Lithium in Drinking Water as a Public Policy for Suicide Prevention: Relevance and Considerations

Too early to add lithium to drinking water? No association between lithium and suicides in a pre-registered Swiss study

BACKGROUND

Suicide remains a significant public health concern worldwide. Ecological studies reported decreased suicide rates with higher levels of trace lithium levels in drinking water, leading to suggestions of adding lithium to drinking water as a preventative anti-suicide strategy. However, the evidence remains inconclusive, and thus more data are needed.

METHODS

This pre-registered study analyzed the association between lithium concentrations in drinking water and suicide rates across 1043 municipalities in Switzerland between 1981 and 2021. We used bivariate correlation analysis, ordinary regression models, and spatial regression models, while accounting for potential confounding variables.

RESULTS

There were no significant associations between lithium levels in drinking water and suicide rates, as determined by correlation analysis (r = -0.03, 95 % CI -0.09-0.03, p = 0.33), and by multivariable ordinary and spatial regression models.

LIMITATIONS

The correlation between levels of lithium in tap water and the serum of individuals is unknown and ecological studies are inherently limited to establish a causal association.

CONCLUSIONS

The null finding in our study adds to the ongoing debate on the effectiveness of trace lithium in drinking water as a public health intervention for suicide prevention, indicating that calls for lithium supplementation are still premature. These findings highlight the need for further research with transparent and replicable methodologies to clarify the potential role of lithium in suicide prevention.

Progress and trends of research on mineral elements for depression

Objective

To explore the research progress and trends on mineral elements and depression.

Methods

After querying the MeSH database and referring to the search rules, the search terms were selected and optimized to obtain the target literature collection. We analyzed the general characteristics of the literature, conducted network clustering and co-occurrence analysis, and carried out a narrative review of crucial literature.

Results

Bipolar disorder was a dominant topic in the retrieved literature, which saw a significant increase in 2010 and 2019-2020. Most studies focused on mineral elements, including lithium, calcium, magnesium, zinc, and copper. The majority of journals and disciplines were in the fields of psychiatry, neuropsychology, neuropharmacology, nutrition, medical informatics, chemistry, and public health. The United States had the highest proportion in terms of paper sources, most-cited articles, high-frequency citations, frontier citations, and high centrality citation. Regarding the influence of academic institutions, the top five were King's College London, the Chinese Academy of Sciences, University of Barcelona, INSERM, and Heidelberg University. Frontier keywords included bipolar disorder, drinking water, (neuro)inflammation, gut microbiota, and systematic analysis. Research on lithium response, magnesium supplementation, and treatment-resistant unipolar depression increased significantly after 2013.

Conclusion

Global adverse events may have indirectly driven the progress in related research. Although the literature from the United States represents an absolute majority, its influence on academic institutions is relatively weaker. Multiple pieces of evidence support the efficacy of lithium in treating bipolar disorder (BD). A series of key discoveries have led to a paradigm shift in research, leading to increasingly detailed studies on the role of magnesium, calcium, zinc, and copper in the treatment of depression. Most studies on mineral elements remain diverse and inconclusive. The potential toxicity and side effects of some elements warrant careful attention.

Lithium and its effects: does dose matter?

BACKGROUND

Decades of clinical research have demonstrated the efficacy of lithium in treating acute episodes (both manic and depressive), as well as in preventing recurrences of bipolar disorder (BD). Specific to lithium is its antisuicidal effect, which appears to extend beyond its mood-stabilizing properties. Lithium's clinical effectiveness is, to some extent, counterbalanced by its safety and tolerability profile. Indeed, monitoring of lithium levels is required by its narrow therapeutic index. There is consensus that adequate serum levels should be above 0.6 mEq/L to achieve clinical effectiveness. However, few data support the choice of this threshold, and increasing evidence suggests that lithium might have clinical and molecular effects at much lower concentrations.

CONTENT

This narrative review is aimed at: (1) reviewing and critically interpreting the clinical evidence supporting the use of the 0.6 mEq/L threshold, (2) reporting a narrative synthesis of the evidence supporting the notion that lithium might be effective in much lower doses. Among these are epidemiological studies of lithium in water, evidence on the antisuicidal, anti-aggressive, and neuroprotective effects, including efficacy in preventing cognitive impairment progression, Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS), of lithium; and (3) revieweing biological data supporting clinically viable uses of lithium at low levels with the delineation of a mechanistic hypothesis surrounding its purported mechanism of action. The study selection was based on the authors' preference, reflecting the varied and extensive expertise on the review subject, further enriched with an extensive pearl-growing strategy for relevant reviews and book sections.

