Metabolic syndrome among young adults at high and low familial risk for depression.

BACKGROUND: Our study examined whether the early-onset depression phenotype among young adults (probands) is associated with the metabolic syndrome (MetS) and its components, and if MetS characterizes unaffected but high-risk siblings of probands. METHODS: We studied three groups of young adults (Mage = 25 years, s.d. = 3.84 years): probands with histories of childhood onset depression - i.e. early-onset phenotype - (n = 293), their unaffected siblings (high-risk siblings, n = 273), and healthy controls (n = 171). Participants completed a full psychiatric interview, physical and laboratory assessments, and self-rating scales. MetS was defined using the criteria of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (). RESULTS: Early-onset depression phenotype and being a high-risk sibling were associated with higher MetS composite scores relative to that of controls, but did not differ from one another. With regard to MetS components: Probands and siblings had similarly larger waist circumference and lower HDL than did controls, while siblings and controls had lower triglyceride levels than did probands but did not differ from one another. Groups did not differ on glucose levels and SBP. CONCLUSIONS: Our study extends the literature on the association between MetS and depression and underscores the importance of depression phenotypes: failure to account for the clinical heterogeneity of depression may partly underlie the inconsistent findings regarding its relation to MetS. The results also suggest that, in depression-prone populations, MetS may predate and possibly function as a risk factor for eventual depression.

A commentary on "Don't mind the gap: Why we do not care about the gender gap in mental health?" by P. Patalay and O. Demkowicz.

In their article, Drs. Patalay and Demkowicz raise important questions about research regarding the sex/gender gap in depression rates. However, their perspective on this topic is rather polarizing and yields statements of questionable accuracy. In this Commentary, I respond to several statements in the Article, which I consider potentially misleading. My goal is to present a broader perspective on sex/gender and depression and encourage further discussion of this important topic.

Adiposity and Smoking Mediate the Relationship Between Depression History and Inflammation Among Young Adults.

BACKGROUND: Depression is associated with inflammation, but the mechanisms underlying this association are unclear. We examined adiposity and smoking as potential pathways through which childhood depression may lead to an elevated inflammatory status among young adults. METHODS: The sample included 294 subjects with histories of depression (probands), 270 never-depressed siblings of probands (high-risk siblings), and 169 controls. C-reactive protein (CRP), interleukin-6 (IL-6), and soluble intercellular adhesion molecule-1 (sICAM-1) were assessed in serum samples. An adiposity score was computed from body mass index and waist circumference. Smoking behavior was evaluated during an interview. Mixed-effects models were used to test whether adiposity and smoking mediate the relationship between depression and inflammation. RESULTS: Probands (p = .004), but not siblings (p = .071), had higher levels of sICAM-1 compared to controls. However, depression history and risk status had no direct effects on CRP (ps > .13) or IL-6 (ps > .16). Importantly, adiposity indirectly mediated the effect of group (probands vs. controls; siblings vs. controls) on all three inflammatory markers. Smoking indirectly mediated the effect of group (probands vs. controls; siblings vs. controls) on sICAM-1 only. CONCLUSIONS: Among young adults, the adverse inflammatory consequences of depression history are significant for sICAM-1. Adiposity and smoking are pathways through which depression can indirectly impact several inflammatory markers, suggesting possible preventive interventions to improve the immunologic and cardiovascular health of depression-prone individuals.

3D-Cell-Annotator: an open-source active surface tool for single-cell segmentation in 3D microscopy images.

