Behavioral epigenetics is the field of study examining the role of epigenetics in shaping animal (including human) behaviour. It is an experimental science that seeks to explain how nurture shapes nature, where nature refers to biological heredity and nurture refers to virtually everything that occurs during the life-span (e.g., social-experience, diet and nutrition, and exposure to toxins). Behavioral epigenetics attempts to provide a framework for understanding how the expression of genes is influenced by experiences and the environment to produce individual differences in behaviour, cognition personality, and mental health.
Epigenetic gene regulation involves changes other than to the sequence of DNA and includes changes to histones (proteins around which DNA is wrapped) and DNA methylation. These epigenetic changes can influence the growth of neurons in the developing brain as well as modify activity of the neurons in the adult brain. Together, these epigenetic changes on neuron structure and function can have a marked influence on an organism's behavior.
- 1 Background
- 2 Discovery
- 3 Research into epigenetics in psychology
- 4 Cognition
- 5 Psychopathology and mental health
- 6 Limitations and future direction
- 7 See also
- 8 References
- 9 Further reading
- 10 External links
In biology, and specifically genetics, epigenetics is the study of heritable changes in gene activity which are not caused by changes in the DNA sequence; the term can also be used to describe the study of stable, long-term alterations in the transcriptional potential of a cell that are not necessarily heritable.
Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Gene expression can be controlled through the action of repressor proteins that attach to silencer regions of the DNA.
Epigenetics has a strong influence on the development of an organism and can alter the expression of individual traits. Epigenetic changes occur not only in the developing fetus, but also in individuals throughout the human life-span. Because some epigenetic modifications can be passed from one generation to the next, subsequent generations may be affected by the epigenetic changes that took place in the parents.
The first documented example of epigenetics affecting behavior was provided by Michael Meaney and Moshe Szyf. While working at McGill University in Montréal in 2004, they discovered that the type and amount of nurturing a mother rat provides in the early weeks of the rat's infancy determines how that rat responds to stress later in life. Immediately after birth, they found that methyl groups repress the glucocorticoid receptor gene in all rat pups, making the gene unable to unwind from the histone in order to be transcribed, causing a decreased stress response. Nurturing behaviours from the mother rat were found to stimulate activation of stress signalling pathways that remove methyl groups from DNA. This releases the tightly wound gene, exposing it for transcription. The glutocorticoid gene is activated, resulting in lowered stress response. Rat pups that receive a less nurturing upbringing are more sensitive to stress throughout their life-span. This stress sensitivity is linked to a down-regulation in the expression of the glucocorticoid receptor in the brain. In turn, this down-regulation was found to be a consequence of the extent of methylation in the promoter region of the glucocorticoid receptor gene.
This pioneering work in rodents has been difficult to replicate in humans because of a general lack of availability human brain tissue for measurement of epigenetic changes.
Research into epigenetics in psychology
Anxiety and risk-taking
In a small clinical study in humans published in 2008, epigenetic differences were linked to differences in risk-taking and reactions to stress in monozygotic twins. The study identified twins with different life paths, wherein one twin displayed risk-taking behaviours, and the other displayed risk-averse behaviours. Epigenetic differences in DNA methylation of the CpG islands proximal to the DLX1 gene correlated with the differing behavior. The authors of the twin study noted that despite the associations between epigenetic markers and differences personality traits, epigenetics cannot predict complex decision-making processes like career selection.
Studies in rats have shown correlations between maternal care in terms of the parental licking of offspring and epigenetic changes. A high level of licking results in a long-term reduction in stress response as measured behaviorally and biochemically in elements of the hypothalamic-pituitary-adrenal axis (HPA). Further, decreased DNA methylation of the glucocorticoid receptor gene were found in offspring that experienced a high level of licking; the glucorticoid receptor plays a key role in regulating the HPA. The opposite is found in offspring that experienced low levels of licking, and when pups are switched, the epigenetic changes are reversed. This research provides evidence for an underlying epigenetic mechanism. Further support comes from experiments with the same setup, using drugs that can increase or decrease methylation. Finally, epigenetic variations in parental care can be passed down from one generation to the next, from mother to female offspring. Female offspring who received increased parental care (i.e., high licking) became mothers who engaged in high licking and offspring who received less licking became mothers who engaged in less licking.
In humans, a small clinical research study showed the relationship between prenatal exposure to maternal mood and genetic expression resulting in increased reactivity to stress in offspring. Three groups of infants were examined: those born to mothers medicated for depression with serotonin reuptake inhibitors; those born to depressed mothers not being treated for depression; and those born to non-depressed mothers. Prenatal exposure to depressed/anxious mood was associated with increased DNA methylation at the glucocorticoid receptor gene and to increased HPA axis stress reactivity. The findings were independent of whether the mothers were being pharmaceutically treated for depression.