CONCLUSIONS

Clinical and molecular effects of lithium are numerous, and its effects also appear to have a certain degree of specificity related to the dose administered. In sum, the clinical effects of lithium are maximal for mood stabilisation at concentrations higher than 0.6 mEq/l. However, lower levels may be sufficient for preventing depressive recurrences in older populations of patients, and microdoses could be effective in decreasing suicide risk, especially in patients with BD. Conversely, lithium's ability to counteract cognitive decline appears to be exerted at subtherapeutic doses, possibly corresponding to its molecular neuroprotective effects. Indeed, lithium may reduce inflammation and induce neuroprotection even at doses several folds lower than those commonly used in clinical settings. Nevertheless, findings surrounding its purported mechanism of action are missing, and more research is needed to investigate the molecular targets of low-dose lithium adequately.

Assessment of Human Health Risk Indices Due to Metal Contamination in the Surface Water of the Negro River Sub-Basin, Áncash

The accelerated loss of glacial cover in the Cordillera Blanca in Áncash, Peru, exposes the underlying rocks with high concentrations of sulfides from the Chicama Formation to oxidation and leaching processes, generating acid rock drainage (ARD) in glacial and periglacial areas. These are transported by surface runoff, contaminating the surface water with high concentrations of metals and sulfates, as well as increasing the acidity, which poses a risk to human health and the ecosystem. Therefore, the risk indices for human health due to metal contamination were evaluated at 19 surface water sampling points distributed in the Río Negro sub-basin. Hydrochemical analyses revealed average metal concentrations in the following order: Fe (28.597 mg/L), Al (3.832 mg/L), Mn (1.085 mg/L), Zn (0.234 mg/L), Ni (0.085 mg/L), Co (0.053 mg/L), Li (0.036 mg/L), Cu (0.005 mg/L), and Pb (0.002 mg/L). The risk was determined by calculating the Heavy Metal Pollution Index (HPI) and the Hazard Index (HI). The average HPI value was 360.959, indicating a high level of contamination (HPI ≥ 150). The human health risk assessment indicated that adverse effects caused by iron, lithium, and cobalt in children and adults should be considered. Through the use of Pearson correlation analysis, principal component analysis, and cluster analysis, it was identified that SO42-, Fe, S, Al, Co, Mn, Ni, Zn, and Li originate from natural sources, associated with the generation of ARD in glacial and periglacial areas.

Prevention of suicidal behavior with lithium treatment in patients with recurrent mood disorders

Suicidal behavior is more prevalent in bipolar disorders than in other psychiatric illnesses. In the last thirty years evidence has emerged to indicate that long-term treatment of bipolar disorder patients with lithium may reduce risk of suicide and attempts, with possibly similar benefits in recurrent major depressive disorder. We review and update selected research literature on effects of lithium treatment in reducing suicidal behavior and consider proposals that higher levels of lithium in drinking water may be associated with lower suicide rates. We summarize results of a growing number of randomized, controlled studies of lithium treatment for suicide prevention including comparisons with placebos or alternative treatments, and comment on the severe challenges of such trials. The basis of a proposed protective effect of lithium against suicidal behaviors remains uncertain but may include protective effects against recurrences of depressive phases of mood disorders, especially with mixed features or agitation, and possibly through beneficial effects on impulsivity, agitation and dysphoric mood.

Dietary lithium stimulates female fecundity in Drosophila melanogaster

The trace element lithium exerts a versatile bioactivity in humans, to some extend overlapping with in vivo findings in the model organism Drosophila melanogaster. A potentially essential function of lithium in reproduction has been suggested since the 1980s and multiple studies have since been published postulating a regulatory role of lithium in female gametogenesis. However, the impact of lithium on fruit fly egg production has not been at the center of attention to date. In the present study, we report that dietary lithium (0.1-5.0 mM LiCl) substantially improved life time egg production in D. melanogaster w1118 females, with a maximum increase of plus 45% when supplementing 1.0 mM LiCl. This phenomenon was not observed in the insulin receptor mutant InRE19, indicating a potential involvement of insulin-like signaling in the lithium-mediated fecundity boost. Analysis of the whole-body and ovarian transcriptome revealed that dietary lithium affects the mRNA levels of genes encoding proteins related to processes of follicular maturation. To the best of our knowledge, this is the first report on dietary lithium acting as an in vivo fecundity stimulant in D. melanogaster, further supporting the suggested benefit of the trace element in female reproduction.

