CACNA1C polymorphisms Impact Cognitive Recovery in Patients with Bipolar Disorder in a Six-week Open-label Trial

Pharmacogenetic testing may benefit people receiving low-dose lithium in clinical practice

BACKGROUND

Mental illnesses are leading causes of disability in the United States. Some evidence supports that pharmacogenetic testing may be beneficial in select populations and that lithium is beneficial for treating mood disorders and anxiety in some populations.

PURPOSE

This research aimed to determine whether low-dose lithium effectively decreases depression and anxiety in adults with a risk allele for CACNA1C genotypes.

METHODOLOGY

The study design was correlational. Fifty patients were treated at a nurse practitioner-owned clinic in Prairie Village, Kansas. Chart review was used. Adults older than 18 years diagnosed with major depressive disorder, bipolar disorder, or generalized anxiety disorder presenting with an abnormality in the CACNA1C gene single-nucleotide polymorphism rs1006737 were included in this research. Assessment tools used were the Patient Health Questionnaire-9 for depression and GAD-7 for anxiety.

RESULTS

Low-dose lithium significantly decreased depression by 66% ( p < .001) and anxiety by 65% ( p = <.001). There was a significant difference in pretest depression levels based on CACNA1C genotype ( p = .033). The A allele frequency was 60% higher (48%) in this population than found in general population (30%).

CONCLUSIONS

Low-dose lithium significantly decreased anxiety and depression compared with baseline. People with different versions of the CACNA1C genotype had responses that differed significantly. The A risk allele was 60% more common than in the general population.

IMPLICATIONS

This study could aid in establishing genetic testing as an effective clinical tool for treating depression and anxiety using lithium, an inexpensive and widely available medication.

Impact of ZNF804A rs1344706 or CACNA1C rs1006737 polymorphisms on cognition in patients with severe mental disorders: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis focussed on insights into the relationship between CACNA1C-rs1006737 and ZNF804A-rs1344706 polymorphisms and cognitive performance in schizophrenia (SCZ) spectrum and bipolar disorder (BD) and provide some contributions for clinical practice.

METHODS

We searched the websites databases (PubMED, PsycINFO, Web of Science, EMBASE and Cochrane Library) using eligibility and exclusion criteria to capture all potential studies, based on PICO model and according to the PRISMA.

RESULTS

Eight articles were included in this systematic review (five referring to CACNA1C-rs1006737 and three related to ZNF804A-rs1344706 polymorphisms), with a total of 5759 participants (1751 SCZ patients, 348 BD patients, 3626 controls and 34 first-degree relatives). The results demonstrated that the pooled effect of CACNA1C-rs1006737 (risk difference RD = 0.08; 95% CI 0.02-0.15) was associated with altered cognitive function in patients with severe mental disorders, but not ZNF804A-rs1344706 polymorphism (RD = 0.19; 95% CI 0.09-0.48.

CONCLUSION

The present meta-analysis provides evidence regarding slight association between CACNA1C-rs1006737 polymorphisms and cognitive performance in severe mental disorders, indicating that cognitive impairment in severe mental disorders associated with the CACNA1C rs1006737 risk variants could only be expressed when interacting with environmental exposures. This study is registered with PROSPERO, number CRD42021246726.

Genetic Polymorphisms in miR-137 and Its Target Genes, TCF4 and CACNA1C, Contribute to the Risk of Bipolar Disorder: A Preliminary Case-Control Study and Bioinformatics Analysis

Accumulating evidence has suggested that miR-137 and its target genes, CACNA1C, and TCF4, are amongst the most robustly implicated genes in psychiatric disorders. This preliminary study is aimed at investigating the effects of genetic variations in miR-137 (rs1625579A/C), TCF4 (rs1261084C/T), and CACNA1C (rs10774053A/G and rs10466907G/T) on BD susceptibility. We recruited 252 BD patients and 213 healthy subjects as the control group. Genotyping was performed using PCR-RFLP and ARMS-PCR methods. Enhanced risk of BD was found under the codominant homozygous, dominant, and allelic models of TCF4 rs1261084C/T, codominant homozygous and allelic models of CACNA1C rs10466907G/T polymorphisms, as well as codominant homozygous, dominant, recessive, and allelic models of the CACNA1C rs10774053A/G. Moreover, both TT/AG/GT/AA and TT/GG/GT/AC genotype combinations strongly increased the risk of BD in the participants. The bioinformatics analyses revealed that rs1261084C/T and rs10466907G/T created and disrupted binding sites of some miRNAs in the 3′-untranslated region of TCF4 and CACNA1C genes. In contrast, the rs10774053A/G created a new binding site for a major splicing factor and might have an effective role in the function of the CACNA1C protein. We have found that all the studied SNPs are positively associated with BD susceptibility. Replicated studies on different ethnicities are required to confirm these findings.

Calcium Channel Antagonists for Mood Disorders

PURPOSE

Development of new thymoleptic medications has primarily centered on anticonvulsants and antipsychotic drugs. Based on our studies of intracellular calcium ion signaling in mood disorders, we were interested in the use of novel medications that act on this mechanism of neuronal activation as potential mood stabilizers.

METHOD

We reviewed the dynamics of the calcium second messenger system and the international body of data demonstrating increased baseline and stimulated intracellular calcium levels in peripheral cells of patients with bipolar mood disorders. We then examined studies of the effect of established mood stabilizers on intracellular calcium ion levels and on mechanisms of mobilization of this second messenger. After summarizing studies of calcium channel blocking agents, whose primary action is to attenuate hyperactive intracellular calcium signaling, we considered clinical experience with this class of medications and the potential for further research.

FINDINGS

Established mood stabilizers normalize increased intracellular calcium ion levels in bipolar disorder patients. Most case series and controlled studies suggest an antimanic and possibly mood stabilizing effect of the calcium channel blocking medications verapamil and nimodipine, with fewer data on isradipine. A relatively low risk of teratogenicity and lack of cognitive adverse effects or weight gain suggest possible applications in pregnancy and in patients for whom these are considerations.

IMPLICATIONS

Medications that antagonize hyperactive intracellular signaling warrant more interest than they have received in psychiatry. Further experience will clarify the applications of these medications alone and in combination with more established mood stabilizers.

Cav1.2 L-type calcium channels regulate stress coping behavior via serotonin neurons

Human genetic variation in the gene CACNA1C, which codes for the alpha-1c subunit of Cav1.2 L-type calcium channels (LTCCs), has been broadly associated with enhanced risk for neuropsychiatric disorders including major depression, bipolar and schizophrenia. Little is known about the specific neural circuits through which CACNA1C and Cav1.2 LTCCs impact disease etiology. However, serotonin (5-HT) neurotransmission has been consistently implicated in these neuropsychiatric disorders and Cav1.2 LTCCs may influence 5-HT neuron activity during relevant behavioral states such as stress. We utilized a temporally controlled and 5-HT neuron specific Cacna1c knockout mouse model to assess stress-coping behavior using the forced swim test and dorsal raphe (DR) 5-HT neuron Fos activation. Furthermore, we assessed 5-HT1A receptor function and feedback inhibition of the DR following administration of the 5-HT1A antagonist WAY-100635. We find that 5-HT neuron Cacna1c knockout disrupts active-coping behavior in the forced swim test and that this behavioral effect is rescued by blocking 5-HT1A receptors. Moreover, Cacna1c knockout mice display enhanced Fos expression in caudal DR 5-HT neurons and an enhanced response to a 5-HT1A receptor antagonist in rostral DR 5-HT neurons, indicating that loss of Cacna1c disrupts both 5-HT neuron activation and 5-HT1A dependent feedback inhibition across the caudal to rostral DR. Collectively, these results reveal an important role for 5-HT neuron Cav1.2 LTCCs in stress-coping behavior and 5-HT1A receptor function. This suggests that alterations in CACNA1C function or expression could influence the development or treatment of neuropsychiatric disorder through serotonergic mechanisms.