Leukocyte Telomere Length Predicts SSRI Response in Major Depressive Disorder: A Preliminary Report.

Short leukocyte telomere length (LTL) may be associated with several psychiatric disorders, including major depressive disorder (MDD). Short LTL has previously been associated with poor response to psychiatric medications in bipolar disorder and schizophrenia, but no studies have prospectively assessed the relationship of LTL to selective serotonin reuptake inhibitor (SSRI) response in MDD. We assessed pre-treatment LTL, depression severity [using the Hamilton Depression Rating Scale (HDRS)], and self-reported positive and negative affect in 27 healthy, unmedicated adults with MDD. The subjects then underwent open-label treatment with an SSRI antidepressant for 8 weeks, after which clinical ratings were repeated. The analyses were corrected for age, sex, and body mass index. ‘Non-responders' to treatment (HDRS improvement <50%) had significantly shorter pre-treatment LTL than ‘responders' (p = 0.037). Further, shorter pre-treatment LTL was associated with less improvement in negative affect (p < 0.010) but not with changes in positive affect (p = 0.356). This preliminary study is the first to assess the relationship between LTL and response to SSRIs in MDD and among the first to prospectively assess its relationship to treatment outcome in any psychiatric illness. Our data suggest that short LTL may serve as a vulnerability index of poorer response to SSRI treatment, but this needs examination in larger samples.