Table 1.

Human studies on stress and PBMC telomerase.

Ref	Study design	Predictor	Basal TA	Stimulated TA	Effects
(Epel et al.,2004)	39 healthy caregiving mothers, 19 controls	Chronic stress	TA ↓		Mean TA 48% lower in high-stress group. The group with short TL showed higher perceived stress levels and displayed higher oxidative stress and lower TA levels.
(Epel et al., 2006)	62 healthy mothers	Chronic stress	TA ↓		Lower TA associated with higher stress arousal, perceived stress and chronicity of stress. Lower TA associated with several risk factors for cardiovascular diseases.
(Damjanovic et al., 2007)	41 Alzheimer caregivers, 41 controls	Chronic stress	TA ↑	No difference	Caregivers showed higher TA and shorter TL. Similar results in isolated T-cells. No difference in stimulated TA. Caregivers showed reduced stimulated proliferation and increased cytokine production of T cells.
(Epel et al., 2010)	44 postmenopausal women: 22 caretakers, 22 controls	Chronic stress Acute stress	TA ↓ TA ↑		Caretakers lower TA activity at baseline. 18% higher TA in response to TSST in both groups. TA response higher in persons responding with higher cortisol. TA activity was associated with threat appraisal in controls.
(Zalli et al., 2014)	333 middle aged and elderly healthy men and women	Stress reactivity	TL ↓ + TA ↑		Males with shorter TL and high TA showed blunted stress-reactivity compared to men with longer TL or men with shorter TL and low TA.
		Stress recovery	TL ↓ + TA ↑		Males with shorter TL and high TA showed reduced post-stress recovery. Shorter TL in combination with high TA was associated with reduced social support, lower optimism, higher hostility, and greater early life adversity.
(de Punder etal., 2018)	28 healthy participants	Acute stress		No difference	No difference in stimulated TA levels before and after TSST exposure.
		Stress-reactivity		TA ↓	Inverse correlation between overall TA levels and the cortisol response.
		Chronic stress		TA ↓	Individuals exposed to high levels of chronic stress showed a 25% reduction in induced TA levels compared to individuals perceiving medium or low levels of stress.

Abbreviations: BP, blood pressure; TA, telomerase activity; TL, telomere length; TSST, Trier Social Stress Test.