Gender differences in depression

Depression is twice as common in women as in men, although some concern has been raised in terms of misdiagnosing depression in men. The incidence of depression in women varies during the life span. The peak incidence during childbearing years appears to be associated with cyclic hormonal changes. Women also present with reproductive -specific mood disorders: pre-menstrual dysphoric disorder (PMDD), depression in pregnancy, postpartal mood disorder (PDD) and perimenopausal depressive disorder. Gender differences were repeatedly observed in response to antidepressant medication. Premenopausal women appear to respond poorly and to show low tolerability to TCAs, but they tend to show greater responsiveness to the SSRIs. In contrast, men and postmenopausal women can respond equally to the TCAs and SSRIs. These differences are contributed to gender differences in pharmacokinetics of antidepressants and to the influence of menstrual cycle. These findings suggest the need for a gender-specific approach to the evaluation and management of depression.     

Escitalopram in adolescent major depression

Escitalopram is the purified functional isomer contained in citalopram. Escitalopram is now prescribed in 26 countries. In the United States, the only US Food and Drug Administration (FDA)-approved selective serotonin reuptake inhibiter (SSRI) for adolescents is fluoxetine. However, in clinical practice all antidepressants are used in adolescents. Five patients had parents who opted for the use of escitalopram instead of other treatments. Reasons included poor response and side effects from other SSRIs. Specifically, escitalopram was considered possibly less likely to cause obesity than paroxetine. It also caused a lower frequency of akathisia than fluoxetine, more stable blood levels over years than sertraline, very low drug interactions, and a low onset of anxiety if using a 5-mg starting dose. Although studies in adolescents are very limited for escitalopram, its parent medication--citalopram--has been used in over 40 million patients. Parents and adolescent patients should be made aware of all antidepressant options, if psychopharmacology is indicated. In some patients, escitalopram may have use.     

Frequency-dependent inbreeding depression in Amsinckia

If the competitive ability of plants produced by self-pollination differs from that of plants derived by outcrossing, then the magnitude of inbreeding depression may be influenced by the composition of the competitive environment (i.e., the frequency of plants that have arisen from selfing and outcrossing in the neighborhood of "target" plants in which inbreeding depression is expressed). Here, we report the results of experiments designed to examine whether inbreeding depression is influenced by the frequency of inbred plants in the competitive neighborhood. Two species of the annual plant genus Amsinckia were studied, one a near-complete selfer (Amsinckia gloriosa) and the other a partial outcrosser (Amsinckia douglasiana). Competition experiments were conducted in artificial stands composed of different mixtures of inbred and outbred progeny. The fitnesses of progeny were found to be significantly influenced by the composition of the competing neighborhood. The fitness of target plants, however, did not vary monotonically with the frequency of inbred plants in the neighborhood. Rather, for A. gloriosa, maximum performance was observed when there was an intermediate frequency of inbred neighbors. For A. douglasiana, the opposite pattern was found. The results suggest that competition among progeny has the potential to play a role in the selection of self-fertilization and possibly in the maintenance of mixed mating systems.     

Inbreeding depression in monarch butterflies

Monarch butterflies and their unique system of multigenerational migration have long fascinated the public, and concerns for the fate of this charismatic insect have grown due to the consistent declines in overwintering colony size over the last 20 years. Risks to this migratory insect have been considered in terms of climate change, habitat and thus population fragmentation, and decreased host plant availability. However, another obvious danger, that of decreased heterozygosity resulting from decreasing population size, has yet to be explored. Here we report experimental evidence for immediate inbreeding depression in individuals from the migratory population. Inbred matings produced less viable eggs and inbred offspring had higher developmental mortality and shorter lifespans. We discuss these results in the context of monarch migration extinction risk and suggest that additional genetic monitoring should be undertaken to protect this iconic animal.     

