The Impact of Childhood Trauma on Adult Mental Health
Christian Jonathan Haverkampf
8th November 2022
Dose-Response Relationship and Repeated Trauma. 4
Depression, Anxiety, Psychosis, and Suicide. 6
Brain Functioning and Neural Development. 10
Prevention and Early Treatment. 13
Childhood trauma has wide-ranging negative consequences for the health and well-being of individuals and the proper functioning of society. A study by Rossiter and colleagues demonstrated high rates of adverse childhood experiences amongst adults attending a general adult mental health service. (Rossiter et al., 2015) Childhood trauma can lead to significant mental and physical health issues throughout all stages of adulthood (Carr et al., 2013; Leeb et al., 2011), including substance abuse, such as alcohol (Torgerson et al., 2018). Scientific evidence shows that early life stress triggers, aggravates, maintains, and increases the recurrence of psychiatric disorders (Carr et al., 2013). Unfortunately, mental health professionals often do not ask or document childhood trauma. (Rossiter et al., 2015), which impedes adequate treatment.
Childhood trauma may be in the form of sexual, physical or emotional abuse or physical or emotional neglect or a combination of them. Physical, mental, and emotional symptoms of childhood trauma can persist into adulthood (Dye, 2018), and, unfortunately, many adults carry with them histories of childhood abuse. (Greenfield, 2010) In the US, for example, more than half of the population has experienced at least one childhood traumatic event in their lifetime. (Torgerson et al., 2018) And on a global scale, there are high rates of chronic interpersonal violence against children (De Bellis & Zisk, 2014). The public health burden of childhood trauma may rival or even exceed all other root causes of common, interlinked comorbidities of the brain and body, such as substance abuse. (Zarse et al., 2019) Yet trauma has not only grave consequences for the victim but also for society as a whole (Leeb et al., 2011), such as the tremendous individual, psychosocial, and financial costs from unlived potentials, self-harming behaviours violence to often lifelong treatment.
The long-term consequences of childhood abuse on adult mental health have been a major focus of research. (Chartier et al., 2007) Springer and colleagues found that physical abuse predicted worse mental and physical health decades after the abuse. (Springer et al., 2007) It is not uncommon that there is an intermittent silent period of years or decades between the trauma and overt symptoms, particularly in more severe cases, where at least a partial disconnect from memories of emotions and cognitions associated with the trauma may be greatest.
Childhood trauma often happens in environments that cause more than one trauma over time. Thus, the long-term impact of a prominent trauma in childhood needs to be viewed in the context of other lifetime trauma when assessing PTSD prevalence rates. (McFarlane & Van Hooff, 2009) In a meta-study, Carr and colleagues found the following correlations between early life stress with psychiatric disorders (Carr et al., 2013):
- physical abuse, sexual abuse, and unspecified neglect and mood disorders and anxiety disorders
- emotional abuse and personality disorders and schizophrenia
- physical neglect and personality disorders (the weakest association)
Physical abuse would also include, for example, being spanked as a child. (Merrick et al., 2017) However, one problem with this schema is that emotional abuse, for example, would often be expected to be present with the other types as well, such as sexual abuse. This may explain why a meta-analysis demonstrated that emotional abuse and neglect had the largest effects on the presence of borderline personality disorder (BPD) (Porter et al., 2020), while a systematic review also identified sexual abuse as an important risk factor for BPD (de Aquino Ferreira et al., 2018).