Learning and memory
A 2010 review discusses the role of DNA methylation in memory formation and storage, but the precise mechanisms involving neuronal function, memory, and methylation reversal remain unclear.
Studies in rodents have found that the environment exerts an influence on epigenetic changes related to cognition, in terms of learning and memory; environmental enrichment correlated with increased histone acetylation, and verification by admininistering histone deacetylase inhibitors induced sprouting of dendrites, an increased number of synapses, and reinstated learning behaviour and access to long-term memories. Research has also linked learning and long-term memory formation to reversible epigenetic changes in the hippocampus and cortex in animals with normal-functioning, non-damaged brains. In human studies, post-mortem brains from Alzheimer's patients show increased histone de-acetylase levels.
Psychopathology and mental health
Substance use and addiction
Environmental and epigenetic influences seem to work together to increase the risk of addiction. For example, environmental stress has been shown to increase the risk of substance use. In an attempt to cope with stress, alcohol and drugs can be used as an escape. Once substance use commences, however, epigenetic alterations may further exacerbate the biological and behavioural changes associated with addiction.
Even short-term substance use can produce long-lasting epigenetic changes in the brain of rodents, via DNA methylation and histone modification. Epigenetic modifications have been observed in studies in rodents of alcohol, nicotine, cocaine, amphetamines, and opiate use. Specifically, these epigenetic changes modify gene expression, which in turn increases the vulnerability of an individual to engage in future, repeated substance use. In turn, increased substance use results in even greater epigenetic changes in the rodent brain's pleasure-reward areas (e.g., in the nucleus accumbens). Hence, a cycle emerges whereby changes in the pleasure-reward areas contribute to the long-lasting neural and behavioural changes associated with the increased likelihood of addiction, the maintenance of addiction and relapse. In humans, alcohol consumption has been shown to produce epigenetic changes that contribute to the increased craving of alcohol. As such, epigenetic modifications may play a part in the progression from the controlled intake to the loss of control of alcohol consumption. These alterations may be long-term, as is evidenced in smokers who still possess nicotine-related epigenetic changes ten years after cessation. Therefore, epigenetic modifications may account for some of the behavioural changes generally associated with addiction. These include: repetitive habits that increase the risk of disease, and personal and social problems; need for immediate gratification; high rates of relapse following treatment; and, the feeling of loss of control.
Evidence for related epigenetic changes has come from human studies on alcohol, nicotine and opiate use. Evidence for epigenetic changes stemming from amphetamine and cocaine use derives from animal studies. In animals, drug-related epigenetic changes in fathers have also been shown to negatively affect offspring in terms of poorer spatial working memory, decreased attention and decreased cerebral volume.
Eating disorders and obesity
Epigenetic changes may help to facilitate the development and maintenance of eating disorders via influences in the early environment and throughout the life-span. Pre-natal epigenetic changes due to maternal stress, behaviour and diet may later predispose offspring to persistent, increased anxiety and anxiety disorders. These anxiety issues can precipitate the onset of eating disorders and obesity, and persist even after recovery from the eating disorders.
Epigenetic differences accumulating over the life-span may account for the incongruent differences in eating disorders observed in monozygotic twins. At puberty, sex hormones may exert epigenetic changes (via DNA methylation) on gene expression, thus accounting for higher rates of eating disorders in men as compared to women. Overall, epigenetics contribute to persistent, unregulated self-control behaviours related to the urge to binge.
- For more details on this topic, see Epigenetics of schizophrenia.
Epigenetic changes including hypomethylation of glutamatergic genes (i.e., NMDA-receptor-subunit gene NR3B and the promoter of the AMPA-receptor-subunit gene GRIA2) in the post-mortem human brains of schizophrenics are associated with increased levels of the neurotoxin glutamate. Since glutamate is the most prevalent, fast, excitatory neurotoxin, increased levels may result in the psychotic episodes related to schizophrenia. Interestingly, epigenetic changes affecting a greater number of genes have been detected in men with schizophrenia as compared to women with the illness.
Population studies have established a strong association linking schizophrenia in children born to older fathers. Specifically, children born to fathers over the age of 35 years are up to three times more likely to develop schizophrenia. Epigenetic dysfunction in human male sperm cells, affecting numerous genes, have been shown to increase with age. This provides a possible explanation for increased rates of the disease in men.[not in citation given] To this end, toxins (e.g., air pollutants) have been shown to increase epigenetic differentiation. Animals exposed to ambient air from steel mills and highways show drastic epigenetic changes that persist after removal from the exposure. Therefore, similar epigenetic changes in older human fathers are likely. Schizophrenia studies provide evidence that the nature versus nurture debate in the field of psychopathology should be re-evaluated to accommodate the concept that genes and the environment work in tandem. As such, many other environmental factors (e.g., nutritional deficiencies and cannabis use) have been proposed to increase the susceptibility of psychotic disorders like schizophrenia via epigenetics.
