BackgroundDepression is associated with an unusually high rate of aging-related illnesses and early mortality. One aspect of “accelerated aging” in depression may be shortened leukocyte telomeres. When telomeres critically shorten, as often occurs with repeated mitoses or in response to oxidation and inflammation, cells may die. Indeed, leukocyte telomere shortening predicts early mortality and medical illnesses in non-depressed populations. We sought to determine if leukocyte telomeres are shortened in Major Depressive Disorder (MDD), whether this is a function of lifetime depression exposure and whether this is related to putative mediators, oxidation and inflammation.MethodologyLeukocyte telomere length was compared between 18 unmedicated MDD subjects and 17 controls and was correlated with lifetime depression chronicity and peripheral markers of oxidation (F2-isoprostane/Vitamin C ratio) and inflammation (IL-6). Analyses were controlled for age and sex.Principal FindingsThe depressed group, as a whole, did not differ from the controls in telomere length. However, telomere length was significantly inversely correlated with lifetime depression exposure, even after controlling for age (p<0.05). Average telomere length in the depressed subjects who were above the median of lifetime depression exposure (≥9.2 years' cumulative duration) was 281 base pairs shorter than that in controls (p<0.05), corresponding to approximately seven years of “accelerated cell aging.” Telomere length was inversely correlated with oxidative stress in the depressed subjects (p<0.01) and in the controls (p<0.05) and with inflammation in the depressed subjects (p<0.05).ConclusionsThese preliminary data indicate that accelerated aging at the level of leukocyte telomeres is proportional to lifetime exposure to MDD. This might be related to cumulative exposure to oxidative stress and inflammation in MDD. This suggest that telomere shortening does not antedate depression and is not an intrinsic feature. Rather, telomere shortening may progress in proportion to lifetime depression exposure.

The objective of the present study were (1) to ascertain the lifetime risk of a depression in a representative group of multiple sclerosis (MS) patients, (2) to assess the morbidity risks for depression among first-degree relatives of these MS patients, and (3) to compare these familial risks for first-degree relatives of MS patients with those for first-degree relatives of a primary depression population, i.e., depression but no MS. We psychiatrically evaluated 221 MS patients (index cases) using a structured clinical interview for the DSM-III-R and calculated the rate and lifetime risk of depression for these index cases using the product limit estimate of survival function. We obtained psychiatric histories for all first-degree relatives of index cases, and we calculated morbidity risks for depression for these relatives using the maximum likelihood approach and compared the risks using the likelihood ratio tests. Index cases had a 50.3% lifetime risk of depression. Morbidity risks for depression among first-degree relatives of index cases were decidedly lower when compared with morbidity risks among first-degree relatives of the reference population. Although there appears to be a very high rate of depression among MS patients, the data for their first-degree relatives do not support a clear genetic basis for this depression, or at least the same genetic basis that probably operates within families when depression occurs in the absence of MS.

Telomeres are DNA-protein complexes that cap linear DNA strands, protecting DNA from damage. When telomeres critically shorten, cells become susceptible to senescence and apoptosis. Telomerase, a cellular ribonucleoprotein enzyme, rebuilds the length of telomeres and promotes cellular viability. Leukocyte telomeres are reportedly shortened in major depression, but telomerase activity in depression has not been previously reported. Further, there are no published reports of the effects of antidepressants on telomerase activity or on the relationship between telomerase activity and antidepressant response. Peripheral blood mononuclear cell (PBMC) telomerase activity was assessed in 20 medication-free depressed individuals and 18 controls. In total, 16 of the depressed individuals were then treated with sertraline in an open-label manner for 8 weeks, and PBMC telomerase activity was reassessed in 15 of these individuals after treatment. Pre- and post-treatment symptom severity was rated with the Hamilton Depression Rating Scale. All analyses were corrected for age and sex. Pretreatment telomerase activity was significantly elevated in the depressed individuals compared with the controls (P = 0.007) and was directly correlated with depression ratings (P< 0.05) across all subjects. In the depressed group, individuals with relatively lower pretreatment telomerase activity and with relatively greater increase in telomerase activity during treatment, showed superior antidepressant responses (P < 0.05 and P < 0.005, respectively). This is the first report characterizing telomerase activity in depressed individuals. PBMC telomerase activity might reflect a novel aspect of depressive pathophysiology and might represent a novel biomarker of antidepressant responsiveness.

