New metric detects early Alzheimer’s changes in brain's white matter

Alzheimer's disease has traditionally been studied as a condition that primarily affects the brain's gray matter, where neuronal cell bodies are located and some of the disease's most characteristic lesions accumulate. However, growing evidence indicates that white matter is also impacted during the early stages of the neurodegenerative process.

A study led by the Neuroimaging of Aging and Neurodegenerative Diseases research group at the Sant Pau Research Institute (IR Sant Pau) analyzed these abnormalities using a diffusion magnetic resonance imaging metric known as PSMD-short for peak width of skeletonized mean diffusivity-which can detect microscopic changes in white matter tracts that may not be visible on conventional MRI scans.

The findings, published in the journal Alzheimer's & Dementia, show that PSMD identifies early white matter abnormalities in both sporadic Alzheimer's disease and Alzheimer's disease associated with Down syndrome. In the latter population, these changes are observed at around age 38, approximately 15 years before Alzheimer's dementia typically becomes clinically apparent.

This study supports the idea that Alzheimer's disease does not affect only gray matter. White matter is also altered early in the disease and can provide relevant information about its progression."