We doctors aren’t very evidence-based (we just think we are)

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I went to a meeting for journalists and broadcasters on Tuesday night, organised by the Guild of Health Writers, dedicated to the subject of dementia. One of the speakers there was Jerome Burne – a London-based health writer of some repute (he won an award from the Medical Journalists Association in January). Jerome in the co-author of a book entitled ’10 Secrets to Health Ageing’ which is to be published in April in the UK. Jerome talked a lot about the general inadequacies of the research in the area, but also highlighted one study which I didn’t know about and found interesting.

The study concerns an amino acid called homocysteine, which previous studies has linked with an increased risk of dementia. Then some researchers in Oxford decided to see if lowering homocysteine levels with B-vitamins might help individuals with ‘mild cognitive impairment’. The results of this study were published in 2010 [1]. Compared to placebo, those taking B-vitamins saw reduced ‘brain atrophy’ (essentially, shrinking degeneration of the brain).

The same research group followed this study up with an analysis revealing improved brain functioning in those who had taken the B-vitamins [2].

Jerome made the point that the first study was largely ignored, and derided in some quarters. He stressed the need for the work to be repeated, but also gave the impression that the work is of potential significance, and I agree.

After the talks, a couple of people took exception to Jerome’s highlighting of the brain atrophy study. One of them was general practitioner Dr Tom Smith, author of the book ‘Reducing your risk of dementia’. Dr Smith said he found it ‘disappointing’ that Jerome highlighted homocysteine as a potential factor in dementia. He asked for there to be research into whether homocysteine and dementia are linked in populations. Actually, there already is such research, and Jerome had already referred to it briefly in his talk.

Dr Smith then went on to highlight the findings of his own research, which has identified two things linked to reduced risk of dementia: light exposure and playing in an orchestra. Yet, these lines of evidence are ‘epidemiological’ in nature, and can only tell us these factors are associated with dementia risk. As evidence goes, they are weak compared to the clinical evidence presented by Jerome earlier (by the way, Jerome was allowed no right of reply to Dr Smith as time ran short due to Dr Smith’s verbosity).

Earlier on, Jerome had made the comment that he believes in evidence-based approaches, but he also wishes doctors would actually do more of it. He’s right about this: doctors often talk about being ‘evidence-based’ in their practice, but the fact remains that much of what we do as doctors is not evidence-based at all.

When Dr Smith got up, he proclaimed to be ‘evidence-based’ in his work. The irony is, of course, that it seems Dr Smith does not appear to actually understand the relevance of different types of evidence at all.

Jerome, during his talk, gave the impression that one of the reason the homocysteine/B-vitamin/brain atrophy research did not get the attention it deserved and has not been repeated is because, well, there’s not much commercial potential here. After all, B-vitamins are non-patentable. In comparison, millions have been spent on drugs that don’t work. While this view may appear cynical, I share it. It also occurs to me, like it does I think to Jerome, that some will ignore or deride research simply on the basis that it is perceived a ‘natural’. As Dr Smith appears to demonstrate, these opinions on not always on the firmest of scientific footings, and appear to be borne more out of bias than a quest for the truth.


1. Smith AD, et al. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One 2010;5(9):e12244.

2. de Jager CA, et al. Cognitive and clinical outcomes of homocysteine-lowering B-vitamin treatment in mild cognitive impairment: a randomized controlled trial. Int J Geriatr Psychiatry. 2011 Jul 21 [Epub ahead of print]

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