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Increased CBF velocity during word fluency in Huntington's disease patients
1Dept. Psychiatry, Huntington's Disease Treatment Center, University of Connecticut Medical School, Farmington, USA. Deckel@Psychiatry.uchc.edu
Insights
Huntington's disease (HD) patients show altered cerebral blood flow (CBF) during cognitive tasks. Speech production increased CBF velocity in HD, unlike other tasks, indicating a fundamental regulation disturbance.
Area of Science:
- Neuroscience
- Neurology
- Cerebrovascular Physiology
Background:
- Huntington's disease (HD) is a neurodegenerative disorder affecting cognitive and motor functions.
- Previous research indicates abnormal cerebral blood flow (CBF) in HD patients during certain tasks.
- Understanding CBF regulation is crucial for managing HD progression.
Purpose of the Study:
- To investigate the impact of word fluency and reading tasks on cerebral blood flow velocity in HD patients.
- To differentiate the effects of cognitive versus motor components of word fluency on CBF.
- To explore potential correlations between CBF changes and disease severity in HD.
Main Methods:
- Functional transcranial Doppler ultrasonography (fTCD) was used to measure cerebral flow velocity in the anterior (ACA) and middle (MCA) cerebral arteries.
- Thirteen healthy controls and nine gene-positive HD patients participated.
- Tasks included aloud word fluency, silent word fluency, and a reading test to isolate motor and cognitive demands.
Main Results:
- HD patients exhibited increased CBF velocity in the ACA during aloud word fluency compared to controls.
- Silent word fluency led to decreased CBF velocity in HD patients relative to controls, suggesting motor involvement.
- CBF velocity changes correlated with word fluency scores and could predict group assignment (control, mild HD, moderate HD).
Conclusions:
- CBF velocity in HD is dysregulated during both cognitive and motor tasks.
- Speech production uniquely increases CBF velocity in HD patients, contrasting with findings from motor tasks.
- These results suggest a fundamental disturbance in CBF regulation in Huntington's disease, potentially involving pathways like nitric oxide.
Abstract:
1. This study examined the effects of word fluency and reading on cerebral blood flow in Huntington's disease (HD) patients. 2. Changes in cerebral flow velocity in the anterior (ACA) and middle (MCA) cerebral arteries were measured with functional transcranial Doppler ultrasonography (fTCD) in 13 normal controls and 9 gene positive HD patients. To control for motor effects of word fluency, two "control" conditions, including silent word fluency and a reading test, were also administered to all subjects. 3. Cerebral blood flow velocity was increased during the out loud word fluency test in the ACA, but not MCA, in the HD group compared to controls. This increase was due to motor components of the test, as during silent word fluency the HD group had a decrease in cerebral blood flow relative to controls. Significant correlations between blood flow in the ACA and word fluency test scores were found. Cerebral blood flow velocity during testing also was able to predict group assignment (i.e., control vs. mild HD vs. moderate HD). 4. These findings add to a growing body of literature suggesting that CBF velocity in HD is abnormal during cognitive and motor tasks. Although previous work reported that CBF velocity in HD is decreased during hand use on a maze test, the current experiment finds that speech production increases cerebral blood flow velocity in HD patients. Collectively, these results point to a fundamental disturbance in the regulation of CBF in HD. Mechanisms that could account for these findings, including the potential involvement of nitric oxide, are discussed.