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. Author manuscript; available in PMC: 2021 Jul 30.
Published in final edited form as: Fam Relat. 2016 Mar 22;65(1):151–162. doi: 10.1111/fare.12177

Should Parents’ Physical Punishment of Children Be Considered a Source of Toxic Stress That Affects Brain Development?

Elizabeth T Gershoff 1
PMCID: PMC8323998  NIHMSID: NIHMS1676374  PMID: 34334857

Abstract

The notion that negative childhood experiences can be sources of toxic stress that have short-and long-term consequences for children’s health and well-being has gained increasing attention in recent years. The family environment can be a key source of stress, particularly when parents inflict pain on children; when that pain rises to the level of physical abuse the stress is thought to be toxic. In this article the author considers the possibility that nonabusive physical punishment may also constitute a source of toxic stress in the lives of children that affects their brain structure and functioning. The research linking physical abuse and physical punishment to children’s brain structure and functioning is summarized, and the article concludes with a discussion of implications for future research, policy, and practice.

Keywords: brain development, parenting, physical abuse, physical punishment, toxic stress

Special Issue Guest Editor’s Note:

In this article the author examines children’s experience of physical punishment and proposes a link between physical punishment and children’s brain development that is similar to that identified between physical abuse and children’s brain structure and functioning. The argument builds on the research presented in the paired article, “Neurobiology, Neuroimaging, and Neuropsychology of Children and Adolescents with Disruptive Behavior Disorders” (this issue, pp. 134–150), in which Puzzo and colleagues present an overview of the role of the prefrontal cortex in supporting emotional and social behavior as well as moral judgment.

The concept of toxic stress has gained momentum in recent years as a way to understand how harmful aspects of the environmental contexts in which children live affect their health and development. Although characteristics of the physical contexts in which children develop, such as pollution or crowding (Evans, 2006), have been identified as sources of stress, the family context has also been implicated as a potential source of toxic stress (Shonkoff et al., 2012). Families can be a source of stress for many reasons; children can experience the stress of material hardship if their families have low income (Gershoff, Aber, Raver, & Lennon, 2007), or they can experience the stress associated with instability and unpredictability if their family life is characterized by chaos (Evans, 2006). Strained or violent family relationships can also be a key source of stress and, given the primacy of parent–child relationships to the healthy development of children (Collins, Maccoby, Steinberg, Hetheringon, & Bornstein, 2000), tension or violence in parent–child relationships may be particularly harmful to children.

In this article I make the argument that one particular aspect of parent–child relationships— namely, parents’ physical harming of children in the name of discipline—is a source of stress in the lives of children. I hypothesize that physical punishment of children by parents is a potential source of toxic stress that is linked with long-term detrimental changes to the structure and functioning of the brain. As will be demonstrated, direct empirical evidence related to this question is limited, and thus the main goal of this article is to spur more research that can test this hypothesis, in part by drawing on research showing that a related parent behavior, physical abuse, constitutes a toxic stress in children’s lives that affects their brain development and functioning.

Toxic Stress and Children’s Brain Development

When a child is exposed to a frightening or threatening situation, exposure to the stressor activates the cardiovascular system, the metabolic system, the immune system, and the central nervous system, including the hypothalamic–pituitary–adrenal (HPA) axis, through the coordinated actions of the amygdala, hippocampus, and prefrontal cortex regions of the brain (Lupien, McEwan, Gunnar, & Heim, 2009; McEwen, 1998). The amygdala is essential to detecting threat, whereas the hippocampus and prefrontal cortex mobilize the response to the threat (Danese & McEwen, 2012). A child under stress experiences an increase in heart rate, a secretion of stress hormones, increased flow of blood to the brain, and a heightened feeling of vigilance and fear (Shonkoff, Boyce, & McEwen, 2009). These physiological reactions underlie the body’s fight-or-flight response, mobilizing the child to respond to a threat in the environment.

When the stressor is not overwhelming, and when children have caring adults to whom they can turn for support, they are able to regulate their current distress and thereby learn how to manage their own stress response in the future (National Scientific Council on the Developing Child, 2005/2014). In such cases, the stress hormone levels return to normal and the brain can recover from the short-term harm to the brain. This process of adapting to environmental challenges and returning to normal is called allostasis (McEwen, 1998).

