[Stress during prenatal and early postnatal period when everything begins]

Early severe stresses are known to affect the biological and psychological development in childhood. Good and adaptable stress during prenatal and early postnatal period can switch to traumatic during these highly susceptible developmental stages. These different stresses modulate genetic/epigenetic processes and the setting up of connectome during these highly plastic and adaptable time periods. The polyvagal processes control the base of the security/well-being perception of the newborn by the onset of synchronized interactions between the mother/parent/nurse and the baby. These positive adjustments in mirror lead to attachment and social links and to implicit learning processes leading to a balanced emotional and cognitive development.

[Anatomy and physiology of traumatic stress]

Facing a more or less intrusive stress, some individuals can cope as they are more resilient, while others get traumatized and further develop a Post Traumatic Stress Disorder (PTSD). Individuals are not equal facing traumatic stress for genetic/epigenetic or personal reasons. This review analyzes from animal models to human, the neurobiological changes detected when the stress switch from adaptable in everyday life to pathological leading to PTSD. Fear memories lead to the disruption of the anatomy/morphology of emotional-memory networks centered on the amygaloïd complex and hippocampal hub associated with the homeostatic unbalance of the body-brain exchanges of molecules such as hormones, neuromodulators or peptides. Persistent fear memories are hardly handled by the frontal ability for decision making towards action. But these fear memories can be revisited by different therapies recruiting cerebral plasticity and resilience. Current understanding of PTSD allowed to develop a series of efficient treatments associating precise medicine to diverse body-mind therapies.

[Screening for Alzheimer's disease by assessing memory impairment]

The feeling of memory failure is the most frequently expressed discomfort with age. The difficulty is to distinguish between a memory complaint and a memory pathology. Alzheimer's disease is diagnosed at the stage of dementia. Early detection and the prospect of treatments likely to act lead to an interest in its pre-dementia phase, which is known to precede the appearance of the dementia syndrome by several years.

Anti-Lingo-1 antibody ameliorates spatial memory and synapse loss induced by chronic stress

Chronic stress can induce cognitive impairment, and synapse number was significantly decreased in the hippocampus of rats suffering from chronic stress. Lingo-1 is a potent negative regulator of axonal outgrowth and synaptic plasticity. In the current study, the effects of anti-Lingo-1 antibody on the spatial learning and memory abilities and hippocampal synapses of stressed rats were investigated. After 4 weeks of stress exposure, the model group was randomly divided into a chronic stress group and an anti-Lingo-1 group. Then, the anti-Lingo-1 group rats were treated with anti-Lingo-1 antibody (8 mg/kg) for 3 weeks. The effects of anti-Lingo-1 antibody on the spatial learning and memory abilities were investigated with the Morris water maze test. Immunohistological staining and an unbiased stereological method were used to estimate the total number of dendritic spine synapses in the hippocampus. At the behavioral level, after 3 weeks of treatment, the anti-Lingo-1 group rats displayed significantly more platform location crossings in the Morris water maze test than the chronic stress group rats. Anti-Lingo-1 significantly prevented the declines in dendritic spine synapses and postsynaptic density protein-95 (PSD-95) expression in the dentate gyrus and the CA1 and CA3 regions of the hippocampus. The present results indicated that anti-Lingo-1 antibody may be a safe and effective drug for alleviating memory impairment in rats after chronic stress and protecting synapses in the hippocampus of stressed rats.

Acute and Post-Traumatic Stress Disorders: A biased nervous system

Acute stress disorder and post-traumatic stress disorder are generally triggered by an exceptionally intense threat. The consequences of this traumatogenic situation are explored here in chronological order, from exposure to the threat to development of symptoms. Such a situation may disrupt the equilibrium between two fundamental brain circuits, referred to as the "defensive" and "cognitive". The defensive circuit triggers the stress response as well as the formation of implicit memory. The cognitive circuit triggers the voluntary response and the formation of explicit autobiographical memory. During a traumatogenic situation, the defensive circuit could be over-activated while cognitive circuit is under-activated. In the most severe cases, overactivation of the defensive circuit may cause its brutal deactivation, resulting in dissociation. Here, we address the underlying neurobiological mechanisms at every scale: from neurons to behaviors, providing a detailed explanatory model of trauma.

Designing meditation for doctor well-being: can 'Om' help obstetrics and gynaecology doctors?

OBJECTIVE

The study aimed to measure the impact of meditation on participants' ability to regulate brain wave activity in high-stress situations, control physiological stress responses and improve subjective wellbeing.