It seems that the emotional quality of the trauma plays an important role in the manifestation of symptoms. An interpersonal trauma seems to have more powerful effects in this regard than, for example, a non-interpersonal ‘chance’ accident. The association between childhood trauma and later mental illness seems particularly evident for exposure to bullying, emotional abuse, maltreatment, and parental loss. (McKay et al., 2021) Cecil and colleagues showed that emotional abuse emerged as the main independent predictor of psychiatric symptomatology – over and above other maltreatment types. (Cecil et al., 2017) Child sexual abuse in particular is an unspeakably devastating and destructive interpersonal event. Banyard and colleagues observed that victims of child sexual abuse reported a lifetime history of greater exposure to various traumas and higher levels of mental health symptoms, while exposure to other trauma types mediated the relationship between child sexual abuse and psychological distress in adulthood. (Banyard et al., 2001)
Classes of childhood traumatic experiences predict specific psychiatric and behavioural outcomes in adolescence and young adulthood. The long-term adverse effects of childhood traumas are primarily concentrated in victims of sexual and non-sexual violence (Ballard et al., 2015) Cecil and colleagues found in their study that severity linearly increased with the number of maltreatment types experienced. And, while most forms of maltreatment were significantly associated with mental health outcomes when examined individually, few unique effects were observed when maltreatment types were modelled simultaneously, which, according to the authors, pointed to an important role of shared variance in driving maltreatment effects on mental health. (Cecil et al., 2017)
Dose-Response Relationship and Repeated Trauma
Cumulative childhood trauma exposure is associated with negative outcomes in health and functioning in adulthood. (Copeland et al., 2018) There have been indications that a higher frequency of the same trauma leads to greater symptoms. Research has shown that exposures to adverse childhood experiences converge dose-dependently to potently increase the risk for a wide array of causally interlinked mental illnesses, addictions, and multi-organ medical diseases. (Zarse et al., 2019) Sugaya and colleagues found a dose-response relationship between frequency of abuse and several adult psychiatric disorder groups, and higher frequencies of assault were significantly associated with increasing odds. (Sugaya et al., 2012) In a study by McKay and colleagues, there was some evidence of a dose-response relationship with those exposed to multiple forms of maltreatment having more than three times the odds of developing a mental disorder (McKay et al., 2021)
Childhood trauma has repeatedly shown to lead to higher rates of psychiatric and somatic illnesses in adults. Chartier and colleagues found a moderate strength association between childhood abuse and multiple health problems, poor or fair self-rated health, pain that interferes with activities, disability due to physical health problems, and frequent emergency room and health professional visits. (Chartier et al., 2007) In a study by Sugaya and colleagues, child physical abuse was associated with significantly higher odds of a broad range of DSM-IV psychiatric disorders, especially ADHD, PTSD, and bipolar disorder. (Sugaya et al., 2012)
Mental Health Impairment
The negative effect of trauma on social functioning takes away one route to recovery and healthier self-regulation through healthy social interactions. A study by Davidson and colleagues found a significant relationship between trauma history and all aspects of social functioning. Those with no history of trauma showed improved psychosocial functioning over time, whereas those with a history of trauma deteriorated. (Davidson et al., 2009) In addition to criminality, childhood trauma is associated with the risk for emotional disorders (e.g., depression and anxiety) and co-morbid conditions such as alcohol and drug abuse and antisocial behaviours in adulthood. (Wolff & Shi, 2012)
The impaired social functioning can lead to tertiary effects from trauma. For example, it has been shown that the school dropout rate was higher in those with childhood trauma experiences and varied by trauma. (Porche et al., 2011) Also, rates of childhood and adult trauma are high among incarcerated persons. (Wolff & Shi, 2012)
Depression, Anxiety, Psychosis, and Suicide
Children who are exposed to sexual or physical abuse or the death of a parent are at higher risk for development of depressive and anxiety disorders later in life. (Nemeroff, 2004) In a study by Li and colleagues, individuals with experiences of childhood maltreatment were twice as likely as those without to develop both recurrent and persistent depressive episodes. (Li et al., 2020) Childhood trauma has also been linked to adult suicides. Results of a study with a sample of 7465 adults indicated a graded dose-response relationship between adverse childhood experiences and the likelihood of alcohol and drug use, depressed affect, and suicide attempts in adulthood. (Merrick et al., 2017) In a longitudinal study over more than three decades, patients maltreated in childhood reported more symptoms of adult depression, anxiety, and more impairment due to mental and physical health problems. (Herrenkohl et al., 2012) The results of a study by Alvarez and colleagues showed that a diagnosis of schizophrenia came about four years earlier in victims of childhood abuse, and hospital admissions were twice as high in victims of psychological abuse. Patients with a history of sexual abuse were more than twice as likely to attempt suicide. (Álvarez et al., 2011)
