Dimethylarginines, Homocysteine Metabolism, and Cerebrospinal Fluid Markers for Alzheimer's Disease
Authors: Arlt, Sönke | Schwedhelm, Edzard | Kölsch, Heike | Jahn, Holger | Linnebank, Michael | Smulders, Yvo | Jessen, Frank | Böger, Rainer H. | Popp, Julius
Article Type: Research Article
Abstract: Dimethylarginine and homocysteine metabolism are closely linked and alterations of both were observed in plasma and cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD). CSF parameters of homocysteine metabolism have recently been found to be associated with the CSF level of the AD biomarker phosphorylated tau (ptau) in AD patients. To investigate possible relationships between homocysteine and dimethylarginine metabolism and the AD CSF biomarkers ptau181 and amyloid-β 1-42 (Aβ42 ), we assessed parameters of homocysteine metabolism (CSF homocysteine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), 5-methyltetrahydrofolate (5-MTHF)) and dimethylarginine metabolism (plasma and CSF asymmetric dimethylarginine (ADMA), symmetric dimethylarginine, L-arginine) as well as …CSF Aβ42 and ptau181 in 98 controls and 51 AD patients. Multivariate linear regression analyses were performed to assess associations between the considered parameters. SAH concentrations show significant associations to CSF ADMA levels, and CSF ADMA and L-arginine to ptau181, but not to Aβ42 concentrations in AD patients. When including concentrations of homocysteine, 5-MTHF, SAM, and SAH into the analysis, CSF ADMA concentrations independently predicted ptau181 levels in AD patients but homocysteine-related metabolites were associated with ptau181 only when ADMA was removed from the analysis model. These results suggest that CSF ADMA may interact with CNS homocysteine metabolism and may contribute to neurodegeneration and accumulation of phosphorylated tau in AD. Functional and interventional studies are needed to further proof this hypothesis. Show more
Keywords: Alzheimer's disease, asymmetric dimethylarginine, cerebrospinal fluid, homocysteine, S-adenosylhomocysteine, S-adenosylmethionine
DOI: 10.3233/JAD-2012-112138
Citation: Journal of Alzheimer's Disease, vol. 31, no. 4, pp. 751-758, 2012
Homocysteine Metabolism and Cerebrospinal Fluid Markers for Alzheimer's Disease
Authors: Popp, Julius | Lewczuk, Piotr | Linnebank, Michael | Cvetanovska, Gabriela | Smulders, Yvo | Kölsch, Heike | Frommann, Ingo | Kornhuber, Johannes | Maier, Wolfgang | Jessen, Frank
Article Type: Research Article
Abstract: Disturbed homocysteine metabolism is a risk factor for Alzheimer's disease (AD) and may contribute to the disease pathophysiology by increasing both amyloid-β (Aβ) production and phosphorylated tau (P-tau) accumulation. Here, we evaluated the relationship between the cerebrospinal fluid (CSF) concentrations of homocysteine (Hcys), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and 5-methyltetrahydrofolate (5-MTHF), and the markers for AD pathology, Aβ1-42 and P-tau181, in 98 cognitively healthy subjects aged 16-81 years and 54 AD patients. In multivariate regression tests including age, gender, creatinine, and presence of the apolipoprotein E ε4 allele, P-tau181 was associated with SAH (β = 0.490; p < 0.001), 5-MTHF (β …= -0.273; p = 0.010) levels, and SAM/SAH ratio (β = -0.319; p = 0.013) in controls, and with SAH (β = 0.529; p = 0.001) in AD patients. The levels of Aβ1-42 were not associated with the CSF concentrations of Hcys, SAM, SAH, or 5-MTHF neither in the AD nor in the control group. The results suggest that alteration of the homocysteine metabolism is related to increased accumulation of phosphorylated tau and may contribute to the neurofibrillary pathology in normal aging and in AD. Show more
Keywords: Alzheimer's disease, amyloid-β, cerebrospinal fluid, homocysteine, phosphorylated tau
DOI: 10.3233/JAD-2009-1187
Citation: Journal of Alzheimer's Disease, vol. 18, no. 4, pp. 819-828, 2009
Hyperhomocysteinemia in Alzheimer's Disease: The Hen and the Egg?
Authors: Farkas, Melinda | Keskitalo, Salla | Smith, Desiree E.C. | Bain, Nadja | Semmler, Alexander | Ineichen, Benjamin | Smulders, Yvo | Blom, Henk | Kulic, Luka | Linnebank, Michael
Article Type: Research Article
Abstract: Hyperhomocysteinemia is associated with Alzheimer's disease (AD). The causality of this association is controversial. In this study we tested the effect of a hyperhomocysteinemia-inducing diet in the ArcAβ transgenic AD mouse model. At 14 months of age, the hyperhomocysteinemia-inducing diet yielded higher plasma homocysteine levels in ArcAβ mice compared with wild-type mice. Levels of plasma 5-methyltetrahydrofolate (5-MTHF) in 14-month-old mice on hyperhomocysteinemia-inducing diet were lower in the transgenic than in the wild-type mice. The folate derivate 5-MTHF serves as cofactor in homocysteine metabolism. Oxidative stress, which occurs in the course of disease in the ArcAβ mice, consumes 5-MTHF. Thus, the …transgenic mice may plausibly be more vulnerable to 5-MTHF-depleting effects of hyperhomocysteinemia and more vulnerable to hyperhomocysteinemia-inducing diet. This argues that AD pathology predisposes to hyperhomocysteinemia, i.e., as a facultative consequence of AD. However, we also observed that dietary-induced folate reduction and homocysteine increase was associated with an increase of plasma (young animals) and brain (older animals) amyloid-β concentrations. This suggests that the hyperhomocysteinemia-inducing diet worsened pathology in the transgenic mice. In conclusion, this data may argue that folate reduction and hyperhomocysteinemia may contribute to neurodegeneration and may also be triggered by neurodegenerative processes, i.e., represent both a cause and a consequence of neurodegeneration. Such a vicious cycle may be breakable by dietary or supplementation strategies increasing the availability of 5-MTHF. Show more
Keywords: Alzheimer's disease, diet, folic acid, homocysteine, hyperhomocysteinemia, mice, transgenic, vitamin B6, vitamin B12
DOI: 10.3233/JAD-2012-121378
Citation: Journal of Alzheimer's Disease, vol. 33, no. 4, pp. 1097-1104, 2013