Neurovascular coupling in early stage dementia - A case-control study

Area of Science:

• Neuroscience
• Radiology
• Neurology

Background:

• Cerebral amyloid angiopathy (CAA) is common in Alzheimer's dementia but often undetected during life.
• In vivo markers for CAA and its vascular damage typically appear late in the disease process.
• Decreased neurovascular coupling during visual stimulation is a potential early MRI marker for CAA severity.

Purpose of the Study:

• To investigate the role of neurovascular coupling in Alzheimer's disease (AD) dementia and its early stages.
• To assess neurovascular coupling as an early indicator of cognitive impairment.
• To determine the association between neurovascular coupling and cognitive function in AD spectrum disorders.

Main Methods:

• Included 25 subjective cognitive impairment, 33 mild cognitive impairment, 17 dementia patients, and 44 controls.
• All participants underwent magnetic resonance imaging (MRI) of the brain and neuropsychological assessment.
• Univariate general linear modeling and linear regression analyses were used to assess neurovascular coupling and its association with cognition.

Main Results:

• Blood-oxygen-level-dependent (BOLD) amplitude was significantly lower in dementia (mean 0.8±0.2, p=0.001) and mild cognitive impairment (MCI) patients (mean 0.9±0.3, p=0.004) compared to controls (mean 1.1±0.2).
• Lower BOLD amplitude was independently associated with reduced scores across multiple cognitive domains.
• These findings suggest impaired neurovascular coupling is present even in early stages of cognitive decline.

Conclusions:

• Cerebrovascular dysfunction, likely due to CAA, is a significant comorbidity in early dementia stages.
• Impaired neurovascular coupling has an independent negative effect on cognitive function.
• Neurovascular coupling may serve as an early diagnostic marker for cognitive impairment related to CAA in AD.