Childhood trauma predicts the development of adult physical disorders, digestive, musculoskeletal, and respiratory disorders, even after controlling for sociodemographic and lifestyle factors. This association is in turn substantially influenced by mental health disorders. (Noteboom et al., 2021) Physical long-term effects may have PTSD as a mediator variable. (Mulvihill, 2009) These can also include irritable bowel syndrome, rheumatoid arthritis, and autoimmune disorders, aside from the physical effects of eating disorders, substance abuse, phobias, and multiple personality disorders. (Mulvihill, 2009) and substance use disorders and obesity (Wiss & Brewerton, 2020). In the case of adult obesity, social disruption, changes in health behaviours, and chronic stress response are frequently given as explanations. (Wiss & Brewerton, 2020)
Over the lifespan of victims of child abuse, social, psychological, and biological consequences of abuse interact in complex ways (Coates, 2010). The nervous system is affected both in term of its psychological ‘software’ and biological ‘hardware’, which are really one substrate from a perspective of neural network plasticity. A meta-study has shown that cognitive factors mediate the relationship between early trauma and later psychopathology. (Aafjes-Van Doorn et al., 2020) McLaughlin and colleagues focused on three areas that are frequently affected in childhood trauma (McLaughlin et al., 2020):
- social information processing (prioritizing threat-related information),
- emotional processing, and
- accelerated biological aging.
Li and colleagues provided preliminary evidence for hyper-mentalizing and hypo-mentalizing as mechanisms whereby early emotional abuse can lead to later depression. (Li et al., 2020) On the emotional side, the nonacceptance of emotional responses, impulse control difficulties, and lack of access to emotion regulation strategies seem to significantly affect psychological distress in adulthood. (Rudenstine et al., 2019) Kealy and colleagues found a significant indirect effect for the relationship between emotional abuse and shame, but not guilt, in contributing to somatic symptoms. (Kealy et al., 2018)
Traumatisation leads to alterations in information processing, which can be even strengthened through internal and external feedback effects. Trauma-induced alterations in threat perception are expressed in how victims think, feel, behave, and regulate their biological systems. (Van der Kolk, 2003) Trauma exposure affects what children anticipate and focus on and how they organize the way they appraise and process information. The effect of trauma on social functioning can lead to a vicious cycle. Social withdrawal and fewer interactions can lead to even less trust in and reliance on other people. Shevlin and colleagues observed in a large, general population sample that loneliness appeared as a mediator in the relationship between childhood trauma and several adult psychiatric disorders. (Shevlin et al., 2014) Furthermore, the intergenerational transmission of the burden of trauma via disrupted parenting and insecure rearing contexts has been observed consistently. (Zarse et al., 2019) Converging evidence supports the idea that offspring are affected by parental trauma exposures occurring before their birth, and possibly even prior to their conception. (Yehuda & Lehrner, 2018)
Psychosocially, there can be adverse and protective factors. Substance abuse, incarceration, and co-occurring psychiatric problems create further problems, while protective factors can lead to greater resiliency. (Dye, 2018) As an example for resiliency, results of a study by Torgerson and colleagues indicated that having a greater sense of belonging was associated with greater mental health and reduced reports of risky alcohol use in those who experienced childhood trauma. (Torgerson et al., 2018)
Brain Functioning and Neural Development
Early childhood trauma, especially complex trauma, can cause changes in brain structures that are responsible for cognitive and physical functioning. (Dye, 2018) These neurobiological changes in the developing brain can lead to lifelong psychiatric afflictions, reaching far into adulthood (Nemeroff, 2004). Empirical data suggests that there are functional changes in brain networks, which underlie working memory, attention, social cognition, executive function, and verbal learning. (Popovic et al., 2019)
The brain does not exist in a vacuum but is part of a matrix in which child-intrinsic factors, developmental maturation and experience, life events, and evolving family and social ecologies all interact (see Pynoos et al., 1999). Experiences during the more rapid neural development in the first years of life have a greater impact on multiple brain areas. Of central developmental importance are the systems for threat appraisal, emotional response, emotional and physiological regulation, and protective action (Pynoos et al., 1999). Internalization of elements of the traumatic experience can result in the persistence of fear-related neurophysiologic patterns. (Perry & Pollard, 1998) The individual is then in a constant state of hypervigilance and arousal, which can affect emotional, cognitive, behavioural, and social functioning.