SUMMARY: Segmentation of single cells in microscopy images is one of the major challenges in computational biology. It is the first step of most bioimage analysis tasks, and essential to create training sets for more advanced deep learning approaches. Here, we propose 3D-Cell-Annotator to solve this task using 3D active surfaces together with shape descriptors as prior information in a semi-automated fashion. The software uses the convenient 3D interface of the widely used Medical Imaging Interaction Toolkit (MITK). Results on 3D biological structures (e.g. spheroids, organoids and embryos) show that the precision of the segmentation reaches the level of a human expert. AVAILABILITY AND IMPLEMENTATION: 3D-Cell-Annotator is implemented in CUDA/C++ as a patch for the segmentation module of MITK. The 3D-Cell-Annotator enabled MITK distribution can be downloaded at: www.3D-cell-annotator.org. It works under Windows 64-bit systems and recent Linux distributions even on a consumer level laptop with a CUDA-enabled video card using recent NVIDIA drivers. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

The persistence of hedonically-based mood repair among young offspring at high- and low-risk for depression.

The aim of the present study was to examine whether offspring at high and low familial risk for depression differ in the immediate and more lasting behavioural and physiological effects of hedonically-based mood repair. Participants (9- to 22-year olds) included never-depressed offspring at high familial depression risk (high-risk, n = 64), offspring with similar familial background and personal depression histories (high-risk/DEP, n = 25), and never-depressed offspring at low familial risk (controls, n = 62). Offspring provided affect ratings at baseline, after sad mood induction, immediately following hedonically-based mood repair, and at subsequent, post-repair epochs. Physiological reactivity, indexed via respiratory sinus arrhythmia (RSA), was assessed during the protocol. Following mood induction and mood repair, high- and low-risk (control) offspring reported comparable changes in levels of sadness and RSA. However, sadness increased among high-risk offspring following the post-repair epoch, whereas low-risk offspring maintained mood repair benefits. High-risk/DEP offspring also reported higher levels of sadness following the post-repair epoch than did low-risk offspring. Change in RSA did not differ across the three offspring groups. Self-ratings confirm that one source of difficulty associated with depression risk is diminished ability to maintain hedonically-based mood repair gains, which were not apparent at the physiological level.

["Risk factors of childhood depression" research grant - past, present, future].

The authors summarize the last 10 years of an ongoing collaborative study between the Universities of Szeged and Pittsburgh on early onset major depression. First, the "Risk factors of childhood depression" grant is presented briefly as an initial research study in which the subjects of the current studies were recruited. This is a prominently large clinical sample in the field of child psychiatry even on an international level. In addition to the follow-up of the prognosis of the disorder, recent studies continue to explore the early onset depression in two directions. On the one hand, two studies investigate the role of biobehavioral inflexibility markers in the development of major depression ("Biobehavioral inflexibility and risk for juvenile-onset depression" and "Biobehavioral inflexibility and risk for juvenile-onset depression - renewal grant"). On the other hand, the authors would like to have a better understanding of the possible relationship between the major depression and cardiovascular diseases ("Pediatric depression and subsequent cardiac risk factors: a longitudinal study"). The most significant aims of the three studies will be demonstrated, as well as how the studies were prepared and organized along with the already existing experience concerning research management and involvement of new collaborating partners and experts.

The Development of Mood Repair Response Repertories: I. Age-Related Changes Among 7- to 14-Year-Old Depressed and Control Children and Adolescents.

The purpose of this study was to test developmentally informed hypotheses about regulatory responses to sadness that attenuate versus exacerbate it (adaptive versus maladaptive mood repair responses, respectively) across late childhood, early adolescence, and mid-adolescence. In a multi-site study in Hungary, clinic-based, 7- to 14-year-olds with Diagnostic and Statistical Manual of Mental Disorders' (4th ed., text rev.) depressive disorders (N = 697; 55% male) and age/sex matched (at 1:2) nondepressed, school-based controls (N = 1,394) reported on their usual responses to sadness/dysphoria; parental reports were obtained separately. Adaptive and maladaptive response repertoire scores were compared across ages within and across subject groups, and by informant, controlling for confounds. Contrary to Hypothesis 1, older (vs. younger) youths in both groups reported fewer adaptive regulatory responses. Maladaptive response repertoires were unrelated to age among controls but significantly increased with age among depressed youths, particularly the girls. Partially supporting Hypothesis 2, subject groups differed in age-related trajectories of mood repair repertories, but not as expected (e.g., younger depressed children reported larger adaptive response repertoires than did controls). Parental reports revealed no developmental changes in offspring's mood repair repertories. Parent-offspring reports were most discordant for younger (vs. older) offspring, tended to converge around age 11, and were consistently and significantly larger in the depressed sample. Self-reported adaptive mood repair repertories appear to have been laid down by late childhood and then undergo "trimming" across ages 7-14 years. The extensive maladaptive mood repair response repertoires of depressed youths, which increased with age, distinguish them primarily from controls. Therefore, reducing maladaptive regulatory responses to sadness should be a priority when treating depressed youths.