Evidence for epigenetic modifications for bipolar disorder is unclear. One study found hypomethylation of a gene promoter of a prefrontal lobe enzyme (i.e., membrane-bound catechol-O-methyl transferase, or COMT) in post-mortem brain samples from individuals with bipolar disorder. COMT is an enzyme that metabolizes dopamine in the synapse. These findings suggest that the hypomethylation of the promoter results in over-expression of the enzyme. In turn, this results in increased degradation of dopamine levels in the brain. These findings provide evidence that epigenetic modification in the prefrontal lobe is a risk factor for bipolar disorder. However, a second study found no epigenetic differences in post-mortem brains from bipolar individuals.
Major depressive disorder
The causes of major depressive disorder (MDD) are poorly understood from a neuroscience perspective. The epigenetic changes leading to changes in glucocorticoid receptor expression and its effect on the HPA stress system discussed above, have also been applied to attempts to understand MDD.
Much of the work in animal models has focused on the indirect downregulation of brain derived neurotrophic factor (BDNF) by over-activation of the stress axis. Studies in various rodent models of depression, often involving induction of stress, have found direct epigenetic modulation of BDNF as well.
Epigenetics may be relevant to aspects of psychopathic behaviour through methylation and histone modification. These processes are heritable but can also be influenced by environmental factors such as smoking and abuse. Epigenetics may be one of the mechanisms through which the environment can impact the expression of the genome. Studies have also linked methylation of genes associated with nicotine and alcohol dependence in women, ADHD, and drug abuse. It is probable that epigenetic regulation as well as methylation profiling will play an increasingly important role in the study of the play between the environment and genetics of psychopaths.
A study of the brains of 24 suicide completers, 12 of whom had a history of child abuse and 12 who did not, found decreased levels of glucocorticoid receptor in victims of child abuse and associated epigenetic changes.
Limitations and future direction
Many researchers contribute information to the Human Epigenome Consortium. The aim of future research is to reprogram epigenetic changes to help with addiction, mental illness, age related changes, memory decline, and other issues. However, the sheer volume of consortium-based data makes analysis difficult. Most studies also focus on one gene. In actuality, many genes and interactions between them likely contribute to individual differences in personality, behaviour and health. As social scientists often work with many variables, determining the number of affected genes also poses methodological challenges. More collaboration between medical researchers, geneticists and social scientists has been advocated to increase knowledge in this field of study.
Limited access to human brain tissue poses a challenge to conducting human research. Not yet knowing if epigenetic changes in the blood and (non-brain) tissues parallel modifications in the brain, places even greater reliance on brain research. Although some epigenetic studies have translated findings from animals to humans, some researchers caution about the extrapolation of animal studies to humans. One view notes that when animal studies do not consider how the subcellular and cellular components, organs and the entire individual interact with the influences of the environment, results are too reductive to explain behaviour.
Some researchers note that epigenetic perspectives will likely be incorporated into pharmacological treatments. Others caution that more research is necessary as drugs are known to modify the activity of multiple genes and may, therefore, cause serious side effects. However, the ultimate goal is to find patterns of epigenetic changes that can be targeted to treat mental illness, and reverse the effects of childhood stressors, for example. If such treatable patterns eventually become well-established, the inability to access brains in living humans to identify them poses an obstacle to pharmacological treatment. Future research may also focus on epigenetic changes that mediate the impact of psychotherapy on personality and behaviour.
Most epigenetic research is cross-sectional in that it establishes associations. More longitudinal research is necessary to help establish causation. Lack of resources has also limited the number of intergenerational studies. Therefore, advancing longitudinal and multigenerational, experience-dependent studies will be critical to further understanding the role of epigenetics in psychology.
- Behavioral genetics
- Behavioral neuroscience
- Evolutionary neuroscience
- Personality psychology
- Miller G (July 2010). "Epigenetics. The seductive allure of behavioral epigenetics". Science 329 (5987): 24–7. doi:10.1126/science.329.5987.24. PMID 20595592.
- Powledge T (2011). "Behavioral epigenetics: How nurture shapes nature". BioScience 61 (8): 588–592. doi:10.1525/bio.2011.61.8.4.
- Kail RV, Barnfield A (2011). Children and Their Development, Second Canadian Edition with MyDevelopmentLab. Toronto: Pearson Education Canada. ISBN 0-13-255770-3.
- Champagne FA, Mashoodh R (2012). "Genes in context: Gene-environment interplay and the origins of individual differences in behaviour". Current Directions in Psychological Science 18 (3): 127–131. doi:10.1111/j.1467-8721.2009.01622.x.
- Zhang TY, Meaney MJ (2010). "Epigenetics and the environmental regulation of the genome and its function". Annu Rev Psychol 61: 439–66, C1–3. doi:10.1146/annurev.psych.60.110707.163625. PMID 19958180.
