Mechanisms of neuroplasticity linking early adversity to depression: developmental considerations

Early exposure to psychosocial adversity is among the most potent predictors of depression. Because depression commonly emerges prior to adulthood, we must consider the fundamental principles of developmental neuroscience when examining how experiences of childhood adversity, including abuse and neglect, can lead to depression. Considering that both the environment and the brain are highly dynamic across the period spanning gestation through adolescence, the purpose of this review is to discuss and integrate stress-based models of depression that center developmental processes. We offer a general framework for understanding how psychosocial adversity in early life disrupts or calibrates the biobehavioral systems implicated in depression. Specifically, we propose that the sources and nature of the environmental input shaping the brain, and the mechanisms of neuroplasticity involved, change across development. We contend that the effects of adversity largely depend on the developmental stage of the organism. First, we summarize leading neurobiological models that focus on the effects of adversity on risk for mental disorders, including depression. In particular, we highlight models of allostatic load, acceleration maturation, dimensions of adversity, and sensitive or critical periods. Second, we expound on and review evidence for the formulation that distinct mechanisms of neuroplasticity are implicated depending on the timing of adverse experiences, and that inherent within certain windows of development are constraints on the sources and nature of these experiences. Finally, we consider other important facets of adverse experiences (e.g., environmental unpredictability, perceptions of one’s experiences) before discussing promising research directions for the future of the field.

Genetic and Environmental Influences on Early Development

This chapter considers the genetic and environmental influences that may lead to the appearance of neurodevelopmental changes in early life. Behavioural genetics considers similarities between individuals in the light of their degree of biological relatedness, and has established high levels of heritability for several problems. Molecular genetics has therefore progressed to identifying individual genes. Single environmental risk factors can be identified and aggregated into a concept of adversity. Defined chromosome and single-gene changes are described for conditions such as Down and fragile-X. They emphasize the power and the complexity of genetic influences. Most complex psychiatric disorders are the result of large numbers of genes of small effect considered individually, but large effect in interactions with each other and with the environment. Environmental influences are considered in this chapter both from the perspectives of gene–environment correlation and interaction, and as known associations that can be causes. Infections, toxins, and deficiencies are described. Challenges from psychosocial adversity are included, together with their possible modes of action.

Psychosocial stratification of antenatal indicators to guide population-based programs in perinatal depression

Background There is increasing awareness that perinatal psychosocial adversity experienced by mothers, children, and their families, may influence health and well-being across the life course. To maximise the impact of population-based interventions for optimising perinatal wellbeing, health services can utilise empirical methods to identify subgroups at highest risk of poor outcomes relative to the overall population. Methods This study sought to identify sub-groups using latent class analysis within a population of mothers in Sydney, Australia, based on their differing experience of self-reported indicators of psychosocial adversity. This study sought to identify sub-groups using latent class analysis within a population of mothers in Sydney, Australia, based on their differing experience of self-reported indicators of psychosocial adversity. Subgroup differences in antenatal and postnatal depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale. Results Latent class analysis identified four distinct subgroups within the cohort, who were distinguished empirically on the basis of their native language, current smoking status, previous involvement with Family-and-Community Services (FaCS), history of child abuse, presence of a supportive partner, and a history of intimate partner psychological violence. One group consisted of socially supported ‘local’ women who speak English as their primary language (Group L), another of socially supported ‘migrant’ women who speak a language other than English as their primary language (Group M), another of socially stressed ‘local’ women who speak English as their primary language (Group Ls), and socially stressed ‘migrant’ women who speak a language other than English as their primary language (Group Ms.). Compared to local and not socially stressed residents (L group), the odds of antenatal depression were nearly three times higher for the socially stressed groups (Ls OR: 2.87 95%CI 2.10–3.94) and nearly nine times more in the Ms. group (Ms OR: 8.78, 95%CI 5.13–15.03). Antenatal symptoms of depression were also higher in the not socially stressed migrant group (M OR: 1.70 95%CI 1.47–1.97) compared to non-migrants. In the postnatal period, Group M was 1.5 times more likely, while the Ms. group was over five times more likely to experience suboptimal mental health compared to Group L (OR 1.50, 95%CI 1.22–1.84; and OR 5.28, 95%CI 2.63–10.63, for M and Ms. respectively). Conclusions The application of empirical subgrouping analysis permits an informed approach to targeted interventions and resource allocation for optimising perinatal maternal wellbeing.

25 Years of the International Bipolar Collaborative Network (BCN)

Background The Stanley Foundation Bipolar Treatment Outcome Network (SFBN) recruited more than 900 outpatients from 1995 to 2002 from 4 sites in the United States (US) and 3 in the Netherlands and Germany (abbreviated as Europe). When funding was discontinued, the international group of investigators continued to work together as the Bipolar Collaborative Network (BCN), publishing so far 87 peer-reviewed manuscripts. On the 25th year anniversary of its founding, publication of a brief summary of some of the major findings appeared appropriate. Important insights into the course and treatment of adult outpatients with bipolar disorder were revealed and some methodological issues and lessons learned will be discussed. Results The illness is recurrent and pernicious and difficult to bring to a long-term remission. Virtually all aspects of the illness were more prevalent in the US compared to Europe. This included vastly more patients with early onset illness and those with more psychosocial adversity in childhood; more genetic vulnerability; more anxiety and substance abuse comorbidity; more episodes and rapid cycling; and more treatment non-responsiveness. Conclusions The findings provide a road map for a new round of much needed clinical treatment research studies. They also emphasize the need for the formation of a new network focusing on child and youth onset of mood disorders with a goal to achieve early precision diagnostics for intervention and prevention in attempting to make the course of bipolar illness more benign.

Psychosocial Adversity in Early Childhood and Language and Literacy Skills in Adolescence: The Role of Speech-Language Pathology in Prevention, Policy, and Practice

Purpose This clinical focus article outlines key forms of childhood maltreatment (various types of abuse and neglect) and their co-occurrence with other developmental risk factors, such as parental poverty, living in crime-prone communities, and disrupted educational experiences, to focus on their implications for language and literacy skills in adolescence. Children exposed to psychosocial adversity early in life experience a range of poor outcomes in adolescence, relative to their typically developing peers, and language and literacy skills are particularly vulnerable skill sets in the face of this adversity. Conclusions The continuum from disrupted schooling to child protection and youth justice involvement is emphasized, and the expanding scope of practice for speech-language pathology at all stages of prevention, assessment, and intervention is outlined. Greater advocacy by speech-language pathologists is needed so that policy makers and practitioners in other service sectors have a better appreciation of the importance of language and literacy skills in early life.