Frequently Asked Questions

Lithium is certainly not harmful in low, most likely essential doses and is not a cause for autism, quite the contrary. But how does this false claim come about, and where exactly does the mistake lie?

According to a Danish study from 2023, which was widely disseminated in the media, there is supposed to be a connection between the regional lithium concentration in drinking water or the possible consumption of this water during pregnancy and the risk of autism in the child.[1]

We are talking about lithium concentrations in drinking water of 0.6 to 30.7 µg/L (micrograms per liter). Dividing this range into four concentration ranges (so-called quartiles), an approximately 23% increased rate of autism was observed in the second, third, and fourth quartiles compared to the respective lower quartile.

It is not known whether and in what quantities the pregnant women actually consumed drinking water. But let’s assume a liter per day, then it becomes clear that there can be no causality. Comparing the lithium intake observed here of 0.6 to 30.7 µg per day with the lithium intake of 100,000 µg and more per day in connection with the treatment of bipolar disorders, it is clear how small the amounts are. In a Dutch study from 2012, even at high dosages for the treatment of bipolar disorders, no neuropathological abnormalities were observed in the children of the patients: “Continuing lithium therapy during pregnancy did not cause adverse effects on growth, neurological, cognitive and behavioral development of exposed children.”[2] A larger follow-up study from 2022, which also examined the consequences of lithium treatment during pregnancy, came to the same conclusion: “In this study, we found no evidence for significantly altered neuropsychological functioning of lithium-exposed children at the age of 6-14 years, when compared to non-lithium-exposed controls.”[3]

Therefore, there must necessarily be another explanation if an intake of lithium thousands of times higher, as was the case in the drinking water study, does not cause autism. Moreover, correlation is not proof of causality.

But whether there is even a correlation, as claimed, must first be ensured. Statistical distortions very easily lead to seeing connections where there are none; similar criticism is also expressed by other scientists. Brian Lee, Associate Professor at Drexel University in Philadelphia, provides a detailed critique of the data collection and statistical analysis of the mentioned study in a comprehensive article[4], which also refers to other critical voices. Here are a few excerpts from the criticisms (the actual list is much longer):

1. In a case-control study like this, the main question is whether the sampling strategy leads to distortions. The new study included all eligible autistic children in Denmark, while controls were randomly selected from the Danish population. If cases and controls come from different geographical populations, the results could simply reflect geographical differences in the prevalence of autism or confounding factors and not geographical differences in lithium concentration in drinking water.

2. Another problem is the accuracy of quantifying lithium intake since there is no data on the dose administered to participants. Thus, the “estimated nature” of the possibly administered lithium amount here poses another statistical challenge. However, according to Brian Lee’s analysis, the authors of the study did not use any statistical method to account for the great uncertainty associated with the estimated dosage – hence the point estimates are probably biased (in which direction is only a guess) and the so-called confidence intervals (supposed accuracy) are an artifact.

3. Although the authors found that a single unmeasured confounder cannot explain the results, it is plausible that several factors interact. The mother’s mental health and the socioeconomic status at the individual level are likely both related to lithium intake and autism in children, but neither of these two factors was considered.

Another objection arises, even if one assumes, despite the many statistical problems, that there is indeed a connection between low lithium intake (via drinking water) and autism. Since it cannot be the lithium (as above), one would have to take a closer look at the water itself. For example, the lithium concentration in freshwater from volcanic regions or sources is usually higher. However, volcanic rock also contains many other minerals, and thus the water contains constituents that are typically also unusually high. But this was not investigated. For instance, children with an autism spectrum disorder according to a twin study had increased concentrations of lead in their milk teeth, which are formed in a perinatal developmental phase.[5] But thallium, cadmium, mercury, tin, and tungsten are also discussed alongside lead and some other heavy metals as causal factors in autism.

Conclusion: Lithium in low and very likely essential dosage is with utmost certainty not harmful and not a cause of autism; quite the contrary. In an animal model of autism, for example, the effect of low doses of lithium on clinical symptoms was examined. The authors conclude:

“The results showed a defensive effect of environment-related lithium exposure doses on neurobehavioural deficits in the rat valproic acid model of autism, suggesting that it may be a potential drug for the treatment of autism.”[6]

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