Examination of the Changes in Calcium Homeostasis in the Delayed Antiarrhythmic Effect of Sodium Nitrite.

We have evidence that the intravenous infusion of sodium nitrite (NaNO2) results in an antiarrhythmic effect when given 24 h prior to an ischemia and reperfusion (I/R) insult in anaesthetized dogs. This protection was associated with the reduction of reactive oxygen species resulting from I/R through the attenuation of mitochondrial respiration. Here, we examined whether the changes in calcium, which also contributes to arrhythmia generation, play a role in the NaNO2-induced effect. On the first day, 30 anaesthetized dogs were treated either with saline or NaNO2 (0.2 µmol/kg/min) for 20 min. Some animals were subjected to a 25 min LAD (anterior descending branch of the left coronary artery) occlusion and 2 min reperfusion (I/R = 4; NaNO2-I/R = 6), or the heart was removed 24 h later. We have shown that nitrite prevented the I/R-induced increase in cellular and mitochondrial calcium deposits. During simulated I/R, the amplitude of the calcium transient and the diastolic calcium level were significantly lower in the nitrite-treated hearts and the ERP (effective refractory period) fraction of the action potential was significantly increased. Furthermore, nitrite also enhanced the mitochondrial respiratory response and prevented the MPTPT opening during calcium overload. These results suggest that nitrite can reduce the harmful consequences of calcium overload, perhaps directly by modulating ion channels or indirectly by reducing the mitochondrial ROS (reactive oxygen species) production.

Non-response to sad mood induction: implications for emotion research.

Experimental induction of sad mood states is a mainstay of laboratory research on affect and cognition, mood regulation, and mood disorders. Typically, the success of such mood manipulations is reported as a statistically significant pre- to post-induction change in the self-rated intensity of the target affect. The present commentary was motivated by an unexpected finding in one of our studies concerning the response rate to a well-validated sad mood induction. Using the customary statistical approach, we found a significant mean increase in self-rated sadness intensity with a moderate effect size, verifying the "success" of the mood induction. However, that "success" masked that, between one-fifth and about one-third of our samples (adolescents who had histories of childhood-onset major depressive disorder and healthy controls) reported absolutely no sadness in response to the mood induction procedure. We consider implications of our experience for emotion research by (1) commenting upon the typically overlooked phenomenon of nonresponse, (2) suggesting changes in reporting practices regarding mood induction success, and (3) outlining future directions to help scientists determine why some subjects do not respond to experimental mood induction.

Positive autobiographical memory deficits in youth with depression histories and their never-depressed siblings.

