Depression and anxiety symptoms in older adults: a joint association study of candidate genes

Abstract

Abstract Introduction: As the share of elderly in the population is increasing, so is the presence of depression and anxiety in this group, including in Brazil. There are studies suggesting common pathophysiological mechanisms for depressive and anxiety disorders, as well as the existence of vulnerability genes in the etiopathogenesis of both depression and anxiety. The different candidate genes reported in the literature associated with depression and/or anxiety phenotypes have rarely been investigated together in a single study. Objective: To investigate candidate gene polymorphisms, reported as associated with a higher risk of developing depression and/or anxiety symptoms in the literature, in an elderly population. Methodology: Peripheral venous blood was collected from a total of 874 elderly people aged 60 years or older. Genotypic DNA analysis was performed by real-time PCR of 27 polymorphisms of 11 candidate genes for symptoms of depression and/or anxiety. Depressive and/or Anxious Symptomatology Groups (DASG) were also included in the analysis based on the median of three applied scales: the CES-D for depression, the GAI for anxiety, and the MMSE for cognition. For statistical analysis, Pearson's chi-square test was performed with a significance level of 5% (p= ≤ 0.05), both for individual analysis of polymorphisms and for the joint analysis. Results: Four polymorphisms showed statistically significant results associated with DASG: rs8071667 (p=0.03) of the 5HTT gene, rs6265 (p=0.004) of the BDNF gene, rs165599 (p=0.023) of the COMT gene, and rs1417938 (p= 0.006) of the CRP gene. The rs165599 (COMT) and rs1417938 (CRP) variants remained significant when analyzed together, with a p-value of 1.72E-10. Conclusion: The COMT gene variant rs165599 and CRP gene variant rs1417938 provided the most robust results in our analysis. However, it is necessary to confirm the reproduction of these preliminary results in independent samples.