Bowman GL, Dodge H, Frei B, Calabrese C, Oken BS, Kaye JA, Quinn JF. (2009) J Alzheimers Dis. 16(1):. 93-8
The brain maintains high levels of ascorbic acid (AscA) despite a concentration gradient favoring diffusion from brain to peripheral tissues. Dietary antioxidants, including AscA, 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 AscA. 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 AscA and albumin content. Cognitive measures were collected at baseline and one year.
CSF and plasma AscA failed to predict cognitive decline independently, however, CSF: plasma AscA ratio did. After adding CSF Albumin Index (an established marker of blood-brain barrier integrity) to the regression models the effect of CSF: plasma AscA ratio as a predictor of cognitive decline was weakened.
CSF: plasma AscA ratio predicts rate of decline in AD. This relationship may indicate that the CSF: plasma AscA ratio is an index of AscA availability to the brain or may be an artifact of a relationship between blood-brain barrier impairment and neurodegeneration.