Three well-established domains in which adversity is linked to psychopathology through neurodevelopmental pathways are threat-related social information processing biases, heightened emotional reactivity and difficulties with emotion regulation, and disruptions in reward processing. (McLaughlin et al., 2019) Childhood abuse has widely been shown to impact neuroendocrine functioning and the structure of the brain, in particular the amygdala, hippocampus, left hemisphere, and corpus callosum. (Coates, 2010) Empirical evidence suggests neurodevelopmental stage-related vulnerabilities in neurophysiology and neuroendocrinology. (Pynoos et al., 1999) While less is known about the mechanisms underlying trauma’s mental health consequences in children as compared to those in adults with childhood trauma, (De Bellis & Zisk, 2014) one can hypothesize using general neurofunctional considerations. For example, the amygdala plays an important role in the memorisation and memory retrieval of conditions associated with experiences of fear and anger, and thus specific trauma-related triggers, while the limbic system largely regulates emotional states through linking higher cognitive areas with lower brain centres coordinating and regulating physiological functioning.
Childhood trauma leads to disturbances in the stress axis, immune-inflammatory mechanisms, and metabolic dysregulation.  (Jaworska-Andryszewska & Rybakowski, 2019) Alterations in the corticotropin-releasing factor system have been observed, which lead to increased responsiveness to stress. (Nemeroff, 2004) The severity of childhood trauma contributes to increased hypothalamic-pituitary-adrenal (HPA) axis activity and higher cortisol production, (Nikkheslat et al., 2020) which can lead to persistent levels of elevated stress and hyperalertness, but also provide biomarkers (see De Bellis & Zisk, 2014) for monitoring posttraumatic stress symptoms treatment.
The effect of the experience of trauma may be “passed” from one generation to the next also through epigenetic mechanisms affecting DNA function or gene transcription. (Yehuda & Lehrner, 2018) They modify the regulation of which genes are turned on or off and can lead to enduring changes in the expression of proteins and thus brain and physical functioning. Several epigenetic mediators between childhood trauma and psychiatric disorders have been identified.(Nöthling et al., 2019)
Prevention and Early Treatment
When it comes to trauma, time is of the essence. Empirical findings suggest a need for early prevention, as well as early intervention and appropriate treatment. (Messina & Grella, 2011) The past cannot be reversed and even merely coping with the consequences of childhood trauma can be a life-long journey. Primary prevention strategies can avoid risk for maltreatment. (Leeb et al., 2011) A prevented trauma is always superior to a treated trauma. Timeliness and easy access to professional support are of the essence. The associations between childhood trauma) and several adult mental and behavioural health clearly establish the need for prevention (Merrick et al., 2017).
The Traumatised Helper
Caring for others begins with caring for oneself and actively seeking needed help. In a study by Elliott and Guy, psychotherapists reported higher rates of physical abuse, sexual molestation, parental alcoholism, psychiatric hospitalization of a parent, death of a family member, and greater family dysfunction in their families of origin than did other professionals. However, on a positive note, the researchers found that, as adults, the psychotherapists experienced less anxiety, depression, dissociation, sleep disturbance, and impairment in interpersonal relationships than did those in professions other than mental health. (Elliott & Guy, 1993)
Given the growing evidence of the long-term effects of childhood abuse, greater efforts are clearly needed to develop more effective strategies for the prevention and treatment of child abuse. (Chartier et al., 2007) Given the frequent failure to miss childhood trauma and its widespread clinical underreporting, there is a need for the wider use of effective screening instruments, such as the childhood trauma questionnaire (CTQ) (Rossiter et al., 2015), and for clinicians to take the time needed to explore trauma in a safe and empathetic setting. Ideally, any risk of trauma should be eliminated already at the source in childhood, which also means that parents and primary caretakers have easy access to high-quality care and society and its institutions are more proactive, more supportive, and more vigilant in protecting those who cannot protect themselves.