Chronic inflammation and oxidative stress have been implicated in the pathophysiology of Major Depressive Disorder (MDD), as well as in a number of chronic medical conditions. The aim of this study was to examine the relationship between peripheral inflammatory and oxidative stress markers in un-medicated subjects with MDD compared to non-depressed healthy controls and compared to subjects with MDD after antidepressant treatment. We examined the relationships between IL-6, IL-10, and the IL-6/IL-10 inflammatory ratio vs. F2-isoprostanes (F2-IsoP), a marker of oxidative stress, in un-medicated MDD patients (n = 20) before and after 8 weeks of open-label sertraline treatment (n = 17), compared to healthy non-depressed controls (n = 20). Among the un-medicated MDD subjects, F2-IsoP concentrations were positively correlated with IL-6 concentrations (p < 0.05) and were negatively correlated with IL-10 concentrations (p < 0.01). Accordingly, F2-IsoP concentrations were positively correlated with the ratio of IL-6/IL-10 (p < 0.01). In contrast, in the control group, there were no significant correlations between F2-IsoPs and either cytokine or their ratio. After MDD subjects were treated with sertraline for 8 weeks, F2-IsoPs were no longer significantly correlated with IL-6, IL-10 or the IL-6/IL-10 ratio. These data suggest oxidative stress and inflammatory processes are positively associated in untreated MDD. Our findings are consistent with the hypothesis that the homeostatic buffering mechanisms regulating oxidation and inflammation in healthy individuals become dysregulated in untreated MDD, and may be improved with antidepressant treatment. These findings may help explain the increased risk of comorbid medical illnesses in MDD.

Residual symptoms of major depressive disorder (MDD) following treatment are increasingly recognized as having a negative impact on the patient because of their association with lack of remission, poorer psychosocial functioning, and a more chronic course of depression. Although the effects of specific residual symptoms have not been as systematically studied, several symptoms, including fatigue, sleep disturbance, anxiety, and concentration difficulties, commonly occur as part of the residual state in MDD. In particular, the relatively high prevalence of residual fatigue suggests that this symptom is not being adequately addressed by standard antidepressant therapies. A review of the clinical relevance of residual fatigue was undertaken, using the published literature with respect to its assessment, neurobiology, and treatment implications. The findings of this review suggest that fatigue is highly prevalent as a residual symptom; its response to treatment is relatively poor or delayed; and the presence of residual fatigue is highly predictive of inability to achieve remission with treatment as well as impaired psychosocial functioning. Recognition of the significant consequences of residual fatigue should reinforce the need for further therapeutic interventions to help reduce the impact of this symptom of MDD.

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OBJECTIVES The “neurotrophin hypothesis” of depression posits a role of brain-derived neurotrophic factor (BDNF) in depression, although it is unknown whether BDNF is more involved in the etiology of depression or in the mechanism of action of antidepressants. . It is also unknown whether pre-treatment serum BDNF levels predict antidepressant response. METHODS Thirty un-medicated depressed subjects were treated with escitalopram (N=16) or sertraline (N=14) for eight weeks. Twenty-five of the depressed subjects completed 8 weeks of antidepressant treatment and had analyzable data. Twenty-eight healthy controls were also studied. Serum for BDNF assay was obtained at baseline in all subjects and after 8 weeks of treatment in the depressed subjects. Depression ratings were obtained at baseline and after 8 weeks of treatment in the depressed subjects. RESULTS Pre-treatment BDNF levels were lower in the depressed subjects than the controls (p= 0.001) but were not significantly correlated with pre-treatment depression severity. Depression ratings improved with SSRI treatment (p< 0.001), and BDNF levels increased with treatment (p= 0.005). Changes in BDNF levels were not significantly correlated with changes in depression ratings. However, pre-treatment BDNF levels were directly correlated with antidepressant responses (p<0.01), and “Responders” to treatment (≥ 50% improvement in depression ratings) had higher pre-treatment BDNF levels than did “Non-responders” (p< 0.05). CONCLUSIONS These results confirm low serum BDNF levels in unmedicated depressed subjects and confirm antidepressant-induced increases in BDNF levels, but they suggest that antidepressants do not work simply by correcting BDNF insufficiency. Rather, these findings are consistent with a permissive or facilitatory role of BDNF in the mechanism of action of antidepressants.

When fixed doses of haloperidol or perphenazine were used in two separate studies, we found that psychotic males with a prior history of psychotogenic drug use had a poorer early neuroleptic response even in the early stages of their psychotic disorder than psychotic males who had not previously used significant amounts of psychotogenic drugs. Relative neuroleptic refractoriness may be characteristic of some dual diagnosis patients at the beginning of their illness. Antecedent psychotogenic drug use may contribute to the development of psychosis and to relative neuroleptic refractoriness by means of effects upon dopaminergic mechanisms.