What is this article about?

In 2014, around 3.9 million children were under investigation for allegations of abuse or neglect. In this paper, the focus is on the relationship between childhood maltreatment and mental health in childhood and adulthood, and on biological and psychosocial factors that mediate and moderate the relationship.

Maltreatment includes neglect and emotional, sexual, and physical abuse. Neglect refers to not providing children with the necessary clothes, hygiene, foods, and safety. Physical abuse is defined as harm by a caregiver or by someone who has responsibility for the child. It refers to physical injury on purpose.

Based on statistics it seems that children under three are more often victimized compared to older children. Also, children under one year were victimized most often. Boys and girls are equally victims, but there is a difference between African-American children and White and Hispanic children, with African-American children being abused more than White and Hispanic children.

Some predictors of maltreatment include family poverty, young motherhood, parental history of antisocial behavior, and a perpetrator’s history of maltreatment.

How is maltreatment measured?

When adults are studied, childhood maltreatment is measured by retrospective self-report. However, these retrospective self-reports are often biased, for example by the current mental state and they are subject to omission. For instance, some adults were asked during two interviews about whether they had experienced maltreatment as children. 51% of the adults with documented records of sexual abuse did not report their abuse in these interviews. Also, 21% of the adults without documented records stated to be sexually abused, which would mean that their sexual abuse was not detected, or that they made it up. Also, the experiences that people have in adulthood also bias retrospective records. For instance, 75% of adults who had a lifetime diagnosis of drug abuse reported that they had been victims of abuse or neglect in childhood. However, only 35% of the victims of abuse or neglect are diagnosed with drug abuse. Also, drug abuse in adulthood is the same for those with and without a history of childhood abuse. Thus, experiencing childhood maltreatment is not a good predictor for drug abuse in adulthood.

Thus, there are some issues with retrospective self-report. Therefore, the authors describe studies in which maltreatment was measured in childhood and in which these children were followed into adulthood.

What is the relationship between maltreatment and the risk for psychopathology?

In the following sections, studies will be described that have looked into whether experiencing childhood maltreatment puts individuals at risk for psychopathology in adulthood. All these studies involve a prospective research design in which maltreatment predated the onset of psychopathology; a demographically matched control sample or statistical adjustments for variables that could confound the association between maltreatment and risk for psychopathology; and psychometrically valid measures of psychopathology, including diagnostic measures. Information about maltreatment came from Child Protective Services. Official records are probably lower than the true prevalence of maltreatment, so studies that combine official records with informant reports probably provide the most valid information.

Maltreatment and the risk on externalizing and internalizing psychopathology

It seems that children who experience maltreatment are at higher risk for experiencing externalizing problems in their childhood and adolescence, such as attention deficit/hyperactivity disorder (ADHD), conduct disorder (CD), oppositional defiant disorder (ODD), delinquency, and antisocial behavior. The risk on externalizing problems in adulthood is also present. Some victims show higher rates of antisocial personality disorder, crime, and criminal arrests. Findings with regard to drug use are mixed. Experiencing maltreatment also increases the risk on internalizing problems in childhood, such as major depressive disorder, anxiety disorders, posttraumatic stress disorder (PTSD), and internalizing symptoms. This risk extends into adulthood. In adulthood, they experience more often major depressive disorder, depressive symptoms, and anxiety disorders.

Childhood maltreatment and mental disorders are predictive of PTSD in adulthood, through two ways. First, children who have been maltreated have a higher risk on mental disorders in childhood and adolescence, and a history of mental health problems increases the risk that an adult develops PTSD after experiencing a trauma. Second, maltreatment sensitizes the neurobiological response to subsequent trauma, again increasing the risk that an adult who experiences trauma will develop PTSD.

Maltreatment and the risk on personality pisorders, psychotic pymptoms, and suicide

Children who experience maltreatment are at higher risk for borderline personality disorder in adulthood. They are also at higher risk for suicide in adolescence and adulthood, and they more often engage in self-injury. One study also demonstrated that child victims experience psychotic symptoms in early adolescence. Lastly, one study found that victims of maltreatment were also at higher risk for psychotic disorder, schizoaffective disorder, and schizophrenia.

What is the causal status of effects?

It is difficult to determine causality. For example, if we find that child victims of maltreatment develop mental disorders in childhood or adulthood. This could be explained by that maltreatment causes mental disorders, or that there is a (non)genetic factor that is associated with maltreatment and with mental disorders. One way to test this would be by looking at adopted kids: when they are maltreated, do they also develop mental disorders? This would rule out a genetic factor. However, fortunately, adoption parents are screened and maltreatment is low in adopted children.

