Genome-wide Association Analysis in Humans Links Nucleotide Metabolism to Leukocyte Telomere Length.

Leukocyte telomere length (LTL) is a heritable biomarker of genomic aging. In this study, we perform a genome-wide meta-analysis of LTL by pooling densely genotyped and imputed association results across large-scale European-descent studies including up to 78,592 individuals. We identify 49 genomic regions at a false dicovery rate (FDR) < 0.05 threshold and prioritize genes at 31, with five highlighting nucleotide metabolism as an important regulator of LTL. We report six genome-wide significant loci in or near SENP7, MOB1B, CARMIL1, PRRC2A, TERF2, and RFWD3, and our results support recently identified PARP1, POT1, ATM, and MPHOSPH6 loci. Phenome-wide analyses in >350,000 UK Biobank participants suggest that genetically shorter telomere length increases the risk of hypothyroidism and decreases the risk of thyroid cancer, lymphoma, and a range of proliferative conditions. Our results replicate previously reported associations with increased risk of coronary artery disease and lower risk for multiple cancer types. Our findings substantially expand current knowledge on genes that regulate LTL and their impact on human health and disease.

Design and rationale of the REStoring mood after early life trauma with psychotherapy (RESET-psychotherapy) study: a multicenter randomized controlled trial on the efficacy of adjunctive trauma-focused therapy (TFT) versus treatment as usual (TAU) for adult patients with major depressive disorder (MDD) and childhood trauma.

BACKGROUND: Major depressive disorder (MDD) is a common, recurrent mental disorder and a leading cause of disability worldwide. A large part of adult MDD patients report a history of childhood trauma (CT). Patients with MDD and CT are assumed to represent a clinically and neurobiologically distinct MDD subtype with an earlier onset, unfavorable disease course, stress systems' dysregulations and brain alterations. Currently, there is no evidence-based treatment strategy for MDD that specifically targets CT. Given the central role of trauma in MDD patients with CT, trauma-focused therapy (TFT), adjunctive to treatment as usual (TAU), may be efficacious to alleviate depressive symptoms in this patient population. METHODS: The RESET-psychotherapy study is a 12-week, single-blind, randomized controlled trial testing the efficacy of TFT in 158 adults with moderate to severe MDD, as a 'stand-alone' depression diagnosis or superimposed on a persistent depressive disorder (PDD), and CT. TFT (6-10 sessions of Eye Movement Desensitization and Reprocessing and/or imagery rescripting) + TAU is compared to TAU only. Assessments, including a wide range of psychological/psychiatric and biological characteristics, take place before randomization (T0), during treatment (T1), at post-treatment (T2) and at 6-month follow-up (T3). Pre-post treatment stress-related biomarkers in hair (cortisol) and blood (epigenetics and inflammation) will be assessed to better understand working mechanisms of TFT. A subgroup of 60 participants will undergo structural and functional Magnetic Resonance Imaging (MRI) assessments to determine pre-post treatment brain activity. The primary outcome is self-reported depression symptom severity at post-treatment, measured with the 30-item Inventory of Depressive Symptomatology - Self Report (IDS-SR). DISCUSSION: If adjunctive TFT efficaciously alleviates depressive symptoms in MDD patients with CT, this novel treatment strategy could pave the way for a more personalized and targeted MDD treatment. TRIAL REGISTRATION: ClinicalTrials.gov, registered at 08-12-2021, number of identification: NCT05149352.

A DNA methylation clock associated with age-related illnesses and mortality is accelerated in men with combat PTSD.

