1 6266 102 THE NEUROBIOLOGY OF SUICIDE. THE STRESS-DIATHESIS MODEL POSITS THAT SUICIDE IS THE RESULT OF AN INTERACTION BETWEEN STATE-DEPENDENT (ENVIRONMENTAL) STRESSORS AND A TRAIT-LIKE DIATHESIS OR SUSCEPTIBILITY TO SUICIDAL BEHAVIOUR, INDEPENDENT OF PSYCHIATRIC DISORDERS. FINDINGS FROM POST-MORTEM STUDIES OF THE BRAIN AND FROM GENOMIC AND IN-VIVO NEUROIMAGING STUDIES INDICATE A BIOLOGICAL BASIS FOR THIS DIATHESIS, INDICATING THE IMPORTANCE OF NEUROBIOLOGICAL SCREENING AND INTERVENTIONS, IN ADDITION TO COGNITIVE AND MOOD INTERVENTIONS, IN THE PREVENTION OF SUICIDE. EARLY-LIFE ADVERSITY AND EPIGENETIC MECHANISMS MIGHT EXPLAIN SOME OF THE LINK BETWEEN SUICIDE RISK AND BRAIN CIRCUITRY AND NEUROCHEMISTRY ABNORMALITIES. RESULTS FROM A RANGE OF STUDIES USING DIVERSE DESIGNS AND POST-MORTEM AND IN-VIVO TECHNIQUES SHOW IMPAIRMENTS OF THE SEROTONIN NEUROTRANSMITTER SYSTEM AND THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS STRESS-RESPONSE SYSTEM IN THE DIATHESIS FOR SUICIDAL BEHAVIOUR. THESE IMPAIRMENTS MANIFEST AS IMPAIRED COGNITIVE CONTROL OF MOOD, PESSIMISM, REACTIVE AGGRESSIVE TRAITS, IMPAIRED PROBLEM SOLVING, OVER-REACTIVITY TO NEGATIVE SOCIAL SIGNS, EXCESSIVE EMOTIONAL PAIN, AND SUICIDAL IDEATION, LEADING TO SUICIDAL BEHAVIOUR. BIOMARKERS RELATED TO THE DIATHESIS MIGHT HELP TO INFORM RISK-ASSESSMENT PROCEDURES AND TREATMENT CHOICE IN THE PREVENTION OF SUICIDE. 2014 2 4622 20 NEUROBIOLOGICAL DEVELOPMENT IN THE CONTEXT OF CHILDHOOD TRAUMA. NEUROBIOLOGICAL SYSTEMS MAY BE PARTICULARLY SUSCEPTIBLE TO DELETERIOUS IMPACT OF CHILDHOOD TRAUMA, AND THE IMPACT OF CHILDHOOD TRAUMA ON DEVELOPMENT AND SUBSEQUENT FUNCTIONAL OUTCOMES ACROSS THE LIFESPAN HAS BEEN WELL-DOCUMENTED. THE CURRENT REVIEW ADDRESSES THE NEUROBIOLOGICAL IMPACT OF EXPOSURE TO INTERPERSONAL TRAUMA IN CHILDHOOD IN THE CONTEXT OF EXECUTIVE FUNCTION, EMOTION REGULATION, AND DISSOCIATION/INTEROCEPTIVE AWARENESS. SUBSEQUENT RISK FOR PTSD AND DEPRESSION IS ALSO DISCUSSED. THE PATHWAY OF RISK FROM CHILDHOOD TRAUMA TO THESE COGNITIVE, EMOTIONAL, AND PSYCHIATRIC OUTCOMES IS ADDRESSED IN TERMS OF POTENTIAL STRUCTURAL AND FUNCTIONAL ALTERATIONS WITHIN THE HIPPOCAMPUS, PREFRONTAL CORTEX, AND AMYGDALA RESULTING FROM CHRONIC OR REPEATED ACTIVATION OF THE HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS AND ITS INTERACTION WITH AND INFLUENCE ON GENETIC AND EPIGENETIC PROCESSES DURING SENSITIVE PERIODS OF DEVELOPMENT. IMPLICATIONS FOR PRACTICE ARE DISCUSSED. 2017 3 1750 20 EARLY LIFE STRESS AND PEDIATRIC POSTTRAUMATIC STRESS DISORDER. TRAUMATIC STRESS EXPOSURE DURING CRITICAL PERIODS OF DEVELOPMENT MAY HAVE ESSENTIAL AND LONG-LASTING EFFECTS ON THE PHYSICAL AND MENTAL HEALTH OF INDIVIDUALS. TWO THIRDS OF YOUTH ARE EXPOSED TO POTENTIALLY TRAUMATIC EXPERIENCES BY THE AGE OF 17, AND APPROXIMATELY 5% OF ADOLESCENTS MEET LIFETIME CRITERIA FOR POSTTRAUMATIC STRESS DISORDER (PTSD). THE ROLE OF THE STRESS SYSTEM IS THE MAINTENANCE OF HOMEOSTASIS IN THE PRESENCE OF REAL/PERCEIVED AND ACUTE/CHRONIC STRESSORS. EARLY-LIFE STRESS (ELS) HAS AN IMPACT ON NEURONAL BRAIN NETWORKS INVOLVED IN STRESS REACTIONS, AND COULD EXERT A PROGRAMMING EFFECT ON GLUCOCORTICOID SIGNALING. STUDIES ON PEDIATRIC PTSD REVEAL DIVERSE NEUROENDOCRINE RESPONSES TO ADVERSE EVENTS AND RELATED LONG-TERM NEUROENDOCRINE AND EPIGENETIC ALTERATIONS. NEUROENDOCRINE, NEUROIMAGING, AND GENETIC STUDIES IN CHILDREN WITH PTSD AND ELS EXPERIENCES ARE CRUCIAL IN UNDERSTANDING RISK AND RESILIENCE FACTORS, AND ALSO THE NATURAL HISTORY OF PTSD. 2020 4 747 19 CANNABIS-INDUCED HYPODOPAMINERGIC ANHEDONIA AND COGNITIVE DECLINE IN HUMANS: EMBRACING PUTATIVE INDUCTION OF DOPAMINE HOMEOSTASIS. OVER YEARS, THE REGULAR USE OF CANNABIS HAS SUBSTANTIALLY INCREASED AMONG YOUNG ADULTS, AS INDICATED BY THE RISE IN CANNABIS USE DISORDER (CUD), WITH AN ESTIMATED PREVALENCE OF 8. 