1 2231 83 EPIGENETIC MODIFICATIONS OF MAJOR DEPRESSIVE DISORDER. MAJOR DEPRESSIVE DISORDER (MDD) IS A CHRONIC DISEASE WHOSE NEUROLOGICAL BASIS AND PATHOPHYSIOLOGY REMAIN POORLY UNDERSTOOD. INITIALLY, IT WAS PROPOSED THAT GENETIC VARIATIONS WERE RESPONSIBLE FOR THE DEVELOPMENT OF THIS DISEASE. NEVERTHELESS, SEVERAL STUDIES WITHIN THE LAST DECADE HAVE PROVIDED EVIDENCE SUGGESTING THAT ENVIRONMENTAL FACTORS PLAY AN IMPORTANT ROLE IN MDD PATHOPHYSIOLOGY. ALTERATIONS IN EPIGENETICS MECHANISM, SUCH AS DNA METHYLATION, HISTONE MODIFICATION AND MICRORNA EXPRESSION COULD FAVOR MDD ADVANCE IN RESPONSE TO STRESSFUL EXPERIENCES AND ENVIRONMENTAL FACTORS. THE AIM OF THIS REVIEW IS TO DESCRIBE GENETIC ALTERATIONS, AND PARTICULARLY ALTERED EPIGENETIC MECHANISMS, THAT COULD BE DETERMINANTS FOR MDD PROGRESS, AND HOW THESE ALTERATIONS MAY ARISE AS USEFUL SCREENING, DIAGNOSIS AND TREATMENT MONITORING BIOMARKERS OF DEPRESSIVE DISORDERS. 2016 2 2288 42 EPIGENETIC REGULATION IN MAJOR DEPRESSION AND OTHER STRESS-RELATED DISORDERS: MOLECULAR MECHANISMS, CLINICAL RELEVANCE AND THERAPEUTIC POTENTIAL. MAJOR DEPRESSIVE DISORDER (MDD) IS A CHRONIC, GENERALLY EPISODIC AND DEBILITATING DISEASE THAT AFFECTS AN ESTIMATED 300 MILLION PEOPLE WORLDWIDE, BUT ITS PATHOGENESIS IS POORLY UNDERSTOOD. THE HERITABILITY ESTIMATE OF MDD IS 30-40%, SUGGESTING THAT GENETICS ALONE DO NOT ACCOUNT FOR MOST OF THE RISK OF MAJOR DEPRESSION. ANOTHER FACTOR KNOWN TO ASSOCIATE WITH MDD INVOLVES ENVIRONMENTAL STRESSORS SUCH AS CHILDHOOD ADVERSITY AND RECENT LIFE STRESS. RECENT STUDIES HAVE EMERGED TO SHOW THAT THE BIOLOGICAL IMPACT OF ENVIRONMENTAL FACTORS IN MDD AND OTHER STRESS-RELATED DISORDERS IS MEDIATED BY A VARIETY OF EPIGENETIC MODIFICATIONS. THESE EPIGENETIC MODIFICATION ALTERATIONS CONTRIBUTE TO ABNORMAL NEUROENDOCRINE RESPONSES, NEUROPLASTICITY IMPAIRMENT, NEUROTRANSMISSION AND NEUROGLIA DYSFUNCTION, WHICH ARE INVOLVED IN THE PATHOPHYSIOLOGY OF MDD. FURTHERMORE, EPIGENETIC MARKS HAVE BEEN ASSOCIATED WITH THE DIAGNOSIS AND TREATMENT OF MDD. THE EVALUATION OF EPIGENETIC MODIFICATIONS HOLDS PROMISE FOR FURTHER UNDERSTANDING OF THE HETEROGENEOUS ETIOLOGY AND COMPLEX PHENOTYPES OF MDD, AND MAY IDENTIFY NEW THERAPEUTIC TARGETS. HERE, WE REVIEW PRECLINICAL AND CLINICAL EPIGENETIC FINDINGS, INCLUDING DNA METHYLATION, HISTONE MODIFICATION, NONCODING RNA, RNA MODIFICATION, AND CHROMATIN REMODELING FACTOR IN MDD. IN ADDITION, WE ELABORATE ON THE CONTRIBUTION OF THESE EPIGENETIC MECHANISMS TO THE PATHOLOGICAL TRAIT VARIABILITY IN DEPRESSION AND DISCUSS HOW SUCH MECHANISMS CAN BE EXPLOITED FOR THERAPEUTIC PURPOSES. 2023 3 4321 29 MICRORNAS IN MAJOR DEPRESSIVE DISORDER. MAJOR DEPRESSIVE DISORDER (MDD) IS A SEVERE AND CHRONIC PSYCHIATRIC DISORDER WITH A HIGH PREVALENCE IN THE POPULATION. ALTHOUGH OUR UNDERSTANDING OF ITS PATHOPHYSIOLOGICAL MECHANISMS HAS SIGNIFICANTLY INCREASED OVER THE YEARS, AVAILABLE TREATMENTS STILL PRESENT SEVERAL LIMITATIONS AND ARE NOT EFFECTIVE TO ALL MDD PATIENTS. EPIGENETIC MECHANISMS HAVE RECENTLY BEEN SUGGESTED TO PLAY KEY ROLES IN MDD PATHOGENESIS AND TREATMENT, INCLUDING THE EFFECTS OF SMALL NONCODING RNAS KNOWN AS MICRORNAS (MIRNAS). MIRNAS CAN MODULATE GENE EXPRESSION POSTTRANSCRIPTIONALLY BY INTERFERING WITH THE STABILITY AND TRANSLATION OF MESSENGER RNA MOLECULES AND ARE ALSO KNOWN TO CROSS-TALK WITH OTHER EPIGENETIC MECHANISMS. IN THIS REVIEW, WE WILL SUMMARIZE AND DISCUSS RECENT FINDINGS OF ALTERATIONS IN MIRNAS IN TISSUES OF PATIENTS WITH MDD AND EVIDENCE OF TREATMENT-INDUCED EFFECTS IN THESE MOLECULES. 