However, although these stress responses can be essential to survival, if they are activated over and over they can become harmful to the child (Shonkoff et al., 2009). When a child experiences this repeated activation of the stress-response system, and does so without an adult caregiver to provide support, the child is said to be experiencing toxic stress (Shonkoff et al, 2009). The defining aspects of toxic stress are thus that it is severe and chronic and that the child does not have an adult to help her or him regulate her or his stress response and choose appropriate behavioral responses.

When an individual’s stress response system is overworked by chronic stress or fails to ramp down after a stressful event is over, it is said to be in a state of allostatic load (McEwen, 1998). Allostatic load has been linked with detrimental structural and functional changes in all three brain regions related to stress management, namely (a) atrophied dendrites and impairments in emotion regulation in the prefrontal cortex, (b) atrophied dendrites and heightened fear response in the amygdala, and (c) reductions in overall volume and accompanying deficits in memory in the hippocampus (Danese & McEwen, 2012). Studies of humans are consistent with animal studies, the latter of which have found that animals exposed to chronic stress as juveniles experience restriction in growth and even atrophy of dendritic connections in the hippocampus, prefrontal cortex, and amygdala (Eiland, Ramroop, Hill, Manley, & McEwen, 2012).

When a child suffers adverse experiences and the accompanying allostatic load early in his or her brain development, long-term structural and functional changes to the brain are likely, leading to the notion that this early stress becomes “biologically embedded” in the child (Danese & McEwen, 2012). Toxic stress is thought to lead to permanent changes in brain functioning, behavior, and physiological responses to stress that precipitate higher levels of stress-related chronic disease (Shonkoff et al., 2012).

The Case for Considering Physical Punishment as a Source of Toxic Stress

The notion that physical punishment is a stressor in the lives of children was first put forward by Turner and Finkelhor (1996). They argued that physical punishment is a stressor for children because it is chronic, negative, and uncontrollable. They examined whether a history of physical punishment was linked with distress in a large sample of 10- to 16-year-olds who were asked how often they were spanked, slapped, or hit by their parents and were asked questions about their general psychological distress. As the frequency of reported physical punishment increased, so did children’s levels of distress (Turner & Finkelhor, 1996). It is important to note that this association was over and above the association of physical abuse with more distress, suggesting that physical punishment is linked with children’s general levels of distress independent of any experience of recognizably harmful physical abuse.

But does physical punishment qualify as a toxic stressor? For a stressor to be considered toxic for a child, it must be chronic and severe, and it must occur in the absence of adult support (Shonkoff et al., 2009). Although physical punishment is not as obviously traumatic as physical abuse, it does have these three characteristics of a toxic stressor. First, physical punishment meets the criteria that the toxic stressor be chronic. Parents of 3-year-olds who use spanking, the most common form of physical punishment, report doing so an average of twice per week (Holden, Coleman, & Schmidt, 1995). While this finding indicates that most children are not being spanked every day, spanking is indeed chronic at an average of 100 times per year. Second, physical punishment—including its most common form, spanking—is physically painful and emotionally upsetting. Spanking involves a parent striking a child, either with a hand or an object, with the intention of causing pain but not injury (Straus, 2001). “Spanking” is thus a euphemism for a socially acceptable form of hitting that constitutes parent-to-child violence (Gershoff, 2013). Whenever one person uses violence against another there is a potential for physical and mental injury, and children report that physical punishment is indeed physically and emotionally painful. Children in a New Zealand study reported that being “smacked” (another term for spanking) “hurts and makes you cry” (Dobbs & Duncan, 2004, p. 371). The children reported strong emotional reactions, including feeling sad, angry, and scared (Dobbs & Duncan, 2004). Similarly, children in an interview study in the United Kingdom reported both physical pain and emotional distress when they were smacked (e.g., “It really hurts, it stings you and makes you horrible inside”; Willow & Hyder, 1998, p. 49). Thus, physical punishment causes physical and mental pain and distress which, given the chronic nature of many parents’ spanking, can accumulate over time.

Third, when a child is physically punished, the parent is the source of the pain and emotional distress the child is feeling, and thus the child has a difficult time using the parent as a source of comfort to help reduce the stress (Turner & Finkelhor, 1996). To the extent that physical punishment involves the experience of physical and emotional pain in the absence of adult support to help the child manage the pain and distress, physical punishment can be considered a toxic stressor. This is not to say that all instances of physical punishment constitute a toxic stressor; indeed, parents often say that they reconcile with their children right after the spanking to reassure the children that they still love them. However, over time, the experience of being hit by someone the child loves and depends on may lead to learned helplessness and mistrust. It may also lead to confusion, as the parent is sometimes a source of comfort in the face of stress and sometimes the source of the stress; confusion that can interfere with the quality of the parent–child relationship and engenders mental health problems.

Physical punishment should thus be considered a potential toxic stressor according to the criteria put forward by the National Scientific Council on the Developing Child (2005/2014). It is chronic; it is painful and distressing to the child; and the parent is not available as a source of comfort, in large part because the parent is the source of the stress itself.

Physical Punishment and Changes in the Brain: Emerging Evidence

If physical punishment is indeed a source of toxic stress in the lives of children, then it should be linked with changes in brain architecture that have been hypothesized to result from toxic stress (National Scientific Council on the Developing Child, 2005/2014). The notion that parenting generally or physical punishment specifically—a common experience for so many children in the United States and around the world—might have lasting impacts on children’s brains has only recently been considered in the research literature.

There is extensive evidence from rat studies indicating that parents’ everyday behaviors affect brain development (Romeo, Tang, & Sullivan, 2009). Rat pups whose mothers engaged in less licking and grooming of them in the first week of life grow up to have more exaggerated glucocorticoid responses to stressful situations as adults than adult rats who were licked and groomed more as pups, indicating effects on the HPA axis functioning (see Meaney, 2010, for a review). The pups with low-grooming mothers also displayed behavioral differences in response to stress, including more fearfulness and increased startle response (Meaney, 2010). This finding has been confirmed in studies with humans, which have found links between nurturance in early childhood and the volume of the hippocampus later in childhood or adolescence (Luby et al., 2012; Rao et al., 2010).

If the presence of a chronic positive behavior such as nurturing can affect children’s brains, it is reasonable to expect that a chronic negative parent behavior such as physical punishment may also affect the brain. Indeed, parents’ verbal hostility at ages 4 to 7 has been found to predict smaller volume of the hippocampus several years later, and to mediate the impact of poverty on the hippocampus (Luby et al., 2013). These findings, taken together with the facts that the hippocampus is most susceptible to abuse between the ages of 3 and 5 (Andersen et al., 2008) and that physical punishment peaks at age 3 (Holden et al., 1995), provide support for the idea that physical punishment may affect brain development.

Preliminary evidence that physical punishment may affect children’s brains first came from a study in which toddlers’ cortisol levels were assessed before, during, and after the Strange Situation assessment of attachment, in which stress is induced in the child by having the parent first leave the child in a laboratory setting with a stranger and then alone (Bugental, Martorell, & Baraza, 2003). Mothers’ reports of how often they spanked or slapped their children were found to significantly predict children’s production of cortisol in reaction to these stressful events: more spanking or slapping predicted more cortisol. Parents’ emotional unavailability did not predict children’s cortisol reactivity. The authors concluded that the experience of physical punishment creates short-term stress that accumulates over time to affect the brain’s stress hormone production in the HPA axis (Bugental et al., 2003).

Another study linking physical punishment with changes in children’s brain functioning was conducted with 4- to 10-year-old boys in Mongolia, whose salivary cortisol was assessed four times over 4 days (Kohrt et al., 2014). Boys whose caregivers endorsed the use of harsh physical punishment (e.g., beating, spanking with a belt or stick) were found to have significantly lower levels of cortisol than boys whose caregivers did not endorse harsh discipline, with these disciplinary attitudes explaining 11% of the between-child variance in cortisol once time of day, age, and food consumption were controlled (Kohrt et al., 2014). This finding provides additional support that at least some forms of physical punishment are linked with depressed HPA activity.

