Major Depressive Disorder and Measures of Cellular Aging: An Integrative Review

Table 1

Overview of studies: telomere length and depression.

First author, date	Type of study, total 𝑛	Method	TL shorter in participants with MDD or MDE or depression symptoms	Mean difference in TL, approx. years of accelerated aging	Other findings	Study; limitations
Studies of participants with MDD
Simon, 2006 [46]	Cross-section, 𝑛=88	LTL-Southern blot	Yes*	660 bps, ~10 yrs	—	a, b, c
Lung, 2007 [47]	Cross-section, 𝑛=664	LTL-Southern blot	Yes*	96 bps, ~2 yrs	—	a, b, c
Hartmann, 2010 [45]	Cross-section, 𝑛=74	LTL-Southern blot	Yes*	350 bps, ~5 yrs	—	a, b, c
Hoen, 2011 [44]	Cross-section, 𝑛=952	PBMCs-qPCR	Yes**	97 bps, ~2 yrs	—	c
Wolkowitz, 2011 [18]	Cross-section, 𝑛=35	LTL-qPCR	Yes*	280, ~7 yrs	IL6 inversely correlated with TL in depressed pts*	b
Malan, 2011 [48]	Cross-section, 𝑛=64	LTL-qPCR	BTL not associated with development of MDD in 3 months	—	TL associated with development of PTSD**	b, d
Wolkowitz, 2012 [49]	Longitudinal, 𝑛=34	PBMCs TRAPeze assay for TA	Yes* (reported in Wolkowitz 2011 [18])	280, ~7 yrs	BTA elevated in depression* and high stress*; lower BTA predicted better response to antidepressant*; no correlation between TA, IL6, CRP, and TL	—
Wikgren, 2012 [50]	Cross-section, 𝑛=542	LTL-qPCR	Yes*	277 bps, ~4 yrs	TL shorter and CRP higher in MDD with low post-DST cortisol levels*	a, c
Studies of participants with history of MDEs or self-reported depression symptoms
Elvsashagen, 2011 [51]	Cross-section, 𝑛=56	PBMCs-qFISH	Yes**	552 bps, ~9 yrs	—	b, c, e
Shaffer, 2012 [52]	Cross-section, 𝑛=2225	LTL-qPCR	No	—	—	a, b, c, e
Hoen, 2013 [53]	Longitudinal, 𝑛=974	LTL-qPCR	No	—	Anxiety disorder associated with shorter TL over time**	e, f

^∗Significant: P < 0.05; **trend: P < 0.10.
LTL: leukocyte telomere length; BTL: baseline telomere length; BTA: baseline telomerase activity; DST: dexamethasone suppression test; qPCR: quantitative polymerase chain reaction; qFISH: quantitative fluorescence in situ hybridization.
^aUnclear if controls actually screened for MDD or controls answered in negative regarding previous diagnosis of MDD.
^bFactors potentially affecting TL not evaluated/reported (stress, BMI, smoking status, physical activity, anti-inflammatory medications).
^cHomogeneous group or ethnicity/races unreported.
^dTesting unidirectional hypothesis (telomere length leads to development of depression).
^eNo clinical diagnosis of depression (self-report of previous MDE or depression symptoms).
^fBiomarkers measured at different time point than depression diagnosis.