2019 4 2572 32 EPIGENETICS OF DEPRESSION. MAJOR DEPRESSIVE DISORDER (MDD) IS A LEADING CAUSE OF DISABILITY WORLDWIDE AND IS ASSOCIATED WITH POOR PSYCHOLOGICAL, MEDICAL, AND SOCIOECONOMIC OUTCOMES. ALTHOUGH MUCH HAS BEEN LEARNED ABOUT THE ETIOLOGY AND TREATMENT OPTIONS OF MDD OVER THE PAST DECADE, THERE REMAIN UNANSWERED QUESTIONS THAT POSE CHALLENGES TO IMPROVING ACUTE AND CHRONIC OUTCOMES FOR THOSE WITH MDD. MDD IS A CLINICALLY HETEROGENEOUS DISORDER. GENETIC STUDIES TO DATE HAVE INDICATED A NUMBER OF GENES, INCLUDING TRANSPORTERS, NEUROTRANSMITTERS, NEUROTROPHINS, AND THEIR ASSOCIATED SIGNALING NETWORKS THAT MAY PREDISPOSE INDIVIDUALS TO MDD AND MAY ALSO PREDICT TREATMENT OUTCOMES. HOWEVER, TWIN STUDIES INDICATE THAT GENES ACCOUNT FOR ONLY A SMALL DEGREE OF THE VARIATION IN MDD. THUS, OTHER MECHANISMS, THROUGH EPIGENETIC MARKS, MAY ACT TO FORM A MOLECULAR MEMORY OF PREVIOUS GENE-TO-ENVIRONMENT INTERACTIONS AND TO ESTABLISH VULNERABILITIES (OR, CONVERSELY, RESISTANCE) TO MDD. CURRENT EVIDENCE SUPPORTS A ROLE FOR PRE-, PERI-, AND EARLY POSTNATAL ADVERSITIES AND STRESSFUL LIFE EVENTS INTO ADULTHOOD AFFECTING EPIGENETIC PATTERNS, PROVIDING A MECHANISTIC FOUNDATION TO DEVELOP EPIGENETIC MARKS AS BIOMARKERS FOR MDD. THIS REVIEW PRESENTS THE EVIDENCE SUPPORTING A ROLE FOR EPIGENETIC EFFECTS IN MDD AND IN TREATMENT RESPONSE. WE ALSO DISCUSS THE CONTROVERSY BEHIND MODULATING EPIGENETIC MECHANISMS IN LONG-TERM ANTIDEPRESSANT PHARMACOTHERAPY. 2014 5 2963 26 GENETIC AND EPIGENETIC MECHANISMS LINKING PAIN AND PSYCHIATRIC DISORDERS. THE NEUROPHYSIOLOGICAL LINK BETWEEN NEUROPATHIC PAIN AND DEPRESSION REMAINS UNKNOWN DESPITE EVIDENT HIGH COMORBIDITY OF THESE TWO DISORDERS. HOWEVER, THERE IS CONVINCING EVIDENCE THAT GENOTYPE PLAYS A ROLE IN BOTH PAIN AND DEPRESSION. USING VARIOUS TYPES OF GENETIC ANALYSIS - POPULATION GENETICS, CYTOGENETICS AND MOLECULAR TECHNOLOGIES - SPECIFIC GENES HAVE BEEN IMPLICATED IN MEDIATING ALMOST ALL ASPECTS OF NOCICEPTION AND MOOD DISORDERS. THE CURRENT REVIEW ATTEMPTS TO IDENTIFY SPECIFIC GENES AND EPIGENETIC MECHANISMS COMMON TO BOTH DISORDERS. IT IS CONCLUDED THAT EXTERNAL AND INTERNAL FACTORS (INFLAMMATION, STRESS, GENDER, ETC.) THAT CONTRIBUTE TO THE PATHOLOGIES MAY DO SO THROUGH EPIGENETIC MECHANISMS THAT MAY AFFECT EXPRESSION OF THESE PARTICULAR GENES. THE POSSIBLE INVOLVEMENT OF EPIGENETIC REGULATION IN PAIN AND PSYCHIATRIC DISORDERS SUGGESTS THAT TREATMENTS TARGETING EPIGENETIC MECHANISMS THAT MEDIATE ADVERSE LIFE EVENTS SHOULD BE CONSIDERED. 2015 6 641 33 BIOMARKERS OF MAJOR DEPRESSIVE DISORDER: KNOWING IS HALF THE BATTLE. MAJOR DEPRESSIVE DISORDER (MDD) IS A HETEROGENEOUS DISEASE WHICH IS WHY THERE ARE CURRENTLY NO SPECIFIC METHODS TO ACCURATELY TEST THE SEVERITY, ENDOPHENOTYPE OR THERAPY RESPONSE. THIS LACK OF PROGRESS IS PARTLY ATTRIBUTED TO THE COM-PLEXITY AND VARIABILITY OF DEPRESSION, IN ASSOCIATION WITH ANALYTICAL VARIABILITY OF CLINICAL LITERATURE AND THE WIDE NUMBER OF THEORETICALLY COMPLEX BIOMARKERS. THE LITERATURE ACCESSIBLE, INDICATES THAT MARKERS INVOLVED IN INFLAMMATORY, NEURO-TROPHIC AND METABOLIC PROCESSES AND COMPONENTS OF NEUROTRANSMITTERS AND NEUROENDOCRINE SYSTEMS ARE RATHER STRONG INDICATORS TO BE CONSIDERED CLINICALLY AND CAN BE MEASURED THROUGH GENETIC AND EPIGENETIC, TRANSCRIPTOMIC AND PROTEOMIC, METABOLOMICS AND NEUROIMAGING ASSESSMENTS. PROMISING BIOLOGIC SYSTEMS/MARKERS FOUND WERE I.E., GROWTH BIOMARKERS, ENDOCRINE MARKERS, OXIDANT STRESS MARKERS, PROTEOMIC AND CHRONIC INFLAMMATORY MARKERS, ARE DISCUSSED IN THIS REVIEW. SEVERAL LINES OF EVIDENCE SUGGEST THAT A PORTION OF MDD IS A DOPAMINE