3% IN THE UNITED STATES. RESEARCH SHOWS THAT EXPOSURE TO CANNABIS IS ASSOCIATED WITH HYPODOPAMINERGIC ANHEDONIA (DEPRESSION), COGNITIVE DECLINE, POOR MEMORY, INATTENTION, IMPAIRED LEARNING PERFORMANCE, REDUCED DOPAMINE BRAIN RESPONSE-ASSOCIATED EMOTIONALITY, AND INCREASED ADDICTION SEVERITY IN YOUNG ADULTS. THE ADDICTION MEDICINE COMMUNITY IS INCREASING CONCERN BECAUSE OF THE HIGH CONTENT OF DELTA-9-TETRAHYDROCANNABINOL (THC) CURRENTLY FOUND IN ORAL AND VAPING CANNABIS PRODUCTS, THE COGNITIVE EFFECTS OF CANNABIS MAY BECOME MORE PRONOUNCED IN YOUNG ADULTS WHO USE THESE CANNABIS PRODUCTS. PRELIMINARY RESEARCH SUGGESTS THAT IT IS POSSIBLE TO INDUCE 'DOPAMINE HOMEOSTASIS,' THAT IS, RESTORE DOPAMINE FUNCTION WITH DOPAMINE UPREGULATION WITH THE PROPOSED COMPOUND AND NORMALIZE BEHAVIOR IN CHRONIC CANNABIS USERS WITH CANNABIS-INDUCED HYPODOPAMINERGIC ANHEDONIA (DEPRESSION) AND COGNITIVE DECLINE. THIS PSYCHOLOGICAL, NEUROBIOLOGICAL, ANATOMICAL, GENETIC, AND EPIGENETIC RESEARCH ALSO COULD PROVIDE EVIDENCE TO USE FOR THE DEVELOPMENT OF AN APPROPRIATE POLICY REGARDING THE DECRIMINALIZATION OF CANNABIS FOR RECREATIONAL USE. 2021 5 4632 28 NEUROIMAGING GENETIC APPROACHES TO POSTTRAUMATIC STRESS DISORDER. NEUROIMAGING GENETIC STUDIES THAT ASSOCIATE GENETIC AND EPIGENETIC VARIATION WITH NEURAL ACTIVITY OR STRUCTURE PROVIDE AN OPPORTUNITY TO LINK GENES TO PSYCHIATRIC DISORDERS, OFTEN BEFORE PSYCHOPATHOLOGY IS DISCERNABLE IN BEHAVIOR. HERE WE REVIEW NEUROIMAGING GENETICS STUDIES WITH PARTICIPANTS WHO HAVE POSTTRAUMATIC STRESS DISORDER (PTSD). RESULTS SHOW THAT GENES RELATED TO THE PHYSIOLOGICAL STRESS RESPONSE (E.G., GLUCOCORTICOID RECEPTOR AND ACTIVITY, NEUROENDOCRINE RELEASE), LEARNING AND MEMORY (E.G., PLASTICITY), MOOD, AND PAIN PERCEPTION ARE TIED TO NEURAL INTERMEDIATE PHENOTYPES ASSOCIATED WITH PTSD. THESE GENES ARE ASSOCIATED WITH AND SOMETIMES PREDICT NEURAL STRUCTURE AND FUNCTION IN AREAS INVOLVED IN ATTENTION, EXECUTIVE FUNCTION, MEMORY, DECISION-MAKING, EMOTION REGULATION, SALIENCE OF POTENTIAL THREATS, AND PAIN PERCEPTION. EVIDENCE SUGGESTS THESE RISK POLYMORPHISMS AND NEURAL INTERMEDIATE PHENOTYPES ARE VULNERABILITIES TOWARD DEVELOPING PTSD IN THE AFTERMATH OF TRAUMA, OR VULNERABILITIES TOWARD PARTICULAR SYMPTOMS ONCE PTSD HAS DEVELOPED. WORK DISTINGUISHING BETWEEN THE RE-EXPERIENCING AND DISSOCIATIVE SUB-TYPES OF PTSD, AND EXAMINING OTHER PTSD SYMPTOM CLUSTERS IN ADDITION TO THE RE-EXPERIENCING AND HYPERAROUSAL SYMPTOMS, WILL FURTHER CLARIFY NEUROBIOLOGICAL MECHANISMS AND INCONSISTENT FINDINGS. FURTHERMORE, AN EXCITING POSSIBILITY IS THAT GENETIC ASSOCIATIONS WITH PTSD MAY EVENTUALLY BE UNDERSTOOD THROUGH DIFFERENTIAL INTERMEDIATE PHENOTYPES OF NEURAL CIRCUIT STRUCTURE AND FUNCTION, POSSIBLY UNDERLYING THE DIFFERENT SYMPTOM CLUSTERS SEEN WITHIN PTSD. 2016 6 5310 20 PSYCHOBIOLOGY AND MOLECULAR GENETICS OF RESILIENCE. EVERY INDIVIDUAL EXPERIENCES STRESSFUL LIFE EVENTS. IN SOME CASES ACUTE OR CHRONIC STRESS LEADS TO DEPRESSION AND OTHER PSYCHIATRIC DISORDERS, BUT MOST PEOPLE ARE RESILIENT TO SUCH EFFECTS. RECENT RESEARCH HAS BEGUN TO IDENTIFY THE ENVIRONMENTAL, GENETIC, EPIGENETIC AND NEURAL MECHANISMS THAT UNDERLIE RESILIENCE, AND HAS SHOWN THAT RESILIENCE IS MEDIATED BY ADAPTIVE CHANGES IN SEVERAL NEURAL CIRCUITS INVOLVING NUMEROUS NEUROTRANSMITTER AND MOLECULAR PATHWAYS. THESE CHANGES SHAPE THE FUNCTIONING OF THE NEURAL CIRCUITS THAT REGULATE REWARD, FEAR, EMOTION REACTIVITY AND SOCIAL BEHAVIOUR, WHICH TOGETHER ARE THOUGHT TO MEDIATE SUCCESSFUL COPING WITH STRESS. 