OBJECTIVES: Impaired positive autobiographical memory (AM) is closely linked to emotional disorders. AM impairments are often found in depressed adults and may be related to the difficulties such persons have in regulating their dysphoric mood. By contrast, less is known about AM disturbances among adolescents, or about the functional relationship of AM disturbances to early-onset depression. DESIGN: A high-risk family design served to compare four groups of youth who differed in depression histories and familial depression risk. METHODS: Thirty-one currently depressed probands, 185 remitted probands, 204 never-depressed siblings of probands, and 180 healthy control youth were induced into a negative mood prior to recalling positive AMs via a novel memory elicitation procedure. Several positive AM characteristics were assessed. RESULTS: Relative to control youth, unaffected siblings and probands exhibited consistently impaired positive AMs. Moreover, we also found some evidence that probands were more impaired than siblings, who were in turn more impaired than controls, consistent with a gradient effect. CONCLUSIONS: Positive AM disturbances may not only precede the onset of depression in vulnerable youth, but also continue to persist after remission of a depressive episode. Clinical and basic research implications of the findings are discussed. PRACTITIONER POINTS: Positive AM impairments may be trait-like, persist in the euthymic phase of depression, and may serve as a risk marker for early-onset depression among vulnerable adolescents. Disturbances in positive AM may negatively impact the mood-regulatory functions of positive memory recall and contribute to persistent sadness and anhedonia, which are core features of depression. Our sample of currently depressed youth was relatively small, tempering our conclusions. Although we collected data on some important covariates (e.g., socioeconomic status), we lacked information on other relevant variables such as youths' executive functioning or IQ.

Examination of the effect of sodium nitrite on gap junction function during ischaemia and reperfusion in anaesthetized dogs.

It has previously been proved that sodium nitrite, infused prior to coronary artery occlusion or before reperfusion, results in marked antiarrhythmic effect in anaesthetized dogs. We have now examined whether this protection involves the modulation of gap junction (GJ) function by nitric oxide (NO), derived from nitrite administration under ischaemic conditions. Two groups of chloralose and urethane anaesthetized dogs, each containing 13 animals, were subjected to a 25 min period occlusion of the left anterior descending (LAD) coronary artery, followed by reperfusion. One group was infused with sodium nitrite (0.2 µmol/kg/min, i.v.), the other group with saline 10 min prior to reperfusion. The severities of arrhythmias and of ischaemia (epicardial ST-segment, total activation time), parallel with changes in myocardial tissue impedance, a measure of electrical coupling of gap junctions, were assessed during the experiments. Compared to the controls, nitrite infusion administered prior to reperfusion significantly attenuated the severity of ischaemia, the ischaemia-induced impedance changes and, consequently, the severity of arrhythmias, occurring during the 1B phase of the occlusion, and increase survival following reperfusion (0% vs. 85%). It is concluded that the marked antiarrhythmic effect of sodium nitrite is partly due, to the preservation of the electrical coupling of GJs by NO.

Familiality of mood repair responses among youth with and without histories of depression.

Affect regulation skills develop in the context of the family environment, wherein youths are influenced by their parents', and possibly their siblings', regulatory responses and styles. Regulatory responses to sadness (mood repair) that exacerbate or prolong dysphoria (maladaptive mood repair) may represent one way in which depression is transmitted within families. We examined self-reported adaptive and maladaptive mood repair responses across cognitive, social and behavioural domains in Hungarian 11- to 19-year-old youth and their parents. Offspring included 214 probands with a history of childhood-onset depressive disorder, 200 never depressed siblings and 161 control peers. Probands reported the most problematic mood repair responses, with siblings reporting more modest differences from controls. Mood repair responses of parents and their offspring, as well as within sib-pairs, were related, although results differed as a function of the regulatory response domain. Results demonstrate familiality of maladaptive and adaptive mood repair responses in multiple samples. These familial associations suggest that relationships with parents and siblings within families may impact the development of affect regulation in youth.

Mood repair via attention refocusing or recall of positive autobiographical memories by adolescents with pediatric-onset major depression.