The most feasible currently is to compare maltreated children to sociodemographically similar, non-maltreated youth. These studies have shown that maltreated children significantly show more depressive symptoms and suicidal thoughts, substance use problems, and criminal behaviors in young adulthood compared to non-maltreated children.

How does intergenerational transmission of maltreatment take place?

According to the ‘cycle of violence hypothesis’, adults who experience maltreatment in their childhood are at higher risk for maltreating their own children. This hypothesis seems to be supported. However, it could also be a reflect detection bias: among parents who reported engaging in abuse or neglect, 31% of those were investigated by Child Protective Services, because they were themselves maltreated in childhood.

However, there are two important remarks. First, a cycle of violence is not inevitable: it can be broken through. The majority of adults with a history of maltreatment do not maltreat their own children. Second, the hypothesis is based on the bias of the Child Protective Services to investigate and substantiate cases of abuse or neglect, when they know that the parent had a history of maltreatment.

What are mediators of maltreatment effects?

There are certain ways in which maltreatment increases the risk for psychopathology, called mediators. There are three mediators that have been studied: hypervigilance to threat, deficits in emotion recognition, and insensitivity to reward.

Hypervigilance to threat

This mediator has to do with attention bias. Attention bias refers to the tendency to focus on threats, even mild threats. Because of their experience with anger and other negative emotions in their families, children become sensitized to attend to threatening stimuli. This could lead to more anxiety. This is often measured by showing children pairs of faces, with a neutral and an angry face. The results have shown that children and adults who have experienced maltreatment, exhibit biased attention towards angry faces, but not to sad or happy faces. These children and adults also show higher levels of anxiety. This is also true for children who experienced harsh forms of parenting; they also showed this attention bias. This biased attention involves limbic and prefrontal activity. Maltreated children show heightened amygdala reactivity to threat cues compared to nonmaltreated children. However, these responses can also be modulated. When the respondents are told that they should try to decrease their emotional response to negative stimuli, they show greater activation in prefrontal regions.

Maltreated children also show different social information processing styles. For example, they are more likely to attribute hostile intent to others when their behavior is ambiguous. This may lead them to also act more aggressively. For example, in an online game, they acted more aggressively towards an online ‘partner’.

Thus, maltreated children are more attentive to anger cues, find it difficult to disengage attention from anger cues, they identify ambiguous cues as threatening, and they recognize anger faster compared to nonmaltreated children. However, some studies found the opposite. This could probably be explained by the fact that samples vary in terms of their maltreatment exposure: the specific form of maltreatment. It could also be that high rates of PTSD in the samples disturbed the results. PTSD involves hypervigilance toward threatening stimuli and avoidance of threat. Therefore, in these samples, one may find an attentional bias away from threat.

Deficits in emotion recognition

When children and adults are less skilled in recognizing emotions, this may lead to social rejection. Differences in children’s recognition abilities are partly the result of parents’ efforts to model and explain emotions, called emotion socialization. This may differ between abuse and non-abusive family environments. For example, mothers who are physically abusive produce less prototypical facial expressions of anger and vocal expressions of anger, fear, and happiness compared to non-abusive mothers.  They also engage less in coaching, validation and they more often invalidate their children’s emotions. Also, parents who were at high risk for child physical abuse are less accurate in emotion recognition.

From studies it has been shown that children who have been maltreated are also less skilled in recognizing facial expressions of emotions. For instance, in one study, children were presented with stories in which children are experiencing a certain emotion. Then, they have to pick between three photos the photo that matches the story the best. Maltreated children do not do well on this task. One study found that the specific form of emotion recognition deficit matches the type of maltreatment experienced. For example, neglected children are less able to differentiate facial expressions of emotion. Physically abused children show a bias to recognize angry emotions. Maltreated children also experience difficulties in matching emotional outcomes with common elicitors. Healthy, nonmaltreated children are often able to predict which kinds of situations will elicit positive versus negative emotions, but maltreated children are less able to do this. Instead, they report that positive, equivocal, and negative events are all possible elicitors of anger or fear in a task. In this task, emotional outcomes (happy, sad, angry) were presented to children, and then they were asked how likely it was that a positive, negative, or equivocal event might have elicited that emotion.

Maltreated children are poor at emotion recognition and understanding compared to nonmaltreated children. The magnitude of this effect is also bigger for emotion recognition compared to emotion understanding. The effects are the largest in early childhood.

Thus, maltreated children experience difficulties in emotion recognition. This may affect their ability to respond appropriately when others express emotions. They also find it difficult to determine which situations elicit positive and negative emotions: this may affect their ability to predict what reactions they will get from their environment when they perform a certain behavior.

