Identified a strong link between childhood emotional abuse and schizophrenia-like experiences in healthy adults


A new University of Hertfordshire study has, for the first time, identified a strong link between childhood emotional abuse and schizophrenia-like experiences in healthy adults, such as paranoia, hearing voices, and social withdrawal.

Researchers say that those who have experienced emotional abuse in early life are 3.5 times more likely to have schizophrenia-like experiences in adulthood. Researchers also say that the more significant the abuse, the more severe the schizophrenia-like experiences adults have.

The research, published in PLOS ONE, is the first to summarize and quantify studies (25 in total) that have explored the relationship between childhood trauma and schizophrenia-like experiences in over 15,000 healthy people.

Researchers at the University of Hertfordshire analyzed the findings of past research to see whether specific types of abuse, such as emotional, sexual and physical abuse, as well as emotional and physical neglect, increased the likelihood of having schizophrenia-like experiences in later life.

They found a much stronger link between childhood emotional abuse and schizophrenic-like experiences in adulthood than other types of childhood abuse.

The relationship between childhood trauma and schizophrenia, a serious mental health condition, is well known. However, far less research has examined the impact of childhood trauma on the prevalence of less severe schizophrenia-like experiences in healthy adults.

Researchers believe their findings could show that schizophrenia is a condition on a spectrum, like autism, where healthy people can have schizophrenia-like episodes without meeting the diagnosable threshold.

University of Hertfordshire researcher Dr. Diamantis Toutountzidis led on this study with supervision from Keith Laws, Professor of Neuropsychology at the University.

Dr. Toutountzidis says that “emotional abuse differs from other types of abuse. It is more common, often happens over longer periods of time, and is not treated in law the same way that physical or sexual abuse is.”

“Our research has shown a significant link between childhood emotional abuse and schizophrenia-like experiences in healthy adults, and that emotional abuse is a stronger predictor of schizophrenia-like experiences than other types of abuse. This is something mental health professionals should consider when looking to tackle the root causes of schizophrenia-like experiences in people suffering from them.”

Professor Laws added that their “research has opened the door to future studies that help better understand how specific types of childhood abuse are linked to specific schizophrenia-like experiences much later in life. It will also help us start to understand why such trauma is linked to disorders like schizophrenia in some, while others experience milder manageable experiences.”

Classification of childhood trauma
Here, a caregiver refers to any responsible adult with a relationship with or in a place of authority over a child.

Schizophrenia (SCZ) affects 20 million people worldwide, and it is one of the top 15 leading causes of disability. SCZ typically presents with positive, negative, and cognitive symptoms. Auditory hallucinations and thought disorders are consistent with positive symptoms. These symptoms usually respond favorably to antipsychotic treatment in most individuals. On the contrary, negative symptoms such as social withdrawal and flat affect, and cognitive symptoms including learning and attention disorders pose significant resistance to available therapy modalities [1].

Based on the dopamine hypothesis, positive symptoms are related to the hyperfunctionality of dopamine D2 receptor neurotransmission in limbic and subcortical brain regions. Hypoactivity of D1 receptor neurotransmission contributes to negative and cognitive symptoms of SCZ [2].

An alteration in dopamine function is strongly associated with the onset of psychotic symptoms. Increased subcortical dopamine production and release are predictable for positive SCZ findings and treatment success [3]. Although the incidence of SCZ is higher in family members of affected individuals, there are theories of several natural surrounding factors in the development of SCZ. The involvement of these exposures favors the neurodevelopmental hypothesis of SCZ, suggesting that SCZ arises from both heritable traits and environmental exposures occurring throughout development from the prenatal period well onto adolescence [4].

Psychosis is a range of behavioral alterations related to a loss of connection with reality and insight. Psychosis is closely associated with SCZ; individuals with psychosis present with hallucinations and delusions. An altered connection within the thalamocortical pathway, specifically with the hippocampus, may cause an impediment to auditory processing. The prefrontal cortex (PFC) overactivation and deactivation of the striatal/thalamic network is closely associated with delusions. This interwoven relationship between these brain regions is crucial in understanding the complexity of psychotic disorders [3].