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 The article by Greenfield (Greenfield, 2010) concludes with a discussion of conceptualizing child abuse as a life-course social determinant of adult health.
 Using a sample of 654 adults aged 26–40 years old, the study examined the relationship between childhood traumatic experiences and adult risky alcohol use mediated by mental health status and perceptions of belonging.
 The authors reviewed 134 articles selected from various electronic databases. The main instrument was the Adverse Childhood Experiences-Questionnaire (ACE-Q), a 10-item scale used to correlate childhood maltreatment and adverse rearing contexts with adult health outcomes, published first in 1998 by Felitti and colleagues. The authors call for greater integration of mental health and addiction services for parents.
 The authors note also that there has been far less research on the effects of childhood abuse on physical health outcomes.
 However, these effects were found to be attenuated by age, sex, family background, and childhood adversities. The authors analysed population-based survey data from over 2,000 middle-aged men and women in the Wisconsin Longitudinal Study using self-reported measures. Parental physical abuse was reported by 11.4% of respondents (10.6% of males and 12.1% of females). They found that childhood physical abuse predicted a graded increase in depression, anxiety, anger, physical symptoms, and medical diagnoses. Childhood physical abuse also predicted severe ill health and an array of specific medical diagnoses and physical symptoms. Family background and childhood adversities attenuated but did not eliminate the childhood abuse versus adult health relationship.
 McFarlane and Van Hooff examined the rates of PTSD and other lifetime DSM–IV disorders in adults exposed to an Australian bushfire disaster as children in 1983. A total of 1011 adults recruited from an original sample of 1531 were assessed 20 years following the fires using the Composite International Diagnostic Interview (CIDI–2.1). Results showed only a small direct impact of the fires on adult psychiatric morbidity. A higher proportion of bushfire survivors met criteria for ‘any DSM–IV disorder’ and ‘any anxiety’. (McFarlane & Van Hooff, 2009)
 Merrick and colleagues investigated the relationship between ACE scores and adult mental health outcomes. Data were drawn from Wave II of the CDC-Kaiser ACE Study, consisting of 7465 adults in southern California. Interestingly, the ACE scores also included being spanked as a child, which was not captured by traditional ACE questionnaires. They observed in their adjusted models that being spanked as a child was significantly associated with all self-reported mental health outcomes.
 This effect was comparable for males and females. The authors drew their data from a community sample of high-risk youth (n = 204, M = 18.85). Outcome measures included multi-informant reports of internalizing difficulties, as well as data on externalizing problems and trauma-related symptoms.
 There were also some significant direct effects for child sexual abuse on some outcome measures. The authors note that the results pointed to the importance of understanding the interconnected nature of trauma exposure for some survivors. 174 women participated in the study.
 Gender was a key covariate in the classes of trauma exposure and outcomes. In the study 1,815 participants completed comprehensive psychiatric assessments as young adults. The authors also noted the following statistics: 8% of the sample, primarily female, was characterized by experiences of sexual assault and reported significantly higher rates of a range of psychiatric outcomes by young adulthood. Another 8%, primarily male, was characterized by experiences of violence exposure and reported higher levels of antisocial personality disorder and post-traumatic stress. 84% reported low levels of childhood traumatic experiences. The also indicated that parental psychopathology was related to membership in the sexual assault group.
 The authors also noted that this was the case more so for self-report than informant ratings. The data was drawn from a community sample of high-risk youth (n = 204, M = 18.85).
 The researchers compared the prevalence of childhood trauma recorded in individual’s clinical notes to those ascertained with the Childhood Trauma Questionnaire (CTQ). 129 individuals attending a general adult mental health service participated. Using the CTQ, childhood trauma was noted in 77% of individuals and recorded in 38% of individual’s clinical notes. The greatest differences between CTQ reporting and clinical note documentation were noted for emotional neglect (62% versus 13.2%), physical neglect (48.1% versus 5.4%) and childhood sexual assault (24.8% versus 8.5%). Childhood trauma was associated with increased psychopathology and greater symptom severity and was particularly prevalent for individuals with personality disorders.