AGONIST-RESPONSIVE SUBTYPE. THIS REVIEW ANALYZES CONCISE REPORTS ON THE PATHOPHYSIOLOGICAL BIOMARKERS OF MDD AND THERAPEUTIC REACTIONS VIA PERIPHERAL DEVELOPMENTAL FACTORS, INFLAMMATIVE CYTOKINES, ENDOCRINE FACTORS AND METABOLIC MARKERS. VARIOUS LITERATURES ALSO SUPPORT THAT ENDOCRINE AND METABOLISM CHANGES ARE ASSOCIATED WITH MDD. ACCUMULATING EVIDENCE SUGGESTS THAT AT LEAST A PORTION OF MDD PATIENTS SHOW CHARACTERISTICS PATHOLOGICAL CHANGES REGARDING DIFFERENT CLINICAL PATHOLOGICAL BIOMARKERS. BY THIS REVIEW WE SUM UP ALL THE DIFFERENT BIOMARKERS PLAYING AN IMPORTANT ROLE IN THE DETECTION OR TREATMENT OF THE DIFFERENT PATIENTS SUFFERING FROM MDD. THE REVIEW ALSO GIVES AN OVERVIEW OF DIFFERENT BIOMARKER'S PLAYING A POTENTIAL ROLE IN MODULATING EFFECT OF MDD. 2021 7 2011 43 EPIGENETIC BASIS OF MENTAL ILLNESS. PSYCHIATRIC DISORDERS ARE COMPLEX MULTIFACTORIAL ILLNESSES INVOLVING CHRONIC ALTERATIONS IN NEURAL CIRCUIT STRUCTURE AND FUNCTION AS WELL AS LIKELY ABNORMALITIES IN GLIAL CELLS. WHILE GENETIC FACTORS ARE IMPORTANT IN THE ETIOLOGY OF MOST MENTAL DISORDERS, THE RELATIVELY HIGH RATES OF DISCORDANCE AMONG IDENTICAL TWINS, PARTICULARLY FOR DEPRESSION AND OTHER STRESS-RELATED SYNDROMES, CLEARLY INDICATE THE IMPORTANCE OF ADDITIONAL MECHANISMS. ENVIRONMENTAL FACTORS SUCH AS STRESS ARE KNOWN TO PLAY A ROLE IN THE ONSET OF THESE ILLNESSES. EXPOSURE TO SUCH ENVIRONMENTAL INSULTS INDUCES STABLE CHANGES IN GENE EXPRESSION, NEURAL CIRCUIT FUNCTION, AND ULTIMATELY BEHAVIOR, AND THESE MALADAPTATIONS APPEAR DISTINCT BETWEEN DEVELOPMENTAL VERSUS ADULT EXPOSURES. INCREASING EVIDENCE INDICATES THAT THESE SUSTAINED ABNORMALITIES ARE MAINTAINED BY EPIGENETIC MODIFICATIONS IN SPECIFIC BRAIN REGIONS. INDEED, TRANSCRIPTIONAL DYSREGULATION AND THE ABERRANT EPIGENETIC REGULATION THAT UNDERLIES THIS DYSREGULATION IS A UNIFYING THEME IN PSYCHIATRIC DISORDERS. HERE, WE PROVIDE A PROGRESS REPORT OF EPIGENETIC STUDIES OF THE THREE MAJOR PSYCHIATRIC SYNDROMES, DEPRESSION, SCHIZOPHRENIA, AND BIPOLAR DISORDER. WE REVIEW THE LITERATURE DERIVED FROM ANIMAL MODELS OF THESE DISORDERS AS WELL AS FROM STUDIES OF POSTMORTEM BRAIN TISSUE FROM HUMAN PATIENTS. WHILE EPIGENETIC STUDIES OF MENTAL ILLNESS REMAIN AT EARLY STAGES, UNDERSTANDING HOW ENVIRONMENTAL FACTORS RECRUIT THE EPIGENETIC MACHINERY WITHIN SPECIFIC BRAIN REGIONS TO CAUSE LASTING CHANGES IN DISEASE SUSCEPTIBILITY AND PATHOPHYSIOLOGY IS REVEALING NEW INSIGHT INTO THE ETIOLOGY AND TREATMENT OF THESE CONDITIONS. 2016 8 110 30 A ROLE FOR ACTIVITY-DEPENDENT EPIGENETICS IN THE DEVELOPMENT AND TREATMENT OF MAJOR DEPRESSIVE DISORDER. CHRONIC STRESSORS, DURING DEVELOPMENTAL SENSITIVE PERIODS AND BEYOND, CONTRIBUTE TO THE RISK OF DEVELOPING PSYCHIATRIC CONDITIONS, INCLUDING MAJOR DEPRESSIVE DISORDER (MDD). EPIGENETIC MECHANISMS INCLUDING DNA METHYLATION AND HISTONE MODIFICATIONS, AT KEY STRESS RESPONSE AND NEUROTROPHIN GENES, ARE INCREASINGLY IMPLICATED IN MEDIATING THIS RISK. ALTHOUGH THE EXACT MECHANISMS THROUGH WHICH STRESSFUL ENVIRONMENTAL STIMULI ALTER THE EPIGENOME ARE STILL UNCLEAR, RESEARCH FROM THE LEARNING AND MEMORY FIELDS INDICATES THAT EPIGENOMIC MARKS CAN BE ALTERED, AT LEAST IN PART, THROUGH CALCIUM-DEPENDENT SIGNALING CASCADES IN DIRECT RESPONSE TO NEURONAL ACTIVITY. IN THIS REVIEW, WE HIGHLIGHT KEY FINDINGS FROM THE STRESS, MDD, AND LEARNING AND MEMORY FIELDS TO PROPOSE A MODEL WHERE STRESS REGULATES DOWNSTREAM CELLULAR FUNCTIONING THROUGH ACTIVITY-DEPENDENT EPIGENETIC CHANGES. FURTHERMORE, WE SUGGEST THAT BOTH TYPICAL AND NOVEL ANTIDEPRESSANT TREATMENTS MAY EXERT POSITIVE INFLUENCE THROUGH SIMILAR, ACTIVITY-DEPENDENT PATHWAYS. 