USC study links brain's local wiring to cognition in older adults
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Scientists at USC's Stevens INI found that the condition of superficial white matter, the brain's local communication pathways, may influence how gray matter loss affects cognition in older adults. The study, published in Alzheimer's & Dementia, analyzed brain imaging and cognitive tests from 459 adults aged 60 and older in India. Healthier superficial white matter was most consistently linked to better language performance.
Key Facts
- The study included 459 adults aged 60 and older from communities across India.
- The research was published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.
- Superficial white matter consists of short, curved nerve fibers directly beneath the brain's gray matter.
- Participants underwent cognitive assessments covering language, memory, executive function, and visuospatial ability.
- The most consistent link between superficial white matter health and cognition was in language performance.
Study Design
The study was conducted by scientists at the Mark and Mary Stevens Neuroimaging and Informatics Institute (Stevens INI) at the Keck School of Medicine of USC. Researchers used diffusion MRI to examine microscopic features of superficial white matter, focusing on neurite density and free water content. The cohort comprised 459 adults aged 60 and older living in communities across India, making it one of the first studies of superficial white matter in a low- and middle-income country population. Cognitive testing covered language, memory, executive function, and visuospatial ability.
Brain Tissue Roles
Gray matter contains many of the nerve cells responsible for processing information, while superficial white matter forms a thin layer of short, curved fibers directly beneath it. These local fibers connect nearby regions of the cerebral cortex, functioning like local roads linking neighboring areas. Yingxu Liu, PhD, a postdoctoral scholar at Stevens INI and first author, stated that cognitive health depends not only on gray matter preservation but also on the condition of the connecting wiring. Lower neurite density or increased free water in superficial white matter can indicate tissue damage from processes such as myelin loss, inflammation, or swelling.
Cognitive Associations
The most consistent relationship between superficial white matter health and cognitive performance was observed in language abilities. People with healthier superficial white matter tended to perform better on language tests. The findings suggest that the condition of local communication pathways may influence how strongly gray matter loss affects cognition later in life.
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