DNA methylation patterns at specific cytosine-phosphate-guanine (CpG) sites predictably change with age and can be used to derive "epigenetic age", an indicator of biological age, as opposed to merely chronological age. A relatively new estimator, called "DNAm GrimAge", is notable for its superior predictive ability in older populations regarding numerous age-related metrics like time-to-death, time-to-coronary heart disease, and time-to-cancer. PTSD is associated with premature mortality and frequently has comorbid physical illnesses suggestive of accelerated biological aging. This is the first study to assess DNAm GrimAge in PTSD patients. We investigated the acceleration of GrimAge relative to chronological age, denoted "AgeAccelGrim" in combat trauma-exposed male veterans with and without PTSD using cross-sectional and longitudinal data from two independent well-characterized veteran cohorts. In both cohorts, AgeAccelGrim was significantly higher in the PTSD group compared to the control group (N = 162, 1.26 vs -0.57, p = 0.001 and N = 53, 0.93 vs -1.60 Years, p = 0.008), suggesting accelerated biological aging in both cohorts with PTSD. In 3-year follow-up study of individuals initially diagnosed with PTSD (N = 26), changes in PTSD symptom severity were correlated with AgeAccelGrim changes (r = 0.39, p = 0.049). In addition, the loss of CD28 cell surface markers on CD8 + T cells, an indicator of T-cell senescence/exhaustion that is associated with biological aging, was positively correlated with AgeAccelGrim, suggesting an immunological contribution to the accelerated biological aging. Overall, our findings delineate cellular correlates of biological aging in combat-related PTSD, which may help explain the increased medical morbidity and mortality seen in this disease.

The impact of depression and anxiety treatment on biological aging and metabolic stress: study protocol of the MOod treatment with antidepressants or running (MOTAR) study.

BACKGROUND: Depressive and anxiety disorders have shown to be associated to premature or advanced biological aging and consequently to adversely impact somatic health. Treatments with antidepressant medication or running therapy are both found to be effective for many but not all patients with mood and anxiety disorders. These interventions may, however, work through different pathophysiological mechanisms and could differ in their impact on biological aging and somatic health. This study protocol describes the design of an unique intervention study that examines whether both treatments are similarly effective in reducing or reversing biological aging (primary outcome), psychiatric status, metabolic stress and neurobiological indicators (secondary outcomes). METHODS: The MOod Treatment with Antidepressants or Running (MOTAR) study will recruit a total of 160 patients with a current major depressive and/or anxiety disorder in a mental health care setting. Patients will receive a 16-week treatment with either antidepressant medication or running therapy (3 times/week). Patients will undergo the treatment of their preference and a subsample will be randomized (1:1) to overcome preference bias. An additional no-disease-no-treatment group of 60 healthy controls without lifetime psychopathology, will be included as comparison group for primary and secondary outcomes at baseline. Assessments are done at week 0 for patients and controls, and at week 16 and week 52 for patients only, including written questionnaires, a psychiatric and medical examination, blood, urine and saliva collection and a cycle ergometer test, to gather information about biological aging (telomere length and telomerase activity), mental health (depression and anxiety disorder characteristics), general fitness, metabolic stress-related biomarkers (inflammation, metabolic syndrome, cortisol) and genetic determinants. In addition, neurobiological alterations in brain processes will be assessed using structural and functional Magnetic Resonance Imaging (MRI) in a subsample of at least 25 patients per treatment arm and in all controls. DISCUSSION: This intervention study aims to provide a better understanding of the impact of antidepressant medication and running therapy on biological aging, metabolic stress and neurobiological indicators in patients with depressive and anxiety disorders in order to guide a more personalized medicine treatment. TRIAL REGISTRATION: Trialregister.nl Number of identification: NTR3460, May 2012.

Reconsidering the prognosis of major depressive disorder across diagnostic boundaries: full recovery is the exception rather than the rule.