2018 9 5164 33 PRECLINICAL AND CLINICAL EVIDENCE OF DNA METHYLATION CHANGES IN RESPONSE TO TRAUMA AND CHRONIC STRESS. EXPOSURE TO CHRONIC STRESS, EITHER REPEATED SEVERE ACUTE OR MODERATE SUSTAINED STRESS, IS ONE OF THE STRONGEST RISK FACTORS FOR THE DEVELOPMENT OF PSYCHOPATHOLOGIES SUCH AS POST-TRAUMATIC STRESS DISORDER AND DEPRESSION. CHRONIC STRESS IS LINKED WITH SEVERAL LASTING BIOLOGICAL CONSEQUENCES, PARTICULARLY TO THE STRESS ENDOCRINE SYSTEM BUT ALSO AFFECTING INTERMEDIATE PHENOTYPES SUCH AS BRAIN STRUCTURE AND FUNCTION, IMMUNE FUNCTION, AND BEHAVIOR. ALTHOUGH GENETIC PREDISPOSITION CONFERS A PROPORTION OF THE RISK, THE MOST RELEVANT MOLECULAR MECHANISMS DETERMINING THOSE SUSCEPTIBLE AND RESILIENT TO THE EFFECTS OF STRESS AND TRAUMA MAY BE EPIGENETIC. EPIGENETICS REFERS TO THE MECHANISMS THAT REGULATE GENOMIC INFORMATION BY DYNAMICALLY CHANGING THE PATTERNS OF TRANSCRIPTION AND TRANSLATION OF GENES. MOUNTING EVIDENCE FROM PRECLINICAL RODENT AND CLINICAL POPULATION STUDIES STRONGLY SUPPORT THAT EPIGENETIC MODIFICATIONS CAN OCCUR IN RESPONSE TO TRAUMATIC AND CHRONIC STRESS. HERE, WE DISCUSS THIS LITERATURE EXAMINING STRESS-INDUCED EPIGENETIC CHANGES IN PRECLINICAL MODELS AND CLINICAL COHORTS OF STRESS AND TRAUMA OCCURRING EARLY IN LIFE OR IN ADULTHOOD. WE HIGHLIGHT THAT A COMPLEX RELATIONSHIP BETWEEN THE TIMING OF ENVIRONMENTAL STRESSORS AND GENETIC PREDISPOSITIONS LIKELY MEDIATE THE RESPONSE TO CHRONIC STRESS OVER TIME, AND THAT A BETTER UNDERSTANDING OF EPIGENETIC CHANGES IS NEEDED BY FURTHER INVESTIGATIONS IN LONGITUDINAL AND POSTMORTEM BRAIN CLINICAL COHORTS. 2017 10 6676 31 USING EPIGENETIC TOOLS TO INVESTIGATE ANTIDEPRESSANT RESPONSE. MAJOR DEPRESSIVE DISORDER IS A CHRONIC AND DEBILITATING ILLNESS. IT IS MOST COMMONLY TREATED WITH ANTIDEPRESSANT DRUGS, HOWEVER, AS THE MAJORITY OF PATIENTS DO NOT RESPOND ON THEIR FIRST TRIAL OR FOLLOWING SEVERAL ADEQUATE TRIALS, THERE IS GREAT INTEREST IN IDENTIFYING BIOLOGICAL FACTORS THAT MAY HELP SELECT THE MOST APPROPRIATE TREATMENT FOR EACH PATIENT AND IN UNDERSTANDING BIOLOGICAL PROCESSES THAT MEDIATE TREATMENT RESPONSE. EPIGENETIC FACTORS, SUCH AS NON-CODING RNAS (NCRNAS), HOLD POTENTIAL AS BIOMARKERS OF ANTIDEPRESSANT RESPONSE. IN THIS CHAPTER, WE REVIEW KEY METHODOLOGICAL CONSIDERATIONS WHEN INVESTIGATING NCRNA BIOMARKERS, INCLUDING BIOLOGICAL SAMPLES AND TECHNOLOGIES WHICH HAVE BEEN USED IN THESE STUDIES. SECONDLY, WE SUMMARIZE FINDINGS FROM STUDIES INVESTIGATING NCRNAS IN ANTIDEPRESSANT TREATMENT RESPONSE. FINALLY, WE DISCUSS SOME OF THE FUTURE DIRECTIONS WHICH WILL BE NECESSARY FOR THE DEVELOPMENT OF CLINICALLY RELEVANT EPIGENETIC TOOLS. 2018 11 1329 33 DEPRESSION ASSOCIATED WITH DIABETES: FROM PATHOPHYSIOLOGY TO TREATMENT. DIABETES IS A CHRONIC AND PROGRESSIVE SYNDROME COMMONLY ASSOCIATED WITH SEVERAL NEUROPSYCHIATRIC COMORBITIES, OF WHICH DEPRESSION IS THE MOST STUDIED. THE PREVALENCE OF DEPRESSION IS ABOUT TWO OR THREE TIMES HIGHER IN DIABETIC PATIENTS COMPARED TO THE GENERAL POPULATION. IT IS BELIEVED THAT THE DIABETES - DEPRESSION RELATION MAY BE BIDIRECTIONAL, I.E., THE DEPRESSION CAN LEAD TO DIABETES AND CONVERSELY DIABETES COULD FACILITATE THE EMERGENCE OF DEPRESSION. DEPRESSION IS ONE OF THE MOST NEGLECTED SYMPTOMS IN DIABETIC PATIENTS AND IS DIRECTLY LINKED WITH LOWERING OF QUALITY OF LIFE. THE TREATMENT OF DEPRESSION IN THESE PATIENTS IS STILL QUITE INEFFECTIVE AND IN MANY CASES TREATMENTREFRACTORY. FURTHERMORE, SOME OF THE FIRST CHOICE DRUGS USED TO TREAT THE DEPRESSION AFFECT THE BLOOD GLUCOSE