Lithium interacts with cardiac remodeling: the fundamental value in the pharmacotherapy of bipolar disorder

Lithium downregulates phosphorylated acetyl‑CoA carboxylase 2 and attenuates mitochondrial fatty acid utilization and oxidative stress in cardiomyocytes

Acetyl-CoA carboxylase 2 plays a crucial role in regulating mitochondrial fatty acid oxidation in cardiomyocytes. Lithium, a monovalent cation known for its cardioprotective potential, has been investigated for its influence on mitochondrial bioenergetics. The present study explored whether lithium modulated acetyl-CoA carboxylase 2 and mitochondrial fatty acid metabolism in cardiomyocytes and the potential therapeutic applications of lithium in alleviating metabolic stress. Mitochondrial bioenergetic function, fatty acid oxidation, reactive oxygen species production, membrane potential and the expression of proteins involved in fatty acid metabolism in H9c2 cardiomyocytes treated with LiCl for 48 h was measured by using a Seahorse extracellular flux analyzer, fluorescence microscopy and western blotting. Small interfering RNA against glucose transporter type 4 was transfected into H9c2 cardiomyocytes for 48 h to induce metabolic stress mimicking insulin resistance. The results revealed that LiCl at a concentration of 0.3 mM (but not at a concentration of 0.1 or 1.0 mM) upregulated the expression of phosphorylated (p-)glycogen synthase kinase-3 beta and downregulated the expression of p-acetyl-CoA carboxylase 2 but did not affect the expression of adenosine monophosphate-activated protein kinase or calcineurin. Cotreatment with TWS119 (8 µM) and LiCl (0.3 mM) downregulated p-acetyl-CoA carboxylase 2 expression to a similar extent as did treatment with TWS119 (8 µM) alone. Moreover, LiCl (0.3 mM) inhibited mitochondrial fatty acid oxidation, improved coupling efficiency and the cellular respiratory control ratio, hindered reactive oxygen species production and proton leakage and restored mitochondrial membrane potential in glucose transporter type 4 knockdown-H9c2 cardiomyocytes. These findings suggested that low therapeutic levels of lithium can downregulate p-acetyl-CoA carboxylase 2, thus reducing mitochondrial fatty acid oxidation and oxidative stress in cardiomyocytes.

Lithium and risk of cardiovascular disease, dementia and venous thromboembolism

OBJECTIVE

To determine if long-term lithium treatment is associated with protective effects or increased risk of vascular, neurological, and renal disorders.

METHODS

Using nationwide registers, we included all citizens of Finland with dispensations of lithium for three or more consecutive years between 1995 and 2016. We identified 9698 cases and matched 96,507 controls without lithium treatment. Studied outcomes were vascular, neurological, renal disorders, and suicide. Analyses were performed applying Cox proportional hazards modeling in full cohort and in further subcohort analysis of individuals with a comparable diagnosis of mood or psychotic disorder.

RESULTS

Lithium users had a significantly higher overall disease burden compared to matched population controls, including a higher risk of cardiovascular and cerebrovascular disorders and dementia. However, compared to individuals with a diagnosis of mood or psychotic disorders without lithium treatment, we observed a lower risk of cardiovascular and cerebrovascular disorders (HR = 0.80, 99% CI = 0.73-0.89), and no significant difference for dementia (HR = 1.15, 99% CI = 0.99-1.33), in lithium users. Pulmonary embolism was more common in the lithium-treated cases both in comparison to the general population (HR = 2.86, 99% CI = 2.42-3.37) and in comparison to the psychiatric subcohort (HR = 1.68, 99% CI = 1.31-2.17). Similarly, the risks of Parkinson's disease and kidney disease were higher in both comparisons.

CONCLUSIONS

We conclude that individuals prescribed lithium have a lower risk of cardiovascular and cerebrovascular disease, but no marked effect on dementia, compared to individuals with a mood or psychotic disorder not prescribed lithium. Venous thromboembolism, Parkinson's disease, and kidney disease were significantly more prevalent in individuals prescribed lithium.

Mood stabilizers and risk of all-cause, natural, and suicide mortality in bipolar disorder: A nationwide cohort study

OBJECTIVES

People with bipolar disorder have an elevated risk of mortality. This study evaluated associations between the use of mood stabilizers and the risks of all-cause mortality, suicide, and natural mortality in a national cohort of people with bipolar disorder.

METHODS

In this nationwide cohort study, we used data from January 1, 2000, to December 31, 2016, collected from Taiwan's National Health Insurance Research Database and included 25,787 patients with bipolar disorder. Of these patients, 4000 died during the study period (including 760 and 2947 from suicide and natural causes, respectively). Each standardized mortality ratio (SMR) was calculated as the ratio of observed mortality in the bipolar cohort to the number of expected deaths in the general population. Multivariable Cox proportional hazards regression with a time-dependent model was performed to estimate the hazard ratio (HR) of each mood stabilizer with each mortality outcome.