BACKGROUND: Major depressive disorder (MDD) is often handled as an episodic and isolated disorder, resulting in an optimistic view about its prognosis. Herein, we test the idea that the prognosis of MDD changes if we vary the perspective in terms of (1) a longer time frame and (2) a broader diagnostic conceptualisation including dysthymia, (hypo)mania and anxiety disorders as relevant outcomes. METHODS: Patients with current MDD at baseline (n = 903) and available 2-, 4-, and/or 6-year follow-up assessments were selected from the Netherlands Study of Depression and Anxiety, a psychiatric cohort study. Combining psychiatric DSM-IV-based diagnoses and life-chart data, patient course trajectories were classified as (1) recovered (no diagnoses at 2-year follow-up or thereafter), (2) recurrent without chronic episodes, (3) recurrent with chronic episodes or (4) consistently chronic since baseline. A chronic episode was defined as having a current diagnosis at the follow-up assessment and consistent symptoms over 2 years. Proportions of course trajectories were provided moving from a short, narrow perspective (2-year follow-up, considering only MDD diagnosis) to a long, broad perspective (6-year follow-up, including MDD, dysthymia, (hypo)mania and anxiety diagnoses). RESULTS: With the short, narrow perspective, the recovery rate was 58% and 21% had a chronic episode. However, in the long, broad perspective the recovery rate was reduced to 17%, while 55% of the patients experienced chronic episodes. CONCLUSIONS: Results from a long and rigorous follow-up in a large cohort suggests that most MDD patients have an unfavourable prognosis. Longer follow-up and broader diagnostic conceptualisation show that the majority of patients have a disabling and chronic disorder. Conceptualising and handling MDD as a narrowly defined and episodic disorder may underestimate the prognosis of the majority of depressed patients and, consequently, the type of care that is appropriate.

The Association Between Psychiatric Disorders and Telomere Length: A Meta-Analysis Involving 14,827 Persons.

OBJECTIVE: This study examined the relationship between leukocyte telomere length (LTL), a marker of cell aging, and psychiatric disorders in adults compared with controls using meta-analytic methods. METHODS: Data were abstracted from studies examining the relationship between LTL and adult psychiatric disorders. In addition to an overall estimate of effect size, subgroup analyses and meta-regression were performed to examine whether covariates (including psychiatric diagnoses) moderated the estimate. RESULTS: A significant overall effect size showing LTL shortening was found across all psychiatric disorders (Hedge g = -0.50, p < .001). Subgroup analyses did not demonstrate significant differences in effect size based on individual covariates (psychiatric disorder, sex, age, or assay method). The meta-regression indicated that although type of disorder and, likely, age moderate the overall effect size, the heterogeneity between studies could not be explained by a model that included these variables as well as sex and assay method. Although not significantly different, posttraumatic stress disorder, anxiety disorders, and depressive disorders had comparatively larger effect sizes (-1.27, -0.53, and -0.55), and psychotic and bipolar disorders had comparatively smaller ones (-0.23 and -0.26). CONCLUSIONS: We observed a robust effect size of LTL shortening for psychiatric disorders as a whole compared with controls. The results were less straightforward regarding relative differences in the strength of this association by specific disorder. Future studies should focus on mechanisms explaining accelerated cell aging with psychiatric illness, defining directions (if any) of causality and elucidating possible differences in this association between disorders.

Cellular aging in depression: Permanent imprint or reversible process?: An overview of the current evidence, mechanistic pathways, and targets for interventions.

Depression might be associated with accelerated cellular aging. However, does this result in an irreversible state or is the body able to slow down or recover from such a process? Telomeres are DNA-protein complexes that protect the ends of chromosomes and generally shorten with age; and therefore index cellular aging. The majority of studies indicate that persons with depression have shorter leukocyte telomeres than similarly aged non-depressed persons, which may contribute to the observed unfavorable somatic health outcomes in the depressed population. Some small-scale preliminary studies raise the possibility that behavioral or pharmacological interventions may either slow down or else reverse this accelerated telomere shortening, possibly through increasing the activity of the telomere-lengthening enzyme telomerase. This paper covers the current state of evidence in the relationship between depression and the telomere-telomerase system and debates whether depression-related cellular aging should be considered a reversible process or permanent damage.

Early and recent psychosocial stress and telomere length in older adults.