Reward responsiveness

It seems that maltreated children are less sensitive to cues for reward. This puts them at higher risk for depression, and particularly anhedonic symptoms. In a task in which participants were presented with reward, loss, and no-incentives, children who had been maltreated rated rewards as less positive compared to control participants. They show less ventral striatum activation. Other research focused on the anterior cingulate cortex (ACC). It seems that children and adults who have experienced maltreatment are less responsive to reward compared to nonmaltreated individuals. They do not discriminate between cues for high risk/high reward and low risk/low reward in terms of reaction times. They also rate cues for reward less positively compared to control participants. They also show different neural activation. This may explain why they are at increased risk for depression: they have a reduced responsivity to reward and they experience deficits in learning from positive experiences.

What are moderators of child maltreatment?

Moderators of maltreatment are defined as factors that make the effects of maltreatment on the risk of psychopathology, greater or lower. Studies have shown that the effect of maltreatment on risk for psychopathology is similar across demographic groups. However, the effects of maltreatment on risk for psychopathology differ as a function of genotype, and other individual and environmental factors.

Genetic moderators of maltreatment effects

MAOA x maltreatment. The MAOA gene regulates the metabolism of dopamine, serotonin, and norepinephrine. Interest in this gene increased when studies showed that a mutation in this gene was associated with violent behavior among males in Dutch families. Caspi (2002) showed that men in the Dunedin Longitudinal Study birth cohort, who had experienced childhood maltreatment, had elevated levels of childhood conduct and adult antisocial behavior problems, if they carried the low activity variant of the MAOA gene. In contrast, men who had the high activity variant were not at this elevated risk for antisocial behaviors.

5-HTTLPR x maltreatment. 5-HTT plays an important role in the regulation of serotonin uptake. Dysregulated 5-HT is associated with both depression and aggression. The Dunedin Longitudinal Study showed that individuals who had the short form of this gene and who had experienced childhood maltreatment were at elevated risk for depression and depressive symptomatology in adulthood. Individuals who carry the 5-HTTLPR S allele also have a more pronounced physiological response to stress than L allele carriers. Coping is also associated with the 5-HTTLPR genotype. Adults who carried the S allele reported that they were less able to cope with situations that evoked strong feelings of sadness or fear than individuals who were homozygous for the L allele.

What are psychosocial moderators of maltreatment?

Studies have shown that children who do not experience a lot of negative effects of maltreatment (thus, children who are resilient to maltreatment), often have high ego control, high self-esteem, high self-reliance, and they attribute their successes to themselves. These are thus protective factors. However, when children are exposed to more stressors next to maltreatment, these protective factors may disappear. Social support is also a protective factor. It buffers, protects, children and adults from the adverse effects of experiencing maltreatment during childhood. Social support can refer to different domains, such as material support, emotional support, and the satisfaction of relationships with parents, friends, intimate partners, and other relatives.

However, individuals who have experienced maltreatment often have lower levels of social support, and also less stable social support. This may be an explanation for why children and adults with such a history of maltreatment have higher rates of psychopathology. But, when they do have social support, this buffers them against psychopathology. Then, they have the same levels of psychopathology as compared to nonmaltreated children and adults. For example, women who have experienced childhood maltreatment or rape show lower PTSD symptoms when they have high social support. However, for women who did not experience these traumas, social support was not related to PTSD symptoms.

Thus, children and adults with histories of maltreatment have less social support compared to children and adults without such a history. But, the evidence is a bit mixed in whether social support has a buffering effect or whether it has a direct protective effect (which means that having social support is beneficial, regardless of whether someone has been maltreated or not).

What are the conclusions?

Maltreatment has serious negative consequences and thus is an important public health problem. There needs to be more research conducted in a prospective way and with the use of longitudinal data. This can help to better understand the course of resilience and dysfunctions over time, and can help to determine what the effects of maltreatment are on mental and physical health. Thus, there needs to be a mix of research strategies. There needs to be an integrative and multilevel perspective to determine on the pathways from genes to brain to behavior. There also needs to be more research that can help to evaluate treatment efficacy for maltreated children, and to improve access to services and the quality of services. More research is also needed to know why some children respond better to treatment compared to others.

Summary points

• Children under the age of 3 have the highest risk on being maltreated;
• Having a childhood history of maltreatment increases the chance that an individual will also engage in abuse and neglect as an adult, however most of the children who have experienced maltreatment do not themselves engage in abuse or neglect;
• Having experienced maltreatment increases the risk for mental health problems, such as depression, anxiety, substance abuse, antisocial behavior, psychotic symptoms, and personality disorders;
• Maltreatment also increases the risk on psychopathology, because of increased threat sensitivity, decreased responsivity to reward, and because it produces deficits in emotion recognition and understanding;
• Even though maltreatment increases the risk on being mental health problems, this is not inevitable. Having social support can buffer against the adverse effects of being maltreated. Also, some people have genes that make them less susceptible to maltreatment.