Comments on: Daily Mail and Its Frame of a Recent Homocysteine and Depression Study http://holfordwatch.info/2008/12/17/daily-mail-and-its-frame-of-a-recent-homocysteine-and-depression-study/ The truth about Patrick Holford, media nutritionist Fri, 14 Oct 2011 15:11:39 +0000 hourly 1 http://wordpress.com/ By: dvnutrix http://holfordwatch.info/2008/12/17/daily-mail-and-its-frame-of-a-recent-homocysteine-and-depression-study/comment-page-1/#comment-13729 Wed, 17 Dec 2008 23:47:34 +0000 http://holfordwatch.info/?p=2186#comment-13729 Neuroskeptic – thank you. Life and the train service intervened to prevent the visit to the national library so I have still not seen the full paper so am grateful for your informed comments. How very odd, even for the Daily Mail. Even odder about the MTHFR and depression as I had wondered where the authors were going with that and had expected the paper to deliver a coherent account – plainly, I would have been disappointed.

jdc – Greenhalgh is excellent and deserves much praise. I hope that she knows that this much affection for her work is out there in the blogosphere.

]]> By: jdc325 http://holfordwatch.info/2008/12/17/daily-mail-and-its-frame-of-a-recent-homocysteine-and-depression-study/comment-page-1/#comment-13727 Wed, 17 Dec 2008 16:23:35 +0000 http://holfordwatch.info/?p=2186#comment-13727 “Vasan gave some excellent advice about biomarkers that continues to be ignored”
Excellent – a follow-up to the part of my Bad Science 101 Course that dealt with surrogate markers (I say “course”, I actually just read the Greenhalgh “How to Read a Paper” series you link to from your sidebar).

]]> By: Neuroskeptic http://holfordwatch.info/2008/12/17/daily-mail-and-its-frame-of-a-recent-homocysteine-and-depression-study/comment-page-1/#comment-13726 Wed, 17 Dec 2008 16:01:43 +0000 http://holfordwatch.info/?p=2186#comment-13726 Reading the whole paper now – it’s a bit odd.

They had a nice big sample of 3752 men. They measured depression using an old-age depression scale, they measured tHcy, and they genotyped for MTHFR C/T which is a polymorphism which affects tHcy levels.

They found a correlation between depression and tHcy, and they found a correlation between MTHFR and tHcy, but they found no hint of an association between the gene and depression.

“There was no association between
TT homozygosity and ever receiving a diagnosis
of depression (OR, 1.01; 95% CI, 0.75-1.37). The Cuzick
test for trend showed a dose-effect response of the
MTHFR C677T genotype on tHcy (z=3.84, P.001) but
not on GDS-15 scores (z=0.03, P=.98)”

However they then do a meta-analysis of previous studies (including their own) and find that, even if you include their negative data, there is an association between MTHFR and depression.

This is bizarre because their own finding is that there is no such association. they’re essentially saying that their own results are wrong (about the genetic association), but in that case why should we trust them to be right about anything else?

So when in the abstract they say “The triangular association between the
MTHFRgenotype, tHcy, and depression implies that higher
concentrations of tHcy increase the risk of depression and
that lowering tHcy by 0.19 mg/L could reduce the odds
of depression by about 20%” – there is no such triangular relationship according to the data presented in the paper which follows!

Presumably they did the study (which seems excellent in itself), didn’t get the results they wanted, and decided to throw in some meta-analysis until they did. Nice trick.

Also, needless to say, there is nothing about B12 in the prevention of depression. They do mention some studies of folate & tetrahydrofolate in depression but there are only 5, 1 one of them had no placebo, and in another 1 the patients weren’t even depressed; in others the benefits of vitamins were only significant in subgroups etc. etc.

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