- Bagot RC, Meaney MJ (August 2010). "Epigenetics and the biological basis of gene x environment interactions". J Am Acad Child Adolesc Psychiatry 49 (8): 752–71. doi:10.1016/j.jaac.2010.06.001. PMID 20643310.
- Stuffrein-Roberts S, Joyce PR, Kennedy MA (February 2008). "Role of epigenetics in mental disorders". Aust N Z J Psychiatry 42 (2): 97–107. doi:10.1080/00048670701787495. PMID 18197504.
- Mill J, Tang T, Kaminsky Z, Khare T, Yazdanpanah S, Bouchard L, Jia P, Assadzadeh A, Flanagan J, Schumacher A, Wang SC, Petronis A (March 2008). "Epigenomic profiling reveals DNA-methylation changes associated with major psychosis". Am. J. Hum. Genet. 82 (3): 696–711. doi:10.1016/j.ajhg.2008.01.008. PMC 2427301. PMID 18319075.
- Pennisi E (August 2001). "Behind the scenes of gene expression". Science 293 (5532): 1064–7. doi:10.1126/science.293.5532.1064. PMID 11498570.
- Juliandi B, Abematsu M, Nakashima K (August 2010). "Epigenetic regulation in neural stem cell differentiation". Dev. Growth Differ. 52 (6): 493–504. doi:10.1111/j.1440-169X.2010.01175.x. PMID 20608952.
- Ma DK, Marchetto MC, Guo JU, Ming GL, Gage FH, Song H (November 2010). "Epigenetic choreographers of neurogenesis in the adult mammalian brain". Nat. Neurosci. 13 (11): 1338–44. doi:10.1038/nn.2672. PMC 3324277. PMID 20975758.
- Sun J, Sun J, Ming GL, Song H (March 2011). "Epigenetic regulation of neurogenesis in the adult mammalian brain". Eur. J. Neurosci. 33 (6): 1087–93. doi:10.1111/j.1460-9568.2011.07607.x. PMC 3076719. PMID 21395852.
- Bird A (May 2007). "Perceptions of epigenetics". Nature 447 (7143): 396–8. Bibcode:2007Natur.447..396B. doi:10.1038/nature05913. PMID 17522671.
- "Overview of the Roadmap Epigenomics Project".
- Mehler MF (December 2008). "Epigenetic principles and mechanisms underlying nervous system functions in health and disease". Prog. Neurobiol. 86 (4): 305–41. doi:10.1016/j.pneurobio.2008.10.00. PMC 2636693. PMID 18940229.
- Maze I, Nestler EJ (January 2011). "The epigenetic landscape of addiction". Ann. N. Y. Acad. Sci. 1216: 99–113. doi:10.1111/j.1749-6632.2010.05893.x. PMC 3071632. PMID 21272014.
- Reik W (May 2007). "Stability and flexibility of epigenetic gene regulation in mammalian development". Nature 447 (7143): 425–32. doi:10.1038/nature05918. PMID 17522676.
- Gottesman II, Hanson DR (2005). "Human development: biological and genetic processes". Annu Rev Psychol 56: 263–86. doi:10.1146/annurev.psych.56.091103.070208. PMID 15709936.
- Campbell IC, Mill J, Uher R, Schmidt U (January 2011). "Eating disorders, gene-environment interactions and epigenetics". Neurosci Biobehav Rev 35 (3): 784–93. doi:10.1016/j.neubiorev.2010.09.012. PMID 20888360.
- Goto T, Monk M (June 1998). "Regulation of X-chromosome inactivation in development in mice and humans". Microbiol. Mol. Biol. Rev. 62 (2): 362–78. PMC 98919. PMID 9618446.
- Kaminsky Z, Petronis A, Wang SC, Levine B, Ghaffar O, Floden D, Feinstein A (February 2008). "Epigenetics of personality traits: an illustrative study of identical twins discordant for risk-taking behavior". Twin Res Hum Genet 11 (1): 1–11. doi:10.1375/twin.11.1.1. PMID 18251670.
- Masterpasqua F (2009). "Psychology and epigenetics". Review of General Psychology 13 (3): 194–201. doi:10.1037/a0016301.
- Szyf M, McGowan P, Meaney MJ (January 2008). "The social environment and the epigenome". Environ. Mol. Mutagen. 49 (1): 46–60. doi:10.1002/em.20357. PMID 18095330.
- González-Pardo H, Pérez Álvarez M (February 2013). "Epigenetics and its implications for Psychology". Psicothema 25 (1): 3–12. doi:10.7334/psicothema2012.327. PMID 23336536.
- Day JJ, Sweatt JD (November 2010). "DNA methylation and memory formation". Nat. Neurosci. 13 (11): 1319–23. doi:10.1038/nn.2666. PMC 3130618. PMID 20975755.
