An analysis of pooled data from 15 population studies around the world suggests that higher levels of trace lithium — a metal used in some psychiatric medicines — in public drinking water is associated with lower rates of suicide.

Lithium is primarily prescribed by doctors to help stabilize the moods of people with bipolar disorder and to reduce their risk of suicide.

Most rocks contain trace amounts of the element. Weathering washes it into groundwater and standing water, which is how the chemical finds its way into the public water supply.

Several studies over the years have found associations between relatively high amounts of lithium in drinking water and lower rates of suicide across various populations.

Recently, researchers at Brighton and Sussex Medical School and King’s College London, both in the United Kingdom, have now pooled data from 15 of these studies in a meta-analysis.

The studies included had been conducted in the United States, Austria, Greece, Italy, Lithuania, the U.K., and Japan, encompassing a total of 1,286 regions, counties, and cities.

The new meta-analysis suggests a clear relationship between higher levels of lithium in public drinking water and lower rates of suicide among these populations.

Individuals who take lithium as a mood stabilizer are monitored to prevent excess amounts from building up in the blood, which can have toxic effects. However, the amounts of lithium in drinking water are hundreds of times lower than those in medications.

“The levels of lithium in drinking water are far lower than those recommended when lithium is used as medicine, although the duration of exposure may be far longer, potentially starting at conception,” says Prof. Allan Young, the senior author of the new analysis and director of Centre for Affective Disorders at King’s College London.

Possibilities and ethical implications

Suicide is a major cause of preventable death around the world, and public health experts are searching for new ways to reduce the toll and address the underlying suffering of individuals and their loved ones.

The National Institute of Mental Health estimate that, in 2017, more than 47,000 people in the U.S. died by suicide. Among people ages 10–34 years old, suicide was the second leading cause of death after “unintentional injury.”

The World Health Organization (WHO) report that globally there are around 800,000 deaths by suicide every year, which is equivalent to one such death every 40 seconds.

“In these unprecedented times of the COVID-19 pandemic and the consequent increase in the incidence of mental health conditions, accessing ways to improve community mental health and reduce the incidence of anxiety, depression, and suicide is ever more important.”

– Lead author Prof. Anjum Memon

The study authors say that the next step may be to investigate the effects of adding lithium in trace amounts to the water supplies of particular communities.

They suggest that the research could focus on communities or areas with a high risk of suicide and high prevalences of mental health problems, chronic substance abuse, and violent criminal behavior.

While this may seem like a promising way of controlling suicide rates at a community level, the notion is highly controversial from an ethical point of view.

In a study paper published in Public Health Ethics in 2019, Dr. Jared Ng, Dr. Manne Sjöstrand, and Prof. Nir Eyal discuss the idea of adding higher levels of lithium to the water sources serving allegedly at-risk communities and critique its ethical implications.

They discuss the potential harms and benefits and focus particularly on the ways in which it would bypass individual autonomy.

“Whether and how we should administer trace amounts of lithium depends in part on what future empirical evidence reveals,” they argue.

Medical reference: Medical News Today