High doses of lithium are already used to treat serious mood disorders. But the team from the universities of Oita and Hiroshima found that even relatively low levels appeared to have a positive impact of suicide rates.
Levels ranged from 0.7 to 59 micrograms per litre. The researchers speculated that while these levels were low, there may be a cumulative protective effect on the brain from years of drinking this tap water.The researchers hace stopped short of recommending that lithium be added to the water supply, in the way that fluoride is.
I think I can see where this is going...
Though the calculations are hardwired for the ancestral environment. The environment has, of course, changed extensively since then, from agriculture onwards. It may be that by the original criteria, parts of the current environment are a suicide trigger, but in this case, that would make the mechanisms that calculate whether to commit suicide dysfunctional.
It's always possible that a changing environment makes instincts unadaptive, but these studies seem to be saying that suicide is working properly today: it is a rational and selfless response to some adverse life circumstances. People who want to suicide turn out to be those whose impact on their relatives becomes negative. Most suicides are not spurned lovers, Marvin the depressed robot etc but rather the incurably sick, addicts, people convicted of crimes etc. Google-scholar "suicide "inclusive fitness"" for some examples, human and otherwise. For example the parasite theory argues that victims of a parasite will suicide if the risk of passing the parasite to their offspring outweighs the resources they are still capable of providing. I think this research raises interesting questions for the debate around the rights of terminally ill patients. For example to deny the right to suicide can be seen not just as compelling the sick to suffer for longer, but as an attack on the sufferer's family.
Yes the pros and cons still need to be weighed carefully. It is important to note that this study was done on naturally existing levels of lithium in the water supply in the Oita area of Japan. Some bloggers on other websites have misunderstood this as being some indication lithium is being added to the water supply in Japan, an assertion which is groundless in fact.
While the BBC report is well written there is also a good report on this from the Telegraph published on 30th April:
http://www.telegraph.co.uk/health/healthnews/5251365/Natural-levels-of-lithium-in-drinking-water-help-reduce-suicides.html
For the orginal article in the British Journal of Psychiatry see:
http://bjp.rcpsych.org/cgi/content/abstract/194/5/464
Useful telephone number for Japanese residents of Japan who speak Japanese or English and are feeling depressed or suicidal:
Inochi no Denwa (Lifeline Telephone Service)：
Japan: 0120-738-556
Tokyo: 3264 4343
Tokyo English Life Line: 03-5774-0992
Andrew Grimes
Tokyo Counseling Services
Phrases like 'protection' and 'serious mood disorders' indicate an underlying viewpoint that suicide (depression, suicidal ideation etc) represents something functionally wrong with the brain. Given that viewpoint, pharmacological interventions like prozac, lithium in the water or whatever seem logical. But there is a solid argument supported by several empirical studies, that suicide is a technique for optimizing inclusive fitness. This article is a good example (http://www.ncbi.nlm.nih.gov/pubmed/10322621) but there are many others if you google-scholar around. It's been demonstrated both in humans and other species. The basic idea is that if you detect that staying alive will lower the reproductive success of your relatives/children, your brain, functioning correctly, will calculate the desire to die. This should be expected in a number of life situations and has found to occur reliably in them. Artificially preventing this natural function is therefore damaging to the 'patient' and their family!