The main test to date of the hypothesis that physical punishment might change the structure of children’s brains comes from a research team that had done previous work with adults who recalled being victims of physical abuse (Teicher, Anderson, & Polcari, 2012). In their study of physical punishment, Tomoda and colleagues (2009) compared the volume of brain gray matter among young adults who had been exposed to chronic and “harsh” physical punishment (defined as occurring at least once per month and involving the use of an object at least once per year) but not to physical abuse (defined as incidents that left a lasting injury or that involved areas of the child’s body other than the buttocks) with that of young adults who did not experience harsh physical punishment or abuse. They found that young adults subject to chronic physical punishment as children had significantly smaller gray matter volume in an area of the prefrontal cortex associated with social cognition than young adults who had not experienced chronic physical punishment (Tomoda et al., 2009).

The importance of this study is twofold. Primarily, it is the first study to link chronic physical punishment with changes in brain structure and thus to confirm that physical punishment can have lasting impacts on children’s developing brains. Second, the region of the prefrontal cortex most affected by physical punishment in this study has been implicated in a range of mental health disorders, including depression (Fitzgerald, Laird, Maller, & Daskalakis, 2008), posttraumatic stress disorder (Bremner et al., 1997), and addiction (Crockford, Goodyear, Edwards, Quickfall, & el-Guebaly, 2005). Thus, changes to the prefrontal cortex may explain the links found between physical punishment and lower mental health (Gershoff, 2002).

These studies provide the first evidence that physical punishment does indeed affect brain structure and functioning in ways that are consistent with it being a toxic stressor. There is still much that needs to be learned about these connections, and I will identify particular research needs later in the article. That said, the limited findings to date regarding physical punishment and brain functioning and development are similar to those from the more robust literature on physical abuse.

Can the Literature on Physical Abuse as a Toxic Stressor Inform Our Understanding of Physical Punishment?

Although American society currently distinguishes acceptable physical punishment from harmful physical abuse, there are several reasons to view them as related phenomena that may have similar impacts on brain development and functioning. Common to both physical abuse and physical punishment is that they involve a parent hurting a child through hitting or some other form of physical force, albeit to different degrees. It is also true that all cases of physical punishment and most cases of physical abuse were initiated with the intention of correcting a child’s misbehavior. Fully three quarters of child physical abuse cases start as a parent disciplining a child (Durrant et al., 2006). Indeed, several states recognize in their family codes that physical punishment can escalate into physical abuse (Gershoff & Bitensky, 2007), such as in the statutes of Nevada, which proclaim that “Excessive corporal punishment may constitute abuse or neglect” (Nevada Revised Statutes, § 432B.150, 1985). Physical punishment and physical abuse can thus be viewed as points along a continuum of violence against children (Gelles & Straus, 1988; Gershoff & Bitensky, 2007).

Physical abuse and physical punishment have also been associated with similar child outcomes. Children who have been physically abused have been found to have more mental health problems, including depression and anxiety, in the short term (Casanueva, Dolan, Smith, Ringeisen, & Dowd, 2012); prospective studies have confirmed that links between physical abuse and mental health problems persist later in childhood (Mills et al., 2013) and into adulthood (Herrenkohl, Hong, Klika, Herrenkohl, & Russo, 2013). Similar results have been found for physical punishment. The more children are physically punished, the more mental health problems they report as children (Coley, Kull, & Carrano, 2014) and as adults (Taillieu & Brownridge, 2013). Behavior problems are also commonly associated with both physical abuse and physical punishment. Physically abused children manifest behavior problems in childhood (Casanueva et al., 2012) and adulthood (Herrenkohl et al., 2013). Physical punishment has also been linked with more behavior problems in childhood (Gershoff, Lansford, Sexton, Davis-Kean, & Sameroff, 2012; Lee, Altschul, & Gershoff, 2013) and in adulthood (McCord, 1991). Cognitive impairments are manifest in children with a history of physical abuse (Noble, Tottenham, & Casey, 2005; Teicher, Samson, Polcari, & McGreenery, 2006) and in children with a history of physical punishment (Straus & Paschall, 2009). Finally, physical abuse has been linked with higher physical health problems in childhood (Lanier, Jonson-Reid, Stahlschmidt, Drake, & Constantino, 2010) and prospectively into adulthood (Herrenkohl et al., 2013; Widom, Czaja, Bentley, & Johnson, 2012). Physical punishment in childhood has been linked with more health problems, including cardiovascular disease and obesity, in adulthood (Afifi, Mota, MacMillan, & Sareen, 2013).

