THE GENETIC INTERPRETATION OF INBREEDING DEPRESSION AND OUTBREEDING DEPRESSION

Inbreeding with close relatives and outbreeding with members of distant populations can both result in deleterious shifts in the means of fitness-related characters, most likely for very different reasons. Such processes often occur simultaneously and have important implications for the evolution of mating systems, dispersal strategies, and speciation. They are also relevant to the design of breeding strategies for captive populations of endangered species. A general expression is presented for the expected phenotype of an individual under the joint influence of inbreeding and crossbreeding. This expression is a simple function of the inbreeding coefficient, of source and hybridity indices of crossbreeding, and of specific forms of gene action. Application of the model may be of use in identifying the mechanistic bases for a number of evolutionary phenomena such as the shift from outbreeding enhancement to outbreeding depression that occurs with population divergence.     

Nutritional Interventions in Depression and Perinatal Depression

Depression is the leading cause of mental disability worldwide. Women who aredepressed during pregnancy are at a higher risk for preterm delivery,preeclampsia, birth difficulties, and postpartum depression. The treatment ofdepression in conventional medicine has focused on physiological factors thatlead to impaired neurotransmitter function and treatments to improveneurotransmitter function. Pharmaceutical substances pose risks for pregnant andlactating women, and lower risk options are preferred. Micronutrients, includingcertain B vitamins, folate, and docosahexaenoic acid (DHA), play a role in thesynthesis and absorption of neurotransmitters. Experimental studies suggest thatsupplementation with specific micronutrients may alleviate depressive symptomsand improve birth outcomes in patients with perinatal depression. Alternativetreatments for depression, including nutritional supplements, are an importanttreatment option for depressive symptoms while limiting potential side effectsand treatment costs. This article explores the biological basis of perinataldepression and reviews the potential benefits of non-pharmacologicalinterventions.     

Efficacy of light therapy for perinatal depression: a review

ABSTRACT: Perinatal depression is an important public health problem affecting 10-20% of childbearing women. Perinatal depression is associated with significant morbidity, and has enormous consequences for the well-being of the mother and child. Treatment of depression during the perinatal period poses a complex problem for both mother and clinician, as antidepressant treatment strategies must consider the welfare of both mother and child during pregnancy and lactation. Bright light therapy may be an attractive treatment for perinatal depression because it is low cost, home-based, and has a much lower side effect profile than pharmacotherapy. The antidepressant effects of bright light are well established, and there are several rationales for expecting that bright light might also be efficacious for perinatal depression. This review describes these rationales, summarizes the available evidence on the efficacy of bright light therapy for perinatal depression, and discusses future directions for investigation of bright light therapy as a treatment for perinatal depression.     

Research advances in geriatric depression

Technical advances have facilitated the exploration of factors related to geriatric depression and have helped generate novel biological and psychosocial treatment approaches. This review summarizes the main advancements in epidemiology, clinical presentation and course, genetics, and other areas of biological research. Treatment interventions outlined in this paper include electroconvulsive therapy, repetitive transcranial magnetic stimulation, magnetic seizure therapy, vagus nerve stimulation, deep brain stimulatn, depression prophylaxis, multidisciplinary approaches to depression treatment, and psychotherapy. Forms of psychotherapy for geriatric depression summarized include interpersonal psychotherapy, supportive psychotherapy, cognitive-behavioral therapy, problem-solving therapy, and ecosystem-focused therapy. Neuroimaging techniques based on magnetic resonance imaging are discussed briefly, including volumetric brain studies, diffusion tensor imaging, fractional anisotropy, fiber tractography, magnetization transfer imaging, and blood-oxygenation-level-dependent functional magnetic resonance imaging. Finally, treatment effectiveness is addressed in a discussion of new models to improve access to and quality of care offered in the community.     