CONTROL, AGGRAVATING THE HYPERGLYCEMIC STATE. THESE ISSUES UNDERSCORE THE URGENCY IN STUDIES SEARCHING FOR NEW PHARMACOLOGICAL TARGETS FOR THE TREATMENT OF DEPRESSION ASSOCIATED WITH DIABETES. FOR THIS, A BETTER UNDERSTANDING OF THE PATHOPHYSIOLOGY THAT RELATES THIS COMORBIDITY BECOMES CRITICAL. IN THIS RESPECT, THIS REVIEW WILL FOCUS ON SOME HYPOTHESES THAT HAVE BEEN PROPOSED TO EXPLAIN THE MECHANISMS UNDERLYING DEPRESSION ASSOCIATED WITH DIABETES, HIGHLIGHTING THE TREATMENT OPTIONS CURRENTLY AVAILABLE AND THEIR LIMITATIONS. AMONG THESE HYPOTHESES, WE WILL POINT OUT THE HYPERGLYCEMIA AS A PRIMARY METABOLIC CAUSE OF THE DEPRESSION DEVELOPMENT, THE INVOLVEMENT OF THE DYSREGULATION OF HYPOTHALAMIC PITUITARY-ADRENAL (HPA) AXIS AND OF NEUROTRANSMITTER SYSTEMS, SPECIALLY MONOAMINERGIC SYSTEM. BESIDES, THE ROLE OF OXIDATIVE STRESS, NEUROINFLAMMATION AND CELL DEATH, ESPECIALLY IN HIPPOCAMPUS AND PREFRONTAL CORTEX, BRAIN AREAS IMPORTANT FOR THE MEDIATION AND MODULATION OF EMOTIONAL BEHAVIOR WILL ALSO BE DISCUSSED. FINALLY, WE WILL BRING UP THE INFLUENCE OF THE EPIGENETIC REGULATION WITH RESPECT TO NEUROPSYCHIATRIC DISORDERS. 2016 12 3404 36 HOW EPIGENETICS IMPACTS ON HUMAN DISEASES. EPIGENETICS IS A RAPIDLY GROWING FIELD OF BIOLOGY THAT STUDIES THE CHANGES IN GENE EXPRESSION THAT ARE NOT DUE TO ALTERATIONS IN THE DNA SEQUENCE BUT RATHER THE CHEMICAL MODIFICATIONS OF DNA AND ITS ASSOCIATED PROTEINS. EPIGENETIC MECHANISMS CAN PROFOUNDLY INFLUENCE GENE EXPRESSION, CELL DIFFERENTIATION, TISSUE DEVELOPMENT, AND DISEASE SUSCEPTIBILITY. UNDERSTANDING EPIGENETIC CHANGES IS ESSENTIAL TO ELUCIDATE THE MECHANISMS UNDERLYING THE INCREASINGLY RECOGNIZED ROLE OF ENVIRONMENTAL AND LIFESTYLE FACTORS IN HEALTH AND DISEASE AND THE INTERGENERATIONAL TRANSMISSION OF PHENOTYPES. RECENT STUDIES SUGGEST EPIGENETICS MAY BE CRITICAL IN VARIOUS DISEASES, FROM CARDIOVASCULAR DISEASE AND CANCER TO NEURODEVELOPMENTAL AND NEURODEGENERATIVE DISORDERS. EPIGENETIC MODIFICATIONS ARE POTENTIALLY REVERSIBLE AND COULD PROVIDE NEW THERAPEUTIC AVENUES FOR TREATING THESE DISEASES USING EPIGENETIC MODULATORS. MOREOVER, EPIGENETICS PROVIDE INSIGHT INTO DISEASE PATHOGENESIS AND BIOMARKERS FOR DISEASE DIAGNOSIS AND RISK STRATIFICATION. NEVERTHELESS, EPIGENETIC INTERVENTIONS HAVE THE POTENTIAL FOR UNINTENDED CONSEQUENCES AND MAY POTENTIALLY LEAD TO INCREASED RISKS OF UNEXPECTED OUTCOMES, SUCH AS ADVERSE DRUG REACTIONS, DEVELOPMENTAL ABNORMALITIES, AND CANCER. THEREFORE, RIGOROUS STUDIES ARE ESSENTIAL TO MINIMIZE THE RISKS ASSOCIATED WITH EPIGENETIC THERAPIES AND TO DEVELOP SAFE AND EFFECTIVE INTERVENTIONS FOR IMPROVING HUMAN HEALTH. THIS ARTICLE PROVIDES A SYNTHETIC AND HISTORICAL VIEW OF THE ORIGIN OF EPIGENETICS AND SOME OF THE MOST RELEVANT ACHIEVEMENTS. 2023 13 2526 32 EPIGENETICS APPLIED TO PSYCHIATRY: CLINICAL OPPORTUNITIES AND FUTURE CHALLENGES. PSYCHIATRIC DISORDERS ARE CLINICALLY HETEROGENEOUS AND DEBILITATING CHRONIC DISEASES RESULTING FROM A COMPLEX INTERPLAY BETWEEN GENE VARIANTS AND ENVIRONMENTAL FACTORS. EPIGENETIC PROCESSES, SUCH AS DNA METHYLATION AND HISTONE POSTTRANSLATIONAL MODIFICATIONS, INSTRUCT THE CELL/TISSUE TO CORRECTLY INTERPRET EXTERNAL SIGNALS AND ADJUST ITS FUNCTIONS ACCORDINGLY. GIVEN THAT EPIGENETIC MODIFICATIONS ARE SENSITIVE TO ENVIRONMENT, STABLE, AND REVERSIBLE, EPIGENETIC STUDIES IN PSYCHIATRY COULD REPRESENT A PROMISING APPROACH TO BETTER UNDERSTANDING AND TREATING DISEASE. IN THE PRESENT REVIEW, WE AIM TO DISCUSS THE CLINICAL OPPORTUNITIES AND CHALLENGES ARISING FROM THE EPIGENETIC RESEARCH IN PSYCHIATRY. USING SELECTED