How to initiate lithium therapy: a systematic review of dose estimation and level prediction methods

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.

Improving lithium dose prediction using population pharmacokinetics and pharmacogenomics: a cohort genome-wide association study in Sweden

BACKGROUND

Lithium is the most effective treatment for bipolar disorder, resulting in strong suicide prevention effects. The therapeutic range of lithium, however, is narrow and treatment initiation requires individual titration to address inter-individual variability. We aimed to improve lithium dose prediction using clinical and genomic data.

METHODS

We performed a population pharmacokinetic study followed by a genome-wide association study (GWAS), including two clinical Swedish cohorts. Participants in cohort 1 were from specialised outpatient clinics at Huddinge Hospital, in Stockholm, Sweden, and participants in cohort 2 were identified using the Swedish National Quality Registry for Bipolar disorder (BipoläR). Patients who received a lithium dose corresponding to at least one tablet of lithium sulphate (6 mmol) per day and had clinically relevant plasma concentrations of lithium were included in the study. Data on age, sex, bodyweight, height, creatinine concentration, estimated glomerular filtration rate (eGFR), lithium preparation, number of tablets of lithium per day, serum lithium concentration, and medications affecting kidney function (C09 antihypertensives, C03 [except C03D] sodium-retaining diuretics, and non-steroidal anti-inflammatory drugs) were obtained retrospectively for several timepoints when possible from electronic health records, BipoläR, and the Swedish prescription registry. The median time between timepoints was 1·07 years for cohort 1 and 1·09 years for cohort 2. The primary outcome of interest was the natural logarithm of total body clearance for lithium (CL_Li) associated with the clinical variables. The residual effects after accounting for age and sex, representing the individual-level effects (CL_Li,age/sex), were used as the dependent variable in a GWAS.

FINDINGS

2357 patients who were administered lithium (1423 women [60·4%] and 934 men [39·6%]; mean age 53·6 years [range 17-89], mainly of European descent) were included and 5627 data points were obtained. Age (variance explained [R²]: R²_cohort1=0·41 and R²_cohort2=0·31; both p<0·0001), sex (R²_cohort1=0·0063 [p=0·045] and R²_cohort2=0·026 [p<0·0001]), eGFR (R²_cohort1=0·38 and R²_cohort2=0·20; both p<0·0001), comedication with diuretics (R²_cohort1=0·0058 [p=0·014] and R²_cohort2=0·0026 [p<0·0001]), and agents acting on the renin-aldosterone-angiotensin system (R²_cohort1=0·028 and R²_cohort2=0·015; both p<0·0001) were clinical predictors of CL_Li. Notably, an association between CL_Li and serum lithium was observed, with a lower CL_Li being associated with higher serum lithium (R²_cohort1=0·13 and R²_cohort2=0·15; both p<0·0001). In a GWAS of CL_Li,age/sex, one locus was associated with a change in CL_Li (rs583503; β=-0·053 [95% CI -0·071 to -0·034]; p<0·00000005). We also found enrichment of the associations with genes expressed in the medulla (p=0·0014, corrected FDR=0·04) and cortex of the kidney (p=0·0015, corrected FDR=0·04), as well as associations with polygenic risk scores for eGFR (p value threshold: 0·05, p=0·01), body-mass index (p value threshold: 0·05, p=0·00025), and blood urea nitrogen (p value threshold: 0·001, p=0·00043). The model based on six clinical predictors explained 61·4% of the variance in CL_Li in cohort 1 and 49·8% in cohort 2. Adding genetic markers did not lead to major improvement of the models: within the subsample of genotyped individuals, the variance explained only increased from 59·32% to 59·36% in cohort 1 and from 49·21% to 50·03% in cohort 2 when including rs583503 and the four first principal components.

INTERPRETATION

Our model predictors could be used clinically to better guide lithium dosage, shortening the time to reach therapeutic concentrations, thus improving care. Identification of the first genomic locus and PRS to be associated with CL_Li introduces the opportunity of individualised medicine in lithium treatment.

FUNDING

Stanley Medical Research Institute, Swedish Research Council, Swedish Foundation for Strategic Research, Swedish Brain Foundation, Swedish Research Council, Söderström-Königska Foundation, Bror Gadelius Minnesfond, Swedish Mental Health Fund, Karolinska Institutet and Hospital.

Dosing of Mood Stabilizers for Bipolar Disorder Patients in the Research on Asian Psychotropic Prescription Patterns Consortium Study

BACKGROUND

Because use and dosing of mood stabilizers (MSs) to treat bipolar disorder (BD) patients in Asia are not well documented, we examined prevalence and clinical correlates of treatment of Asian BD patients with relatively high doses of MSs.

