Affiliations: [a] Department of Neurology, Oregon Health & Science University, Portland, OR, USA | [b] Department of Public Health, Oregon State University, Corvallis, OR, USA | [c] Linus Pauling Institute, Oregon State University, Corvallis, OR, USA | [d] Helfgott Research Institute of the National College of Natural Medicine, Portland, OR, USA
Correspondence:
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Corresponding author: Gene L. Bowman, N.D., Oregon Health & Science University, NIA-Layton Aging and Alzheimer's Disease Center, NCCAM-Oregon Center for Complementary and Alternative Medicine in Neurological Disorders, 3181 Southwest Sam Jackson Park Road, CR-131, Portland, OR 97239, USA. Tel.: +1 503 494 6976; Fax: +1 503 494 7499; E-mail: bowmang@ohsu.edu.
Abstract: The brain maintains high levels of ascorbic acid (AA) despite a concentration gradient favoring diffusion from brain to peripheral tissues. Dietary antioxidants, including AA, appear to modify the risk of Alzheimer's disease (AD). The objective of this study was to test the hypothesis that neurodegeneration in AD is modified by brain levels of AA. Thirty-two patients with mild to moderate AD participated in a biomarker study involving standardized clinical assessments over one year. Cerebrospinal fluid (CSF) and serum were collected at baseline for AA and albumin content. Cognitive measures were collected at baseline and one year. CSF and plasma AA failed to predict cognitive decline independently, however, CSF: plasma AA ratio did. After adding CSF Albumin Index (an established marker of blood-brain barrier integrity) to the regression models the effect of CSF: plasma AA ratio as a predictor of cognitive decline was weakened. CSF: plasma AA ratio predicts rate of decline in AD. This relationship may indicate that the CSF: plasma AA ratio is an index of AA availability to the brain or may be an artifact of a relationship between blood-brain barrier impairment and neurodegeneration.