2009 7 6478 21 TOPICAL REVIEW: THE EMERGING FIELD OF EPIGENETICS: INFORMING MODELS OF PEDIATRIC TRAUMA AND PHYSICAL HEALTH. OBJECTIVE: TRAUMA EXPERIENCED DURING CHILDHOOD AND ADOLESCENCE HAS BEEN LINKED TO A NUMBER OF CHRONIC MEDICAL CONCERNS. WE HIGHLIGHT MAJOR FINDINGS FROM THE PEDIATRIC TRAUMA LITERATURE TO PROVIDE A MODEL FOR UNDERSTANDING THIS ASSOCIATION. METHODS: STUDIES EXAMINING THE EFFECTS OF TRAUMA WERE SYSTEMATICALLY REVIEWED AND SYNTHESIZED INTO A MODEL PROPOSING A CENTRAL ROLE FOR EPIGENETICS IN THE WAYS THAT CHILDHOOD EXPERIENCES CAN AFFECT HEALTH. RESULTS: EARLY HYPOTHALAMIC PITUITARY ADRENAL (HPA) AXIS RESPONSE MAY IMPACT INITIAL TRAUMA EXPERIENCE, WITH DOWNSTREAM EFFECTS ON POSTTRAUMA ADJUSTMENT REFLECTED IN POSTTRAUMA NEUROBIOLOGY, PSYCHOLOGICAL HEALTH, AND PHYSICAL HEALTH. CONCLUSIONS: PROSPECTIVE RESEARCH WITH CHILDREN AND ADOLESCENTS EXPOSED TO TRAUMA IS NEEDED TO BETTER CHARACTERIZE THE GENETIC AND EPIGENETIC INFLUENCES ON THE COURSE OF HPA AND IMMUNE PROCESSES AS RELATED TO POSTTRAUMA PSYCHOLOGICAL AND PHYSICAL HEALTH OUTCOMES. 2016 8 5812 29 STRESS AND ANXIETY: STRUCTURAL PLASTICITY AND EPIGENETIC REGULATION AS A CONSEQUENCE OF STRESS. THE BRAIN IS THE CENTRAL ORGAN OF STRESS AND ADAPTATION TO STRESS BECAUSE IT PERCEIVES AND DETERMINES WHAT IS THREATENING, AS WELL AS THE BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO THE STRESSOR. THE ADULT, AS WELL AS DEVELOPING BRAIN, POSSESS A REMARKABLE ABILITY TO SHOW REVERSIBLE STRUCTURAL AND FUNCTIONAL PLASTICITY IN RESPONSE TO STRESSFUL AND OTHER EXPERIENCES, INCLUDING NEURONAL REPLACEMENT, DENDRITIC REMODELING, AND SYNAPSE TURNOVER. THIS IS PARTICULARLY EVIDENT IN THE HIPPOCAMPUS, WHERE ALL THREE TYPES OF STRUCTURAL PLASTICITY HAVE BEEN RECOGNIZED AND INVESTIGATED, USING A COMBINATION OF MORPHOLOGICAL, MOLECULAR, PHARMACOLOGICAL, ELECTROPHYSIOLOGICAL AND BEHAVIORAL APPROACHES. THE AMYGDALA AND THE PREFRONTAL CORTEX, BRAIN REGIONS INVOLVED IN ANXIETY AND FEAR, MOOD, COGNITIVE FUNCTION AND BEHAVIORAL CONTROL, ALSO SHOW STRUCTURAL PLASTICITY. ACUTE AND CHRONIC STRESS CAUSE AN IMBALANCE OF NEURAL CIRCUITRY SUBSERVING COGNITION, DECISION MAKING, ANXIETY AND MOOD THAT CAN INCREASE OR DECREASE EXPRESSION OF THOSE BEHAVIORS AND BEHAVIORAL STATES. IN THE SHORT TERM, SUCH AS FOR INCREASED FEARFUL VIGILANCE AND ANXIETY IN A THREATENING ENVIRONMENT, THESE CHANGES MAY BE ADAPTIVE; BUT, IF THE DANGER PASSES AND THE BEHAVIORAL STATE PERSISTS ALONG WITH THE CHANGES IN NEURAL CIRCUITRY, SUCH MALADAPTATION MAY NEED INTERVENTION WITH A COMBINATION OF PHARMACOLOGICAL AND BEHAVIORAL THERAPIES, AS IS THE CASE FOR CHRONIC OR MOOD ANXIETY DISORDERS. WE SHALL REVIEW CELLULAR AND MOLECULAR MECHANISMS, AS WELL AS RECENT WORK ON INDIVIDUAL DIFFERENCES IN ANXIETY-LIKE BEHAVIOR AND ALSO DEVELOPMENTAL INFLUENCES THAT BIAS HOW THE BRAIN RESPONDS TO STRESSORS. FINALLY, WE SUGGEST THAT SUCH AN APPROACH NEEDS TO BE EXTENDED TO OTHER BRAIN AREAS THAT ARE ALSO INVOLVED IN ANXIETY AND MOOD. THIS ARTICLE IS PART OF A SPECIAL ISSUE ENTITLED 'ANXIETY AND DEPRESSION'. 2012 9 23 30 60 YEARS OF NEUROENDOCRINOLOGY: REDEFINING NEUROENDOCRINOLOGY: STRESS, SEX AND COGNITIVE AND EMOTIONAL REGULATION. THE DISCOVERY OF STEROID HORMONE RECEPTORS IN BRAIN REGIONS THAT MEDIATE EVERY ASPECT OF BRAIN FUNCTION HAS BROADENED THE DEFINITION OF 'NEUROENDOCRINOLOGY' TO INCLUDE THE RECIPROCAL COMMUNICATION BETWEEN THE BRAIN AND THE BODY VIA HORMONAL AND NEURAL PATHWAYS. THE BRAIN IS THE CENTRAL ORGAN OF STRESS AND ADAPTATION TO STRESS BECAUSE IT PERCEIVES AND DETERMINES WHAT IS THREATENING, AS WELL AS THE BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO THE STRESSOR. THE ADULT AND DEVELOPING BRAIN POSSESS REMARKABLE STRUCTURAL AND FUNCTIONAL PLASTICITY IN RESPONSE TO STRESS, INCLUDING NEURONAL REPLACEMENT, DENDRITIC REMODELING, AND SYNAPSE TURNOVER. STRESS CAUSES AN IMBALANCE OF NEURAL CIRCUITRY SUBSERVING COGNITION, DECISION-MAKING, ANXIETY AND MOOD THAT CAN ALTER EXPRESSION OF THOSE BEHAVIORS AND BEHAVIORAL STATES. THIS IMBALANCE, IN TURN, AFFECTS SYSTEMIC PHYSIOLOGY VIA