A new analysis of several clinical trials has drawn a conclusion that will dismay many: taking B vitamins does not slow the decline in memory and thinking skills that comes with age. The results suggest that B vitamins are unlikely to prevent Alzheimer’s disease. The news is the opposite of what we, and the hundreds of thousands of families affected by the disease, had hoped for – but it does give us new knowledge to help people make more informed decisions about these supplements.
Where has the news come from?
The researchers, led by a team at the University of Oxford, drew their conclusions after pulling together data from 11 separate clinical trials of B vitamins, involving a total of 22,000 people. In each of these trials, the people taking part were randomly assigned to either take B vitamins or a placebo, and tests of the participants’ memory and thinking skills were carried out. The trials varied in size – ranging from just 108 people to 8,891 participants – and in duration, with the shortest lasting around three and a half months, and the longest running for seven years.
Each of the trials also looked at the effects of B vitamins on levels of an amino acid called homocysteine. High homocysteine has been linked to Alzheimer’s disease, and since B vitamins are known to reduce homocysteine levels, researchers have been keen to explore whether the supplements could also prevent or reduce the risk of Alzheimer’s.
However, when they pooled the results of all the trials, the researchers found that – although people taking B vitamins did see a reduction in homocysteine – there were no strong differences in memory and thinking scores between those who took B vitamins, and those who took the dummy pills.
Updating the evidence
These findings appear to be at odds with the VITACOG study from 2010, which involved 168 people and was widely reported in the media when it was first published. That two-year trial, which was part-funded by Alzheimer’s Research UK, showed that people with mild memory problems and high homocysteine had a slower rate of brain shrinkage when they took B vitamins, compared to people who took a placebo. Further analysis of the same trial, published a year later, suggested that B vitamins could also slow declining memory, at least in people with high homocysteine. So why are these new results so different?
When the VITACOG study was first published, both the researchers and Alzheimer’s Research UK highlighted the need for much larger, longer trials to be carried out, in order to confirm the findings and understand the implications for Alzheimer’s. While the VITACOG trial was well run, its small sample size meant that no firm conclusions could be drawn from the results at that stage. As one of the VITACOG researchers warned when the findings were first announced: “I wouldn’t yet recommend that anyone getting a bit older and beginning to be worried about memory lapses should rush out and buy vitamin B supplements without seeing a doctor.”
The need for large studies is explored further in our March blog post on dementia headlines, and it’s an important point in this case. Although this wide-ranging review is not a new trial, by pulling together data from many thousands of people, it gives the most up-to-date, comprehensive picture we have so far of the effects of B vitamins on cognition.
It’s always disappointing when potential preventative treatments fail. At Alzheimer’s Research UK, we’re striving to find treatments that people so desperately need, but to recommend a treatment, we have to have robust evidence that it works.
This analysis does suggest some future avenues for research – for example, the authors suggest that instead of being a cause of Alzheimer’s disease, high homocysteine could potentially be a marker of underlying problems. Research to further investigate exactly why high homocysteine levels and Alzheimer’s are linked could help us to better understand the disease and how to treat it.
The research also further underlines the urgent need for preventions for Alzheimer’s. Research into prevention has dominated the news this week, with one new study suggesting that as many as a third of Alzheimer’s cases could be avoided with simple lifestyle changes – but there’s much we still need to know about how to stave off the condition. It’s one reason we’ve committed to set up a prevention fund as part of our Defeat Dementia campaign, and it’s why we’ve signed up to the Blackfriars Prevention Consensus, which calls for action on risk reduction as well as continued research into preventions.
You can help us support our research into dementia prevention by donating online.
- This post was updated on 13 October 2014 to add clarity on some points.