title: Ascorbic acid and rates of cognitive decline in Alzheimer's disease.
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.
authors.affiliation: Department of Neurology, Oregon Health & Science University, Portland, OR, USA. bowmang@ohsu.edu
authors.forename: Gene L
authors.initials: GL
authors.lastname: Bowman
authors.forename: Hiroko
authors.initials: H
authors.lastname: Dodge
authors.forename: Balz
authors.initials: B
authors.lastname: Frei
authors.forename: Carlo
authors.initials: C
authors.lastname: Calabrese
authors.forename: Barry S
authors.initials: BS
authors.lastname: Oken
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kaye
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Quinn
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000378:metabolism* / Q000523:psychology*; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism; D001923:Brain Chemistry / Q000502:physiology*; D003072:Cognition Disorders / Q000378:metabolism* / Q000523:psychology*; D003627:Data Interpretation, Statistical; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid