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.