 The researchers used the data from the 2000–2001 and 2004–2005 National Epidemiologic Survey on Alcohol and Related Conditions, a large cross-sectional survey of a representative sample (n = 43,093) of the U.S. population. Child physical abuse was reported by 8% of the sample and was frequently accompanied by other childhood adversities. (Sugaya et al., 2012)
 However, they did not find more frequent general practitioner visits. The effects were more pronounced in females and younger respondents. The data used was from the Ontario Health Survey (n = 9,953).
 The confidence interval given by the author for the AOR is 1.16–2.28.
 Interestingly, the investigators found no differences between the no childhood trauma (n=14) and childhood trauma groups on psychiatric symptoms. However, the sample size may have been too small to show statistical significance.
 The researchers recruited 31 participants from the caseloads of community mental health services in Northern Ireland and assessed them at baseline, 9 months, and 18 months. More than half had a history of childhood trauma (n = 17).
 The authors used the Collaborative Psychiatric Epidemiology Surveys, a nationally representative probability sample of African Americans, Afro-Caribbeans, Asians, Latinos, and non-Latino Whites, including 2,532 young adults, aged 21–29. They found a dropout prevalence rate of 16% overall, with variation by childhood trauma, childhood psychiatric diagnosis, race/ethnicity, and nativity. Childhood substance and conduct disorders mediated the relationship between trauma and school dropout.
 Wolff and Shi used in their study a sample of 4,000 incarcerated males. Rates of physical, sexual, and emotional trauma were higher in childhood than in adulthood and ranged from 44.7% (physical trauma in childhood) to 4.5% (sexual trauma in adulthood). Trauma exposure was found to be strongly associated with a wide range of behavioural problems and clinical symptoms.
 Merrick and colleagues investigated the relationship between ACE scores and adult mental health outcomes. Data were drawn from Wave II of the CDC-Kaiser ACE Study, consisting of 7465 adults in southern California. Over 80% of the sample reported exposure to at least one ACE. The ACE scores included also being spanked as a child, which was not captured by traditional ACE questionnaires. They observed in their adjusted models that being spanked as a child was significantly associated with all self-reported mental health outcomes.
 The data was from a longitudinal study of more than 30 years in which individuals were interviewed most recently in their mid-30s. A higher percentage of those with maltreatment histories reported lifetime alcohol problems and appeared at greater risk for substance abuse.
 Alvarez and colleagues conducted a cross-sectional study of 102 patients with schizophrenia, bipolar disorder, or schizoaffective disorder. Patients were evaluated using Brief Psychotic Relative Scale, and Traumatic Life Events and Distressing Event questionnaires. Almost half (47.5%) of these patients had suffered child abuse. A history of sexual abuse increased the percentage of those attempting suicide from 28.9% to 68%.
 The study included 13,489 respondents (aged 18–64 years) of the Netherlands Mental Health Survey and Incidence Study-1 and -2 cohort studies. The 4,054 respondents with a history of childhood trauma suffered significantly more often from digestive (OR: 1.89–2.95), musculoskeletal (OR: 1.21–1.75) and respiratory disorders (OR: 1.39–1.91) and migraine (OR: 1.42–1.66).
 The researchers found indirect associations between childhood trauma and digestive, musculoskeletal, and respiratory disorders through lifetime mood (54%, 52% and 48% respectively), anxiety (44%, 55% and 44% respectively) and substance use disorders (33%, 23% and 38% respectively). Mood (69%) and anxiety disorders (67%) also impacted the relationship with migraine.
 Mulvihill conducted an integrative review of the literature over the last five years across disciplines, including nursing, medicine, psychology, education, social services, and government agencies.