Childhood trauma (ChT), also known as childhood adversity, defines stressful life events such as physical, sexual, emotional abuse, and neglect [5,6]. In early developmental years, adverse childhood experiences (ACEs) comprise exposure to long-term environmental stressors such as childhood maltreatment, domestic violence, living in a household with ongoing substance abuse, and interpersonal loss [7]. Interpersonal loss entails experiencing parental death, divorce, or mental illness early in life before age 17 [8].

The Childhood Trauma Questionnaire (CTQ) is a valuable survey tool used to screen for experiences of abuse and neglect [9]. Growing evidence links ChT with inflammation, proposing that the pathophysiology of trauma-related psychopathology can be explained by inflammation [10]. Although psychotic symptoms typically begin in the age of 18-25 years, those who later develop SCZ have earlier cognitive deficits in childhood, suggesting that these cognitive deficits are an indicator of abnormal neurodevelopment, particularly when considering early developmental adversities [11].

Establishing the role of childhood adverse life events in psychotic disorders is the first step in anticipating and eventually mitigating the adulthood development of these life-altering disorders. This systematic review aims to summarize the effects of ChT in the development of SCZ/psychosis and discuss more specific details of this concept.

Recent studies have demonstrated that individuals with SCZ are 2.7 times more likely to have experiences of ACEs than healthy controls [9]. This systematic review focuses on analysing the current data on ChT, psychosis, and SCZ, comparing individual findings to their interwoven relationships. This section will first address ChT broadly, including assessment tools for trauma identifying and trauma severity scaling. We will further concentrate on the different mechanisms involved in the relationship between SCZ, psychosis, and ACEs, including specific psychological outcomes, genetic findings, neural pathways, and brain modifications.

Exploring Facets of Childhood Trauma

The capability of a caregiver to provide a safe and healthy environment is directly proportional to the quality of a child’s attachment style. A child’s relationship with the caregiver plays a vital role in early attachment style formation. Children with responsive caregivers develop secure attachments and are more open to seeking support when faced with difficulties. On the other hand, children with unreliable caregivers that fail to care for their needs tend to develop an avoidant and resistant attachment style, learning to be emotionally self-reliant at an early age [19].

Around a fourth of children encounter child abuse or neglect in their lifetime. It is crucial to highlight that 78% are neglect, 18% physical abuse, and 9% sexual abuse cases. The fatality rate for child maltreatment is significant annually, being the second leading cause of death in children less than one year of age. Exposure to violence can have lifelong health consequences during childhood, including poor emotional, physical, and mental health.

The key to preventing these poor outcomes lies in preventing, adequately diagnosing, and treating all forms of child abuse. The goal is to decrease undetected and unreported cases by clinicians. The five types of childhood trauma addressed in this review are physical abuse, emotional abuse, sexual abuse, physical neglect, and emotional neglect [13,28]. Figure ​2 provides a brief description of the different types of ChT, highlighting particular behaviors and patterns that caregivers can use to cause trauma [29,30].

Effects of Childhood Trauma on the Developing Brain

ChT is probably the most important environmental factor associated with SCZ [20]. There is evidence of multiple paths between traumatic experiences and psychosis. Mental disorders are systems of interacting symptoms through a framework of networks [21]. Psychotic symptoms in patients with a history of child abuse are more severe, persistent, and refractory to treatment [17]. In developmental years, exposure to neglect and abuse reveals severe adverse effects on the average neurobiological growth, leading to vulnerable neurobiology preceding disadvantageous psychiatric outcomes. Importantly, post-traumatic stress disorder (PTSD) and ACEs have a modifying effect on psychotic symptoms. Independent of ChT, patients with PTSD are five times more likely to be diagnosed with psychotic disorders than individuals without PTSD [24].

ChT is a form of severe stress that puts individuals in vulnerable mental states with the likelihood of developing mental disabilities such as SCZ. Multiple studies indicate that ACEs multiply the risk of developing psychosis and SCZ. In ultra-high-risk (UHR) individuals, higher levels of ChT result in more heightened positive, general, and depressive symptoms and poorer levels of global functioning. Histories of emotional neglect, physical neglect, emotional abuse, and sexual abuse are frequent in individuals at UHR. It is worth noting that female patients reporting episodes of physical abuse during childhood years have more psychotic and depressive symptoms when evaluated than their counterparts without a history of ChT [18].