多巴胺的负调控中枢——缰核在抑郁症中的作用

腹侧被盖区(VTA)在大脑奖赏环路中起到核心调控作用。抑郁症中VTA的多巴胺能神经元电活动发生异常改变。近年来的研究发现,来自缰核的输入能够负调控VTA多巴胺神经元的电活动。在抑郁动物模型中,由于βCaMKII表达水平异常增加所引起的被过度活化的外侧缰核神经元,可以通过降低包括多巴胺在内的单胺水平,最终导致多种核心抑郁表型的产生。     

Mycorrhizal-induced growth depression in plants

As plant mutualists, one would not expect arbuscular mycorrhizal fungi (AMF) to cause growth depression of their host plants. The mechanism responsible for negative effects of AMF is still debated and so here we review the possible abiotic and biotic reasons for AMF-induced growth depression in plants: 1) The Phytocentric explanations, include: a) AMF and non-mycotrophic plants, b) different growth stages of plants. 2) The Mycocentric explanations, include: a) Low effective AMF species, b) The existence of vesicles, c) Genetic variability of AMF, and d) Geographic origin of AMF. 3) Unbalanced C-for-nutrient-trade, involving both partners and 4) Indirect effects of other organisms. We note deficiencies in previous studies and suggest improvements in experimental designs such as the use of realistic mixtures of AM fungal species, and growing plants in mixtures in field situations, rather than single pot studies, with and without fungi. Determining whether and how AM fungi cheat on their hosts will enable a better understanding of their roles in natural communities and their use as biofertilizers in agriculture.     

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.     

Reproductive depression

Reproductive depression is the depression in women that is related to the hormonal changes of the menstrual cycle, pregnancy and the menopause and is manifested clinically as premenstrual depression, postnatal depression and climacteric depression. These three components occur in the same vulnerable women in that a woman with depression in the menopausal transition will usually have a history of premenstrual syndrome (PMS; premenstrual dysphoric disorder [PMDD]), would have been in a good mood during pregnancy and then develop postnatal depression. When the periods return the depression becomes cyclical as PMS. These three conditions are effectively treated with transdermal estrogens which should be the first-choice therapy rather than antidepressants. Estrogens can be used together with antidepressants. The critical time to prevent long-term mood problems is the correct treatment of postnatal depression. In women with low energy and libido, often a side effect of antidepressants, the addition of transdermal testosterone is useful. These women with reproductive depression are often progesterone/progestogen intolerant and a smaller dose or duration of progestogen is a necessary compromise. Alternatively a Mirena IUS or rarely a hysterectomy is required.     

Inbreeding depression and outbreeding depression in Digitalis purpurea: optimal outcrossing distance in a tetraploid

An optimal crossing distance exists within plant populations if inbreeding and outbreeding depression operate simultaneously. In a population of tetraploid Digitalis purpurea, maternal plants were pollinated with donors at four distances: 0 (self-pollination), 1, 6 and 30 m. Lifetime fitness of F1 progeny was investigated in greenhouse experiments, and significant inbreeding and outbreeding depression were detected at five vs. three life history traits. Inbreeding depression increased at later life stages, whereas outbreeding depression was relatively constant. The existence of within-population outbreeding depression suggests substantial genetic structuring at moderate distances in D. purpurea, and corroborates recent findings of significant outbreeding depression in F1 progeny in polyploids. The moderate inbreeding depression found in this predominately outcrossing population supports the notion that effects of inbreeding are less severe in polyploids than in diploids.     

Reliable change in depression during behavioral weight loss treatment among women with major depression

Objective: Although behavioral weight loss interventions generally have been shown to improve depressive symptoms, little is known as to whether some people with major depressive disorder experience worsening of depression during a weight loss intervention. Design and Methods: Rates and predictors of change in depression symptoms among 148 obese women with major depressive disorder who participated in a trial comparing depression treatment plus behavioral weight loss treatment (Behavioral Activation; BA) to behavioral weight loss treatment alone (Lifestyle Intervention; LI) were examined. A statistically reliable change in depression was calculated as ≥9 points on the Beck Depression Inventory in this sample. Results: At 6 months, 73% of participants in BA and 54% of participants in LI showed reliable improvement in depression symptoms and 1.5% of participants in BA and 1.3% of participants in LI showed reliable worsening in depression symptoms. Rates of reliable change were similar at 12 months. Participants who experienced reliable improvement in depression lost significantly more weight than those who did not in both conditions. In the LI condition, baseline psychiatric variables and change in physical activity during treatment were also related to reliable improvement in depression. Conclusion: No evidence for an iatrogenic effect of behavioral weight loss treatment on depressive symptoms among obese women with major depressive disorder was detected; rather, behavioral weight loss treatment appears to be associated with significant concurrent improvement in depression. Even greater rates of reliable improvement were observed when depression treatment was added to weight loss treatment.