First study
The researchers say that, to their knowledge, this is the first study to find major abnormalities in WM tracts within the brain and correlations between DTI indexes and clinical features in patients with HD.
The frontothalamic circuit is “thought to play an important role in executive functions, including working memory, attention, reward processing, and decision-making,” the investigators write.
Previous research implied that frontothalamic circuit–related cognitive functions are “impaired in patients with HD” and suggested that these impairments “underlie hoarding symptoms such as acquiring, saving, and cluttering relevant to HD.”
The decreased FA in the left SLF “reflects alterations in WM in the frontoparietal network in these patients and may be associated with cognitive impairments, such as task switching and inhibition, as shown in previous studies,” the researchers write.
Additionally, changes in FA and RD often “indicate myelin pathology,” which suggest that HD pathophysiology “may include abnormalities of myelination.”
However, the investigators cite several study limitations, including the “relatively small” sample size, which kept the DTI analysis from being “robust.” Moreover, many patients with HD had comorbid psychiatric disorders, which have also been associated with microstructural abnormalities in WM, the researchers note.
Novel approach
Commenting for this news organization, Michael Stevens, PhD, director, CNDLAB, Olin Neuropsychiatry Research Center, and adjunct professor of psychiatry at Yale University School of Medicine, New Haven, Conn., said the study “provides useful new clues for understanding HD neurobiology” because of its novel approach in assessing microstructural properties of major WM tracts.
The study’s “main contribution is to identify specific WM pathways between brain regions as worth looking at closely in the future. Some of these regions already have been implicated by brain function neuroimaging as abnormal in patients who compulsively hoard,” said Dr. Stevens, who was not involved in the research.
He noted that, when WM pathway integrity is affected, “it is thought to have an impact on how well information is communicated” between the brain regions.
“So once these specific findings are replicated in a separate study, they hopefully can guide researchers to ask new questions to learn exactly how these WM tracts might contribute to hoarding behavior,” Dr. Stevens said.
The study had no specific funding. The investigators and Dr. Stevens have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.