EXAMPLES, WE FIRST RECAPITULATE KEY FINDINGS SUPPORTING THE ROLE OF ADVERSE LIFE EVENTS, ALONE OR IN COMBINATION WITH GENETIC RISK, IN EPIGENETIC PROGRAMMING OF NEUROPSYCHIATRIC SYSTEMS. EPIGENETIC STUDIES FURTHER REPORT ENCOURAGING FINDINGS ABOUT THE USE OF METHYLATION CHANGES AS DIAGNOSTIC MARKERS OF DISEASE PHENOTYPE AND PREDICTIVE TOOLS OF PROGRESSION AND RESPONSE TO TREATMENT. THEN WE DISCUSS THE POTENTIAL OF USING TARGETED EPIGENETIC PHARMACOTHERAPY, COMBINED WITH PSYCHOSOCIAL INTERVENTIONS, FOR FUTURE PERSONALIZED MEDICINE FOR PATIENTS. FINALLY, WE REVIEW THE METHODOLOGICAL LIMITATIONS THAT COULD HINDER INTERPRETATION OF EPIGENETIC DATA IN PSYCHIATRY. THEY MAINLY ARISE FROM HETEROGENEITY AT THE INDIVIDUAL AND TISSUE LEVEL AND REQUIRE FUTURE STRATEGIES IN ORDER TO REINFORCE THE BIOLOGICAL RELEVANCE OF EPIGENETIC DATA AND ITS TRANSLATIONAL USE IN PSYCHIATRY. OVERALL, WE SUGGEST THAT EPIGENETICS COULD PROVIDE NEW INSIGHTS INTO A MORE COMPREHENSIVE INTERPRETATION OF MENTAL ILLNESS AND MIGHT EVENTUALLY IMPROVE THE NOSOLOGY, TREATMENT, AND PREVENTION OF PSYCHIATRIC DISORDERS. 2018 14 6414 36 THE STRESSED SYNAPSE 2.0: PATHOPHYSIOLOGICAL MECHANISMS IN STRESS-RELATED NEUROPSYCHIATRIC DISORDERS. STRESS IS A PRIMARY RISK FACTOR FOR SEVERAL NEUROPSYCHIATRIC DISORDERS. EVIDENCE FROM PRECLINICAL MODELS AND CLINICAL STUDIES OF DEPRESSION HAVE REVEALED AN ARRAY OF STRUCTURAL AND FUNCTIONAL MALADAPTIVE CHANGES, WHEREBY ADVERSE ENVIRONMENTAL FACTORS SHAPE THE BRAIN. THESE CHANGES, OBSERVED FROM THE MOLECULAR AND TRANSCRIPTIONAL LEVELS THROUGH TO LARGE-SCALE BRAIN NETWORKS, TO THE BEHAVIOURS REVEAL A COMPLEX MATRIX OF INTERRELATED PATHOPHYSIOLOGICAL PROCESSES THAT DIFFER BETWEEN SEXES, PROVIDING INSIGHT INTO THE POTENTIAL UNDERPINNINGS OF THE SEX BIAS OF NEUROPSYCHIATRIC DISORDERS. ALTHOUGH MANY PRECLINICAL STUDIES USE CHRONIC STRESS PROTOCOLS, LONG-TERM CHANGES ARE ALSO INDUCED BY ACUTE EXPOSURE TO TRAUMATIC STRESS, OPENING A PATH TO IDENTIFY DETERMINANTS OF RESILIENT VERSUS SUSCEPTIBLE RESPONSES TO BOTH ACUTE AND CHRONIC STRESS. EPIGENETIC REGULATION OF GENE EXPRESSION HAS EMERGED AS A KEY PLAYER UNDERLYING THE PERSISTENT IMPACT OF STRESS ON THE BRAIN. INDEED, HISTONE MODIFICATION, DNA METHYLATION AND MICRORNAS ARE CLOSELY INVOLVED IN MANY ASPECTS OF THE STRESS RESPONSE AND REVEAL THE GLUTAMATE SYSTEM AS A KEY PLAYER. THE SUCCESS OF KETAMINE HAS STIMULATED A WHOLE LINE OF RESEARCH AND DEVELOPMENT ON DRUGS DIRECTLY OR INDIRECTLY TARGETING GLUTAMATE FUNCTION. HOWEVER, THE CHALLENGE OF TRANSLATING THE EMERGING UNDERSTANDING OF STRESS PATHOPHYSIOLOGY INTO EFFECTIVE CLINICAL TREATMENTS REMAINS A MAJOR CHALLENGE. 2022 15 738 31 CANCER SUSCEPTIBILITY: EPIGENETIC MANIFESTATION OF ENVIRONMENTAL EXPOSURES. CANCER IS A DISEASE THAT RESULTS FROM BOTH GENETIC AND EPIGENETIC CHANGES. DISCORDANT PHENOTYPES AND VARYING INCIDENCES OF COMPLEX DISEASES SUCH AS CANCER IN MONOZYGOTIC TWINS AS WELL AS GENETICALLY IDENTICAL LABORATORY ANIMALS HAVE LONG BEEN ATTRIBUTED TO DIFFERENCES IN ENVIRONMENTAL EXPOSURES. ACCUMULATING EVIDENCE INDICATES, HOWEVER, THAT DISPARITIES IN GENE EXPRESSION RESULTING FROM VARIABLE MODIFICATIONS IN DNA METHYLATION AND CHROMATIN STRUCTURE IN RESPONSE TO THE ENVIRONMENT ALSO PLAY A ROLE IN DIFFERENTIAL SUSCEPTIBILITY TO DISEASE. DESPITE A GROWING CONSENSUS ON THE IMPORTANCE OF EPIGENETICS IN THE ETIOLOGY OF CHRONIC HUMAN DISEASES, THE GENES MOST PRONE TO EPIGENETIC DYSREGULATION ARE INCOMPLETELY DEFINED. MOREOVER, NEITHER THE ENVIRONMENTAL AGENTS MOST STRONGLY AFFECTING THE EPIGENOME NOR THE CRITICAL WINDOWS OF VULNERABILITY TO ENVIRONMENTALLY INDUCED EPIGENETIC ALTERATIONS ARE ADEQUATELY CHARACTERIZED. THESE MAJOR DEFICITS IN KNOWLEDGE MARKEDLY IMPAIR OUR ABILITY TO UNDERSTAND FULLY THE ETIOLOGY OF CANCER AND THE IMPORTANCE OF THE EPIGENOME IN DIAGNOSING AND PREVENTING THIS DEVASTATING DISEASE. 