NEUROENDOCRINE, AUTONOMIC, IMMUNE AND METABOLIC MEDIATORS. IN THE SHORT TERM, AS FOR INCREASED FEARFUL VIGILANCE AND ANXIETY IN A THREATENING ENVIRONMENT, THESE CHANGES MAY BE ADAPTIVE. BUT, IF THE DANGER PASSES AND THE BEHAVIORAL STATE PERSISTS ALONG WITH THE CHANGES IN NEURAL CIRCUITRY, SUCH MALADAPTATION MAY NEED INTERVENTION WITH A COMBINATION OF PHARMACOLOGICAL AND BEHAVIORAL THERAPIES, AS IS THE CASE FOR CHRONIC ANXIETY AND DEPRESSION. THERE ARE IMPORTANT SEX DIFFERENCES IN THE BRAIN RESPONSES TO STRESSORS THAT ARE IN URGENT NEED OF FURTHER EXPLORATION. MOREOVER, ADVERSE EARLY-LIFE EXPERIENCE, INTERACTING WITH ALLELES OF CERTAIN GENES, PRODUCE LASTING EFFECTS ON BRAIN AND BODY OVER THE LIFE-COURSE VIA EPIGENETIC MECHANISMS. WHILE PREVENTION IS MOST IMPORTANT, THE PLASTICITY OF THE BRAIN GIVES HOPE FOR THERAPIES THAT TAKE INTO CONSIDERATION BRAIN-BODY INTERACTIONS. 2015 10 1754 29 EARLY LIFE STRESS, THE DEVELOPMENT OF AGGRESSION AND NEUROENDOCRINE AND NEUROBIOLOGICAL CORRELATES: WHAT CAN WE LEARN FROM ANIMAL MODELS? EARLY LIFE STRESS (CHILD AND ADOLESCENT ABUSE, NEGLECT AND TRAUMA) INDUCES ROBUST ALTERATIONS IN EMOTIONAL AND SOCIAL FUNCTIONING RESULTING IN ENHANCED RISK FOR THE DEVELOPMENT OF PSYCHOPATHOLOGIES SUCH AS MOOD AND AGGRESSIVE DISORDERS. HERE, AN OVERVIEW IS GIVEN ON RECENT FINDINGS IN PRIMATE AND RODENT MODELS OF EARLY LIFE STRESS, DEMONSTRATING THAT CHRONIC DEPRIVATION OF EARLY MATERNAL CARE AS WELL AS CHRONIC DEPRIVATION OF EARLY PHYSICAL INTERACTIONS WITH PEERS ARE PROFOUND RISK FACTORS FOR THE DEVELOPMENT OF INAPPROPRIATE AGGRESSIVE BEHAVIORS. ALTERATIONS IN THE HYPOTHALAMIC-PITUITARY-ADRENOCORTICAL (HPA), VASOPRESSIN AND SEROTONIN SYSTEMS AND THEIR RELEVANCE FOR THE REGULATION OF AGGRESSION ARE DISCUSSED. DATA SUGGEST THAT SOCIAL DEPRIVATION-INDUCED INAPPROPRIATE FORMS OF AGGRESSION ARE ASSOCIATED WITH HIGH OR LOW HPA AXIS (RE)ACTIVITY AND A GENERALLY LOWER FUNCTIONING OF THE SEROTONIN SYSTEM IN ADULTHOOD. MOREOVER, GENETIC AND EPIGENETIC MODIFICATIONS IN HPA AND SEROTONIN SYSTEMS INFLUENCE THE OUTCOME OF EARLY LIFE STRESS AND MAY EVEN MODERATE ADVERSE EFFECTS OF EARLY SOCIAL DEPRIVATION ON AGGRESSION. A MORE COMPREHENSIVE STUDY OF AGGRESSION, NEUROENDOCRINE, NEUROBIOLOGICAL AND (EPI)GENETIC CORRELATES OF EARLY LIFE STRESS USING ANIMAL MODELS IS NECESSARY TO PROVIDE A BETTER UNDERSTANDING OF THE INVASIVE AGGRESSIVE DEFICITS OBSERVED IN HUMANS EXPOSED TO CHILD MALTREATMENT. 2009 11 235 21 ADDING FUEL TO THE FIRE: THE IMPACT OF STRESS ON THE AGEING BRAIN. BOTH AGEING AND CHRONIC STRESS ARE ASSOCIATED WITH ALTERED BRAIN PLASTICITY, DYSREGULATION OF THE IMMUNE SYSTEM, AND AN INCREASED RISK OF DEVELOPING BRAIN DISORDERS; ALL OF WHICH HAVE CONSEQUENCES FOR COGNITIVE AND EMOTIONAL PROCESSING. HERE WE EXAMINE THE SIMILARITIES BETWEEN BEHAVIOURAL CHANGES DURING AGEING AND STRESS ALTERED BEHAVIOURS (ANXIETY, DEPRESSIVE-LIKE BEHAVIOUR, COGNITION, AND SOCIABILITY) IN RODENTS AND HUMANS. THE MOLECULAR MECHANISMS HYPOTHESISED TO MEDIATE AGE-RELATED CHANGES IN BRAIN FUNCTION INCLUDING DYSFUNCTION OF THE HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS, DYSREGULATION OF NEUROTRANSMISSION AND NEUROTROPHIC FACTOR SIGNALLING, INCREASED INFLAMMATORY STATE, GENETIC AND EPIGENETIC CHANGES, OXIDATIVE STRESS, METABOLIC CHANGES, AND CHANGES IN THE MICROBIOTA-GUT-BRAIN AXIS ARE DISCUSSED. FINALLY, WE EXPLORE HOW THE ALREADY STRESSED AGED BRAIN PSYCHOLOGICALLY AND PHYSIOLOGICALLY RESPONDS TO EXTERNAL STRESSORS. 