 The study was based on a systematic review of population-based studies. (Wiss & Brewerton, 2020)
 This includes heightened perceptual sensitivity to threat, misclassification of negative emotions and neutral emotions as anger, and attention biases towards threat-related cues. (McLaughlin et al., 2020)
 This includes elevated emotional reactivity to threat-related stimuli, low emotional awareness, and difficulties with emotional learning and emotion regulation. (McLaughlin et al., 2020)
 Accelerated biological ageing can be found across multiple biological metrics, including pubertal development and cellular ageing. (McLaughlin et al., 2020)
 Kealy and colleagues obtained a similar result regarding the mediating role of shame in the relationship between emotional neglect and somatic symptoms. Mediation was non-significant regarding childhood sexual abuse, which was directly related to somatic distress after controlling for depressive symptoms. (Kealy et al., 2018)
 The concept of intergenerational trauma describes how exposure to pronounced adverse events impacts individuals to such an extent that “their children find themselves grappling with their parents’ post-traumatic state”. (see Yehuda & Lehrner, 2018)
 It needs to be added that the study by Popovic and colleagues was carried out on schizophrenia patients, in whom some cognitive functions are already impacted by their illness. The researchers showed in a functional magnetic resonance imaging study that childhood trauma exposure resulted in the aberrant function of parietal areas involved in working memory and of visual cortical areas involved in attention. In a theory of mind task reflecting social cognition, childhood trauma was associated with activation of the posterior cingulate gyrus, praecuneus, and dorsomedial prefrontal cortex in patients with schizophrenia. In addition, decreased connectivity was shown between the posterior cingulate/praecuneus region and the amygdala in patients with high levels of physical neglect and sexual abuse during childhood. (Popovic et al., 2019)
 Traumatic events disrupt homeostasis in multiple areas of the brain that are recruited to respond to the threat. (Perry & Pollard, 1998)
 Pynoos and colleagues suggested a developmental life-trajectory model that incorporates a tripartite aetiology of post-trauma distress. It is described as an intricate matrix of child-intrinsic factors, developmental maturation and experience, life events, and evolving family and social ecologies. Individual variability in proximal and distal effects is explained by multiple stress diatheses. (Pynoos et al., 1999)
 There are several studies on the psychobiological effects of trauma during development in animal models. (De Bellis & Zisk, 2014) However, it is not entirely clear how transferable they are to understanding the complex effects of trauma in humans since the influence of higher cognitive and regulatory brain functions in humans is quite substantial.
 The HPA axis as a neuroendocrine mechanism mediates the effects of stressors by regulating numerous physiological processes, such as metabolism, immune responses, and the autonomic nervous system (ANS). (Sheng et al., 2021)
 It does so also in depressed patients who present glucocorticoid resistance, which could potentially worsen the depression according to the current model of the condition.
 DNA methylation is one mechanism that can have a long-lasting effect on specific cellular mechanisms, and thus the brain and other organs. (Jaworska-Andryszewska & Rybakowski, 2019) Methylation (the transfer of a methyl group to the cytosine ring of DNA) can change the activity of a DNA segment without changing its sequence.
 However, cause and effect associations are still not entirely clear. Nothling and colleagues reviewed the literature up to March 2018 in four main journal databases. Thirty-six studies investigating childhood trauma exposure both in healthy adults (18 years and older) and adults with psychiatric disorders were included. For mood disorders, methylation of the glucocorticoid receptor NR3C1 gene and correlation with childhood trauma was a robust finding according to the authors. Several studies documented differential methylation of SLC6A4, BDNF, OXTR and FKBP5 in association with childhood trauma. Common pathways identified include neuronal functioning and maintenance, immune and inflammatory processes, chromatin and histone modification, and transcription factor binding. (Nöthling et al., 2019)
 Messina and Grella analysed baseline interview data for 500 women participating in the Female Offender Treatment and Employment Program evaluation. Regression results in their study showed that the impact of childhood traumatic events on health outcomes is strong and cumulative. Greater exposure to childhood traumatic events increased the likelihood of 12 of 18 health-related outcomes, ranging from a 15% increase in the odds of reporting fair or poor health to a 40% increase in the odds of mental health treatment in adulthood. (Messina & Grella, 2011)
 However, Leeb and colleagues do not fail to point out that subsequent interventions for victims also have the potential to greatly improve their health.
 The study by Elliott and Guy examined the prevalence of childhood trauma, family dysfunction, and current psychological distress among female mental health professionals (n = 340). They then compared it with the prevalence among women working in other professions (n = 2,623). The researchers note that the study results suggest that therapists are often raised in dysfunctional families and experience significant psychological distress in adult life.