- Fischer A, Sananbenesi F, Wang X, Dobbin M, Tsai LH (May 2007). "Recovery of learning and memory is associated with chromatin remodelling". Nature 447 (7141): 178–82. doi:10.1038/nature05772. PMID 17468743.
- Gupta S, Kim SY, Artis S, Molfese DL, Schumacher A, Sweatt JD, Paylor RE, Lubin FD (March 2010). "Histone methylation regulates memory formation". J. Neurosci. 30 (10): 3589–99. doi:10.1523/JNEUROSCI.3732-09.2010. PMC 2859898. PMID 20219993.
- Gräff J, Rei D, Guan JS, Wang WY, Seo J, Hennig KM, Nieland TJ, Fass DM, Kao PF, Kahn M, Su SC, Samiei A, Joseph N, Haggarty SJ, Delalle I, Tsai LH (March 2012). "An epigenetic blockade of cognitive functions in the neurodegenerating brain". Nature 483 (7388): 222–6. doi:10.1038/nature10849. PMC 3498952. PMID 22388814.
- Peleg S, Sananbenesi F, Zovoilis A, Burkhardt S, Bahari-Javan S, Agis-Balboa RC, Cota P, Wittnam JL, Gogol-Doering A, Opitz L, Salinas-Riester G, Dettenhofer M, Kang H, Farinelli L, Chen W, Fischer A (May 2010). "Altered histone acetylation is associated with age-dependent memory impairment in mice". Science 328 (5979): 753–6. doi:10.1126/science.1186088. PMID 20448184.
- Kanehisa Laboratories (10 October 2014). "Amphetamine – Homo sapiens (human)". KEGG Pathway. Retrieved 31 October 2014.
- Renthal W, Nestler EJ (September 2009). "Chromatin regulation in drug addiction and depression". Dialogues Clin. Neurosci. 11 (3): 257–268. PMC 2834246. PMID 19877494. Retrieved 21 July 2014.
- Nestler EJ (October 2008). "Review. Transcriptional mechanisms of addiction: role of DeltaFosB". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 (1507): 3245–3255. doi:10.1098/rstb.2008.0067. PMC 2607320. PMID 18640924.
Recent evidence has shown that ΔFosB also represses the c-fos gene that helps create the molecular switch—from the induction of several short-lived Fos family proteins after acute drug exposure to the predominant accumulation of ΔFosB after chronic drug exposure—cited earlier (Renthal et al. in press).
- Robison AJ, Nestler EJ (November 2011). "Transcriptional and epigenetic mechanisms of addiction". Nat. Rev. Neurosci. 12 (11): 623–637. doi:10.1038/nrn3111. PMC 3272277. PMID 21989194.
ΔFosB serves as one of the master control proteins governing this structural plasticity.
- Nestler EJ (December 2012). "Transcriptional mechanisms of drug addiction". Clin. Psychopharmacol. Neurosci. 10 (3): 136–143. doi:10.9758/cpn.2012.10.3.136. PMC 3569166. PMID 23430970.
The 35-37 kD ΔFosB isoforms accumulate with chronic drug exposure due to their extraordinarily long half-lives. ... As a result of its stability, the ΔFosB protein persists in neurons for at least several weeks after cessation of drug exposure. ... ΔFosB overexpression in nucleus accumbens induces NFκB
- Wong CC, Mill J, Fernandes C (March 2011). "Drugs and addiction: an introduction to epigenetics". Addiction 106 (3): 480–9. doi:10.1111/j.1360-0443.2010.03321.x. PMID 21205049.
- Andersen SL, Teicher MH (April 2009). "Desperately driven and no brakes: developmental stress exposure and subsequent risk for substance abuse". Neurosci Biobehav Rev 33 (4): 516–24. doi:10.1016/j.neubiorev.2008.09.009. PMC 2688959. PMID 18938197.
- Carver C (2010). "Coping". In Baum A, Contrada RJ. The Handbook of Stress Science: Biology, Psychology, and Health. New York: Springer Publishing Company. p. 223. ISBN 0-8261-1471-7.
- Renthal W, Nestler EJ (August 2008). "Epigenetic mechanisms in drug addiction". Trends Mol Med 14 (8): 341–50. doi:10.1016/j.molmed.2008.06.004. PMC 2753378. PMID 18635399.
- Naassila M (2011). "Epigenetics in alcohol addiction: New mechanisms for new treatments?". Alcohol and Alcoholism 46 (Suppl 1): i1–63. doi:10.1093/alcalc/agr085. PMID 21863600.
- Launay JM, Del Pino M, Chironi G, Callebert J, Peoc'h K, Mégnien JL, Mallet J, Simon A, Rendu F (2009). "Smoking induces long-lasting effects through a monoamine-oxidase epigenetic regulation". PLoS ONE 4 (11): e7959. doi:10.1371/journal.pone.0007959. PMC 2775922. PMID 19956754.
