Lithium: past, present, and future

Identifying the neuropsychiatric health effects of low-dose lithium interventions: A systematic review

BACKGROUND

Lithium is widely evidenced for its neuropsychiatric benefits. Advantages of 'sub-therapeutic' doses are increasingly being reported, which is apposite given enduring concerns around adverse effects of 'therapeutic' doses. We aimed to synthesise all available evidence from interventional studies investigating low-dose lithium (LDL) across neuropsychiatric outcomes.

METHODS

Electronic databases were systematically searched to include studies where a group of adult humans were treated with LDL (∼serum level ≤0.6 mmol/L), where data describing a neuropsychiatric outcome were reported either before and after treatment, and/or between lithium and a comparator.

RESULTS

18 articles were examined and grouped according to outcome domain (cognition, depression, mania, and related constructs e.g., suicidality). Significant benefits (versus placebo) were identified for attenuating cognitive decline, and potentially as an adjunctive therapy for people with depression/mania. Across studies, LDL was reported to be safe.

CONCLUSIONS

Despite the paucity and heterogeneity of studies, LDL's apparent pro-cognitive effects and positive safety profile open promising avenues in the fields of neurodegeneration, and augmentation in affective disorders. We urge future examinations of LDL's potential to prevent cognitive/affective syndromes.

Lithium Ascorbate as a Promising Neuroprotector: Fundamental and Experimental Studies of an Organic Lithium Salt

Given the observable toxicity of lithium carbonate, neuropharmacology requires effective and non-toxic lithium salts. In particular, these salts can be employed as neuroprotective agents since lithium ions demonstrate neuroprotective properties through inhibition of glycogen synthetase kinase-3β and other target proteins, increasing concentrations of endogenous neurotrofic factors. The results of theoretical and experimental studies of organic lithium salts presented here indicate their potential as neuroprotectors. Chemoreactomic modeling of lithium salts made it possible to select lithium ascorbate as a suitable candidate for further research. A neurocytological study on cerebellar granular neurons in culture under conditions of moderate glutamate stress showed that lithium ascorbate was more effective in supporting neuronal survival than chloride or carbonate, i.e., inorganic lithium salts. Biodistribution studies indicated accumulation of lithium ions in a sort of “depot”, potentially consisting of the brain, aorta, and femur. Lithium ascorbate is characterized by extremely low acute and chronic toxicity (LD50 > 5000 mg/kg) and also shows a moderate antitumor effect when used in doses studied (5 or 10 mg/kg). Studies on the model of alcohol intoxication in rats have shown that intake of lithium ascorbate in doses either 5, 10 or 30 mg/kg did not only reduced brain damage due to ischemia, but also improved the preservation of myelin sheaths of neurons.

Lithium as a Neuroprotective Agent for Bipolar Disorder: An Overview

Lithium (Li⁺) is a first option treatment for adult acute episodes of Bipolar Disorder (BD) and for the prophylaxis of new depressed or manic episodes. It is also the preferred choice as maintenance treatment. Numerous studies have shown morphological abnormalities in the brains of BD patients, suggesting that this highly heritable disorder may exhibit progressive and deleterious changes in brain structure. Since treatment with Li⁺ ameliorates these abnormalities, it has been postulated that Li⁺ is a neuroprotective agent in the same way atypical antipsychotics are neuroprotective in patients diagnosed with schizophrenia spectrum disorders. Li⁺'s neuroprotective properties are related to its modulation of nerve growth factors, inflammation, mitochondrial function, oxidative stress, and programmed cell death mechanisms such as autophagy and apoptosis. Notwithstanding, it is not known whether Li⁺-induced neuroprotection is related to the inhibition of its putative molecular targets in a BD episode: the enzymes inositol-monophosphatase, (IMPase), glycogen-synthase-kinase 3β (GSK3), and Protein kinase C (PKC). Furthermore, it is uncertain whether these neuroprotective mechanisms are correlated with Li⁺'s clinical efficacy in maintaining mood stability. It is expected that in a nearby future, precision medicine approaches will improve diagnosis and expand treatment options. This will certainly contribute to ameliorating the medical and economic burden created by this devastating mood disorder.

A phase 2a randomised, double-blind, placebo-controlled, parallel-group, add-on clinical trial of ebselen (SPI-1005) as a novel treatment for mania or hypomania

RATIONALE

Lithium is an effective prophylactic and anti-manic treatment in bipolar disorder; however, its use is declining through perceived poor tolerance and toxicity. Lithium inhibits inositol monophosphatase (IMPase), a probable key therapeutic mechanism. The anti-inflammatory drug, ebselen, also inhibits IMPase and appears well-tolerated and safe.

OBJECTIVES

To assess the efficacy of adjunctive ebselen in mania using the Young Mania Rating Scale (YMRS) (primary outcome) and the Altman Self-Rating Mania (ASRM) Scale and Clinical Global Impression-Severity Scale (CGI-S) among the secondary outcomes.

METHODS

Randomised, double-blind, placebo-controlled, parallel-group trial conducted between October 2017 and June 2019, at Oxford Health NHS Foundation Trust. Pharmacy-controlled randomisation was computer-generated, with full allocation concealment. In/outpatients (n = 68) aged 18-70, experiencing mania or hypomania, were assigned to 3 weeks ebselen (600 mg bd) (n = 33) or placebo (n = 35). Participants received usual clinical care and psychotropic medication.

RESULTS

Ebselen was numerically, but not statistically, superior to placebo in lowering scores on the YMRS (adjusted mean difference and 95% confidence interval, - 1.71 (- 5.34 to 1.91), p = 0.35) and ASRM (- 1.36 (- 3.75 to 1.17), p = 0.29). However, scores on the CGI-S were significantly lower at week 3 in ebselen-treated participants (adjusted mean difference, - 0.58 (- 1.14 to - 0.03), p = 0.04). A post hoc analysis excluding patients taking concomitant valproate treatment magnified the difference between ebselen and placebo on the YMRS. Adverse events were comparable between groups, and mild.

CONCLUSIONS

Ebselen merits further investigation where concomitant psychotropic medication is better controlled and participants taking valproate are excluded. If effective, ebselen's superior tolerance and safety could make it a useful alternative to lithium.

TRIAL REGISTRATION

Trial Registry: www.clinicaltrials.gov , Identifier: NCT03013400.