Aging and central vision loss: Relationship between the cortical macro-structure and micro-structure.

Area of Science:

• Neuroimaging
• Neuroscience
• Ophthalmology

Background:

• Aging and central vision loss are linked to cortical atrophy.
• The relationship between cortical thinning and cellular structure remains unclear.

Purpose of the Study:

• To compare macro- and micro-structure of gray and white matter in macular degeneration patients and healthy controls.
• To investigate the association between vision loss, cortical thinning, and underlying cellular changes using multimodal MRI.

Main Methods:

• Multimodal MRI, including diffusion-tensor imaging (DTI), was used on 38 patients with juvenile (JMD) or age-related (AMD) macular degeneration and 38 healthy controls (aged 19-84).
• Factor analysis was employed to assess distinct components of brain structure using cortical thickness, tissue-dependent, and DTI-based measures.

Main Results:

• Age-related cortical thinning and increased diffusion were widespread across the cortex.
• Specific micro-structural changes (e.g., altered T1/T2 intensities, reduced anisotropy) were regionally confined.
• Vision loss correlated with occipital cortical thinning and gray matter diffusion enhancement; AMD patients showed additional diffusion changes and thinning in specific regions compared to JMD patients.

Conclusions:

• Multimodal imaging effectively quantifies brain structural changes.
• Age-related cortical thinning results from diverse micro-structural causes.
• Juvenile and age-related macular degeneration are associated with distinct patterns of micro-structural brain alterations.