artery velocity increased during cognitive testing (p = 0.001). HD patients showed a smaller blood flow velocity increase in the anterior cerebral arteries during the Porteus Maze Test (p < 0.001) and the Trails Test, Part B (p < 0.001). In the left anterior cerebral artery, flow velocity fell an average of 4.2% below resting baseline levels during the Porteus Maze Test, and 1.2% below resting levels during the Trails Test. The magnitude of the cerebral blood flow velocity changes in the anterior cerebral artery correlated with a number of cognitive test scores and with a rating scale of functional disability. In addition, logistic regression was able to discriminate the KD patients from the control 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 left anterior cerebral artery flow velocity during visual spatial executive cognition testing compared with control subjects. Conclusions: These results suggest that activation of visual spatial executive functions cause decreased flow velocity in the anterior cerebral artery, but not the middle cerebral artery, in HD patients. These changes are related to test performance and functional capabilities.