RESULTS

The SMRs of all-cause mortality, suicide, and natural mortality in the bipolar disorder cohort were 5.26, 26.02, and 4.68, respectively. The use of mood stabilizers was significantly associated with decreased risks of all-cause mortality (adjusted HR [aHR] = 0.58, p< 0.001), suicide (aHR = 0.60, p < 0.001), and natural mortality (aHR = 0.55, p < 0.001) within a 5-year follow-up period after index admission. Among the individual mood stabilizers, lithium was associated with the lowest risks of all-cause mortality (aHR = 0.38, p < 0.001), suicide (aHR = 0.39, p < 0.001), and natural mortality (aHR = 0.37, p < 0.001).

CONCLUSION

In addition to having protective effects against suicide and all-cause mortality, mood stabilizers also exert a substantial protective effect against natural mortality, with lithium associated with the lowest risk of mortality.

Degree of exposure to psychotropic medications and mortality in people with bipolar disorder

OBJECTIVES

To investigate the associations between psychotropic medication dosage and mortality in patients with bipolar disorder.

METHODS

A nationwide cohort of individuals aged ≥15 years who had received a diagnosis of bipolar disorder in 2010 was identified from the Taiwanese national health-care database linked with the mortality registry and followed up for 5 years. The mean defined daily dose (DDD) of mood stabilizers, antipsychotics, antidepressants, and sedative-hypnotics was estimated, and survival analyses were conducted to assess the effects of degree of exposure to psychotropic medications on mortality.

RESULTS

A total of 49,298 individuals (29,048 female individuals, 58.92%) with bipolar disorder were included. Compared with individuals without exposure to mood stabilizers, those prescribed mood stabilizers had a decreased overall mortality risk, regardless of exposure dosage. By contrast, compared with a reference group with no exposure to antipsychotics, individuals using antipsychotics had dose-dependent, increased mortality in both overall causes of deaths and deaths due to cardiovascular diseases, with hazard ratios of 1.13 (95% CI: 1.21-1.42) in the low-dose (<0.5 DDD) group, 1.69 (1.51-1.90) in the moderate-dose (0.5-1.5 DDD) group, and 2.08 (1.69-2.57) in the high-dose (>1.5 DDD) group for overall mortality.

CONCLUSIONS

In sum, mood stabilizers were associated with decreased overall mortality in individuals with bipolar disorder, regardless of the dosage. However, the use of antipsychotics appeared to be associated with a dose-dependent increased mortality risk. Owing to study limitations, precise information on prior use of psychotropic medications, and patient's adherence to medication are not available. Potential adverse effects and benefits should be carefully considered when prescribing psychotropic medications for long-term use in patients with bipolar disorder.

Cardioprotective potential of lithium and role of fractalkine in euthymic patients with bipolar disorder

OBJECTIVE

Over a half century, lithium has been used as the first-line medication to treat bipolar disorder. Emerging clinical and laboratory studies suggest that lithium may exhibit cardioprotective effects in addition to neuroprotective actions. Fractalkine (CX3CL1) is a unique chemokine associated with the pathogenesis of mood disorders and cardiovascular diseases. Herein we aimed to ascertain whether lithium treatment is associated with favorable cardiac structure and function in relation to the reduced CX3CL1 among patients with bipolar disorder.

METHODS

We recruited 100 euthymic patients with bipolar I disorder aged over 20 years to undergo echocardiographic study and measurement of plasma CX3CL1. Associations between lithium treatment, cardiac structure and function and peripheral CX3CL1 were analyzed according to the cardiovascular risk. The high cardiovascular risk was defined as (1) age ⩾ 45 years in men or ⩾ 55 years in women or (2) presence of concurrent cardiometabolic diseases.

RESULTS

In the high cardiovascular risk group (n = 61), patients who received lithium as the maintenance treatment had significantly lower mean values of left ventricular internal diameters at end-diastole (Cohen's d = 0.65, p = 0.001) and end-systole (Cohen's d = 0.60, p = 0.004), higher mean values of mitral valve E/A ratio (Cohen's d = 0.51, p = 0.019) and superior performance of global longitudinal strain (Cohen's d = 0.51, p = 0.037) than those without lithium treatment. In addition, mean plasma levels of CX3CL1 in the high cardiovascular risk group were significantly lower among patients with lithium therapy compared with those without lithium treatment (p = 0.029). Multiple regression models showed that the association between lithium treatment and mitral value E/A ratio was contributed by CX3CL1.

CONCLUSION

Data from this largest sample size study of the association between lithium treatment and echocardiographic measures suggest that lithium may protect cardiac structure and function in patients with bipolar disorder. Reduction of CX3CL1 may mediate the cardioprotective effects of lithium.

Echocardiographic study of cardiac structure and function in people with bipolar disorder after midlife

BACKGROUND

Heart failure is the leading cause of mortality in older people with bipolar disorder (BD). Studies examining cardiac structure and function in middle-aged patients with BD by using echocardiography and cardiac strain imaging are scant.