BACKGROUND: Impaired emotion regulation is increasingly recognized as a core feature of depressive disorders. Indeed, currently and previously depressed adults both report greater problems in attenuating sadness (mood repair) in daily life than healthy controls. In contrast, studies of various strategies to attenuate sad affect have mostly found that currently or previously depressed adults and controls were similarly successful at mood repair in the laboratory. But few studies have examined mood repair among depression-prone youths or the effects of trait characteristics on mood repair outcomes in the laboratory. METHODS: Adolescents, whose first episode of major depressive disorder (MDD) had onset at age 9, on average (probands), and were either in remission or depressed, and control peers, watched a sad film clip. Then, they were instructed to engage in refocusing attention (distraction) or recalling happy memories. Using affect ratings provided by the youths, we tested two developmentally informed hypotheses about whether the subject groups would be similarly able to attenuate sadness via the two mood repair strategies. We also explored if self-reported habitual (trait) mood repair influenced laboratory performance. RESULTS: Contrary to expectations, attention refocusing and recall of happy memories led to comparable mood benefits across subjects. Control adolescents reported significantly greater reductions in sadness than did depressed (Cohen's d = .48) or remitted (Cohen's d = .32) probands, regardless of mood repair strategy, while currently depressed probands remained the saddest after mood repair. Habitual mood repair styles moderated the effects of instructed (state) mood repair in the laboratory. CONCLUSIONS: Whether depressed or in remission, adolescents with MDD histories are not as efficient at mood repair in the laboratory as controls. But proband-control group differences in mood repair outcomes were modest in scope, suggesting that the abilities that subserve affect regulation have been preserved in probands to some degree. Further information about the nature of mood repair problems among youths with depression histories would help to better understand the clinical course of MDD and to design personalized interventions for depression.

Reward learning in pediatric depression and anxiety: preliminary findings in a high-risk sample.

BACKGROUND: Reward learning has been postulated as a critical component of hedonic functioning that predicts depression risk. Reward learning deficits have been established in adults with current depressive disorders, but no prior studies have examined the relationship of reward learning and depression in children. The present study investigated reward learning as a function of familial depression risk and current diagnostic status in a pediatric sample. METHOD: The sample included 204 children of parents with a history of depression (n = 86 high-risk offspring) or parents with no history of major mental disorder (n = 118 low-risk offspring). Semistructured clinical interviews were used to establish current mental diagnoses in the children. A modified signal detection task was used for assessing reward learning. We tested whether reward learning was impaired in high-risk offspring relative to low-risk offspring. We also tested whether reward learning was impaired in children with current disorders known to blunt hedonic function (depression, social phobia, PTSD, GAD, n = 13) compared to children with no disorders and to a psychiatric comparison group with ADHD. RESULTS: High- and low-risk youth did not differ in reward learning. However, youth with current anhedonic disorders (depression, social phobia, PTSD, GAD) exhibited blunted reward learning relative to nondisordered youth and those with ADHD. CONCLUSIONS: Our results are a first demonstration that reward learning deficits are present among youth with disorders known to blunt anhedonic function and that these deficits have some degree of diagnostic specificity. We advocate for future studies to replicate and extend these preliminary findings.

Further evidence for the role of gap junctions in the delayed antiarrhythmic effect of cardiac pacing.

UNLABELLED: The objective of this study was to provide evidence that gap junctions are involved in the delayed antiarrhythmic effect of cardiac pacing. Twenty-four dogs were paced through the right ventricle (4 × 5 min, rate of 240 beats/min) 24 h prior to a 25 min occlusion of the left anterior descending coronary artery. Some of these paced dogs were infused with 50 (n = 7) or 100 µmol/L (n = 7) of the gap junction uncoupler carbenoxolone (CBX), prior to and during the occlusion. Ten sham-paced dogs, subjected only to occlusion, served as the controls. Cardiac pacing markedly reduced the number of ectopic beats and episodes of ventricular tachycardia (VT), as well the incidence of VT and ventricular fibrillation during occlusion. The changes in severity of ischaemia and tissue electrical resistance were also less marked compared with the unpaced controls. Pacing also preserved the permeability of gap junctions, the phosphorylation of connexin43, and the structural integrity of the intercalated discs. The closing of gap junctions with CBX prior to and during ischaemia markedly attenuated or even abolished these protective effects of pacing. CONCLUSION: Our results support the previous findings that gap junctions play a role in the delayed antiarrhythmic effect of cardiac pacing.