Meta-analysis in individuals with psychotic disorders proposes a three-fold likelihood of having experienced some childhood adversity compared to healthy controls [23]. The relationship between trauma exposure and psychosis is heavily dependent on the onset, time frame, and nature of trauma. The risk of developing psychopathology is exceptionally high in home environments with recurrent exposure to ongoing traumatic events [24].

The relationship between exposure to ChT and SCZ is strongly dose-responsive as noted above, concluding that diagnosis is most feasible in individuals with multiple exposures to ACEs. A recent study in South Africa made a similar discovery when exploring the relationship between childhood trauma and SCZ. One experience of physical or emotional trauma had no significant association with SCZ; still, in individuals with greater than two experiences of these traumas, there is an increase in the odds of developing SCZ, suggesting that physical and emotional childhood adversity, when occurring infrequently, does not necessarily increase the risk of SCZ. On the other hand, one experience of sexual abuse increases the odds and severity of SCZ [14,16,25]. Although these findings are slightly controversial compared to other studies, a study on ChT found a significant link between physical and sexual abuse with the severity of positive psychotic symptoms in minority ethnic groups [9].

There is strong evidence between ChT and hallucination and delusions [13]. A couple of researchers propose that symptoms such as hallucinations and delusions are intrusions or an individual’s perception of intrusions resulting in despair. ChT has a more significant link to positive symptoms than negative symptoms. Emotional neglect is related to paranoia by an individual’s belief in a just world. A high perception of injustice and feelings of being a specific target of unfair treatment can cause an individual to be paranoid [24,25].

Comparing reports of ChT between individuals with first-episode psychosis and schizophrenia, the former shows a prevalence rate of 28%-53% while the latter a rate of 9%-83% [26]. SCZ spectrum disorders are associated with lower premorbid adjustment in those exposed to childhood maltreatment. ACEs contribute to neurodevelopment impairment, unveiling poor premorbid adjustment before the onset of psychosis.

When addressing premorbid adjustment, findings are not specific to one type of trauma but cover all different categories of ChT [22]. Generally, patients with psychotic disorders and histories of child abuse have common clinical characteristics, such as a higher hospitalization rate for symptoms, a more relentless course of psychosis, earlier onset of symptoms, more severe episodes, heightened rates of treatment failure and noncompliance, greater likelihoods of mood and behavioral disturbances alongside psychosis symptoms, greater risk of suicide and substance disorders [17].

Consideration of trauma histories is an essential factor when studying experiences of psychosis. Children with histories of physical or psychological trauma during periods of personality development in infancy and early childhood years are prone to anxiety and panic episodes in adult years. Panic attacks occur in 45% of patients with SCZ leading to the speculation that early trauma increases the risk of both disorders. A trauma-based approach is necessary when evaluating patients with psychosis since an increase in frequency and severity of ChT correlates with paranoia [19,25,27].

Assessment Tools

Several assessment tools help identify ChT. They take into account severity, context, and cultural influences. The Childhood Trauma Questionnaire (CTQ) is most common across the board, both in non-clinical and clinical individuals [31]. CTQ is an international assessment tool used to assess ChT. This self-report survey, along with other measures, is essential in identifying experiences of abuse and neglect [9]. Most observational studies utilize the Positive and Negative Syndrome Scale (PANSS) to assess psychotic positive and negative symptoms [32]. Additional assessment tools are available to fully explore psychotic traits and symptoms of other mental disabilities. Table ​Table2 contains2 contains a summary of necessary assessment tools relating to ACEs and mental health issues.

