The effect is apparent in participants with high levels of an amino acid, homocysteine, in the blood. But larger trials will be necessary to confirm such a result and determine whether B vitamins can halt progression to Alzheimer’s in this group.
The findings are published in the International Journal of Geriatric Psychiatry.
Around one in six elderly people (70+) has MCI and experiences problems with memory, language, or other mental functions, but not to a degree that interferes with daily life. Around half of people with MCI develop dementia, mainly Alzheimer’s, within five years of diagnosis.
The B vitamins folic acid, vitamin B6 and vitamin B12 are known to control levels of homocysteine in the blood, high levels of which are associated with an increased Alzheimer’s risk.
The Oxford University team set out to establish whether high doses of the B vitamins taken as daily tablets could slow the rate of brain shrinkage (atrophy) observed in MCI. The results – that people taking B vitamins had a reduced rate of brain shrinkage compared with those on placebo – were published in September last year in the journal PLoS ONE.
As part of the trial, the participants also completed a set of standard, validated tests of cognitive and clinical status. These were secondary outcome measures in the study. That is, the trial was not primarily designed to investigate these measures or have sufficient statistical weight to pick up any differences between the treatment groups, and so the findings should be treated with more caution.
The two-year, double-blind clinical trial involved 266 people over the age of 70 with MCI. The group was randomly assigned to receive either a daily dose of vitamins comprising 0.8 mg folic acid, 0.5 mg vitamin B12 and 20 mg vitamin B6, or a placebo pill.
Prof David Smith of Oxford University, who co-led the study, said:
“These are high doses of the B vitamins that could not be obtained from a normal diet or standard supplements and should be treated like a drug.”
Although almost all the cognitive tests showed no difference overall between those on placebo and those receiving B vitamins, there were statistically significant benefits of the B vitamin treatment among those participants with high blood homocysteine levels.
Over the two-year trial, the 50% of participants with the highest homocysteine levels that received the B vitamins saw significantly less decline in a range of tests of cognitive performance than those on placebo. And, for the quarter of participants with the very highest homocysteine levels, those treated with B vitamins showed more improvement on a clinical rating of dementia at the end of two years than those on placebo.
David Smith of the Department of Pharmacology and Founding Director of OPTIMA, Oxford University said:
“The striking parallel effect of B vitamins in slowing brain atrophy and at the same time reducing cognitive decline is consistent with a disease-modifying effect of this treatment.”
Dr Celeste de Jager, neuropsychologist at OPTIMA in the Nuffield Department of Medicine, said:
“These results are very promising for older people with mild memory problems. We hope to be funded to do a large scale trial, UK-wide, to confirm our results, and to determine if we can slow progression to dementia for those with MCI. We hope the public will be interested in joining our research project.’’
Prof Smith added:
“Should our findings be replicated in larger trials, in future years you could see people coming into GP surgeries who are diagnosed with MCI being prescribed B vitamins at high doses if they have high homocysteine levels. That is how we see it. It won’t be people with vague worries about memory problems buying standard vitamin supplements over the counter at health stores.”
Rebecca Wood, Chief Executive of Alzheimer’s Research UK, which co-funded the study, said:
“These are further encouraging findings for B vitamins, but without large scale trials, we won’t know for sure how protective they might be against mental decline for elderly people. People should speak to their doctor before embarking on any vitamin plan.
“Follow up clinical trials must have a particular emphasis on establishing whether B vitamins could head off conversion from MCI to Alzheimer’s.
“Research is the only answer to dementia, the greatest medical challenge of our time. Unless we invest in research from the lab bench all the way to large scale trials, we will fail the many thousands of people set to develop dementia in the next generation.”
The trial was supported by grants from Charles Wolfson Charitable Trust, Medical Research Council, Alzheimer’s Research UK, Henry Smith Charity, Thames Valley Dementias and Neurodegenerative Diseases Research Network of the National Institute for Health Research, John Coates Charitable Trust, Sidney and Elizabeth Corob Charitable Trust, and Meda AB/Recip AB, who also donated the vitamin (TrioBe+) and placebo tablets.
Alzheimer’s Research UK