- Marlatt GA, Baer JS, Donovan DM, Kivlahan DR (1988). "Addictive behaviors: etiology and treatment". Annu Rev Psychol 39: 223–52. doi:10.1146/annurev.ps.39.020188.001255. PMID 3278676.
- Bönsch D, Lenz B, Reulbach U, Kornhuber J, Bleich S (December 2004). "Homocysteine associated genomic DNA hypermethylation in patients with chronic alcoholism". J Neural Transm 111 (12): 1611–6. doi:10.1007/s00702-004-0232-x. PMID 15565495.
- He F, Lidow IA, Lidow MS (2006). "Consequences of paternal cocaine exposure in mice". Neurotoxicol Teratol 28 (2): 198–209. doi:10.1016/j.ntt.2005.12.003. PMID 16458479.
- Raney TJ, Thornton LM, Berrettini W, Brandt H, Crawford S, Fichter MM, Halmi KA, Johnson C, Kaplan AS, LaVia M, Mitchell J, Rotondo A, Strober M, Woodside DB, Kaye WH, Bulik CM (May 2008). "Influence of overanxious disorder of childhood on the expression of anorexia nervosa". Int J Eat Disord 41 (4): 326–32. doi:10.1002/eat.20508. PMID 18213688.
- Mostafavi-Abdolmaleky H, Glatt SJ, Tsuang MT (2011). "Epigenetics in Psychiatry". In Bronner F, Helmtrud I. Epigenetic Aspects of Chronic Diseases. Berlin: Springer. pp. 163–174. ISBN 1-84882-643-5.
- Abdolmaleky HM, Thiagalingam S, Wilcox M (2005). "Genetics and epigenetics in major psychiatric disorders: dilemmas, achievements, applications, and future scope". Am J Pharmacogenomics 5 (3): 149–60. doi:10.2165/00129785-200505030-00002. PMID 15952869.
- Malaspina D, Harlap S, Fennig S, Heiman D, Nahon D, Feldman D, Susser ES (April 2001). "Advancing paternal age and the risk of schizophrenia". Arch. Gen. Psychiatry 58 (4): 361–7. doi:10.1001/archpsyc.58.4.361. PMID 11296097.
- Rutten BP, Mill J (November 2009). "Epigenetic mediation of environmental influences in major psychotic disorders". Schizophr Bull 35 (6): 1045–56. doi:10.1093/schbul/sbp104. PMC 2762629. PMID 19783603.
- Yauk C, Polyzos A, Rowan-Carroll A, Somers CM, Godschalk RW, Van Schooten FJ, Berndt ML, Pogribny IP, Koturbash I, Williams A, Douglas GR, Kovalchuk O (January 2008). "Germ-line mutations, DNA damage, and global hypermethylation in mice exposed to particulate air pollution in an urban/industrial location". Proc. Natl. Acad. Sci. U.S.A. 105 (2): 605–10. doi:10.1073/pnas.0705896105. PMC 2206583. PMID 18195365.
- McGowan PO, Kato T (January 2008). "Epigenetics in mood disorders". Environ Health Prev Med 13 (1): 16–24. doi:10.1007/s12199-007-0002-0. PMC 2698240. PMID 19568875.
- Abdolmaleky HM, Cheng KH, Faraone SV, Wilcox M, Glatt SJ, Gao F, Smith CL, Shafa R, Aeali B, Carnevale J, Pan H, Papageorgis P, Ponte JF, Sivaraman V, Tsuang MT, Thiagalingam S (November 2006). "Hypomethylation of MB-COMT promoter is a major risk factor for schizophrenia and bipolar disorder". Hum. Mol. Genet. 15 (21): 3132–45. doi:10.1093/hmg/ddl253. PMC 2799943. PMID 16984965.
- Dempster EL, Mill J, Craig IW, Collier DA (2006). "The quantification of COMT mRNA in post mortem cerebellum tissue: diagnosis, genotype, methylation and expression". BMC Med. Genet. 7: 10. doi:10.1186/1471-2350-7-10. PMC 1456954. PMID 16483362.
- Massart R, Mongeau R, Lanfumey L (2012). "Beyond the monoaminergic hypothesis:neuroplasticity and epigenetic changes in a transgenic mouse model of depression". Phil. Trans. R. Soc. B. 367: 2485–2494. doi:10.1098/rstb.2012.0212. PMC 3405682. PMID 22826347.
- Pariante CM, Lightman CL (2008). "The HPA axis in major depression: classical theories and new developments.". Trends In Neurosciences. 31 (9): 464–468. doi:10.1016/j.tins.2008.06.006. PMID 18675469.