Identification and functional characterisation of a novel KCNJ2 mutation, Val302del, causing Andersen-Tawil syndrome.

Loss-of-function mutations of the KCNJ2 gene encoding for the inward rectifier potassium channel subunit Kir2.1 cause Andersen-Tawil Syndrome (ATS), a rare genetic disorder characterised by periodic paralysis, ventricular arrhythmias, and dysmorphic features. Clinical manifestations of the disease appear to vary greatly with the nature of mutation, therefore, functional characterisation of ATS-causing mutations is of clinical importance. In this study, we describe the identification and functional analysis of a novel KCNJ2 mutation, Val302del, identified in a patient with ATS. Heterologously expressed wild type (WT) and Val302del mutant alleles showed similar subcellular distribution of the Kir2.1 protein with high intensity labelling from the membrane region, demonstrating normal membrane trafficking of the Val302del Kir2.1 variant. Cells transfected with the WT allele displayed a robust current with strong inward rectification, while no current above background was detected in cells expressing the Val302del Kir2.1 subunit. Co-transfection of CHO cells with the WT and the Val302del Kir2.1 revealed a dose-dependent inhibitory effect of the Val302del Kir2.1 mutant subunit on WT Kir2.1 currents. These observations indicate that the WT and the Val302del mutant subunits co-assemble in the cell membrane and that the mutation affects potassium conductivity and (or) gating of the WT/Val302del heteromeric Kir2.1 channels.

The association between major depressive disorder in childhood and risk factors for cardiovascular disease in adolescence.

OBJECTIVE: Depression in adults is associated with risk factors for cardiovascular disease (CVD). It is unclear, however, when the association between clinical depression and cardiac risk factors develops or how early in life this association can be detected. METHODS: In an ongoing study of pediatric depression, we compared CVD risk factors including smoking, obesity, physical activity level, sedentary behavior, and parental history of CVD across three samples of adolescents: probands with established histories of childhood-onset major depressive disorder (n = 210), never-depressed siblings of probands (n = 195), and controls with no history of any major psychiatric disorder (n = 161). RESULTS: When assessed during adolescence, 85% of the probands were not in a major depressive episode. Nevertheless, at that assessment, probands had a higher prevalence of regular smoking (odds ratio [OR] = 12.54, 95% confidence interval [CI] = 4.36-36.12) and were less physically active than controls (OR = 0.59, CI = 0.43-0.81) and siblings (OR = 0.70, CI = 0.52-0.94) and had a higher rate of obesity than did controls (OR = 3.67, CI = 1.42-9.52). Parents of probands reported high rates of CVD (significantly higher than did parents of controls), including myocardial infarction and CVD-related hospitalization (ORs = 1.62-4.36, CIs = 1.03-15.40). Differences in CVD risk factors between probands and controls were independent of parental CVD. CONCLUSIONS: Major depression in childhood is associated with an unfavorable CVD risk profile in adolescence, and risks for pediatric depression and CVD may coincide in families. Effective prevention and treatment of childhood depression may be a means to reduce the incidence of adult CVD.

Practitioner review: Dysphoria and its regulation in child and adolescent depression.