2007 16 2186 32 EPIGENETIC MECHANISMS UNDERLYING PATHOBIOLOGY OF ALCOHOL USE DISORDER. PURPOSE OF REVIEW: CHRONIC ALCOHOL USE IS A WORLDWIDE PROBLEM WITH MULTIFACETED CONSEQUENCES INCLUDING MULTIPLYING MEDICAL COSTS AND SEQUELAE, SOCIETAL EFFECTS LIKE DRUNK DRIVING AND ASSAULT, AND LOST ECONOMIC PRODUCTIVITY. THESE LARGE-SCALE OUTCOMES ARE DRIVEN BY THE CONSUMPTION OF ETHANOL, A SMALL PERMEABLE MOLECULE THAT HAS MYRIAD EFFECTS IN THE HUMAN BODY, PARTICULARLY IN THE LIVER AND BRAIN. IN THIS REVIEW, WE HAVE SUMMARIZED EFFECTS OF ACUTE AND CHRONIC ALCOHOL CONSUMPTION ON EPIGENETIC MECHANISMS THAT MAY DRIVE PATHOBIOLOGY OF ALCOHOL USE DISORDER (AUD) WHILE IDENTIFYING AREAS OF NEED FOR FUTURE RESEARCH. RECENT FINDINGS: EPIGENETICS HAS EMERGED AS AN INTERESTING FIELD OF BIOLOGY AT THE INTERSECTION OF GENETICS AND THE ENVIRONMENT, AND ETHANOL IN PARTICULAR HAS BEEN IDENTIFIED AS A POTENT MODULATOR OF THE EPIGENOME WITH VARIOUS EFFECTS ON DNA METHYLATION, HISTONE MODIFICATIONS, AND NON-CODING RNAS. THESE CHANGES ALTER CHROMATIN DYNAMICS AND REGULATE GENE EXPRESSION THAT CONTRIBUTE TO BEHAVIORAL AND PHYSIOLOGICAL CHANGES LEADING TO THE DEVELOPMENT OF AUD PSYCHOPATHOLOGY AND CANCER PATHOLOGY. SUMMARY: EVIDENCE AND DISCUSSION PRESENTED HERE FROM PRECLINICAL RESULTS AND AVAILABLE TRANSLATIONAL STUDIES HAVE INCREASED OUR KNOWLEDGE OF THE EPIGENETIC EFFECTS OF ALCOHOL CONSUMPTION. THESE STUDIES HAVE IDENTIFIED TARGETS THAT CAN BE USED TO DEVELOP BETTER THERAPIES TO REDUCE CHRONIC ALCOHOL ABUSE AND MITIGATE ITS SOCIETAL BURDEN AND PATHOPHYSIOLOGY. 2020 17 2523 36 EPIGENETICS AND THE TRANSITION FROM ACUTE TO CHRONIC PAIN. OBJECTIVE: THE OBJECTIVE OF THIS STUDY WAS TO REVIEW THE EPIGENETIC MODIFICATIONS INVOLVED IN THE TRANSITION FROM ACUTE TO CHRONIC PAIN AND TO IDENTIFY POTENTIAL TARGETS FOR THE DEVELOPMENT OF NOVEL, INDIVIDUALIZED PAIN THERAPEUTICS. BACKGROUND: EPIGENETICS IS THE STUDY OF HERITABLE MODIFICATIONS IN GENE EXPRESSION AND PHENOTYPE THAT DO NOT REQUIRE A CHANGE IN GENETIC SEQUENCE TO MANIFEST THEIR EFFECTS. ENVIRONMENTAL TOXINS, MEDICATIONS, DIET, AND PSYCHOLOGICAL STRESSES CAN ALTER EPIGENETIC PROCESSES SUCH AS DNA METHYLATION, HISTONE ACETYLATION, AND RNA INTERFERENCE. AS EPIGENETIC MODIFICATIONS POTENTIALLY PLAY AN IMPORTANT ROLE IN INFLAMMATORY CYTOKINE METABOLISM, STEROID RESPONSIVENESS, AND OPIOID SENSITIVITY, THEY ARE LIKELY KEY FACTORS IN THE DEVELOPMENT OF CHRONIC PAIN. ALTHOUGH OUR KNOWLEDGE OF THE HUMAN GENETIC CODE AND DISEASE-ASSOCIATED POLYMORPHISMS HAS GROWN SIGNIFICANTLY IN THE PAST DECADE, WE HAVE NOT YET BEEN ABLE TO ELUCIDATE THE MECHANISMS THAT LEAD TO THE DEVELOPMENT OF PERSISTENT PAIN AFTER NERVE INJURY OR SURGERY. DESIGN: THIS IS A FOCUSED LITERATURE REVIEW OF EPIGENETIC SCIENCE AND ITS RELATIONSHIP TO CHRONIC PAIN. RESULTS: SIGNIFICANT LABORATORY AND CLINICAL DATA SUPPORT THE NOTION THAT EPIGENETIC MODIFICATIONS ARE AFFECTED BY THE ENVIRONMENT AND LEAD TO DIFFERENTIAL GENE EXPRESSION. SIMILAR TO MECHANISMS INVOLVED IN THE DEVELOPMENT OF CANCER, NEURODEGENERATIVE DISEASE, AND INFLAMMATORY DISORDERS, THE LITERATURE ENDORSES AN IMPORTANT POTENTIAL ROLE FOR EPIGENETICS IN CHRONIC PAIN. CONCLUSIONS: EPIGENETIC ANALYSIS MAY IDENTIFY MECHANISMS CRITICAL TO THE DEVELOPMENT OF CHRONIC PAIN AFTER INJURY, AND MAY PROVIDE NEW PATHWAYS AND TARGET MECHANISMS FOR FUTURE DRUG DEVELOPMENT AND INDIVIDUALIZED MEDICINE. 