- Tsankova NM, Berton O, Renthal W, Kumar A, Neve RL, Nestler EJ. (2006). "Sustained hippocampal chromatin regulation in a mouse model of depression and antidepressant action.". Nat. Neurosci. 9 (4): 519–525. doi:10.1038/nn1659. PMID 16501568.
- Gray JD, Milner TA, McEwen BS (2013). "Dynamic Plasticity: The Role of Glucocorticoids, Brain-Derived Neurotrophic Factor and Other Trophic Factors". Neuroscience. 239: 214–227. doi:10.1016/j.neuroscience.2012.08.034. PMID 22922121.
- Hunter RG (2012). "Epigenetic effects of stress and corticosteroids in the brain.". Front. Cell. Neurosci. 6: 1–8. doi:10.3389/fncel.2012.00018. PMID 22529779.
- Jiang Y, Langley B, Lubin FD, Renthal W, Wood MA, Yasui DH, Kumar A, Nestler EJ, Akbarian S, Beckel-Mitchener AC (November 2008). "Epigenetics in the nervous system". J. Neurosci. 28 (46): 11753–9. doi:10.1523/JNEUROSCI.3797-08.2008. PMID 19005036.
- Philibert RA, Beach SR, Gunter TD, Brody GH, Madan A, Gerrard M (March 2010). "The effect of smoking on MAOA promoter methylation in DNA prepared from lymphoblasts and whole blood". Am. J. Med. Genet. B Neuropsychiatr. Genet. 153B (2): 619–28. doi:10.1002/ajmg.b.31031. PMC 3694401. PMID 19777560.
- Philibert RA, Sandhu H, Hollenbeck N, Gunter T, Adams W, Madan A (July 2008). "The relationship of 5HTT (SLC6A4) methylation and genotype on mRNA expression and liability to major depression and alcohol dependence in subjects from the Iowa Adoption Studies". Am. J. Med. Genet. B Neuropsychiatr. Genet. 147B (5): 543–9. doi:10.1002/ajmg.b.30657. PMC 3643119. PMID 17987668.
- Philibert RA, Gunter TD, Beach SR, Brody GH, Madan A (July 2008). "MAOA methylation is associated with nicotine and alcohol dependence in women". Am. J. Med. Genet. B Neuropsychiatr. Genet. 147B (5): 565–70. doi:10.1002/ajmg.b.30778. PMC 3685146. PMID 18454435.
- Bodnar RJ (December 2010). "Endogenous opiates and behavior: 2009". Peptides 31 (12): 2325–59. doi:10.1016/j.peptides.2010.09.016. PMID 20875476.
- Mill J, Petronis A (October 2008). "Pre- and peri-natal environmental risks for attention-deficit hyperactivity disorder (ADHD): the potential role of epigenetic processes in mediating susceptibility". J Child Psychol Psychiatry 49 (10): 1020–30. doi:10.1111/j.1469-7610.2008.01909.x. PMID 18492038.
- Gunter TD, Vaughn MG, Philibert RA (2010). "Behavioral genetics in antisocial spectrum disorders and psychopathy: a review of the recent literature". Behav Sci Law 28 (2): 148–73. doi:10.1002/bsl.923. PMID 20422643.
- McGowan PO, Sasaki A, D'Alessio AC, Dymov S, Labonté B, Szyf M, Turecki G, Meaney MJ (March 2009). "Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse". Nat. Neurosci. 12 (3): 342–8. doi:10.1038/nn.2270. PMC 2944040. PMID 19234457.
- Albert PR (November 2010). "Epigenetics in mental illness: hope or hype?". J Psychiatry Neurosci 35 (6): 366–8. doi:10.1503/jpn.100148. PMC 2964366. PMID 20964959.
- McCaffery JM (2010). "Genetic epidemiology of stress and gene by stress interaction". In Baum A, Contrada RJ. The Handbook of Stress Science: Biology, Psychology, and Health. New York: Springer Publishing Company. pp. 78–85. ISBN 0-8261-1471-7.
- Kalant H (May 2010). "What neurobiology cannot tell us about addiction". Addiction 105 (5): 780–9. doi:10.1111/j.1360-0443.2009.02739.x. PMID 19919596.
- Guo G (2010). "Family influences on children's well being: potential roles of molecular genetics and epigenetics". In Landale N, Booth A, McHale S. Biosocial Foundations of Family Processes (National Symposium on Family Issues). Berlin: Springer. pp. 181–204. ISBN 1-4419-7360-5.
- Dempster EL, Pidsley R, Schalkwyk LC, Owens S, Georgiades A, Kane F, Kalidindi S, Picchioni M, Kravariti E, Toulopoulou T, Murray RM, Mill J (December 2011). "Disease-associated epigenetic changes in monozygotic twins discordant for schizophrenia and bipolar disorder". Hum. Mol. Genet. 20 (24): 4786–96. doi:10.1093/hmg/ddr416. PMC 3221539. PMID 21908516.