Parental relatedness and major histocompatibility effects on early embryo survivorship in Atlantic salmon

Salmon have provided key insights into the relative influence of natural and sexual selection on major histocompatibility complex (MHC) variation. Natural selection on salmon MHC genes has been demonstrated in pathogen studies, and there is evidence of MHC-based mate choice (sexual selection). We tested whether parental MHC genes affect survivorship of juvenile Atlantic salmon (Salmo salar) by quantifying the influence of parental genome-wide relatedness and MHC genotype on survivorship to the swim-up stage. Thirteen microsatellite loci were used to estimate the influence of genome-wide relatedness between parents on offspring survivorship and MHC genotypes were determined by sequencing part of the class IIβ gene. Our results revealed no significant relationship between early offspring survivorship and genome-wide relatedness, predicted MHC heterozygosity, or MHC allelic similarity. Overall, our data are consistent with the contention that excess MHC heterozygosity in Atlantic salmon juveniles is due to sexual selection as well as differential survival of offspring due to MHC genotype.     

Between a rock and a hard place: evaluating the relative risks of inbreeding and outbreeding for conservation and management

As populations become increasingly fragmented, managers are often faced with the dilemma that intentional hybridization might save a population from inbreeding depression but it might also induce outbreeding depression. While empirical evidence for inbreeding depression is vastly greater than that for outbreeding depression, the available data suggest that risks of outbreeding, particularly in the second generation, are on par with the risks of inbreeding. Predicting the relative risks in any particular situation is complicated by variation among taxa, characters being measured, level of divergence between hybridizing populations, mating history, environmental conditions and the potential for inbreeding and outbreeding effects to be occurring simultaneously. Further work on consequences of interpopulation hybridization is sorely needed with particular emphasis on the taxonomic scope, the duration of fitness problems and the joint effects of inbreeding and outbreeding. Meanwhile, managers can minimize the risks of both inbreeding and outbreeding by using intentional hybridization only for populations clearly suffering from inbreeding depression, maximizing the genetic and adaptive similarity between populations, and testing the effects of hybridization for at least two generations whenever possible.     

When does depression become a disorder? Using recurrence rates to evaluate the validity of proposed changes in major depression diagnostic thresholds

High community prevalence estimates of DSM‐defined major depressive disorder (MDD) have led to proposals to raise MDD's diagnostic threshold to more validly distinguish pathology from normal‐range distress. However, such proposals lack empirical validation. We used MDD recurrence rates in the longitudinal 2‐wave Epidemiologic Catchment Area Study to test the predictive validity of three proposals to narrow MDD diagnosis: a) excluding “uncomplicated” episodes (i.e., episodes that last no longer than 2 months and do not include suicidal ideation, psychotic ideation, psychomotor retardation, or feelings of worthlessness); b) excluding mild episodes (i.e., episodes with only five to six symptoms); and c) excluding nonmelancholic episodes. For each proposal, we used lifetime MDD diagnoses at wave 1 to distinguish the group proposed for exclusion, other MDD, and those with no MDD history. We then compared these groups’ 1‐year MDD rates at wave 2. A proposal was considered strongly supported if at wave 2 the excluded group's MDD rate was not only significantly lower than the rate for other MDD but also not significantly greater than the no‐MDD‐history group. Results indicated that all three excluded groups had significantly lower recurrence rates than other MDD (uncomplicated vs. complicated, 3.4% vs. 14.6%; mild vs. severe, 9.6% vs. 20.7%; nonmelancholic vs. melancholic, 10.6% vs. 19.2%, respectively). However, only uncomplicated MDD's recurrence rate was also not significantly greater than the MDD occurrence rate for the no‐MDD‐history group (3.4% vs. 1.7%, respectively). This low recurrence rate resulted from an interaction between uncomplicated duration and symptom criteria. Multiple‐episode uncomplicated MDD did not entail significantly elevated recurrence over single‐episode cases (3.7% vs. 3.0%, respectively). Uncomplicated MDD's general‐distress symptoms, transient duration, and lack of elevated recurrence suggest it may generally represent nonpathologic intense sadness that should be addressed in treatment guidelines and considered for exclusion from MDD diagnosis to increase the validity of the MDD/normal sadness boundary.     