2015 12 5465 23 RESILIENCE TO STRESS: LESSONS FROM RODENTS ABOUT NATURE VERSUS NURTURE. INDIVIDUAL DIFFERENCES IN HUMAN TEMPERAMENT INFLUENCE HOW WE RESPOND TO STRESS AND CAN CONFER VULNERABILITY (OR RESILIENCE) TO EMOTIONAL DISORDERS. FOR EXAMPLE, HIGH LEVELS OF BEHAVIORAL INHIBITION IN CHILDREN PREDICT INCREASED RISK OF MOOD AND ANXIETY DISORDERS IN LATER LIFE. THE BIOLOGICAL UNDERPINNINGS OF TEMPERAMENT ARE UNKNOWN, ALTHOUGH IMPROVED UNDERSTANDING CAN OFFER INSIGHT INTO THE PATHOGENESIS OF EMOTIONAL DISORDERS. OUR LABORATORY HAS USED A RAT MODEL OF TEMPERAMENTAL DIFFERENCES TO STUDY NEURODEVELOPMENTAL FACTORS THAT LEAD TO A HIGHLY INHIBITED, STRESS VULNERABLE PHENOTYPE. SELECTIVE BREEDING FOR HIGH VERSUS LOW BEHAVIORAL RESPONSE TO NOVELTY CREATED TWO RAT STRAINS THAT EXHIBIT DRAMATIC BEHAVIOR DIFFERENCES OVER MULTIPLE DOMAINS RELEVANT TO EMOTIONAL DISORDERS. LOW NOVELTY RESPONDER (BLR) RATS EXHIBIT HIGH LEVELS OF BEHAVIORAL INHIBITION, PASSIVE STRESS COPING, ANHEDONIA, DECREASED SOCIABILITY AND VULNERABILITY TO CHRONIC STRESS COMPARED TO HIGH NOVELTY RESPONDERS (BHRS). ON THE OTHER HAND, BHRS EXHIBIT HIGH LEVELS OF BEHAVIORAL DIS-INHIBITION, ACTIVE COPING, AND AGGRESSION. THIS REVIEW ARTICLE SUMMARIZES OUR WORK WITH THE BHR/BLR MODEL SHOWING THE DEVELOPMENTAL EMERGENCE OF THE BHR/BLR PHENOTYPES, THE ROLE THE ENVIRONMENT PLAYS IN SHAPING IT, AND THE INVOLVEMENT OF EPIGENETIC PROCESSES SUCH AS DNA METHYLATION THAT MEDIATE DIFFERENCES IN EMOTIONALITY AND STRESS REACTIVITY. 2022 13 2949 23 GENETIC AND EPIGENETIC CONSEQUENCE OF EARLY-LIFE SOCIAL STRESS ON DEPRESSION: ROLE OF SEROTONIN-ASSOCIATED GENES. EARLY-LIFE ADVERSITY CAUSED BY POOR SOCIAL BONDING AND DEPRIVED MATERNAL CARE IS KNOWN TO AFFECT MENTAL WELLBEING AND PHYSICAL HEALTH. IT IS A FORM OF CHRONIC SOCIAL STRESS THAT PERSISTS BECAUSE OF A NEGATIVE ENVIRONMENT, AND THE CONSEQUENCES ARE LONG-LASTING ON MENTAL HEALTH. THE PRESENCE OF SOCIAL STRESS DURING EARLY LIFE CAN HAVE AN EPIGENETIC EFFECT ON THE BODY, POSSIBLY RESULTING IN MANY COMPLEX MENTAL DISORDERS, INCLUDING DEPRESSION IN LATER LIFE. HERE, WE REVIEW THE EVIDENCE FOR EARLY-LIFE SOCIAL STRESS-INDUCED EPIGENETIC CHANGES THAT MODULATE JUVENILE AND ADULT SOCIAL BEHAVIOR (DEPRESSION AND ANXIETY). THIS REVIEW HAS A PARTICULAR EMPHASIS ON THE INTERACTION BETWEEN EARLY-LIFE SOCIAL STRESS AND GENETIC VARIATION OF SEROTONIN ASSOCIATE GENES INCLUDING THE SEROTONIN TRANSPORTER GENE (5-HTT; ALSO KNOWN AS SLC6A4), WHICH ARE KEY MOLECULES INVOLVED IN DEPRESSION. 2020 14 5008 23 PERIPUBERTAL STRESS WITH SOCIAL SUPPORT PROMOTES RESILIENCE IN THE FACE OF AGING. THE PERIPUBERTAL PERIOD OF DEVELOPMENT IS A SENSITIVE WINDOW, DURING WHICH ADVERSE EXPERIENCES CAN INCREASE THE RISK FOR PRESENTATION OF COGNITIVE AND AFFECTIVE DYSFUNCTION THROUGHOUT THE LIFESPAN, ESPECIALLY IN WOMEN. HOWEVER, SUCH EXPERIENCES IN THE CONTEXT OF A SUPPORTIVE SOCIAL ENVIRONMENT CAN ACTUALLY AMELIORATE THIS RISK, SUGGESTING THAT RESILIENCE CAN BE PROGRAMMED IN EARLY LIFE. AFFECTIVE DISORDERS AND COGNITIVE DEFICITS COMMONLY EMERGE DURING AGING, WITH MANY WOMEN REPORTING INCREASED DIFFICULTY WITH PREFRONTAL CORTEX (PFC)-DEPENDENT EXECUTIVE FUNCTIONS. WE HAVE DEVELOPED A MOUSE MODEL TO EXAMINE THE INTERACTION BETWEEN PERIPUBERTAL EXPERIENCE AND AGE-RELATED CHANGES IN COGNITION AND STRESS REGULATION. FEMALE MICE WERE EXPOSED TO PERIPUBERTAL CHRONIC STRESS, DURING WHICH THEY WERE EITHER INDIVIDUALLY HOUSED OR HOUSED WITH SOCIAL INTERACTION. ONE YEAR AFTER THIS STRESS EXPERIENCE, MICE WERE EXAMINED IN TASKS TO ACCESS THEIR COGNITIVE ABILITY AND FLEXIBILITY IN STRESS REACTIVE MEASURES. IN A TEST OF SPATIAL MEMORY ACQUISITION AND REVERSAL LEARNING WHERE AGED FEMALES NORMALLY DISPLAY A DECREASED PERFORMANCE, THE FEMALES THAT HAD EXPERIENCED STRESS WITH SOCIAL INTERACTION A YEAR EARLIER SHOWED IMPROVED PERFORMANCE IN REVERSAL LEARNING, A MEASURE OF COGNITIVE FLEXIBILITY. BECAUSE PERIPUBERTY IS A TIME OF MAJOR PFC MATURATION, WE PERFORMED TRANSCRIPTOMIC AND BIOCHEMICAL ANALYSIS OF THE AGED PFC, IN WHICH LONG-TERM CHANGES IN MICRORNA EXPRESSION AND IN MYELIN PROTEINS WERE FOUND. THESE DATA SUGGEST THAT STRESS IN THE CONTEXT OF SOCIAL SUPPORT EXPERIENCED OVER THE PUBERTAL WINDOW CAN PROMOTE EPIGENETIC REPROGRAMMING IN THE BRAIN TO INCREASE THE RESILIENCE TO AGE-RELATED COGNITIVE DECLINE IN FEMALES. 