Estimating Lithium Concentrations in Groundwater Used as Drinking Water for the Conterminous United States

Lithium (Li) concentrations in drinking-water supplies are not regulated in the United States; however, Li is included in the 2022 U.S. Environmental Protection Agency list of unregulated contaminants for monitoring by public water systems. Li is used pharmaceutically to treat bipolar disorder, and studies have linked its occurrence in drinking water to human-health outcomes. An extreme gradient boosting model was developed to estimate geogenic Li in drinking-water supply wells throughout the conterminous United States. The model was trained using Li measurements from ∼13,500 wells and predictor variables related to its natural occurrence in groundwater. The model predicts the probability of Li in four concentration classifications, ≤4 μg/L, >4 to ≤10 μg/L, >10 to ≤30 μg/L, and >30 μg/L. Model predictions were evaluated using wells held out from model training and with new data and have an accuracy of 47-65%. Important predictor variables include average annual precipitation, well depth, and soil geochemistry. Model predictions were mapped at a spatial resolution of 1 km2 and represent well depths associated with public- and private-supply wells. This model was developed by hydrologists and public-health researchers to estimate Li exposure from drinking water and compare to national-scale human-health data for a better understanding of dose-response to low (<30 μg/L) concentrations of Li.

Lithium concentration in tap water, bottled mineral water, and Danube River water in Hungary

Due to increased manufacture and recycling of lithium batteries across the world, we may anticipate a rise in lithium pollution in the aquatic environment and drinking water reservoirs. In order to investigate the current status regarding the lithium content in Hungarian tap waters, samples were collected from the public drinking water supply systems of 19 county seats in Hungary during seasonally selected times. Depending on the water sources, such as bank-filtrated river water, surface water from open reservoirs, and groundwater, the lithium concentrations varied between 0.90-4.23, 2.12-11.7 and 1.11-31.4 µg/L, respectively, while the median values were 3.52, 5.02 and 8.55 µg/L, respectively. The lithium concentration in the bottled Hungarian mineral waters was also determined since the daily intake of lithium can be influenced by the consumption of mineral waters. The concentrations ranged from 4.2 to 209 µg/L, while the median value was only 17.8 µg/L. Additionally, a correlation was only found between lithium and potassium concentrations. The lithium concentration was also assessed at ten sampling locations in the Hungarian segment of the Danube River since the Danube water is also a water source for additional drinking water utilities using bank filtration technology. The mean and median lithium concentrations were 2.78 and 2.64 µg/L, respectively.

Low-Dose Lithium Supplementation Influences GSK3β Activity in a Brain Region Specific Manner in C57BL6 Male Mice

BACKGROUND

Lithium, a commonly used treatment for bipolar disorder, has been shown to have neuroprotective effects for other conditions including Alzheimer's disease via the inhibition of the enzyme glycogen synthase kinase-3 (GSK3). However, dose-dependent adverse effects of lithium are well-documented, highlighting the need to determine if low doses of lithium can reliably reduce GSK3 activity.

OBJECTIVE

The purpose of this study was to evaluate the effects of a low-dose lithium supplementation on GSK3 activity in the brain of an early, diet-induced Alzheimer's disease model.

METHODS

Male C57BL/6J mice were divided into either a 6-week or 12-week study. In the 6-week study, mice were fed a chow diet or a chow diet with lithium-supplemented drinking water (10 mg/kg/day) for 6 weeks. Alternatively, in the 12-week study, mice were fed a chow diet, a high-fat diet (HFD), or a HFD with lithium-supplemented drinking water for 12 weeks. Prefrontal cortex and hippocampal tissues were collected for analysis.

RESULTS

Results demonstrated reduced GSK3 activity in the prefrontal cortex as early as 6 weeks of lithium supplementation, in the absence of inhibitory phosphorylation changes. Further, lithium supplementation in an obese model reduced prefrontal cortex GSK3 activity as well as improved insulin sensitivity.

CONCLUSION

Collectively, these data provide evidence for low-dose lithium supplementation to inhibit GSK3 activity in the brain. Moreover, these results indicate that GSK3 activity can be inhibited despite any changes in phosphorylation. These findings contribute to an overall greater understanding of low-dose lithium's ability to influence GSK3 activity in the brain and its potential as an Alzheimer's disease prophylactic.