Vitamin B12 and Homocysteine Levels Predict Different Outcomes in Early Parkinson's Disease

Abstract

In this study of early PD, low B12 status was common. Low B12 at baseline predicted greater worsening of mobility whereas elevated homocysteine predicted greater cognitive decline. Given that low B12 and elevated homocysteine can improve with vitamin supplementation, future studies should test whether prevention or early correction of these nutritionally modifiable conditions slows development of disability. © 2018 International Parkinson and Movement Disorder Society.

Vitamin B12 and Parkinson's Disease: What is the Relationship?

“…In conclusion, the findings of Christine and colleagues, suggesting that lower vitamin B12 levels are associated with more rapid decline of PD are intriguing. Further investigations to address this hypothesis are warranted.…”

“…Another intriguing aspect of the study by Christine and colleagues is the discord with previous investigations of the relationship between PD, parkinsonism in general, and vitamin B12. For instance, the prospective evaluation of 5,289 participants of the Rotterdam study for a mean of 9.7 years failed to identify any relationship between vitamin B12 levels and risk of development of PD .…”

“…It may also improve the understanding of mechanisms underlying the pathogenesis of the disease, revealing potential targets for disease modifying treatments. In this context, the study by Christine and colleagues in the current issue of Movement Disorders is a welcome addition to the literature. Analyzing the DATATOP cohort, the researchers report that lower vitamin B12 levels at early stage of PD are associated with higher scores of the so‐called “ambulatory capacity score” (a composite of the following items of the UPDRS: falling, freezing when walking, walking, and postural stability) along the course of the study.…”

“…To overcome this limitation, most experts in the field agree that it is mandatory to combine measurement of the concentration of the vitamin B12 with determination of homocysteine (tHcy) levels . Although Christine and colleagues have measured B12 and tHcy levels, the statistical analysis of their data and subsequent conclusions are exclusively based on the levels of the vitamin. Moreover, probably because of the limited number of individuals in their sample with low B12 levels (34 subjects; 5%), they created a category of “borderline low B12 levels” whose pathophysiological and clinical value is much more doubtful.…”

“…Taken together, these results cast doubt whether the researchers identified PD subjects who actually had low B12 levels. A second potential methodological shortcoming of the investigation by Christine and colleagues is related to the design of the DATATOP study. As extensively discussed after the publication of the initial results of the trial, the symptomatic effect of selegiline was disregarded and the lack of objective definition of criteria of the primary endpoint, introduction of levodopa .…”