Depression case management by practice nurses in primary care: an audit

Introduction Depression is a common and debilitating condition. A body of evidence exists about improving depression outcomes in primary care, using collaborative care models. Such approaches, however, have not been routinely adopted within general practice settings. In this paper we outline the results of an audit of an enhanced care initiative that trained practice nurses to deliver such approaches.Method An audit of symptom outcome and satisfaction was conducted in depression case-management clinics run by practice nurses. Results were then benchmarked against appropriate randomised trial data. The cost of practice nurse time devoted to the delivery of the service was estimated by multiplying time by unit cost.Results A mean change of 9.07 (standard deviation (SD) 6.67, 95% confidence interval (CI) 7.93-10.22, P < 0.001) points on the Patient Health Questionnaire (PHQ9) score was observed in those who were using/had used the service. Clinical change demonstrated a shift from moderate-to-severe to mild depression. The results reflect the changes seen in randomised controlled trial data from similar interventions in similar samples, and are superior to expected treatment as usual outcomes. Overall, respondents were 'very satisfied' with the service on offer. The mean cost of practice nurse time was estimated at ￡45 per patient.Discussion While acknowledging the limitations of audit data, practice nurses in general practice appear to be able to offer effective and acceptable case management to patients experiencing depression.     

布拉酵母联合舍曲林治疗产后抑郁症的疗效观察

目的探讨布拉酵母菌联合舍曲林对产后抑郁症(PPD)的临床疗效及安全性。方法选择2016年1月至2018年12月我院104例PPD患者为研究对象。入选患者随机分为观察组和对照组各52例,两组患者均给予舍曲林50 mg/次,1次/d,口服。观察组患者同时联用布拉酵母0.5 g/次,2次/d,口服,8周为一疗程。治疗前后检测患者孕酮及雌二醇水平,并于治疗前及治疗第4周、第8周时采用汉密顿抑郁量表(HAMD)评价患者治疗结果、临床疗效及安全性。结果治疗后,两组患者HAMD评分与治疗前比较均降低(t=8.162,P0.001;t=17.916,P0.001;t=16.995,P0.001;t=28.683,P0.001),且观察组患者降低幅度大于对照组(t=7.741,P0.001;t=13.073,P0.001)。观察组患者临床总有效率(90.38%)明显高于对照组(69.23%)。治疗后观察组患者孕酮水平低于对照组,雌二醇水平高于对照组,差异均有统计学意义(t=10.774,P0.001;t=7.239,P0.001)。两组母婴无明显不良反应。结论布拉酵母联合舍曲林对产后抑郁症的临床疗效明显,安全性高,值得临床推广。     

Depressing synapse as a detector of frequency change

In this article we discuss the short-term synaptic depression using a mathematical model. We derive the model of synaptic depression caused by the depletion of synaptic vesicles for the case of infinitely short stimulation time and show that the analytical formulas for the postsynaptic potential (PSP) and kinetic functions take simple closed form. A solution in this form allows an analysis of the characteristics of depression as a function of the models parameters and the derivation of analytic formulas for measures of short time synaptic depression commonly used in experimental studies. Those formulas are used to validate the model by fitting it to two types of synapses described in the literature. Given the fitted parameters we discuss the behavior of the synapse in situations involving frequency change. We also indicate a possible role of depressing synapses in information processing as not only a filter of high frequency input but as a detector of the return from high frequency stimulation to the stimulation within frequency band specific for a given synapse.     