Table 2

Analysis of indicated assessment tools

PTSD: post-traumatic stress disorder, CTQ: Childhood Trauma Questionnaire, CTQSF: Childhood Trauma Questionnaire Short Form, DSM: Diagnostic and Statistical Manual of Mental Disorders, OCD: obsessive-compulsive disorder

Assessment toolSpecifics of the assessment tool
Clinician-Administered PTSD Scale (CAPS)Structured clinical interview with 30 items used as a gold standard for assessing PTSD and quantifying symptom severity [33,34].
CTQA retrospective method of measuring childhood trauma using a 70-item questionnaire. It addresses five subscales of trauma: physical neglect, emotional neglect, physical abuse, emotional abuse, and sexual abuse [35,36].
CTQSFA shortened version of the original CTQ. It uses a 28-item questionnaire [36].
The Chinese version of CTQSF (Childhood Abuse Questionnaire)A Chinese translated version of the CTQSF, used in the Chinese population due to similar psychometric properties and cultural equivalence [31].
The Dutch version of CTQSFThe self-report CTQSF questionnaire in Dutch [21].
The Childhood Experience of Care and Abuse Questionnaire (CECA.Q)A self-report questionnaire for obtaining information about incidents of parental hostility, neglects, and abuse [37].
Early Trauma Inventory Self Report – Short Form (ETISR-SF)A self-administered questionnaire with 27 items to assess general traumatic experiences and childhood trauma occurring before age 18 [38].
Experience in Close Relationships – Relationship Structures (ECR-RS)A scale to measure attachment within a relational context like family and friends. It can be used on children and adolescents [39].
Liebowitz Social Anxiety Scale (LSAS)This assessment scale helps measure the severity of social anxiety symptoms. It also measures response to treatment. The scale comprises 24 social situations that rate levels of fear and avoidance. There are two types available: a clinically administered and the other, a self-report version [40].
Neurological Evaluation Scale (NES)A structured clinical examination helps assess the degree of neurological impairment in schizophrenic patients. The scale comprises 26 items [41].
Panic and Schizophrenia Interview (PaSI)Interview for assessing comorbidities of anxiety disorder [19].
Positive and Negative Syndrome Scale (PANSS)The gold standard for evaluating the efficacy of antipsychotic therapy. Evaluation of multidimensional symptoms is done by obtaining data from clinical observations and patient/caregiver reports [42].
Premorbid Adjustment Scale (PAS)This scale helps assess levels of functioning across four developmental periods from childhood to early adulthood. Areas addressed by the scale include adaptation to school, peer relationships, school performance, social sexual aspect, and sociality [22].
Retrospective Bullying QuestionnaireThe questionnaire is helpful in the measurement of victimization during childhood years, assessing physical, verbal, and indirect forms of bullying in school and perceived severity as well as the frequency of bullying [25].
Structured Clinical Interview for DSM-IV (SCID)An assessment tool widely used to evaluate the presence of anxiety and related disorders [43].
The Avon Longitudinal Study of Parents and Children (ALSPAC)A prospective cohort study based on a population in the geographical area of Avon in the UK. Pregnant women recruited in 1990-1992 were studied along with their partners and children, since the initial study in 1990 till date [44,45].
The Diagnostic Interview for Psychosis and Affective Disorders (DI-PAD)An interview using DSM algorithms and the International Classification of Diseases to evaluate symptoms related to depression, mania, and schizophrenia [19].
General Beliefs in a Just World ScaleA six-item, six-point scale, for measuring an individual’s belief in a just world in general [25].
MINI International Neuropsychiatric Interview (MINI)An interview to evaluate psychiatric disorders based on DSM criteria. It measures current and lifetime evidence of substance use, major depression, and psychotic disorders [24].
Personal Belief in a Just World ScaleA seven-item assessment scale with six points; effectively measures individuals’ belief that the world is a just place for them [25].
Traumatic Events Inventory (TEI)A 14-item measurement scale helps screen for a lifetime history of exposure to trauma. It considers the age of first exposure, frequency of traumatic events, and attestation of exposure [46].
Yale-Brown Obsessions and Compulsions Scale (Y-BOCS)A gold standard assessment scale for severity of symptom evaluation in OCD, widely used by trained clinicians. It consists of two interrelated components: a checklist of obsessions and compulsions, and a severity scale assessing the severity of symptoms during the prior week [47].

reference link :

More information: Diamantis Toutountzidis et al, Childhood trauma and schizotypy in non-clinical samples: A systematic review and meta-analysis, PLOS ONE (2022). DOI: 10.1371/journal.pone.0270494


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