title: The three-hit concept of vulnerability and resilience: toward understanding adaptation to early-life adversity outcome.
abstract: Stressful experiences during early-life can modulate the genetic programming of specific brain circuits underlying emotional and cognitive aspects of behavioral adaptation to stressful experiences later in life. Although this programming effect exerted by experience-related factors is an important determinant of mental health, its outcome depends on cognitive inputs and hence the valence an individual assigns to a given environmental context. From this perspective we will highlight, with studies in rodents, non-human primates and humans, the three-hit concept of vulnerability and resilience to stress-related mental disorders, which is based on gene-environment interactions during critical phases of perinatal and juvenile brain development. The three-hit (i.e., hit-1: genetic predisposition, hit-2: early-life environment, and hit-3: later-life environment) concept accommodates the cumulative stress hypothesis stating that in a given context vulnerability is enhanced when failure to cope with adversity accumulates. Alternatively, the concept also points to the individual's predictive adaptive capacity, which underlies the stress inoculation and match/mismatch hypotheses. The latter hypotheses propose that the experience of relatively mild early-life adversity prepares for the future and promotes resilience to similar challenges in later-life; when a mismatch occurs between early and later-life experience, coping is compromised and vulnerability is enhanced. The three-hit concept is fundamental for understanding how individuals can either be prepared for coping with life to come and remain resilient or are unable to do so and succumb to a stress-related mental disorder, under seemingly identical circumstances.
authors.affiliation: Traumatic Stress Studies Division and Laboratory of Molecular Neuropsychiatry, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, USA; Mental Health Care Center, PTSD Clinical Research Program and Laboratory of Clinical Neuroendocrinology and Neurochemistry, James J. Peters Veterans Affairs Medical Center, Bronx, USA; Division of Medical Pharmacology, Leiden Academic Center for Drug Research and Leiden University Medical Center, Leiden University, Leiden, The Netherlands. Electronic address: Nikolaos.daskalakis@mssm.edu.
authors.forename: Nikolaos P
authors.initials: NP
authors.lastname: Daskalakis
authors.forename: Rosemary C
authors.initials: RC
authors.lastname: Bagot
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Parker
authors.forename: Christiaan H
authors.initials: CH
authors.lastname: Vinkers
authors.forename: E R
authors.initials: ER
authors.lastname: de Kloet
mesh_terms: D000223:Adaptation, Psychological; D000818:Animals; D001362:Avoidance Learning; D004195:Disease Models, Animal; D044127:Epigenesis, Genetic; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D005938:Glucocorticoids / Q000502:physiology; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D008425:Maternal Behavior; D008426:Maternal Deprivation; D008959:Models, Neurological; D008960:Models, Psychological; D009473:Neuronal Plasticity; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011323:Primates; D051381:Rats; D055500:Resilience, Psychological; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology / Q000523:psychology; D013315:Stress, Psychological / Q000503:physiopathology / Q000523:psychology*; D035862:Vulnerable Populations
chemical_list: D005938:Glucocorticoids
keywords: Developmental programming; Early life environment; Epigenetics; Genetic predisposition; HPA axis; Later life environment; Resilience; Stress adaptation; Three hit; Vulnerability