According to a recent UCLA Health study, pregnant women whose household tap water included higher levels of lithium had a slightly increased risk of their children being diagnosed with an autism spectrum disease. The study, which was published in JAMA Pediatrics on April 3rd, is thought to be the first to identify naturally occurring lithium in drinking water as a probable environmental risk factor for autism.
“Any drinking water contaminants that may affect the developing human brain deserve intense scrutiny,” said lead study author Beate Ritz, MD, PhD, professor of neurology in the David Geffen School of Medicine at UCLA and professor of epidemiology and environmental health at the UCLA Fielding School of Public Health. “In the future, anthropogenic sources of lithium in water may become more widespread because of lithium battery use and disposal in landfills with the potential for groundwater contamination. The results of our study are based on high-quality Danish data but need to be replicated in other populations and areas of the world.”
Certain lithium compounds have long been utilized as a treatment for depression and bipolar disorders due to their mood-stabilizing properties. Nonetheless, there has been controversy regarding whether mothers can safely take lithium during pregnancy, despite mounting evidence that it is linked to an increased risk of miscarriage and heart abnormalities or malformations in babies.
Ritz, whose research focuses on how environmental exposures influence neurodevelopmental disorders and neurodegenerative diseases, said she decided to investigate the possible link between lithium and autism risk after discovering that there had been little human research on how lithium affects brain growth and development.
Yet, she discovered that some experimental data suggested that lithium, one of several naturally occurring metals contained in water, could influence a key biochemical process involved in neurodevelopment and autism.
According to Zeyan Liew, PhD, MPH, the study’s first author and an Assistant Professor of Epidemiology at the Yale University School of Public Health, this study is important because previous research from Denmark using high-quality medical registry data has shown that ingestion of chronic and low-dose lithium from drinking can influence the occurrence of adult-onset neuropsychiatric disorders. Unfortunately, no research has been conducted to determine whether lithium in drinking water eaten by pregnant women impacts the neurodevelopment of their children.
Ritz and Liew collaborated with Danish researchers who examined lithium levels in 151 public waterworks in Denmark, which served approximately half of the country’s population. The researchers analyzed address information from Denmark’s comprehensive civil registry system to determine which waterworks serviced mothers’ houses at the time of their pregnancy.
Utilizing a countrywide database of individuals with psychiatric problems, the researchers selected children born between 1997 and 2013 and compared them to 63,681 youngsters who did not have an autism diagnosis. The researchers also took into account maternal features, socioeconomic factors, and exposure to air pollution, all of which have been related to an elevated risk of autism in offspring.
According to the researchers, as lithium levels rose, so did the risk of being diagnosed with autism. In comparison to the lowest quartile of observed lithium levels (the 25th percentile), lithium levels in the second and third quartiles were related to a 24-26% increased risk of autism. The risk was 46% higher in the top quartile than in the lowest.
When the data was broken down by autism subtypes, the researchers discovered a similar association between elevated lithium levels and a higher risk of autism diagnosis. They also discovered that the link between lithium levels and autism risk was slightly stronger in urban regions than in smaller cities and rural locations.
Aside from Denmark’s extensive civil databases, which have shown to be excellent tools for public health researchers, a number of other characteristics made Denmark an appropriate location for this study. Denmark’s bottled water use is among the lowest in Europe, implying that Danes primarily rely on tap water. The country also has a solid system in place for monitoring trace metals and other impurities in its water supply. When compared to other countries, lithium levels in Danish water are likely to be in the low to moderate range, according to Ritz.