How our drinking water could help prevent suicide
Some researchers think putting lithium in our water could save lives.
By
Lithium is a potent psychiatric drug, one of the
primary prescribed medications for bipolar disorder. But it’s also an
element that occurs naturally all over the Earth’s crust — including in
bodies of water. That means that small quantities of lithium wind up in
the tap water you consume every day. Just how much is in the water
varies quite a bit from place to place.
Naturally, that made researchers curious: Are places with
more lithium in the water healthier, mentally? Do places with more
lithium have less depression or bipolar or — most importantly of all —
fewer suicides?
A 2014 review of studies
concluded that the answer was yes: Four of five studies reviewed found
that places with higher levels of trace lithium had lower suicide rates.
And Nassir Ghaemi, the Tufts psychiatry professor who co-authored that
review, argues that the effects are large. High-lithium areas, he says,
have suicide rates 50 to 60 percent lower than those of low-lithium
areas.
If you apply that 50 to 60 percent reduction to the US, where about 45,000 people total
died by suicide in 2016, you get a total number of lives saved at
around 22,500 to 27,000 a year. That’s likely too high, since you can’t
reduce suicide rates in places that are already high-lithium. Ghaemi’s
own back-of-the-envelope calculation is that we’d save 15,000 to 25,000.
Ghaemi and a number of other eminent psychiatrists
are making a pretty remarkable claim. They think we could save tens of
thousands of lives a year with a very simple, low-cost intervention:
putting small amounts of lithium, amounts likely too small to have
significant side effects, into our drinking water, the way we put
fluoride in to protect our teeth.
The case for skepticism on lithium
The size of the numbers Ghaemi is claiming should make
you skeptical: Those are huge, arguably implausibly huge, effects. In
2015, the Open Philanthropy Project, a large-scale grantmaking group in
San Francisco, shared an analysis with me implying that if two specific studies
were right, a “small increase in the amount of trace lithium in
drinking water in the U.S. could prevent > 4,000 suicides per year.”
That’s significant, but far short of 15,000 to 25,000.
And while Ghaemi is very enthusiastic about the potential of groundwater lithium, other researchers are more wary. A comprehensive list of lithium studies,
updated just last month, shows that while many studies find positive
effects, plenty more found no impact on suicide or other important
outcomes. In particular, a large-scale Danish study
released in 2017 found “no significant indication of an association
between increasing … lithium exposure level and decreasing suicide
rate.”
The Open Philanthropy Project, which had previously been quite interested in new research on lithium, states on its website that the study “makes us substantially less optimistic” that trace lithium really helps guard against suicides.
Just this year, a study using health care claims data in the US
found that greater amounts of trace lithium in the water didn’t predict
lower diagnoses of bipolar disorder or dementia. That’s a different
outcome than suicides, but also suggests that low doses of lithium might
not have a profound effect.
Why this hasn’t been tried
These recent studies have made me less confident in the
link between lithium and lower suicide rates than I was when I first
encountered Ghaemi’s research. But it’s such a cheap intervention, and
the odds of serious side effects sound low enough, that it seems worth a
try.
At the very least, I’d love for some governments to
conduct real, bona fide experiments on lithium. Maybe a state could
randomly add lithium to some of its reservoirs but not others, or,
conversely, a high-lithium state could try removing it from the water.
There are serious ethical questions
about doing experiments like this that affect whole populations, but if
lithium’s effect is real and we don’t pursue it because we lack
compelling enough evidence, thereby endangering thousands of people —
that’s an ethical problem too.
But no study like that has been conducted. And if you want to know why, you should consider the case of fluoride.
As you probably know, putting fluoride in our drinking water dramatically reduced tooth decay, by around 25 percent per the Centers for Disease Control and Prevention. But as you likely also know, the initial rollout of fluoride in the 1940s and 1950s was intensely controversial.
Jesse Hicks, a science journalist who wrote a great history of the fluoride wars, told me on this week’s Future Perfect
podcast that the backlash started in Stevens Point, Wisconsin, with a
local gadfly named Alexander Y. Wallace who was convinced the substance
was poison, and who wrote a parody song called “Goodnight, Flourine” to
the tune of the folk song “Goodnight, Irene.”
From there, the conspiratorial, far-right John Birch Society became convinced that fluoride was a Communist plot;
the Ku Klux Klan came out against fluoride too. “I think part of the
longevity of this controversy has to do with the way it can activate so
many different biases and prejudices,” Hicks told me. “As soon as you
start talking about putting something in the water supply you have small
or anti-government people responding very vigorously against that.”
The absurd controversy continues to this day. Dr. Mehmet Oz, the wildly popular, wildly irresponsible TV doctor, has brought on a fluoride conspiracist — Erin Brockovich of Julia Roberts movie fame — to sow fear and disinformation.
If that’s the reaction to an effort to improve dental
health, just imagine the public outcry against a major push for adding
lithium to the water. The rap against fluoride, mocked in movies like Dr. Strangelove, is that it’s a mind-control plot. But putting lithium in the water would actually be
a mind-control plot: It would be a concerted effort by the government
to put mind-altering chemicals in the water supply to change the
behavior of the citizenry. And I say that as someone who thinks that, if
it works, that it would be a great idea! Preventing suicide is really
important, but it does require changing how people think, a tiny bit.
So figuring out if, and how well, trace lithium in the
water works is only half the battle. Advocates would then have to win
over a very, very skeptical public.
Hicks thinks we need a rock-solid, impenetrable
scientific case if we’re going to do it. The science so far is
promising, but not firm enough. “When you start making it a public
health policy, you activate all of these other considerations that make
it that much harder to make it happen,” he says.
For more, listen to the full episode above, and be sure to tune in again next Wednesday for more Future Perfect!
Read more
- Anna Fels’s op-ed “Should We All Take a Bit of Lithium?” in the New York Times
- Nassir Ghaemi and colleagues review the evidence on trace lithium and suicide, homicide, crime, and dementia
- The recent Danish study casting doubt on the trace lithium/suicide prevention link
- Jesse Hicks explains the fluoride controversy for the Science History Institute
- Jesse Hicks explains trace lithium, for Vice
- More of Vox’s effective altruism coverage
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