Cerebral Vasomotor Reactivity in Amnestic Mild Cognitive Impairment

Area of Science:

• Neuroscience
• Cerebrovascular Medicine
• Cognitive Neurology

Background:

• Cerebral blood flow (CBF) regulation via cerebral vasomotor reactivity (CVMR) is crucial for brain health.
• Alterations in CVMR are suspected in amnestic mild cognitive impairment (aMCI), a precursor to Alzheimer's disease (AD), but require further investigation.

Purpose of the Study:

• To investigate whether CVMR is altered in individuals with aMCI.
• To explore the association between CVMR and cognitive performance in aMCI patients.

Main Methods:

• Fifty-three aMCI patients and 22 cognitively normal (CN) individuals underwent CBF velocity (CBFV) and end-tidal CO2 (EtCO2) measurements during controlled hypercapnia and hypocapnia.
• Cerebrovascular conductance index (CVCi) was calculated to normalize for blood pressure variations.
• Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and specific neuropsychological tests for memory and executive functions.

Main Results:

• While resting CBFV and MMSE scores did not differ between groups, aMCI patients exhibited significantly reduced CVMR during hypocapnia and increased CVMR during hypercapnia compared to CN.
• Reduced CVMR in aMCI was observed in both CBFV and CVCi measurements (p < 0.05).
• Cognitive performance, particularly in memory (Logical Memory) and executive function (DKEFS Trail Making), was correlated with CVMR measures during both hypocapnia and hypercapnia.

Conclusions:

• The findings demonstrate altered CVMR in individuals with aMCI, suggesting underlying cerebrovascular dysfunction.
• The association between impaired CVMR and cognitive deficits highlights the role of cerebrovascular health in the progression of cognitive decline and AD risk.