2016 15 3313 21 HIPPOCAMPAL BDNF IN PHYSIOLOGICAL CONDITIONS AND SOCIAL ISOLATION. EXPOSURE OF AN ORGANISM TO CHRONIC PSYCHOSOCIAL STRESS MAY AFFECT BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION THAT HAS BEEN IMPLICATED IN THE ETIOLOGY OF PSYCHIATRIC DISORDERS, SUCH AS DEPRESSION. GIVEN THAT DEPRESSION IN HUMANS HAS BEEN LINKED WITH SOCIAL STRESS, THE CHRONIC SOCIAL STRESS PARADIGMS FOR MODELING PSYCHIATRIC DISORDERS IN ANIMALS HAVE THUS BEEN DEVELOPED. CHRONIC SOCIAL ISOLATION IN ANIMAL MODELS GENERALLY CAUSES CHANGES IN HYPOTHALAMIC-PITUITARY-ADRENAL AXIS FUNCTIONING, ASSOCIATED WITH ANXIETY- AND DEPRESSIVE-LIKE BEHAVIORS. ALSO, THIS CHRONIC STRESS CAUSES DOWNREGULATION OF BDNF PROTEIN AND MRNA IN THE HIPPOCAMPUS, A STRESS-SENSITIVE BRAIN REGION CLOSELY RELATED TO THE PATHOPHYSIOLOGY OF DEPRESSION. IN THIS REVIEW, WE DISCUSS THE CURRENT KNOWLEDGE REGARDING THE STRUCTURE, FUNCTION, INTRACELLULAR SIGNALING, INTER-INDIVIDUAL DIFFERENCES AND EPIGENETIC REGULATION OF BDNF IN BOTH PHYSIOLOGICAL CONDITIONS AND DEPRESSION AND CHANGES IN CORTICOSTERONE LEVELS, AS A MARKER OF STRESS RESPONSE. SINCE BDNF LEVELS ARE AGE DEPENDENT IN HUMANS AND RODENTS, THIS REVIEW WILL ALSO HIGHLIGHT THE EFFECTS OF ADOLESCENT AND ADULT CHRONIC SOCIAL ISOLATION MODELS OF BOTH GENDERS ON THE BDNF EXPRESSION. 2017 16 6626 22 UNDERSTANDING RESILIENCE. RESILIENCE IS THE ABILITY TO ADAPT SUCCESSFULLY IN THE FACE OF STRESS AND ADVERSITY. STRESSFUL LIFE EVENTS, TRAUMA, AND CHRONIC ADVERSITY CAN HAVE A SUBSTANTIAL IMPACT ON BRAIN FUNCTION AND STRUCTURE, AND CAN RESULT IN THE DEVELOPMENT OF POSTTRAUMATIC STRESS DISORDER (PTSD), DEPRESSION AND OTHER PSYCHIATRIC DISORDERS. HOWEVER, MOST INDIVIDUALS DO NOT DEVELOP SUCH ILLNESSES AFTER EXPERIENCING STRESSFUL LIFE EVENTS, AND ARE THUS THOUGHT TO BE RESILIENT. RESILIENCE AS SUCCESSFUL ADAPTATION RELIES ON EFFECTIVE RESPONSES TO ENVIRONMENTAL CHALLENGES AND ULTIMATE RESISTANCE TO THE DELETERIOUS EFFECTS OF STRESS, THEREFORE A GREATER UNDERSTANDING OF THE FACTORS THAT PROMOTE SUCH EFFECTS IS OF GREAT RELEVANCE. THIS REVIEW FOCUSES ON RECENT FINDINGS REGARDING GENETIC, EPIGENETIC, DEVELOPMENTAL, PSYCHOSOCIAL, AND NEUROCHEMICAL FACTORS THAT ARE CONSIDERED ESSENTIAL CONTRIBUTORS TO THE DEVELOPMENT OF RESILIENCE. NEURAL CIRCUITS AND PATHWAYS INVOLVED IN MEDIATING RESILIENCE ARE ALSO DISCUSSED. THE GROWING UNDERSTANDING OF RESILIENCE FACTORS WILL HOPEFULLY LEAD TO THE DEVELOPMENT OF NEW PHARMACOLOGICAL AND PSYCHOLOGICAL INTERVENTIONS FOR ENHANCING RESILIENCE AND MITIGATING THE UNTOWARD CONSEQUENCES. 2013 17 575 24 BDNF METHYLATION AND MATERNAL BRAIN ACTIVITY IN A VIOLENCE-RELATED SAMPLE. IT IS KNOWN THAT INCREASED CIRCULATING GLUCOCORTICOIDS IN THE WAKE OF EXCESSIVE, CHRONIC, REPETITIVE STRESS INCREASES ANXIETY AND IMPAIRS BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) SIGNALING. RECENT STUDIES OF BDNF GENE METHYLATION IN RELATION TO MATERNAL CARE HAVE LINKED HIGH BDNF METHYLATION LEVELS IN THE BLOOD OF ADULTS TO LOWER QUALITY OF RECEIVED MATERNAL CARE MEASURED VIA SELF-REPORT. YET THE SPECIFIC MECHANISMS BY WHICH THESE PHENOMENA OCCUR REMAIN TO BE ESTABLISHED. THE PRESENT STUDY EXAMINES THE LINK BETWEEN METHYLATION OF THE BDNF GENE PROMOTER REGION AND PATTERNS OF NEURAL ACTIVITY THAT ARE ASSOCIATED WITH MATERNAL RESPONSE TO STRESSFUL VERSUS NON-STRESSFUL CHILD STIMULI WITHIN A SAMPLE THAT INCLUDES MOTHERS WITH INTERPERSONAL VIOLENCE-RELATED PTSD (IPV-PTSD). 