EEG analysis may help track Huntington’s progression, review finds
Brain's electrical activity could serve as biomarker for early diagnosis, monitoring
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Electroencephalography (EEG), a noninvasive test of electrical activity in the brain, may be a useful tool to help track disease progression in Huntington’s disease, as patients tend to show certain characteristic abnormalities that are associated with symptom severity.
“EEG may serve as a potential biomarker for early diagnosis and monitoring of Huntington’s,” the researchers wrote.
However, there are substantial limitations with the available research on EEG in Huntington’s, so more studies, particularly those tracking how EEG abnormalities evolve over time, are crucial.
These are the main takeaways of a review study, “Electroencephalography biomarkers in Huntington’s disease: A systematic review of resting-state and sleep EEG alterations,” published in Clinical Neurophysiology by a team of researchers in the U.S. and Iran.
Huntington’s disease is a genetic disorder that leads to the death and degeneration of nerve cells in the brain. Huntington’s symptoms include movement disorders, cognitive challenges, and behavioral abnormalities.
EEG is a common, noninvasive test in which electrodes are placed on the scalp to monitor the brain’s electrical activity. EEG recordings can be used to determine absolute relative power (the total amount of electrical activity) and detect changes in specific brainwave patterns known as alpha, beta, delta, and theta bands.
EEG studies show varied results
“In the context of HD [Huntington’s disease], EEG can be used for monitoring changes in brain function, identifying early manifestations of disease, and assessing the effectiveness of treatments,” the researchers wrote.
However, results of EEG studies in Huntington’s disease have been inconsistent, and the researchers noted that this may be due to variability in protocols, EEG analysis, and disease severity.
“A systematic review of the current literature could help address the gap in knowledge and provide a framework for investigating and implementing EEG in HD management,” the team wrote.
The scientists combed through scientific literature published up to January 2024 to identify EEG abnormalities associated with Huntington’s and investigate a potential association between these abnormalities and Huntington’s severity. They identified 23 studies reporting EEG data from people with Huntington’s; most included a control group. Except for one study in Australia, all were conducted in North America or Europe.
Data from resting-state EEGs showed that people with Huntington’s consistently had significantly lower alpha band power.
“Across studies, the most robust finding was the reduction in alpha power in HD patients compared to controls,” the researchers wrote.
Another consistent finding was a significant increase in delta-band activity in Huntington’s patients.
However, beta and theta band activity showed more variability, with some studies reporting significant increases and others significant reductions in people with Huntington’s. Reduced theta activity, however, was consistently reported by a few studies that conducted EEG recordings while patients were asleep.
Some of these changes were detected in people carrying a Huntington’s-causing mutation but not yet showing symptoms (premanifest stage).
A few studies tested whether EEG recordings were altered in patients on medications like antidepressants or antipsychotics, but results generally showed no notable changes in EEG patterns with these medications.
Many of the studies reported statistically significant associations between EEG measures and disease severity assessments. In particular, reduced alpha power was consistently associated with greater cognitive and motor deficits, while greater delta-band activity and reduced theta activity were each linked to more severe disease and cognitive impairment.
“EEG in Huntington’s disease reveals consistent alpha power reduction, increased delta activity … and disrupted sleep architecture,” the researchers wrote. “EEG’s potential as a non-invasive biomarker for early diagnosis and disease monitoring can be seen by these alterations, which are detectable even in premanifest stages and correlate with cognitive and motor impairment.”
However, the team stressed that the available studies had major limitations: Most were small, they used different methods, and they generally assessed patients at a single point in time.
Standardized, [follow-up], and [multi-method] studies are needed to validate these findings and determine their prognostic value,” the researchers concluded.
