A new PLoS article has been published, arguing that
The accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment with homocysteine-lowering B vitamins
I don’t have time to deal with this in as much detail as I would like (lots of things getting in the way of blogging, which is why it has been quiet here lately) but I think this is worth some quick notes. This post is short and a bit messy: for a summary of what the article does and doesn’t know, see Behind the Headlines; for a summary of some concerns with it, see Evidence Matters. Keep reading if you’re interested in the Holford angle.
Tediously predictably, Patrick Holford uses this article to promote homocysteine tests:
for now, I recommend that you get your homocysteine tested. If your doctor won’t do this, you can do it yourself with Yorktest’s home test kit. Smith’s result suggests accelerated brain shrinkage starts from around 10μmol/L, so make sure your level is well below this – ideally below 7…If your test revels levels about 15, then you need slightly higher doses.
However, the article does not justify this recommendation. It provides further evidence for a correllation between brain shrinkage and homocysteine levels, which is interesting. The article certainly does not provide evidence for taking higher dosages for higher homocysteine levels.
Moreover, as Evidence Matters notes:
It is worth reminding readers that (the last time I looked) assays from different laboratories are not standardised and the results are not, therefore, inter-changeable or able to support the sort of interpretation or recommendation that Holford offers.
One hopes, once again, that Holford’s readers do not rely on him for health advice. Holford’s interpretation is also problematic: his post is titled:
B vitamins stop brain shrinkage preventing dementia
However, the article does not show that B vitamins stop brain shrinkage (if anything, it provides evidence that they do not entirely stop this shrinkage). It finds that
The mean rate of brain atrophy per year was 0.76% [95% CI, 0.63–0.90] in the active treatment group
Atrophy may have been slowed. It was not stopped. Sadly, it is also not clear whether slowing brain atrophy will prevent dementia.
Evidence Matters discusses concerns around links between Smith and Refsum (two of the article’s authors) and Holford. Given these links, I hope that these authors will be pushing Holford to correct his misinterpretation of their research and to withdraw his unjustified treatment recommendations.
As Evidence Matters and Behind the Headlines note, there are concerns about the size of the trial, aspects of the methodology and the funding of the trial. This article is clearly far from the last word on the topic: it will be interesting to see what future research finds. However, Holford is already using this research to promote specific products and is already misinterpreting it. I would be delighted (if a little surprised) if future research finds B vitamin supplements to be highly useful in preventing and treating various cognitive impairments; however, I have a horrible feeling that Holford’s response to future research on this topic will be far more predictable than the research’s findings.