46 MOTHERS UNDERWENT FMRI. THE CONTRAST OF NEURAL ACTIVITY WHEN WATCHING CHILDREN-INCLUDING THEIR OWN-WAS THEN CORRELATED TO BDNF METHYLATION. CONSISTENT WITH THE EXISTING LITERATURE, THE PRESENT STUDY FOUND THAT MATERNAL BDNF METHYLATION WAS ASSOCIATED WITH HIGHER LEVELS OF MATERNAL ANXIETY AND GREATER CHILDHOOD EXPOSURE TO DOMESTIC VIOLENCE. FMRI RESULTS SHOWED A POSITIVE CORRELATION OF BDNF METHYLATION WITH MATERNAL BRAIN ACTIVITY IN THE ANTERIOR CINGULATE (ACC), AND VENTROMEDIAL PREFRONTAL CORTEX (VMPFC), REGIONS GENERALLY CREDITED WITH A REGULATORY FUNCTION TOWARD BRAIN AREAS THAT ARE GENERATING EMOTIONS. FURTHERMORE WE FOUND A NEGATIVE CORRELATION OF BDNF METHYLATION WITH THE ACTIVITY OF THE RIGHT HIPPOCAMPUS. SINCE OUR STIMULI FOCUS ON STRESSFUL PARENTING CONDITIONS, THESE DATA SUGGEST THAT THE CORRELATION BETWEEN VMPFC/ACC ACTIVITY AND BDNF METHYLATION MAY BE LINKED TO MOTHERS WHO ARE AT A DISADVANTAGE WITH RESPECT TO EMOTION REGULATION WHEN FACING STRESSFUL PARENTING SITUATIONS. OVERALL, THIS STUDY PROVIDES EVIDENCE THAT EPIGENETIC SIGNATURES OF STRESS-RELATED GENES CAN BE LINKED TO FUNCTIONAL BRAIN REGIONS REGULATING PARENTING STRESS, THUS ADVANCING OUR UNDERSTANDING OF MOTHERS AT RISK FOR STRESS-RELATED PSYCHOPATHOLOGY. 2015 18 4067 17 MATERNAL AND PEDIATRIC HEALTH AND DISEASE: INTEGRATING BIOPSYCHOSOCIAL MODELS AND EPIGENETICS. THE CONCEPTS OF ALLOSTASIS (STABILITY THROUGH ADAPTATION) AND ACCUMULATED LIFE STRESS (MCEWEN'S ALLOSTATIC LOAD) AIM TO UNDERSTAND CHILDHOOD AND ADULT OUTCOMES. CHRONIC MALNUTRITION, CHANGES IN SOCIAL CONDITION, AND ADVERSE EARLY-LIFE EXPERIENCES MAY PROGRAM PHENOTYPES AND CONTRIBUTE TO LONG-LASTING DISEASE RISK. HOWEVER, INTEGRATION OF LIFE COURSE APPROACHES, SOCIAL AND ECONOMIC CONTEXTS, AND COMPARISON AMONG DIFFERENT BIOPSYCHOSOCIAL MODELS HAS NOT GENERALLY BEEN EXPLORED. THIS REVIEW CRITICALLY EXAMINES THE LITERATURE AND EVALUATES RECENT INSIGHTS INTO HOW ENVIRONMENTAL STRESS CAN ALTER LIFELONG HYPOTHALAMIC-PITUITARY-ADRENAL AXIS AND IMMUNE SYSTEM RESPONSIVENESS AND INDUCE METABOLIC AND NEURODEVELOPMENTAL MALADAPTATION. MODELS OF BIOPSYCHOSOCIAL STRESS OVERLAP BUT MAY CONSIDER DIFFERENT CONDITIONS. CONCEPTS INCLUDE ALLOSTASIS, WHICH INCORPORATES HORMONAL RESPONSES TO PREDICTABLE ENVIRONMENTAL CHANGES, AND GERONIMUS'S "WEATHERING," WHICH AIMS TO EXPLAIN HOW SOCIALLY STRUCTURED, REPEATED STRESS CAN ACCUMULATE AND INCREASE DISEASE VULNERABILITY. WEATHERING EMPHASIZES ROLES OF INTERNALIZED/INTERPERSONAL RACISM IN OUTCOMES DISPARITIES. FOR MEXICAN IMMIGRANTS AND MEXICAN AMERICANS, THE "ACCULTURATION" FRAMEWORK HAS PROVEN ESPECIALLY USEFUL TO EXPLORE DISPARITIES, INCLUDING PRETERM BIRTH AND NEUROPSYCHIATRIC RISKS IN CHILDHOOD. COMPLEXITIES OF STRESS ASSESSMENTS AND RECENT RESEARCH INTO EPIGENETIC MECHANISMS MEDIATING EFFECTS OF PHYSICAL, NUTRITIONAL, PSYCHOLOGICAL, AND SOCIAL STRESS ARE REVIEWED. 2016 19 1761 21 EARLY STRESS EVOKES AGE-DEPENDENT BIPHASIC CHANGES IN HIPPOCAMPAL NEUROGENESIS, BDNF EXPRESSION, AND COGNITION. BACKGROUND: ADULT-ONSET STRESSORS EXERT OPPOSING EFFECTS ON HIPPOCAMPAL NEUROGENESIS AND COGNITION, WITH ENHANCEMENT OBSERVED FOLLOWING MILD STRESS AND DYSFUNCTION FOLLOWING SEVERE CHRONIC STRESS. WHILE EARLY LIFE STRESS EVOKES PERSISTENT CHANGES IN ANXIETY, IT IS UNKNOWN WHETHER EARLY STRESS DIFFERENTIALLY REGULATES HIPPOCAMPAL NEUROGENESIS, TROPHIC FACTOR EXPRESSION, AND COGNITION ACROSS THE LIFE SPAN. METHODS: HIPPOCAMPAL-DEPENDENT COGNITIVE BEHAVIOR, NEUROGENESIS, AND EPIGENETIC REGULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION WAS EXAMINED AT DISTINCT TIME POINTS ACROSS THE LIFE SPAN IN RATS SUBJECTED TO THE EARLY STRESS OF MATERNAL SEPARATION (ES) AND CONTROL GROUPS. WE ALSO EXAMINED THE INFLUENCE OF CHRONIC ANTIDEPRESSANT TREATMENT ON THE NEUROGENIC, NEUROTROPHIC, AND COGNITIVE CHANGES IN MIDDLE-AGED ES ANIMALS. RESULTS: ANIMALS SUBJECTED TO EARLY STRESS OF MATERNAL SEPARATION EXAMINED DURING POSTNATAL LIFE AND YOUNG ADULTHOOD EXHIBITED ENHANCED HIPPOCAMPAL NEUROGENESIS, DECREASED