Personalized Medicine in Psychiatry: Concepts for Bringing Associated Testing Into Clinical Practice

Temporal patterns of anxiety disorders and cortisol activity in older adults

INTRODUCTION

Studies focusing on anxiety temporal patterns and cortisol activity in older adults are scarce. The objectives of this study were to examine in older adults the relationship between anxiety temporal patterns and cortisol activity and ascertain the presence of sex differences.

METHODS

Data were retrieved from the Étude sur la santé des ainés - Services study in Quebec and included N = 762 community living adults aged ≥ 65 years having participated in interviews at baseline (T₁) and at 4 years follow-up (T₂). A standardized questionnaire, based on DSM-5 criteria, was used to ascertain in the past 6 months the presence of anxiety (absence, remission, incidence, persistence). Cortisol activity during the interview and cortisol concentration on a regular day (at T₂) were the dependent variables. Adjusted multivariable linear regression models, stratified by sex, were used.

RESULTS

Results showed higher cortisol activity during the interview in participants with anxiety in remission (Beta: 2.59; 95% CI: 0.62 , 4.57), specifically in males, and lower activity in participants with persistent anxiety (Beta: -3.97; 95% CI: -7.05, -0.88). Cortisol concentration on a regular day was higher in males reporting incident anxiety (Beta: 8.07; 95% CI: 2.39 , 13.76).

LIMITATIONS

The convenience sample with losses to follow-up may have led to a potential selection bias.

CONCLUSION

Anxiety temporal patterns were associated with cortisol activity profiles in older adults with sex being a significant moderator. Future studies are recommended to ascertain the longitudinal changes in cortisol activity and anxiety temporal patterns, which may further inform personalized treatment of anxiety.

Point-of-care companion diagnostic tests for personalizing psychiatric medications: fulfilling an unmet clinical need

Over the last decade stable isotope-labeled substrates have been used as probes for rapid, point-of-care, non-invasive and user-friendly phenotype breath tests to evaluate activity of drug metabolizing enzymes. These diagnostic breath tests can potentially be used as companion diagnostics by physicians to personalize medications, especially psychiatric drugs with narrow therapeutic windows, to monitor the progress of disease severity, medication efficacy and to study in vivo the pharmacokinetics of xenobiotics. Several genotype tests have been approved by the FDA over the last 15 years for both cytochrome P450 2D6 and 2C19 enzymes, however they have not been cleared for use in personalizing medications since they fall woefully short in identifying all non-responders to drugs, especially for the CYP450 enzymes. CYP2D6 and CYP2C19 are among the most extensively studied drug metabolizing enzymes, involved in the metabolism of approximately 30% of FDA-approved drugs in clinical use, associated with large individual differences in medication efficacy or tolerability essentially due to phenoconversion. The development and commercialization via FDA approval of the non-invasive, rapid (<60 min), in vivo, phenotype diagnostic breath tests to evaluate polymorphic CYP2D6 and CYP2C19 enzyme activity by measuring exhaled ¹³CO₂ as a biomarker in breath will effectively resolve the currently unmet clinical need for individualized psychiatric drug therapy. Clinicians could personalize treatment options for patients based on the CYP2D6 and CYP2C19 phenotype by selecting the optimal medication at the right initial and subsequent maintenance dose for the desired clinical outcome (i.e. greatest efficacy and minimal side effects).