Brain β-Amyloid and Atrophy in Individuals at Increased Risk of Cognitive Decline

Area of Science:

• Neuroscience
• Gerontology
• Radiology

Background:

• The link between brain beta-amyloid and regional atrophy in elderly individuals at risk for dementia is not fully understood.
• Cardiovascular risk factors are associated with increased risk of cognitive decline.

Purpose of the Study:

• To investigate the association between brain beta-amyloid load and regional gray matter (GM) and white matter (WM) volumes.
• To explore these relationships in older adults at increased risk of cognitive decline.

Main Methods:

• Forty subjects (63-81 years) underwent PET imaging with 11C Pittsburgh compound-B for beta-amyloid and 3D MR imaging for GM/WM volumes.
• Clinical, genetic, and neuropsychological evaluations assessed cognitive function and cardiovascular risk factors.

Main Results:

• Sixteen subjects were positive for cortical beta-amyloid.
• No significant GM or WM volume differences were found between beta-amyloid positive and negative groups.
• In beta-amyloid positive individuals, increased beta-amyloid load correlated with reduced GM volume in the left prefrontal and right temporal lobes.

Conclusions:

• Increases in brain beta-amyloid are significantly associated with regional GM volume reductions in individuals at high risk for cognitive decline.
• Findings support a model where beta-amyloid accumulation initiates neurodegeneration in memory systems prior to clinical cognitive impairment.