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- Lester BM, Tronick E, Nestler E, Abel T, Kosofsky B, Kuzawa CW, Marsit CJ, Maze I, Meaney MJ, Monteggia LM, Reul JM, Skuse DH, Sweatt JD, Wood MA (May 2011). "Behavioral epigenetics". Ann. N. Y. Acad. Sci. 1226: 14–33. doi:10.1111/j.1749-6632.2011.06037.x. PMID 21615751.
- Champagne FA, Rissman EF (March 2011). "Behavioral epigenetics: a new frontier in the study of hormones and behavior". Horm Behav 59 (3): 277–8. doi:10.1016/j.yhbeh.2011.02.011. PMID 21419246.
- Nelson ED, Monteggia LM (July 2011). "Epigenetics in the mature mammalian brain: effects on behavior and synaptic transmission". Neurobiol Learn Mem 96 (1): 53–60. doi:10.1016/j.nlm.2011.02.015. PMC 3463371. PMID 21396474.
- Plazas-Mayorca MD, Vrana KE (January 2011). "Proteomic investigation of epigenetics in neuropsychiatric disorders: a missing link between genetics and behavior?". J. Proteome Res. 10 (1): 58–65. doi:10.1021/pr100463y. PMC 3017635. PMID 20735116.
- Curley JP, Jensen CL, Mashoodh R, Champagne FA (April 2011). "Social influences on neurobiology and behavior: epigenetic effects during development". Psychoneuroendocrinology 36 (3): 352–71. doi:10.1016/j.psyneuen.2010.06.005. PMC 2980807. PMID 20650569.
- Crews D (March 2011). "Epigenetic modifications of brain and behavior: theory and practice". Horm Behav 59 (3): 393–8. doi:10.1016/j.yhbeh.2010.07.001. PMC 3401366. PMID 20633562.
- Mann JJ, Currier DM (June 2010). "Stress, genetics and epigenetic effects on the neurobiology of suicidal behavior and depression". Eur. Psychiatry 25 (5): 268–71. doi:10.1016/j.eurpsy.2010.01.009. PMC 2896004. PMID 20451357.
- Crews D (2010). "Epigenetics, brain, behavior, and the environment". Hormones (Athens) 9 (1): 41–50. doi:10.14310/horm.2002.1251. PMID 20363720.
- Malvaez M, Barrett RM, Wood MA, Sanchis-Segura C (2009). "Epigenetic mechanisms underlying extinction of memory and drug-seeking behavior". Mamm. Genome 20 (9-10): 612–23. doi:10.1007/s00335-009-9224-3. PMC 3157916. PMID 19789849.
- Nicolaïdis S (October 2008). "Prenatal imprinting of postnatal specific appetites and feeding behavior". Metab. Clin. Exp. 57 Suppl 2: S22–6. doi:10.1016/j.metabol.2008.07.004. PMID 18803961.
- McGowan PO, Meaney MJ, Szyf M (October 2008). "Diet and the epigenetic (re)programming of phenotypic differences in behavior". Brain Res. 1237: 12–24. doi:10.1016/j.brainres.2008.07.074. PMC 2951010. PMID 18694740.
- Szyf M, Weaver I, Meaney M (July 2007). "Maternal care, the epigenome and phenotypic differences in behavior". Reprod. Toxicol. 24 (1): 9–19. doi:10.1016/j.reprotox.2007.05.001. PMID 17561370.
- Bonasio R, Zhang G, Ye C, Mutti NS, Fang X, Qin N, Donahue G, Yang P, Li Q, Li C, Zhang P, Huang Z, Berger SL, Reinberg D, Wang J, Liebig J (August 2010). "Genomic comparison of the ants Camponotus floridanus and Harpegnathos saltator". Science 329 (5995): 1068–71. doi:10.1126/science.1192428. PMID 20798317. Lay summary – Scientific American Magazine (August 26, 2010).
- McDonald B (2011). "The Fingerprints of Poverty". Quirks & Quarks. CBC Radio.
Audio interview with Moshe Szyf, a professor of Pharmacology and Therapeutics at McGill University, discusses how epigenetic changes are related to differences in socioeconomic status.
- Oz M (2011). "Control Your Pregnancy". The Dr. Oz Show.
Video explaining how epigenetics can affect the unborn fetus.
- Paylor B (2010). "Epigenetic Landscapes".
This video addresses how, in principle, accumulated epigenetic changes may result in personality differences in identical twins. This video was made by a Ph.D. candidate in experimental medicine and award winning filmmaker Ben Paylor.
- Rusting R (2011). "Epigenetics Explained (Animation)". Scientific American Magazine.
A series of diagrams explaining how epigenetic marks affect genetic expression.