Ascorbic Acid and Rates of Cognitive Decline in Alzheimer's Disease

Department of Neurology, Oregon Health & Science University, Portland, OR, USA.
Journal of Alzheimer's disease: JAD (Impact Factor: 4.15). 02/2009; 16(1):93-8. DOI: 10.3233/JAD-2009-0923
Source: PubMed


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.

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Available from: Hiroko Hayama Dodge
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    • "As noted in Table  1, the mean plasma concentration in the Alzheimer’s patients was 31% lower than in age and sex-matched controls, presumably due to less AA in their dietary intake. In a separate uncontrolled study of 32 Alzheimer’s patients, Bowman et al. found a mean CSF/plasma ratio of 4.0 ± 0.3 (SEM)– confirming the findings summarized in Table  1[37]. Collectively, these data provide no support for abnormal AA transport function in CP of elderly or Alzheimer’s patients. "
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    • "¼ 0.001) and plasma (P ¼ 0.002) and CSF (P ¼ 0.038) were lower in AD. All subjects were well-nourished and without vascular disease 18 Ctls (MMSE 27), 20 AD (MMSE 16) Women Age-matched (75–85 years) Cross sectional Bowman et al. [28] 32 41 6 30 129 6 52 4.0 6 1.6 Higher CSF: plasma AA ratio associated with slower cognitive decline over 1 year (age, gender, education, apoEe4, and cognitive function at baseline adjusted P ¼ 0.025). Interaction between CSF AA ratio and BBB integrity identified AD (MMSE 19 6 5) Men/women Mean age 71 years Prospective "
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    • "Furthermore, plasma levels of the antioxidant vitamin C are lower than normal in Alzheimer's patients, regardless of intake (Charlton et al., 2004; Riviere et al., 1998). Increased vitamin C intake from the diet or supplement form has been shown in some studies to lower the risk of developing Alzheimer's disease (Engelhart et al., 2002; Morris et al., 1998), and Alzheimer's patients with higher baseline CSF/plasma vitamin C ratios exhibit slower disease progression over the course of one year (Bowman et al., 2009). Other studies found no such associations (Gray et al., 2008; Laurin et al., 2004; Luchsinger et al., 2003; Paraskevas et al., 1997). "
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