METHODS

Twelve obstetrics and gynaecology (O&G) doctors meditated for 20 minutes daily for 21 days utilising a portable EEG (electroencephalogram) providing instantaneous audio feedback. Their brain activity levels and salivary cortisol were measured before and after performing three surgical procedures. Participants were interviewed about their experiences and completed self-ratings of distress (e.g. DASS-21, Depression, Anxiety and Depression Scale). Data were analysed statistically and thematically.

RESULTS

(a) Measures of pre- and post-operative brain activity showed no significantly higher levels of alpha waves. (b) Pre- and post-operative salivary cortisol levels did not significantly decrease. (c) DASS-21 scores showed significant decreases in levels of anxiety and stress.

CONCLUSION

Results suggest that, with biofeedback meditation, O&G doctors can learn to reduce situational stress and improve mood overall through a focussed intervention.

[DOHaD: long-term impact of perinatal diseases (IUGR and prematurity)]

The first epidemiological studies showing a link between low birth weight and chronic diseases in adults did not distinguish the origins of low birth weight. A low birth weight may be the result of a premature birth. It can also be caused by an intrauterine growth restriction (IUGR). A child can be both preterm and IUGR. It is clear now that prematurity is an independent risk factor for programming chronic adult diseases. However, unlike adults born IUGR, adults born prematurely do not have an increased risk to develop metabolic syndrome (dyslipidemia or obesity). An increased risk of neurodevelopmental and psychiatric morbidity and hypertension is found after a premature birth. Mechanisms of chronic diseases programming are multiple: they involve both the cause of prematurity and IUGR such as infection / inflammation or placental insufficiency, but also consequences for therapeutic or nutritional strategies needed to support these children. This chapter describes the possible prevention of perinatal programming of noncommunicable diseases.

[DOHaD: epidemiological researches]

Epidemiological researches in the field of DOHaD are in favor of a role of early environment, including chemical (pesticides), physical (air pollution), nutritional or psychosocial environment, on child and adult health. Disentangling the different factors of environment that may affect health, especially over time, and identifying critical periods of exposure remains a major challenge. The biological mechanisms involved remain elusive in human beings. Nevertheless, it seems that whatever the nature of the exposure, epigenetic mechanisms are currently discussed to explain how the environment may alter biological systems over time.

[Epigenetics in transgenerational responses to environmental impacts: from facts and gaps]

The existence of non-genetic and non-cultural mechanisms that transfer information on the memory of parental exposures to various environments, determining the reactivity of the following generations to their environments during their life, are of growing interest. Yet fundamental questions remain about the nature, the roles and relative importance of epigenetic marks and processes, non-coding RNAs, or other mechanisms, and their persistence over generations. A model incorporating the various transmission systems, their cross-talks and windows of susceptibility to the environment as a function of sex/gender of parent and offspring, has yet to be built.

[Early life stressful experiences and neuropsychiatric vulnerability: evidences from human and animal models]

The human newborn is highly dependent on parental care for its survival but also for the healthy development of its brain. A large body of literature demonstrates the impact of early life adversity, even during the prenatal period, on the adult's health. The susceptibility to neuropsychiatric diseases is often potentiated by early stress. If there is an agreement that a critical developmental period exists, the mechanisms underlying the long term effects of early life adversity are still poorly understood. Recent studies in animals highlight the involvement of epigenetic processes in the transmission of such vulnerabilities, notably via modifications in germ cells, which can be transmitted in the next generations.

[Developmental origin of health and adult diseases (DOHaD): evolution of a concept over three decades]

In the 1980s, D. Barker and his team proposed the hypothesis of a fetal origin of adult diseases. The concept subsequently evolved into the developmental origins of health and diseases. Progresses in various domains such as social epidemiology, neuroscience, toxicology have contributed to establish the early years of life as a key period for future health. Finally, epigenetics has provided biological plausibility to long-term programming of health by early exposures. The convergence of all these currents has led to conceptualize human health in a complex and dynamic continuum, the Lifecourse Health Development, beginning in the prenatal period and covering the whole life. Many animal models have been developed to try to unravel the mechanisms involved. Their contributions are described in this paper with the example of type 2 diabetes.

[Toward an explanation for the mnemonic effects of glucocorticoids?]

If the engram of long-term memory is encoded by structural changes of neuronal circuits, they are expected to be present at distant time points after learning, to be specific of circuits activated by learning, and sensitive to behavioral contingencies. In this review we present new concepts that emerged from in vivo imaging studies that tracked the structural bases of the memory trace. A fine balance of spine formation and spine elimination needed for behavioral adaptation to new experience is regulated by glucocorticoids, which are secreted in synchrony with circadian rhythms and in response to stress. Disruption of glucocorticoid oscillations frequently observed in psychiatric disorders like depression and post-traumatic stress produces spine turnover defects and learning disabilities. These new findings provide a new framework for explaining the potent but complex mnemonic effects of glucocorticoids.