METHODS

We conducted a pharmacoepidemiological survey across 13 Asian countries and territory in the Research on Asian Psychotropic Prescription Patterns Consortium. Mood stabilizer doses were converted to lithium carbonate equivalents (Li-eq milligrams per day). We compared relatively high (>900 Li-eq mg/day) versus lower MS doses by bivariate comparisons, followed by multivariable linear regression to identify factors associated with higher MS doses.

RESULTS

Among 1647 participants, MS dose averaged 584 (confidence interval, 565-603 Li-eq mg/d). Preliminarily, the 13.1% of the subjects given greater than 900 mg/d versus those given lower doses were younger, male, currently hospitalized, not currently depressed, and reported lifetime suicidal ideation; they also received relatively high doses of antipsychotics, received electroconvulsive treatment within the previous 12 months, and had greater ratings of tremors and sedation. By linear regression modeling, the mean proportion given high doses of MS was associated significantly and independently with higher doses of antipsychotics, younger age, male sex, hospitalized, more years of illness, country, higher body mass index, recent electroconvulsive treatment, and being in illness remission.

CONCLUSIONS

Relatively high doses of MSs for BD are prevalent, but vary markedly among Asian countries, and are particularly likely among young males, ill for many years, and given high doses of antipsychotics or ECT. These characteristics allow better identification of patient profiles that can guide treatment of BD patients.

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

Although suicide is considered a major preventable cause of mortality worldwide, we do not have effective strategies to prevent it. Lithium has been consistently associated with lowering risk of suicide. This effect could occur at very low concentrations, such as trace doses of lithium in tap water. Several ecological studies and recent meta-analysis have suggested an inverse association between lithium in water and suicide in the general population, with a lack of knowledge of clinically significant side effects. This paper is aimed as a proposal to discuss the addition of lithium to drinking water to decrease the suicide rate. For this, we review the evidence available, use previous experiences, such as water fluoridation to prevent dental caries, and discuss the complexity involved in such a public policy. Considering the limited data available and the controversies contained in this proposal, we suggest that a consensus on lithium concentration in water is needed, where the suicide rates start to reduce, as happened with water fluoridation. This measure will require to develop community-controlled trials with strict monitoring of any side effects, where democratic procedures would constitute one of the most appropriate ways to validate its implementation according to the reality of each community.

Predicting Serum Levels of Lithium-Treated Patients: A Supervised Machine Learning Approach

Routine monitoring of lithium levels is common clinical practice. This is because the lithium prediction strategies available developed by previous studies are still limited due to insufficient prediction performance. Thus, we used machine learning approaches to predict lithium concentration in a large real-world dataset. Real-world data from multicenter electronic medical records were used in different machine learning algorithms to predict: (1) whether the serum level was 0.6–1.2 mmol/L or 0.0–0.6 mmol/L (binary prediction), and (2) its concentration value (continuous prediction). We developed models from 1505 samples through 5-fold cross-validation and used 204 independent samples to test their performance by evaluating their accuracy. Moreover, we ranked the most important clinical features in different models and reconstructed three reduced models with fewer clinical features. For binary and continuous predictions, the average accuracy of these models was 0.70–0.73 and 0.68–0.75, respectively. Seven features were listed as important features related to serum lithium levels of 0.6–1.2 mmol/L or higher lithium concentration, namely older age, lower systolic blood pressure, higher daily and last doses of lithium prescription, concomitant psychotropic drugs with valproic acid and -pine drugs, and comorbid substance-related disorders. After reducing the features in the three new predictive models, the binary or continuous models still had an average accuracy of 0.67–0.74. Machine learning processes complex clinical data and provides a potential tool for predicting lithium concentration. This may help in clinical decision-making and reduce the frequency of serum level monitoring.

The Genetics of Response to and Side Effects of Lithium Treatment in Bipolar Disorder: Future Research Perspectives

Although the mood stabilizer lithium is a first-line treatment in bipolar disorder, a substantial number of patients do not benefit from it and experience side effects. No clinical tool is available for predicting lithium response or the occurrence of side effects in everyday clinical practice. Multiple genetic research efforts have been performed in this field because lithium response and side effects are considered to be multifactorial endophenotypes. Available results from linkage and segregation, candidate-gene, and genome-wide association studies indicate a role of genetic factors in determining response and side effects. For example, candidate-gene studies often report GSK3β, brain-derived neurotrophic factor, and SLC6A4 as being involved in lithium response, and the latest genome-wide association study found a genome-wide significant association of treatment response with a locus on chromosome 21 coding for two long non-coding RNAs. Although research results are promising, they are limited mainly by a lack of replicability and, despite the collaboration of consortia, insufficient sample sizes. The need for larger sample sizes and "multi-omics" approaches is apparent, and such approaches are crucial for choosing the best treatment options for patients with bipolar disorder. In this article, we delineate the mechanisms of action of lithium and summarize the results of genetic research on lithium response and side effects.