BACKGROUND: By emphasizing the importance of emotions, the 'affect revolution' in how human behavior is conceptualized has inspired a new generation of studies on dysphoric experience and its regulation in clinical depression, and novel efforts to characterize the precursors of affective disorders in juveniles at familial risk for depression. METHOD: We review clinical, behavioral, and functional neuroimaging studies of dysphoric experience and its regulation in depressed children and adolescents, and in juvenile offspring of parents with histories of clinical depression. We discuss the implication of the literature in the context of maternal depression. RESULTS: Findings confirm the high rate of clinically significant dysphoria in depressed children and adolescents and reveal notable affective lability in daily life as a function of context and activity. Findings also show that depressed youngsters have problems in attenuating dysphoria. Similarly, never-depressed offspring at familial risk for depression display problems in mood repair and impaired mood repair mechanisms. Brain neuroimaging findings indicate that, overall, depressed, and high-risk youngsters differ from never depressed controls in neural functioning (activation, connectivity) both at rest and in response to emotion triggers. CONCLUSION: The evaluation of depressed youngsters should include questions about reactivity of dysphoric mood to the changing contexts of daily life and about how they manage (respond to) their own sadness and distress. The resultant information may help the clinician to restructure a young patient's day for the better and identify helpful mood repair responses. Evidence of impaired mood repair mechanisms in youngsters at high-risk for depression suggests the need for early intervention. But interventions must consider that many depressed and high-risk children have depressed mothers, who may be constrained in their ability to help offspring's emotion regulation efforts. To optimize treatment response of offspring, mothers of depressed children should therefore be routinely screened for depression and treated, as warranted.

Atypical patterns of respiratory sinus arrhythmia index an endophenotype for depression.

Can atypical patterns of parasympathetic nervous system activity serve as endophenotypes for depression? Using respiratory sinus arrhythmia (RSA) as an index of parasympathetic nervous system function, we examined this question in two studies: one involving mothers with and without depression histories and their offspring (at high and low risk for depression, respectively), and a further study of adolescent sibling pairs concordant and discordant for major depression. In both studies, subjects were exposed to sad mood induction; subjects' RSA was monitored during rest periods and in response to the mood induction. We used Gottesman and Gould's (2003) criteria for an endophenotype and a priori defined "atypical" and "normative" RSA patterns (combinations of resting RSA and RSA reactivity). We found that atypical RSA patterns (a) predicted current depressive episodes and remission status among women with histories of juvenile onset depression and healthy controls, (b) predicted longitudinal trajectories of depressive symptoms among high- and low-risk young offspring, (c) were concordant across mothers and their juvenile offspring, (d) were more prevalent among never-depressed youth at high risk for depression than their low-risk peers, and (e) were more concordant across adolescent sibling pairs in which both versus only one had a history of major depression. Thus, the results support atypical RSA patterns as an endophenotype for depression. Possible mechanisms by which RSA patterns increase depression risk and their genetic contributors are discussed.

Long-term stability of respiratory sinus arrhythmia among adults with and without a history of depression.

Respiratory sinus arrhythmia (RSA) is an index of parasympathetic nervous system activity reflecting respiratory influences on heart rate. This influence is typically measured as high frequency heart rate variability (HF-HRV) or root mean square of successive differences (RMSSD) of adjacent inter-beat intervals. Examining the long-term stability of its measurement is important as levels of resting RSA have been conceptualized as a marker of individual differences; in particular, of an individual's autonomic regulation and affect-related processes, including emotion regulation. At present, it is not known if resting RSA levels reflect stable differences over a long-term period (i.e., >1 year). Even less is known about how RSA stability differs as a function of depression history and whether it relates to depression risk trajectories. In the present study, we examined the 1.5-year test-retest reliability of resting RSA using the intraclass correlation coefficient (ICC) in 82 adults: n = 41 with a history of depression (ever-depressed); n = 41 controls with no depression history (never-depressed). HF-HRV was fairly stable in both groups (ever-depressed ICC = 0.55, never-depressed ICC = 0.54). RMSSD was also fairly stable in ever-depressed adults (ICC = 0.57) and never-depressed controls (ICC = 0.40). ICC values for both indices did not differ between groups per overlapping 95% confidence intervals. Therefore, RSA stability as assessed by both frequency (HF-HRV) and time domain (RMSSD) measures was not attenuated by a depression history. Implications and the need for future research are discussed.