BACKGROUND: Psychosocial stress has been associated with an increased risk for mental and somatic health problems across the life span. Some studies in younger adults linked this to accelerated cellular aging, indexed by shortened telomere length (TL). In older adults, the impact of psychosocial stress on TL may be different due to the lifetime exposure to competing causes of TL-shortening. This study aims to assess whether early and recent psychosocial stressors (childhood abuse, childhood adverse events, recent negative life events, and loneliness) were associated with TL in older adults. METHODS: Data were from the Netherlands Study of Depression in Older Persons (NESDO) in which psychosocial stressors were measured in 496 persons aged 60 and older (mean age 70.6 (SD 7.4) years) during a face-to-face interview. Leukocyte TL was determined using fasting blood samples by performing quantitative polymerase chain reaction (qPCR) and was expressed in base pairs (bp). RESULTS: Multiple regression analyses, adjusted for age, sex, and chronic diseases, showed that childhood abuse, recent negative life events and loneliness were unrelated to TL. Only having experienced any childhood adverse event was weakly but significantly negatively associated with TL. CONCLUSIONS: Our findings did not consistently confirm our hypothesis that psychosocial stress is associated with shorter TL in older adults. Healthy survivorship or other TL-damaging factors such as somatic health problems seem to dominate a potential effect of psychosocial stress on TL in older adults.

The Association of Early and Recent Psychosocial Life Stress With Leukocyte Telomere Length.

OBJECTIVES: Chronic exposure to psychosocial stressors is related to worse somatic health. This association applies both to stressors early in life, such as childhood adversities, and more recent life stress, such as stressful life events. This study examined whether accelerated telomere shortening, as an indicator of cellular aging, might be an explanatory mechanism. METHODS: We examined whether childhood adversities and recent stressful life events were associated with shorter telomeres in 2936 participants (mean [standard deviation] age = 41.8 [13.1] years, 66% women, 57% current depression) of the Netherlands Study of Depression and Anxiety. Telomeres are specialized nucleic acid-protein complexes at the ends of linear DNA that shorten with age; telomere length (TL) was measured with quantitative polymerase chain reaction. RESULTS: Childhood life events (ß = .004, p = .805) and childhood trauma (ß = -.023, p = .205) were not related to shorter TL. However, we found negative associations between recent stressful life events and TL. Persons had shorter telomeres if they reported more stressful life events in the past year (ß = -.039, p = .028) and 1 to 5 years ago (ß = -.042, p = .018, adjusted for sociodemographics). The relationship between stressful life events and TL became borderline significant when further adjusted for smoking status. No associations with TL were found when stressful life events occurred more than 6 years ago (p > .10). CONCLUSIONS: Results show that recent stressful life events are associated with shorter TL. This association is not observed for psychosocial stressors that occur earlier in life. Whether these results are indicative of physiological resiliency remains to be explored by future longitudinal research.

Anxiety disorders and accelerated cellular ageing.

BACKGROUND: Anxiety disorders increase the risk of onset of several ageing-related somatic conditions, which might be the consequence of accelerated cellular ageing. AIMS: To examine the association between anxiety status and leukocyte telomere length (LTL) as an indicator of cellular ageing. METHOD: Data are from individuals with current (n = 1283) and remitted (n = 459) anxiety disorder, and controls (n = 582) with no psychiatric disorder from the Netherlands Study of Depression and Anxiety. We determined DSM-IV anxiety diagnoses and clinical characteristics by structured psychiatric interviews and self-report questionnaires; LTL was assessed using quantitative polymerase chain reaction and converted into base pairs (bp). RESULTS: Patients in the current anxiety group (bp = 5431) had significantly shorter LTL compared with the control group (bp = 5506, P = 0.01) and the remitted anxiety group (bp = 5499, P = 0.03) in analyses adjusted for sociodemographics, health and lifestyle. The remitted anxiety group did not differ from the control group (P = 0.84), however, time since remission was positively related with LTL. Furthermore, anxiety severity scores were associated with LTL in the whole sample, in line with a dose-response association. CONCLUSIONS: Patients with current - but not remitted - anxiety disorder had shorter telomere length, suggesting a process of accelerated cellular ageing, which in part may be reversible after remission.

Leukocyte telomere length and late-life depression.