REPRESSIVE HISTONE METHYLATION AT THE BDNF IV PROMOTER ALONG WITH ENHANCED BDNF LEVELS, AND IMPROVED PERFORMANCE ON THE STRESS-ASSOCIATED MORRIS WATER MAZE. STRIKINGLY, OPPOSING CHANGES IN HIPPOCAMPAL NEUROGENESIS AND EPIGENETIC REGULATION OF BDNF IV EXPRESSION, CONCOMITANT WITH IMPAIRMENTS ON HIPPOCAMPAL-DEPENDENT COGNITIVE TASKS, WERE OBSERVED IN MIDDLE-AGED ES ANIMALS. CHRONIC ANTIDEPRESSANT TREATMENT WITH AMITRIPTYLINE ATTENUATED THE MALADAPTIVE NEUROGENIC, EPIGENETIC, TRANSCRIPTIONAL, AND COGNITIVE EFFECTS IN MIDDLE-AGED ES ANIMALS. CONCLUSIONS: OUR STUDY PROVIDES NOVEL INSIGHTS INTO THE SHORT- AND LONG-TERM CONSEQUENCES OF ES, DEMONSTRATING BOTH BIPHASIC AND UNIQUE, AGE-DEPENDENT CHANGES AT THE MOLECULAR, EPIGENETIC, NEUROGENIC, AND BEHAVIORAL LEVELS. THESE RESULTS INDICATE THAT EARLY STRESS MAY TRANSIENTLY ENDOW ANIMALS WITH A POTENTIAL ADAPTIVE ADVANTAGE IN STRESSFUL ENVIRONMENTS BUT ACROSS A LIFE SPAN IS ASSOCIATED WITH LONG-TERM DELETERIOUS EFFECTS. 2013 20 1677 27 DRUG ADDICTION: HYPERKATIFEIA/NEGATIVE REINFORCEMENT AS A FRAMEWORK FOR MEDICATIONS DEVELOPMENT. COMPULSIVE DRUG SEEKING THAT IS ASSOCIATED WITH ADDICTION IS HYPOTHESIZED TO FOLLOW A HEURISTIC FRAMEWORK THAT INVOLVES THREE STAGES (BINGE/INTOXICATION, WITHDRAWAL/NEGATIVE AFFECT, AND PREOCCUPATION/ANTICIPATION) AND THREE DOMAINS OF DYSFUNCTION (INCENTIVE SALIENCE/PATHOLOGIC HABITS, NEGATIVE EMOTIONAL STATES, AND EXECUTIVE FUNCTION, RESPECTIVELY) VIA CHANGES IN THE BASAL GANGLIA, EXTENDED AMYGDALA/HABENULA, AND FRONTAL CORTEX, RESPECTIVELY. THIS REVIEW FOCUSES ON NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS THAT CONTRIBUTE TO HYPERKATIFEIA, DEFINED AS A GREATER INTENSITY OF NEGATIVE EMOTIONAL/MOTIVATIONAL SIGNS AND SYMPTOMS DURING WITHDRAWAL FROM DRUGS OF ABUSE IN THE WITHDRAWAL/NEGATIVE AFFECT STAGE OF THE ADDICTION CYCLE. HYPERKATIFEIA PROVIDES AN ADDITIONAL SOURCE OF MOTIVATION FOR COMPULSIVE DRUG SEEKING VIA NEGATIVE REINFORCEMENT. NEGATIVE REINFORCEMENT REFLECTS AN INCREASE IN THE PROBABILITY OF A RESPONSE TO REMOVE AN AVERSIVE STIMULUS OR DRUG SEEKING TO REMOVE HYPERKATIFEIA THAT IS AUGMENTED BY GENETIC/EPIGENETIC VULNERABILITY, ENVIRONMENTAL TRAUMA, AND PSYCHIATRIC COMORBIDITY. NEUROBIOLOGICAL TARGETS FOR HYPERKATIFEIA IN ADDICTION INVOLVE NEUROCIRCUITRY OF THE EXTENDED AMYGDALA AND ITS CONNECTIONS VIA WITHIN-SYSTEM NEUROADAPTATIONS IN DOPAMINE, ENKEPHALIN/ENDORPHIN OPIOID PEPTIDE, AND GAMMA-AMINOBUTYRIC ACID/GLUTAMATE SYSTEMS AND BETWEEN-SYSTEM NEUROADAPTATIONS IN PROSTRESS CORTICOTROPIN-RELEASING FACTOR, NOREPINEPHRINE, GLUCOCORTICOID, DYNORPHIN, HYPOCRETIN, AND NEUROIMMUNE SYSTEMS AND ANTISTRESS NEUROPEPTIDE Y, NOCICEPTIN, ENDOCANNABINOID, AND OXYTOCIN SYSTEMS. SUCH NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS ARE HYPOTHESIZED TO MEDIATE A NEGATIVE HEDONIC SET POINT THAT GRADUALLY GAINS ALLOSTATIC LOAD AND SHIFTS FROM A HOMEOSTATIC HEDONIC STATE TO AN ALLOSTATIC HEDONIC STATE. BASED ON PRECLINICAL STUDIES AND TRANSLATIONAL STUDIES TO DATE, MEDICATIONS AND BEHAVIORAL THERAPIES THAT RESET BRAIN STRESS, ANTISTRESS, AND EMOTIONAL PAIN SYSTEMS AND RETURN THEM TO HOMEOSTASIS WOULD BE PROMISING NEW TARGETS FOR MEDICATION DEVELOPMENT. SIGNIFICANCE STATEMENT: THE FOCUS OF THIS REVIEW IS ON NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS THAT CONTRIBUTE TO HYPERKATIFEIA, DEFINED AS A GREATER INTENSITY OF NEGATIVE EMOTIONAL/MOTIVATIONAL SIGNS AND SYMPTOMS DURING WITHDRAWAL FROM DRUGS OF ABUSE IN THE WITHDRAWAL/NEGATIVE AFFECT STAGE OF THE DRUG ADDICTION CYCLE AND A DRIVING FORCE FOR NEGATIVE REINFORCEMENT IN ADDICTION. MEDICATIONS AND BEHAVIORAL THERAPIES THAT REVERSE HYPERKATIFEIA BY RESETTING BRAIN STRESS, ANTISTRESS, AND EMOTIONAL PAIN SYSTEMS AND RETURNING THEM TO HOMEOSTASIS WOULD BE PROMISING NEW TARGETS FOR MEDICATION DEVELOPMENT. 2021