Admixture between native and invasive populations may increase invasiveness of Mimulus guttatus

Self-fertilization and admixture of genotypes from different populations can have major fitness consequences in native species. However, few studies have addressed their potential roles in invasive species. Here, we used plants of Mimulus guttatus from seven native North American, three invasive Scottish and four invasive New Zealand populations to address this. We created seeds from self-fertilization, within-population outcrossing, between-population outcrossing within the same range, and outcrossing between the native and invasive ranges. A greenhouse experiment showed that native and invasive plants of M. guttatus suffered to similar degrees from inbreeding depression, in terms of asexual reproduction and biomass production. After outcrossing with plants from other populations, M. guttatus benefited from heterosis, in terms of asexual and sexual reproduction, and biomass production, particularly when plants from native and invasive populations were crossed. This suggests that, when novel genotypes of M. guttatus from the native North American range will be introduced to the invasive ranges, subsequent outcrossing with M. guttatus plants that are already there might further boost invasiveness of this species.     

Pollen source affects female reproductive success and early offspring traits in the rare endemic plant Polemonium vanbruntiae (Polemoniaceae)

Understanding the relative magnitudes of inbreeding and outbreeding depression in rare plant populations is increasingly important for effective management strategies. There may be positive and negative effects of crossing individuals in fragmented populations. Conservation strategies may include introducing new genetic material into rare plant populations, which may be beneficial or detrimental based on whether hybrid offspring are of increased or decreased quality. Thus, it is important to determine the effects of pollen source on offspring fitness in rare plants. We established pollen crosses (i.e. geitonogamous‐self, autonomous‐self, intrasite‐outcross, intersite‐outcross and open‐pollinated controls) to determine the effects of pollen source on fitness (seeds/fruit and seed mass) and early offspring traits (probability of germination, number of leaves, leaf area and seedling height) in the rare plant Polemonium vanbruntiae. Open‐pollinated, intrasite‐outcross and geitonogamous‐self treatments did not differ in fitness. However, plants receiving autonomous‐self pollen had the lowest fitness and the lowest probability of seed germination. Intersite‐outcross plants contained fewer seeds/fruit, but seeds germinated at higher frequencies and seedlings were more vigorous. We also detected heterosis at the seed germination stage. These data may imply that natural populations of P. vanbruntiae exhibit low genetic variation and little gene flow. Evidence suggests that deleterious alleles were not responsible for reduced germination; rather environmental factors, dichogamy, herkogamy and/or lack of competition among pollen grains may have caused low germinability in selfed offspring. Although self‐pollination may provide some reproductive assurance in P. vanbruntiae, the result is a reduction in germination and size‐related early traits for selfed offspring.     

Does perceived financial strain predict depression among young women? Longitudinal findings from the Southampton Women's Survey

Background Social and financial environment has an influence on the incidence of depression. We studied perceived financial strain as a risk factor for development of depression among a large cohort of young women in Southampton, UK.Methods We recruited a large number of young women in Southampton in the Southampton Women's Survey, a longitudinal study looking at factors influencing the health of women and their offspring. Women were asked to complete a baseline questionnaire, which included the GHQ-12 (an assessment of mental health), as well as questions on perceived financial strain and past history of depression. They were followed up two years later through their general practitioner (GP) records for evidence of incident mental illness.Results A total of 7020 women completed the baseline questionnaire including the GHQ-12. Of these, 5237 (74.6%) had records available for follow-up. Among those developing depression, there was a higher proportion receiving benefits, and a higher level of perceived financial strain. There were also modest elevations in perceived stress, and poorer levels of educational attainment. Among women not depressed at baseline, and with no previous history of depression, those in receipt of state benefits at baseline had a significantly elevated risk of developing the disorder - hazard ratio 1.61 (95% confidence interval (CI) 1.13-2.3). The risk associated with perceived financial strain was 2.16 (95% CI 1.14-4.11), but this did not remain statistically significant after adjustment was made for receipt of benefits, educational qualification, and perceived stress.Conclusion Financial hardship as evidenced by receipt of benefits is a strong independent predictor for the development of depression. Although perception of financial strain is also a predictor for incident depression, the risk associated with this subjective characteristic does not remain significantly elevated after adjustment. Future studies of the aetiology of depression should incorporate ascertainment of actual financial status.