OBJECTIVE: Depressive disorders have been associated with increased risk for aging-related diseases, possibly as a consequence of accelerated cellular aging. Cellular aging, indexed by telomere length (TL) shortening, has been linked to depression in adults younger than 60 years; however, it remains unclear whether this is the case in late-life depression (age >60 years). The objective of this study was to assess differences in TL between persons with current late-life depression and never-depressed comparisons and to examine the association between characteristics of late-life depression and TL. METHODS: In this cross-sectional study using the Netherlands Study of Depression in Older Persons, 355 persons with current late-life depression and 128 never-depressed comparisons, aged 60-93 years (mean age [SD]: 70.5 [7.4] years, 65% women), were recruited through primary care and mental healthcare. Late-life depression was established using a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-based structured psychiatric interview. Leukocyte TL, expressed in base pairs (bp), was determined in fasting blood samples by performing quantitative polymerase chain reaction. RESULTS: Mean TL did not differ between depressed persons (bp [SD]: 5,035 [431]) and never-depressed (bp [SD]: 5,057 [729]) comparisons. Further, TL was not associated with severity, duration, and age at onset of depression; comorbid anxiety disorders; anxiety symptoms; apathy severity; antidepressant use; benzodiazepine use; cognitive functioning; and childhood trauma. CONCLUSION: Late-life depression was not associated with increased cellular aging. This absent association, which contradicts observations in younger adults, may be due to the potential larger heterogenic nature of late-life depression and lifetime cumulative exposure to other TL-damaging factors, possibly overruling effects of late-life depression.

The role of explicit and implicit self-esteem in the relationship between childhood trauma and adult depression and anxiety.

BACKGROUND: Self-esteem is an important psychological concept that can be measured explicitly (reflective processing) and implicitly (associative processing). The current study examined 1) the association between childhood trauma (CT) and both explicit and implicit self-esteem, and 2) whether self-esteem mediated the association between CT and depression/anxiety. METHODS: In 1479 adult participants of the Netherlands Study of Depression and Anxiety, CT was assessed with a semi-structured interview, depression/anxiety symptoms with self-report questionnaires and explicit and implicit self-esteem with the Rosenberg Self-Esteem Scale and Implicit Association Test, respectively. ANOVAs and regression analyses determined the association between CT (no/mild/severe CT), its subtypes (abuse/neglect) and self-esteem. Finally, we examined whether self-esteem mediated the relationship between CT and depression/anxiety. RESULTS: Participants with CT reported lower explicit (but not lower implicit) self-esteem compared to those without CT (p < .001, partial η2 = 0.06). All CT types were associated with lower explicit self-esteem (p = .05 for sexual abuse, p < .001 for other CT types), while only emotional neglect significantly associated with lower implicit self-esteem after adjusting for sociodemographic characteristics (p = .03). Explicit self-esteem mediated the relationship between CT and depression/anxiety symptoms (proportion mediated = 48-77 %). LIMITATIONS: The cross-sectional design precludes from drawing firm conclusions about the direction of the proposed relationships. CONCLUSIONS: Our results suggested that the relationship between CT and depression/anxiety symptoms can at least partly be explained by explicit self-esteem. This is of clinical relevance as it points to explicit self-esteem as a potential relevant treatment target for people with CT.

Antidepressants or running therapy: Comparing effects on mental and physical health in patients with depression and anxiety disorders.

