Visual system integrity and cognition in early Huntington's disease

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Huntington's disease (HD) is associated with posterior cortical volume loss and impaired visuomotor function.
• The relationship between structural changes, neural activity, and cognitive deficits in early HD remains unclear.

Purpose of the Study:

• To investigate brain structure and resting-state visual network activity in early HD patients using MRI.
• To determine if posterior cortical volume loss impacts neural activity and predicts cognitive dysfunction.

Main Methods:

• Utilized magnetic resonance imaging (MRI) for brain structure and functional MRI (fMRI) for visual network activity.
• Employed group independent component analysis for fMRI data and voxel-based morphometry for structural analysis.
• Assessed visuomotor and visual object perception using the Symbol Digit Modalities Test (SDMT) and Visual Object and Space Perception Battery.

Main Results:

• Patients with early HD exhibited occipitotemporal atrophy and poorer visuomotor and visual object performance compared to controls.
• Decreased activity in the left fusiform cortex and increased activity in the left cerebellum were observed in HD patients.
• Lower fusiform cortex activity correlated with reduced SDMT performance and higher disease burden, independent of atrophy.

Conclusions:

• Regionally specific functional abnormalities in the visual system, particularly the fusiform cortex, contribute to visuomotor deficits in Huntington's disease.
• While occipital volume changes occur, they do not fully explain the observed neural dysfunction in HD patients.