Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell's mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. DISCLOSURESJL is a consultant to Telomere Diagnostics Inc., formerly Telome Health, and owns stock in the company. The company had no role in this research or in writing this review. The remaining authors report no current disclosures or conflicts of interest. HHS Public Access

Patients with major depressive disorder (MDD) have an increased onset risk of aging-related somatic diseases such as heart disease, diabetes, obesity and cancer. This suggests mechanisms of accelerated biological aging among the depressed, which can be indicated by a shorter length of telomeres. We examine whether MDD is associated with accelerated biological aging, and whether depression characteristics such as severity, duration, and psychoactive medication do further impact on biological aging. Data are from the Netherlands Study of Depression and Anxiety, including 1095 current MDD patients, 802 remitted MDD patients and 510 control subjects. Telomere length (TL) was assessed as the telomere sequence copy number (T) compared to a single-copy gene copy number (S) using quantitative polymerase chain reaction. This resulted in a T/S ratio and was converted to base pairs (bp). MDD diagnosis and MDD characteristics were determined by self-report questionnaires and structured psychiatric interviews. Compared with control subjects (mean bp=5541), sociodemographic-adjusted TL was shorter among remitted MDD patients (mean bp=5459; P=0.014) and current MDD patients (mean bp=5461; P=0.012). Adjustment for health and lifestyle variables did not reduce the associations. Within the current MDD patients, separate analyses showed that both higher depression severity (P<0.01) and longer symptom duration in the past 4 years (P=0.01) were associated with shorter TL. Our results demonstrate that depressed patients show accelerated cellular aging according to a 'dose-response' gradient: those with the most severe and chronic MDD showed the shortest TL. We also confirmed the imprint of past exposure to depression, as those with remitted MDD had shorter TL than controls.

Objective This study examined the relationship between leukocyte telomere length (LTL), a marker of cell aging, and psychiatric disorders in adults compared to 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’s g = −0.50, p< 0.001). 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 be explained by a model that included these variables as well as sex and assay method. Although not significantly different, post-traumatic stress disorder, anxiety disorders and depressive disorders had comparatively larger effect sizes (−1.27, −.53, and −.55), and psychotic and bipolar disorders had comparatively smaller ones (−.23 and −.26). Conclusions We observed a robust effect size of LTL shortening for psychiatric disorders as a whole compared to 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.

BackgroundMetabolic syndrome components—waist circumference, high‐density lipoprotein cholesterol (HDL‐C), triglycerides, systolic blood pressure and fasting glucose—are cross‐sectionally associated with depression and anxiety with differing strength. Few studies examine the relationships over time or whether antidepressants have independent effects.MethodsParticipants were from the Netherlands Study of Depression and Anxiety (NESDA; N = 2,776; 18–65 years; 66% female). At baseline, 2‐ and 6‐year follow‐up, participants completed diagnostic interviews, depression and anxiety symptom inventories, antidepressant use assessment, and measurements of the five metabolic syndrome components. Data were analyzed for the consistency of associations between psychopathology indicators and metabolic syndrome components across the three assessment waves, and whether psychopathology or antidepressant use at one assessment predicts metabolic dysregulation at the next and vice versa.ResultsConsistently across waves, psychopathology was associated with generally poorer values of metabolic syndrome components, particularly waist circumference and triglycerides. Stronger associations were observed for psychopathology symptom severity than diagnosis. Antidepressant use was independently associated with higher waist circumference, triglycerides and number of metabolic syndrome abnormalities, and lower HDL‐C. Symptom severity and antidepressant use were associated with subsequently increased number of abnormalities, waist circumference, and glucose after 2 but not 4 years. Conversely, there was little evidence that metabolic syndrome components were associated with subsequent psychopathology outcomes.ConclusionsSymptom severity and antidepressant use were independently associated with metabolic dysregulation consistently over time and also had negative consequences for short‐term metabolic health. This is of concern given the chronicity of depression and anxiety and prevalence of antidepressant treatment.

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