BACKGROUND: Antidepressant medication and running therapy are both effective treatments for patients with depressive and anxiety disorders. However, they may work through different pathophysiological mechanisms and could differ in their impact on physical health. This study examined effects of antidepressants versus running therapy on both mental and physical health. METHODS: According to a partially randomized patient preference design, 141 patients with depression and/or anxiety disorder were randomized or offered preferred 16-week treatment: antidepressant medication (escitalopram or sertraline) or group-based running therapy ≥2 per week. Baseline (T0) and post-treatment assessment at week 16 (T16) included mental (diagnosis status and symptom severity) and physical health indicators (metabolic and immune indicators, heart rate (variability), weight, lung function, hand grip strength, fitness). RESULTS: Of the 141 participants (mean age 38.2 years; 58.2 % female), 45 participants received antidepressant medication and 96 underwent running therapy. Intention-to-treat analyses showed that remission rates at T16 were comparable (antidepressants: 44.8 %; running: 43.3 %; p = .881). However, the groups differed significantly on various changes in physical health: weight (d = 0.57; p = .001), waist circumference (d = 0.44; p = .011), systolic (d = 0.45; p = .011) and diastolic (d = 0.53; p = .002) blood pressure, heart rate (d = 0.36; p = .033) and heart rate variability (d = 0.48; p = .006). LIMITATIONS: A minority of the participants was willing to be randomized; the running therapy was larger due to greater preference for this intervention. CONCLUSIONS: While the interventions had comparable effects on mental health, running therapy outperformed antidepressants on physical health, due to both larger improvements in the running therapy group as well as larger deterioration in the antidepressant group. TRIAL REGISTRATION: Trialregister.nl Number of identification: NTR3460.

The time course of perceptual grouping in natural scenes.

Visual perception starts with localized filters that subdivide the image into fragments that undergo separate analyses. The visual system has to reconstruct objects by grouping image fragments that belong to the same object. A widely held view is that perceptual grouping occurs in parallel across the visual scene and without attention. To test this idea, we measured the speed of grouping in pictures of animals and vehicles. In a classification task, these pictures were categorized efficiently. In an image-parsing task, participants reported whether two cues fell on the same or different objects, and we measured reaction times. Despite the participants' fast object classification, perceptual grouping required more time if the distance between cues was larger, and we observed an additional delay when the cues fell on different parts of a single object. Parsing was also slower for inverted than for upright objects. These results imply that perception starts with rapid object classification and that rapid classification is followed by a serial perceptual grouping phase, which is more efficient for objects in a familiar orientation than for objects in an unfamiliar orientation.

An integrative study of five biological clocks in somatic and mental health.

Biological clocks have been developed at different molecular levels and were found to be more advanced in the presence of somatic illness and mental disorders. However, it is unclear whether different biological clocks reflect similar aging processes and determinants. In ~3000 subjects, we examined whether five biological clocks (telomere length, epigenetic, transcriptomic, proteomic, and metabolomic clocks) were interrelated and associated to somatic and mental health determinants. Correlations between biological aging indicators were small (all r < 0.2), indicating little overlap. The most consistent associations of advanced biological aging were found for male sex, higher body mass index (BMI), metabolic syndrome, smoking, and depression. As compared to the individual clocks, a composite index of all five clocks showed most pronounced associations with health determinants. The large effect sizes of the composite index and the low correlation between biological aging indicators suggest that one's biological age is best reflected by combining aging measures from multiple cellular levels.

Getting under the skin: Does biology help predict chronicity of depression?

BACKGROUND: Depressed patients are at risk of an unfavourable course including chronic episodes. Various psychiatric characteristics have shown to be predictive of depression's course trajectory, but whether indicators of somatic health further contribute to course prediction remains unclear. This study aimed to identify somatic health indicators (i.e. biomarkers, health status and lifestyle) that predict 2-year chronicity above and beyond an extensive list of sociodemographic and psychiatric characteristics. METHODS: Data are from patients with current depression at baseline (n = 903) and available 2-year follow-up participating in a longitudinal cohort study. Baseline demographic, psychiatric and somatic health indicators were associated with 2-year course trajectories, classified as non-chronic versus chronic RESULTS: At 2-year follow up, 40% of the patients showed a chronic course. Of the twenty tested somatic health indicators, short sleep and high interleukin-6 improved the regression model predicting chronicity with a significant, but modest, effect (ROC = 0.78; p = 0.03). LIMITATIONS: Due to the observational design we did not have the ability to reliably consider the impact of psychiatric treatment. More elaborate information on somatic health such as dietary patterns would strengthen the study. CONCLUSIONS: This study showed that short sleep duration and high interleukin-6 contributed significantly to the regression model as independent predictors, suggestive of clinical implications for patients with sleep disturbances and elevated inflammation levels. Other somatic health indicators did not add to the model. Overall, somatic health indicators showed modest additive value for predicting chronic course above and beyond sociodemographic and psychiatric indicators.

