Reduced global brain metabolism but maintained vascular function in amnestic mild cognitive impairment

• Published in: Journal of cerebral blood flow and metabolism Vol. 37; no. 4; pp. 1508 - 1516
• Main Authors: Thomas, Binu P, Sheng, Min, Tseng, Benjamin Y, Tarumi, Takashi, Martin-Cook, Kristen, Womack, Kyle B, Cullum, Munro C, Levine, Benjamin D, Zhang, Rong, Lu, Hanzhang
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.04.2017
• Subjects: Aged; Amnesia - diagnostic imaging; Amnesia - metabolism; Amnesia - physiopathology; Brain - blood supply; Brain - diagnostic imaging; Cerebrovascular Circulation - physiology; Cognitive Dysfunction - diagnostic imaging; Cognitive Dysfunction - metabolism; Cognitive Dysfunction - physiopathology; Female; Fluorodeoxyglucose F18; Humans; Magnetic Resonance Imaging - methods; Male; Middle Aged; Original; Oxygen - blood; Oxygen - metabolism; Radiopharmaceuticals; cerebral metabolic rate of oxygen; cerebrovascular reactivity; Mild cognitive impairment; elderly controls; oxygen extraction fraction
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1177/0271678X16658662

Amnestic mild cognitive impairment represents an early stage of Alzheimer’s disease, and characterization of physiological alterations in mild cognitive impairment is an important step toward accurate diagnosis and intervention of this condition. To investigate the extent of neurodegeneration in patients with mild cognitive impairment, whole-brain cerebral metabolic rate of oxygen in absolute units of µmol O2/min/100 g was quantified in 44 amnestic mild cognitive impairment and 28 elderly controls using a novel, non-invasive magnetic resonance imaging method. We found a 12.9% reduction (p = 0.004) in cerebral metabolic rate of oxygen in mild cognitive impairment, which was primarily attributed to a reduction in the oxygen extraction fraction, by 10% (p = 0.016). Global cerebral blood flow was not found to be different between groups. Another aspect of vascular function, cerebrovascular reactivity, was measured by CO2-inhalation magnetic resonance imaging and was found to be equivalent between groups. Therefore, there seems to be a global, diffuse diminishment in neural function in mild cognitive impairment, while their vascular function did not show a significant reduction.