Listening to Lithium

This past spring, researchers revisited a tantalizing finding from the annals of public health. In 1990, researchers had found lower levels of suicide, homicide, rape, and other crimes in Texas counties where the municipal water supply had higher than average levels of naturally occurring lithium salts. The new, finer-grained study [2]looked at a prefecture in Japan. Again, communities with more lithium in the drinking water had lower levels of suicide. The results were striking enough that an editorialist in the British Journal of Psychiatry seriously suggested [3]exploring the utility of adding lithium to drinking water, “as the eventual benefits for community mental health may be considerable.”

By clinical standards, the lithium doses that groundwater provides, even in the “high-lithium” areas, are modest—orders of magnitude below what someone with bipolar disorder might need to prevent mania. So how might this trace element in the water supply work? One suggestion floated by the BJP editorialist is that low-dose lithium might raise the levels of neurotrophic factors in the brain. These factors, made by the brain for the brain, encourage new cell growth, allow for new connections among existing cells, and prevent deterioration in the face of stress. The neurotrophic factors seem to protect against psychiatric and neurological disease. But they may also affect personality traits—and that possibility poses ethical dilemmas for any broad-based effort to improve resilience in the brain.

Neurotrophic factors are a hot topic in psychiatry because they may play a key role in resilience. Scientists have speculated that stimulating the production of these factors might prevent or delay the onset of depression and dementia.

Conventional antidepressants seem to do that job, raising or restoring levels of neurotrophic factors. But researchers have also been looking for less intrusive ways to induce resilience. For instance, this past February, researchers at the Weizmann Institute in Israel announced [4]that they have developed a simple vaccine that raises levels of a neurotrophic factor, at least in rats. Very low-level lithium in the water supply might fill a similar function.

Reading these accounts made me revisit a concept in medical ethics that I introduced in the early 1990s. When I first prescribed Prozac, I had heard certain of my patients say that beyond offering relief from the problem that had led them to seek help—depression, anxiety, obsession—the medication seemed to make them assertive or confident. This testimony led me to wonder whether antidepressants or similar medicines not yet invented might be used not to treat illness but to move people from one normal state to another normal state that is more desired or better rewarded socially. I called this potentially worrisome practice “cosmetic psychopharmacology” and wrote about it first in an essay for psychiatrists and then, more extensively, in my book Listening to Prozac [5]. I believe it is fair to say that this writing energized a field in philosophy that centers on the word “enhancement,” a term that encompasses a set of medical interventions in which the goal is not to cure illness but rather to alter normal traits and abilities.

Cosmetic psychopharmacology is direct and intentional: The goal is to sculpt personality. But perhaps the ethical challenges we face will be of a different sort—“incidental enhancement,” change that just happens to occur while we are pursuing other, unarguably worthy goals. Like antidepressants, neurotrophic factors may affect personality. Researchers have found [6]that a genetic allele that produces higher activity or more efficient use of one factor is associated with lower levels of a trait that psychologists call “neuroticism”—a tendency for negative emotion in the face of stress. The particular aspects of neuroticism that showed through in the study were depression, self-consciousness, anxiety, and vulnerability. This cluster is close to the one I worried over in Listening to Prozac—the disfavored traits that a societal adoption of mood brighteners might push aside.

It was the modest proposal in the BJP editorial—consider adding lithium to the water supply for mental health, as we add fluoride for dental health—that led me to pose a thought experiment in a paper [7]I gave at a conference in Germany this past summer: “Let us imagine that we can induce resilience, preventing a host of diseases and perhaps also inducing cognitive robustness: better learning capacities, better memory, and the like. The price, or let us say, the secondary effect, is a change in the array of temperaments within the population. Is the bargain one we will accept?”

As a society, we would not introduce a broad intervention that came with a price of undesirable traits such as irritability and impulsivity. But if we could fend off Alzheimer’s disease, if we could keep the brain young, might we not accept a decrease in neuroticism? Imagine a Darwinian selection for interventions: Preventive and health-giving measures that (incidentally) confer traits the culture values might be instituted; similar measures that instill undesired traits would be rejected.

Cosmetic psychopharmacology described a concern right on the horizon. Incidental enhancement is more far-fetched. But there is that vaccine, and those findings about lithium. What if enhancement slips in by-the-by, via decisions we make for quite other purposes?