Unraveling the association between depression and telomere length using genomics.

OBJECTIVE: While there is robust evidence for a cross-sectional association between depression and shorter telomere length, suggestive of advanced biological aging, the nature of this association remains unclear. Here, we tested whether both traits share a common genetic liability with novel methods using genomics. METHODS: Data were from 2032 participants of the Netherlands Study of Depression and Anxiety (NESDA) with genome-wide genetic information and multiple waves of data on DSM-IV lifetime depression diagnosis, depression severity, neuroticism and telomere length. Polygenic risk scores (PRS) for both traits were built using summary results from the largest genome-wide association studies (GWAS) on depression (59,851 cases and 113,154 controls) and telomere length (37,684 samples). Additionally, a PRS for neuroticism was built (337,000 samples). Genetic overlap between the traits was tested using PRS for same- and cross-trait associations. Furthermore, GWAS summary statistics were used to estimate the genome-wide genetic correlation between traits. RESULTS: In NESDA data, the PRS for depression was associated with lifetime depression (odds ratio = 1.36; p = 6.49e-7) and depression severity level (ß = 0.13; p = 1.24e-8), but not with telomere length. Similar results were found for the PRS for neuroticism. Conversely, the PRS for telomere length was associated with telomere length (ß = 0.07; p = 8.42e-4) and 6-year telomere length attrition rate (ß = 0.04; p = 2.15e-2), but not with depression variables. In summary-level analyses, the genetic correlation between the traits was small and not significant (rg=-0.08; p = .300). CONCLUSION: The use of genetic methods in this paper indicated that the established phenotypic association between telomere length and depression is unlikely due to shared underlying genetic vulnerability. Our findings suggest that short telomeres in depressed patients may simply represent a generic marker of disease or may originate from non-genetic environmental factors.

Delayed sleep-onset and biological age: late sleep-onset is associated with shorter telomere length.

STUDY OBJECTIVES: We evaluated the relationship between leukocyte telomere length (LTL) and sleep duration, insomnia symptoms, and circadian rhythm, to test whether sleep and chronobiological dysregulations are associated with cellular aging. METHODS: Data from the Netherlands Study of Depression and Anxiety (N = 2,936) were used at two waves 6 years apart, to measure LTL. Telomeres shorten during the life span and are important biomarkers for cellular aging. LTL was assessed by qualitative polymerase chain reaction and converted into base pair number. Sleep parameters were: sleep duration and insomnia symptoms from the Insomnia Rating Scale. Circadian rhythm variables were: indication of Delayed Sleep Phase Syndrome (DSPS), mid-sleep corrected for sleep debt on free days (MSFsc), sleep-onset time, and self-reported chronotype, from the Munich Chronotype Questionnaire. Generalized estimating equations analyzed the associations between LTL, sleep, and chronobiological factors, adjusted for baseline age, sex, North European ancestry, and additionally for current smoking, depression severity, obesity, and childhood trauma. RESULTS: Indicators of delayed circadian rhythm showed a strong and consistent effect on LTL, after adjustment for sociodemographic and health indicators. Late MSFsc (B = -49.9, p = .004), late sleep-onset time (B = -32.4, p = .001), indication of DSPS (B = -73.8, p = .036), and moderately late chronotype in adulthood (B = -71.6, p = .003) were associated with significantly shorter LTL across both waves; whereas sleep duration and insomnia symptoms were not. Extremely early chronotype showed significantly less LTL shortening than intermediate chronotype (B = 161.40, p = .037). No predictors showed accelerated LTL attrition over 6 years. CONCLUSIONS: Individuals with delayed circadian rhythm have significantly shorter LTL, but not faster LTL attrition rates.