- Margaret McCartney, general practitioner, Glasgow
The Daily Mail reported on 14 May that scientists were trying to create tests to detect Alzheimer’s disease early and that one, “the new Cognitive Function Test, which has been devised by Oxford University scientists, can be taken online in the comfort of a person’s own home.” It continued, “The test, which is free to take, follows a landmark Oxford University study published last year which credits a simple vitamin pill with cutting brain shrinkage linked to Alzheimer’s by up to 500 per cent” (www.dailymail.co.uk, 14 May, “15-minute online test for dementia: DIY memory quiz detects early signs of Alzheimer’s in people as young as 50”).
The report goes on to say that the test, “which can be found at foodforthebrain.org, has three sections which use computer-based tasks and games to test different components of memory. Those who are believed to be at risk of Alzheimer’s are advised to have a blood test and given a letter to take to their GP.”
The website claims that the “detectable, preclinical phase of Alzheimer’s disease presents as mild cognitive impairment [MCI].” It states, “The specificity of the CFT [cognitive function test] is not yet clear, ie, individuals may score poorly due to aspects other than MCI, such as medication, depression, acute infection and other factors. However, based on the pilot, it appears that CFT is sensitive to MCI.” The pilot study described by the website involved 50 volunteers, and it says that “a full description of the pilot and analysis will be available on this page by 1st July 2011”—that is, six weeks after the publicity for the online cognitive test. No numerical information about the rate of false negative or positive results is included on the website. In the “frequently asked questions” section, people who have an “at risk” result are told that “it is advisable to follow up your CFT with a homocysteine test . . . take the test in 6 months’ time and see if your results improve or not. If they improve you should have no cause for concern.”
People with a “disappointing test result” are told that “either the test has identified that you may have mild cognitive impairment, in which case you may wish to follow the guidance on the results page, or there was another problem with the test,” and the authors go on to list various internet connection problems. General practitioners are likely to be given letters from the Food for the Brain website printed by patients who have taken the test. The sample letter provides a clue to the enterprise (http://bit.ly/md0HvB). It reads, “To the General Practitioner for Patrick Holford . . . Your patient has completed the Cognitive Function Test . . . This is a validated screening test for those aged 50 and above, designed to test early cognitive impairment . . . Given that the progression from the first sign of cognitive impairment to Alzheimer’s disease may take up to 30 years, early screening and preventative action is imperative . . . There is now a substantive body of evidence, referenced below, that an individual’s plasma homocystine level is a reliable indicator of risk for cognitive impairment and Alzheimer’s disease, that it correlates with both the rate of brain shrinkage and memory decline, and, most importantly, that these may be reversible by supplementing amounts of vitamins B6, B12, and folic acid not achievable by diet alone. Homocysteine testing is also available privately, as a home-test from www.yorktest.com.”
Even if your score indicates a “very low risk,” you are still recommended to take a self test for homocysteine from the same company. The letter from Food for the Brain to the general practitioners expected to mop up the fallout offers five references in support of its claim. The first concludes that “large-scale randomised trials of homocysteine-lowering B vitamins are needed to see if a proportion of dementia in the world can be prevented” (Nutr Health 2006;18:225-6). The second says that “prospective studies on the relation between folate, vitamins B6 and B12 levels and the risk of developing Alzheimers disease are warranted” (Arch Geront Geriatr 2009;48:425-30, doi:10.1016/j.archger.2008.03.009). The third says that “trials should be carried out to see if such treatments can slow the rate of cognitive decline in relatively young patients” (Int J Geriatr Psychiatry 2010;25:82-90). The fourth was a trial of vitamins and magnetic resonance brain imaging: “trials are needed to see if the same treatment will delay the development of Alzheimer’s disease” (PLoS One 2010;5(9):e12244, doi:10.1371/journal.pone.0012244). The last citation is a review-comment article that concludes that more research is needed: “The dementia literature is replete with examples of putative risk factors derived from observational data that did not translate into effective interventions” (Nature Rev Neurol 2011;7:9-10, doi:10.1038/nrneurol.2010.195).
Patrick Holford, who describes himself as a “nutritionist” and chief executive officer of Food for the Brain, told me, “We, the charity, deemed the evidence to have become substantial enough to warrant the launch of our Alzheimer’s prevention project . . . the primary aim of which is to encourage early screening of cognitive function from age 50, followed by homocysteine testing.” Food for the Brain’s adviser, the pharmacologist David Smith, told me that the online test is “not a diagnostic test, and there is no definitive outcome; it simply tells the user about their cognitive status. Hence there is no false positive or negative rate.” He went on, “My personal judgment is that it might in fact be unethical not to offer a person with high homocysteine the chance to lower it and slow the shrinkage of their brain and possibly slow their cognitive decline.”
However, a Cochrane review in 2008 concluded that folic acid with or without vitamin B12 did not have an effect on cognition in healthy elderly people and people with dementia; it did, however, recommend more work, because in one study “long-term use appeared to improve the cognitive function of healthy older people with high homocysteine levels” (Cochrane Database Syst Rev 2003;4:CD004514, doi:10.1002/14651858.CD004514.pub2). However, this review did not include a large randomised controlled trial in JAMA, published the same year, that found that vitamins lowered homocysteine concentrations but without a cognitive effect (2008;300:1774-83, doi:10.1001/jama.300.15.1774). The study also found a higher rate of depression in the treated group.
Holford’s face appears on a range of supplements, sold through the Totally Nourish website (www.totallynourish.com), which says “there’s not much about health that Patrick Holford doesn’t know.” The Brain Bio Centre, a clinic in London, which advertises its appointments with Holford on the Food for the Brain website, says, “Typically, over a year, most patients spend between £600 [€680; $985] and £1100 on consultations and tests” as well as £2-3 a day on supplements. Patients deserve better evidence first.
Cite this as: BMJ 2011;342:d3732
Provenance and peer review: Commissioned; not externally peer reviewed.