Determination of lithium in dried blood spots and dried plasma spots by graphite furnace atomic absorption spectrometry: Method development, validation and clinical application

Therapeutic drug monitoring (TDM) has become a standard of care for the mood stabilizer lithium (Li⁺). Dried Blood Spots (DBS) and Dried Plasma Spots (DPS) are promising alternative sampling strategies for TDM, which allows simple and cost-effective logistics in many settings, particularly in Developing Countries. DBS and DPS are of particular interest to Li + TDM for allowing the estimation of Li + erythrocyte levels. Thus, the aim of this study was to develop and validate an assay for the determination of Li+ in DBS and DPS by Graphite Furnace Atomic Absorption Spectrometry (GFAAS), and to evaluate its application in a clinical setting. Li+ was extracted from one 8 mm DBS disc punch with nitric acid 4.5% and from one 6 mm DPS disc punch with diluent solution (HNO₃ 1% + Triton 0.1%) and injected into GFAAS. The method was applied to Li + TDM in 43 patients with mood disorder. The assays were linear from 0.10 to 3.0 mEq L^-1 (r > 0.99), precise, with CV 3.6-7.2% for DBS and 4.6-9.3% for DPS samples, and accurate, with accuracy values of 97-109% and 98-106% for DBS and DPS samples, respectively. Li+ was stable in dried samples during twenty days at up to 42 °C. The DBS assay accuracy and recovery were not influenced by blood hematocrit. The patients presented Li + serum concentrations of 0.18-1.1 mEq L^-1 and 0.17 to 0.92 mEq L^-1 in DBS and 0.15 to 0.99 mEq L^-1 in DPS samples. DPS had comparable Li + concentrations to the ones found in fresh serum samples. With DBS samples it was possible to estimate the Li + erythrocyte to plasma concentration ratio (LiR). The findings of this study support the clinical application of DBS and DPS samples for the TDM of Li+.

The rapid suicide protection of mood stabilizers on patients with bipolar disorder: A nationwide observational cohort study in Taiwan

BACKGROUND

The suicide rate is high among bipolar disorder (BD) patients. Previous studies have focused on the anti-suicidal effect of long-term treatment with mood stabilizers but less on the immediate preventive effects of interventions. The aim of the study was to evaluate the short-term and immediate anti-suicidal effects of mood stabilizers on recent-onset BD patients.

METHODS

The National Health Insurance Database (NHID) of Taiwan was used to perform a nationwide cohort observation study of suicide behaviors in bipolar disorder. All the recent-onset BD patients (ICD-9-CM code 296 except 296.2 and 296.3) diagnosed between 2000-2005 were collected (n=5091) and followed through 2009. The primary endpoint was the presence of a suicide code or the end of observation; exposure to mood stabilizers in the final month of observation was the independent variable.

RESULTS

The hazard ratios (HRs) of suicide-related events, completed suicide, and all-cause mortality were significantly lower for those treated with lithium, divalproex, or carbamazepine compared with no use in the last month (HRs of suicide-related events were 0.10, 0.14 and 0.10, respectively, and all-cause mortality HRs were 0.03; P<0.0001); there was no significant difference in HR between the mood stabilizers.

LIMITATIONS

The NIHD does not provide information on the severity, mood status, or treatment adherence of BD patients. Neither substance-related disorder nor personality disorder were included in the analysis. We focused on the effect of the final prescription time period, not the long-term protective effect.

CONCLUSIONS

The immediate recent use of any mood stabilizer significantly lowers the rate of death, suicide, or suicidal behavior in BD.

Standing of giants shoulders the story of the mitochondrial Na(+)Ca(2+) exchanger

It is now the 40th anniversary of the Journal of Molecular and Cellular Cardiology paper by Ernesto Carafoli and colleagues. This seminal study described for the first time mitochondrial Ca(2+) extrusion and its coupling to Na(+). This short review will describe the profound impact that this work had on mitochondrial signaling and the cross talk between the mitochondria, the ER, and the plasma membrane. It will further tell how the functional identification and in particular its unique cation selectivity to both Li(+) and Na(+) eventually contributed to the identification of the mitochondrial Na(+)/Ca(2+) exchanger gene NCLX many years later. The last part will describe how molecular tools derived from NCLX identification are used to study the novel physiological aspects of Ca(2+) signaling.