I'm straying a little bit with this post. Straying from the intended autism research blogging path but hopefully not too far beyond my competence as I offer some discussion on yet another very complicated and very emotive topic: suicide.
It's not that I haven't made mention of suicide on this blog before; quite a few times in fact, in relation to issues like poisoning by pesticide as being an important method of suicide which perhaps need further regulation (see here) and how a familiar name to this blog, Toxoplasma gondii (or T.gondii to those who know it well) might very well show some relationship to some cases of suicide (see here).
One previous post in particular on cholesterol levels and autism (see here) may also be of some relevance to half of this post, focused on some potentially important findings from John Umhau and colleagues* (open-access) on vitamin D levels and their potential connection to suicide among active service military personnel. My very limited knowledge of cholesterol and vitamin D stems from articles like this one which might in turn partially explain headlines like: Vitamin D Supplements Won't Help Cholesterol Levels. That being said, I'm not an expert.
The Umhau findings are of great interest, not only because military personnel represent a 'captive audience' (if you'll pardon the pun) in terms of availability for study and the information that can be collected - see my post on schizophrenia and milk here if you don't believe me - but also because this was a study where archived serum samples had already been collected from both those who went on to commit suicide (n=495) and those used as control participants (n=495) in the study.
It wasn't as simple as saying the group mean level of vitamin D - sorry, 25-hydroxyvitamin D [25(OH)D] - calcidiol (the prehormone, as opposed to calcitriol, the active form of vitamin D) were lower in all suicide cases, given that suicide is not just a biochemical process. No, but when various factors such as season of serum collection, any history of depression and ethnicity were controlled for, there was "a statistically significant association between 25(OH)D concentrations and suicide risk, such that subjects with higher concentrations of 25(OH)D displayed a decreased risk for suicide compared to subjects in the lowest octile". The authors add: "We found that the risk for suicide was increased in the lowest octile of 25(OH)D levels, all the members of which had seasonally adjusted levels of 25(OH)D below 20 ng/mL". One perhaps has to bear in mind that active service when it comes to military employment and deployment can bring about its own set of very special circumstances.
Another paper also cropped up fairly recently adding to the possibility of a biochemical factor potentially being related to suicide. Victor Blüml and colleagues** reported again, some interesting findings on how lithium in the water supply might be potentially related to suicide rates in the US State of Texas; to quote: "The findings provide confirmatory evidence that higher lithium levels in the public drinking water are associated with lower suicide rates". I'm not going to go too far into the hows and whys of this paper for a couple of reasons: (a) I don't yet have the full-text version of the paper so am solely reliant on what the abstract says, and (b) there are many others far more competent than I who have talked about lithium and psychiatry before; one of them being Dr Emily Deans and a post she wrote in January 2012 about lithium which offers much more information than I could. All I could add as a sort of peripheral factoid is reference to a paper by Singh and colleagues*** which suggested that lithium might not be the only target compound of future interest bearing in mind its safety profile.
Suicide is not just a biochemical process and neither is it a uniform process with I assume, lots of different factors converging to influence the steps a person takes before reaching such an ultimate decision to take their own life. The studies highlighted in this post offer some interesting correlates related to suicide which at best suggest we should be looking at environment - the physical environment - as a potential player in how some people reach such a point, but not simply to replace the multitude of other important variables which might come into play.
Just in case anyone in the UK needs to talk to someone, the Samaritans are always good listeners (most other countries have similar services).
* Umhau JC. et al. Low vitamin d status and suicide: a case-control study of active duty military service members. PLoS One. 2013; 8: e51543.
** Blüml V. et al. Lithium in the public water supply and suicide mortality in Texas. J Psychiatr Res. January 2013.
*** Singh N. et al. A safe lithium mimetic for bipolar disorder. Nature Comms. 2013; 4.
Umhau JC, George DT, Heaney RP, Lewis MD, Ursano RJ, Heilig M, Hibbeln JR, & Schwandt ML (2013). Low vitamin d status and suicide: a case-control study of active duty military service members. PloS one, 8 (1) PMID: 23308099