METHODS

We recruited 48 patients with bipolar I disorder (BD-I) older than 45 years to undergo conventional and tissue speckle tracking echocardiography. Data of 31 mentally healthy adults older than 45 years were randomly retrieved from the echocardiographic dataset and compared with the data of BD patients.

RESULTS

Patients with BD-I had significantly higher mean values of interventricular septal thickness (Cohen's d = 0.83, p = 0.001) and left ventricular internal diameter (Cohen's d = 0.90, p = 0.001) at end-diastole relative to controls. Additionally, BD-I patients exhibited significantly lower mean values of mitral valve E/A ratio (Cohen's d = 0.67, p = 0.007) and a more reduced global longitudinal strain (Cohen's d = 0.72, p = 0.029) than controls. Multiple linear regression revealed that body mass index was negatively correlated with the mitral valve E/A ratio (adjustment R² = 0.363, p = 0.043) in patients with BD-I.

LIMITATIONS

A relatively small sample size may limit generalization.

CONCLUSIONS

After midlife, BD patients exhibit cardiac diastolic (low mitral valve E/A ratio) and systolic (reduced global longitudinal strain) dysfunction. High body mass index may play a role in the unfavorable cardiac function in aging patients with BD.

Lithium Reduces Migration and Collagen Synthesis Activity in Human Cardiac Fibroblasts by Inhibiting Store-Operated Ca2+ Entry

Cardiac fibrosis plays a vital role in the pathogenesis of heart failure. Fibroblast activity is enhanced by increases in store-operated Ca²⁺ entry (SOCE) and calcium release-activated calcium channel protein 1 (Orai1) levels. Lithium regulates SOCE; however, whether therapeutic concentrations of lithium can be used to inhibit cardiac fibrogenesis is unknown. Migration and proliferation assays, Western blotting, real-time reverse-transcription polymerase chain reaction analysis, and calcium fluorescence imaging were performed in human cardiac fibroblasts treated with or without LiCl at 1.0 mM (i.e., therapeutic peak level) or 0.1 mM (i.e., therapeutic trough level) for 24 h. Results showed that LiCl (0.1 mM, but not 1.0 mM) inhibited the migration and collagen synthesis ability of cardiac fibroblasts. Additionally, thapsigargin-induced SOCE was reduced in fibroblasts treated with LiCl (0.1 mM). The expression level of Orai1 was lower in LiCl (0.1 mM)-treated fibroblasts relative to the fibroblasts without LiCl treatment. Fibroblasts treated with a combination of LiCl (0.1 mM) and 2-APB (10 μM, an Orai1 inhibitor) demonstrated similar migration and collagen synthesis abilities as those in LiCl (0.1 mM)-treated fibroblasts. Altogether, lithium at therapeutic trough levels reduced the migration and collagen synthesis abilities of human cardiac fibroblasts by inhibiting SOCE and Orai1 expression.

Clinical Risk Factors for Therapeutic Lithium-Associated Electrocardiographic Changes in Patients With Bipolar Disorder

PURPOSE/BACKGROUND

Lithium, a common medication used in bipolar disorder treatment, can exert an inhibitory effect on sodium and potassium channels and potentially cause cardiac electrical conduction disturbance and corrected QT (QTc) prolongation. This study aimed to examine whether lithium at therapeutic levels can change electrocardiographic parameters in different groups of patients with bipolar disorder and to identify the potential clinical risk factors.

METHODS/PROCEDURES

Standard 12-lead electrocardiogram data before and after lithium treatment in bipolar disorder patients after at least 2-week dropout of psychotropic medications were analyzed.

FINDINGS/RESULTS

A total of 39 patients with bipolar disorder receiving lithium treatment were enrolled. Nineteen patients (48.7%) exhibited increased from P wave beginning to QRS complex beginning intervals after lithium treatment (mean serum level, 0.653 ± 0.247 mmol/L). Twenty-four patients (61.5%) exhibited increased a combination of Q, R, and S waves complex durations and increased QTc intervals. Twenty-three patients (59.0%) exhibited increased corrected JT (JTc) intervals. The patient group with increased QTc or JTc intervals exhibited a higher mean systolic blood pressure than did the patient group without increased QTc (134.7 ± 19.2 mm Hg vs 115.7 ± 11.8 mm Hg, P = 0.020) or JTc intervals (134.4 ± 19.6 mm Hg vs 117.6 ± 13.3 mm Hg, P = 0.054), respectively. Biochemical and hemodynamic parameters were comparable between patients with and without increased a combination of Q, R, and S waves complex durations or from P wave beginning to QRS complex beginning intervals.

IMPLICATIONS/CONCLUSIONS

Elevated systolic blood pressure may be the risk factor for the ventricular conduction delay in bipolar disorder patients receiving lithium at therapeutic levels.