Telomerase activity and telomere homeostasis in major depressive disorder, schizophrenia and bipolar disorder: a systematic review.

INTRODUCTION

Life expectancy is decreased in individuals diagnosed with Major depressive disorder (MDD), Schizophrenia (SCZ) or Bipolar disorder (BD), which suggests cellular ageing. Telomere length (TL), a biomarker of cellular ageing, has been consistently reported as shorter in these individuals, but the mechanisms involved remain unknown.

METHOD: A literature search was conducted which included studies focusing on telomerase activity and markers involved in telomere homeostasis (Single nucleotide polymorphisms, gene expression, protein levels). We also searched for articles investigating the impact of psychotropic medications and other interventions on any of these markers.

RESULTS

We identified 25 articles among which individuals with MDD were overrepresented (n = 16). Telomerase was the most studied marker in terms of activity and gene expression, and few studies included analyses of other markers. Five studies out of seven reported an elevated telomerase activity in individuals with MDD. Seven of the twelve clinical trials identified, measured the impact of interventions in MDD (antidepressants, electroconvulsive therapy and yoga) with heterogeneous designs.

CONCLUSION

Literature suggests that telomerase activity is increased in MDD, with no major changes following exposure to antidepressants. Case-control and clinical intervention studies in BD and SCZ are too scarce to conclude. Furthermore, this review highlights that the complexity of telomere homeostasis has been overlooked in the literature thus limiting the understanding of the underlying molecular mechanisms. Future research should include larger and trans-nosographic samples, adopt more homogeneous designs for clinical trials, and perform more comprehensive analyses of the TL homeostasis markers.