2012 18 2598 29 EPIGENETICS OF THE DEPRESSED BRAIN: ROLE OF HISTONE ACETYLATION AND METHYLATION. MAJOR DEPRESSIVE DISORDER IS A CHRONIC, REMITTING SYNDROME INVOLVING WIDELY DISTRIBUTED CIRCUITS IN THE BRAIN. STABLE ALTERATIONS IN GENE EXPRESSION THAT CONTRIBUTE TO STRUCTURAL AND FUNCTIONAL CHANGES IN MULTIPLE BRAIN REGIONS ARE IMPLICATED IN THE HETEROGENEITY AND PATHOGENESIS OF THE ILLNESS. EPIGENETIC EVENTS THAT ALTER CHROMATIN STRUCTURE TO REGULATE PROGRAMS OF GENE EXPRESSION HAVE BEEN ASSOCIATED WITH DEPRESSION-RELATED BEHAVIOR, ANTIDEPRESSANT ACTION, AND RESISTANCE TO DEPRESSION OR 'RESILIENCE' IN ANIMAL MODELS, WITH INCREASING EVIDENCE FOR SIMILAR MECHANISMS OCCURRING IN POSTMORTEM BRAINS OF DEPRESSED HUMANS. IN THIS REVIEW, WE DISCUSS RECENT ADVANCES IN OUR UNDERSTANDING OF EPIGENETIC CONTRIBUTIONS TO DEPRESSION, IN PARTICULAR THE ROLE OF HISTONE ACETYLATION AND METHYLATION, WHICH ARE REVEALING NOVEL MECHANISTIC INSIGHT INTO THE SYNDROME THAT MAY AID IN THE DEVELOPMENT OF NOVEL TARGETS FOR DEPRESSION TREATMENT. 2013 19 2282 32 EPIGENETIC REGULATION IN EXPOSOME-INDUCED TUMORIGENESIS: EMERGING ROLES OF NCRNAS. ENVIRONMENTAL FACTORS, INCLUDING POLLUTANTS AND LIFESTYLE, CONSTITUTE A SIGNIFICANT ROLE IN SEVERE, CHRONIC PATHOLOGIES WITH AN ESSENTIAL SOCIETAL, ECONOMIC BURDEN. THE MEASUREMENT OF ALL ENVIRONMENTAL EXPOSURES AND ASSESSING THEIR CORRELATION WITH EFFECTS ON INDIVIDUAL HEALTH IS DEFINED AS THE EXPOSOME, WHICH INTERACTS WITH OUR UNIQUE CHARACTERISTICS SUCH AS GENETICS, PHYSIOLOGY, AND EPIGENETICS. EPIGENETICS INVESTIGATES MODIFICATIONS IN THE EXPRESSION OF GENES THAT DO NOT DEPEND ON THE UNDERLYING DNA SEQUENCE. SOME STUDIES HAVE CONFIRMED THAT ENVIRONMENTAL FACTORS MAY PROMOTE DISEASE IN INDIVIDUALS OR SUBSEQUENT PROGENY THROUGH EPIGENETIC ALTERATIONS. VARIATIONS IN THE EPIGENETIC MACHINERY CAUSE A SPECTRUM OF DIFFERENT DISORDERS SINCE THESE MECHANISMS ARE MORE SENSITIVE TO THE ENVIRONMENT THAN THE GENOME, DUE TO THE INHERENT REVERSIBLE NATURE OF THE EPIGENETIC LANDSCAPE. SEVERAL EPIGENETIC MECHANISMS, INCLUDING MODIFICATIONS IN DNA (E.G., METHYLATION), HISTONES, AND NONCODING RNAS CAN CHANGE GENOME EXPRESSION UNDER THE EXOGENOUS INFLUENCE. NOTABLY, THE ROLE OF LONG NONCODING RNAS IN EPIGENETIC PROCESSES HAS NOT BEEN WELL EXPLORED IN THE CONTEXT OF EXPOSOME-INDUCED TUMORIGENESIS. IN THE PRESENT REVIEW, OUR SCOPE IS TO PROVIDE RELEVANT EVIDENCE INDICATING THAT EPIGENETIC ALTERATIONS MEDIATE THOSE DETRIMENTAL EFFECTS CAUSED BY EXPOSURE TO ENVIRONMENTAL TOXICANTS, FOCUSING MAINLY ON A MULTI-STEP REGULATION BY DIVERSE NONCODING RNAS SUBTYPES. 2022 20 2573 27 EPIGENETICS OF DRUG ABUSE: PREDISPOSITION OR RESPONSE. DRUG ADDICTION CONTINUES TO BE A SERIOUS MEDICAL AND SOCIAL PROBLEM. VULNERABILITY TO DEVELOP AN ADDICTION TO DRUGS IS DEPENDENT ON GENETIC, ENVIRONMENTAL, SOCIAL AND BIOLOGICAL FACTORS. IN PARTICULAR, THE INTERACTIONS OF ENVIRONMENTAL AND GENETIC FACTORS INDICATE THE SIGNIFICANCE OF EPIGENETIC MECHANISMS, WHICH HAVE BEEN FOUND TO OCCUR IN RESPONSE TO ILLICIT DRUG USE OR AS UNDERLYING FACTORS IN CHRONIC SUBSTANCE ABUSE AND RELAPSE. EPIGENETICS IS DEFINED AS THE HERITABLE AND POSSIBLY REVERSIBLE MODIFICATIONS IN GENE EXPRESSION THAT DO NOT INVOLVE ALTERATIONS IN THE DNA SEQUENCE. THIS REVIEW DISCUSSES THE VARIOUS TYPES OF EPIGENETIC MODIFICATIONS AND THEIR RELEVANCE TO DRUG ADDICTION TO ELUCIDATE WHETHER EPIGENETICS IS A PREDISPOSING FACTOR, OR A RESPONSE TO, DEVELOPING AN ADDICTION TO DRUGS OF ABUSE. 2012