Given that physical punishment and physical abuse are points along a continuum of violence against children, with physical punishment sometimes turning into physical abuse, and given that they have been linked with similar child outcomes, it follows that if toxic stress is one process by which physical abuse harms brain development, toxic stress may also be responsible for connections between physical punishment and brain development. Understanding how physical abuse functions as a toxic stressor can thus inform the consideration of physical punishment as a toxic stressor.

Physical Abuse as a Toxic Stressor that Affects Brain Development

Physical abuse is recognized as a clear example of a toxic stressor: It is often chronic; it is severe both physically and mentally; and, because most cases of maltreatment are perpetrated by parents (82%; U.S. Department of Health and Human Services, Administration for Children and Families, 2013), the parent who harmed the child cannot be used by the child as a resource to cope with the stress from the experience. Indeed, researchers and practitioners have proposed that the main reason physical abuse has harmful consequences is that it constitutes a source of toxic stress in the lives of children (National Scientific Council on the Developing Child, 2005/2014). By repeatedly activating the stress system, physical abuse is thought to lead to long-term changes in brain structure and functioning, changes which in turn precipitate negative emotional, behavioral, and cognitive outcomes. A large body of research has linked the experience of physical abuse with changes to children’s brain development and functioning and has been summarized extensively elsewhere (e.g., Jaffee & Christian, 2014), but a brief review is provided here.

Research on the impacts of physical abuse on children’s brains has looked both at changes in brain structure and functioning. One of the main brain structures that has been examined for impacts of physical abuse is the amygdala. Because the job of the amygdala is to detect threat, and because physical abuse poses a chronic threat, the amygdala in children who are victims of physical abuse are likely to be overactive. Researchers have speculated that this overuse would result in smaller amygdala, and this has been found in some studies (Edmiston et al., 2011; Hanson et al., 2015; Woon & Hedges, 2008). There is also some evidence that processes governed by the amygdala are affected by abuse. Children with a history of maltreatment are more attentive to angry cues than neutral ones (Shackman, Shackman, & Pollak, 2007), which suggests a hyperawareness of threat that may be adaptive and self-protective for children growing up in abusive environments (Mead, Beauchaine, & Shannon, 2010).

Researchers have also examined the hippocampus for structural changes related to a history of physical abuse under the hypothesis that the stress of abuse leads to neuronal loss that would manifest as smaller brain structures. Several studies have confirmed that, compared to adults without such histories, adults with a history of abuse have smaller hippocampal volume in areas found to be sensitive to stress (Teicher et al., 2012; Woon & Hedges, 2008). The results of studies conducted with children have been inconsistent, with some finding differences in hippocampal volume (e.g., Hanson et al., 2015) and others not (e.g., De Bellis et al., 2002), leading some to conclude that the effects of abuse on the hippocampus may not manifest until adulthood (Woon & Hedges, 2008).

One job of the hippocampus is to regulate activity in the HPA axis, and thus any structural changes to it likely affect the functioning of the HPA axis. As summarized by Jaffee and Christian (2014), two competing hypotheses have been offered to explain how maltreatment may affect HPA axis functioning. The first explanation, the glucocorticoid cascade hypothesis, suggests that a child under stress experiences an overstimulation of glucocorticoids that, over time, can result in damage to receptors in the hippocampus that turn off the HPA response (Sapolsky, Krey, & McEwen, 1986). Thus, high glucocorticoid levels damage the same area of the hippocampus responsible for tamping them down, leading to high levels of glucocorticoids even after the stressor is no longer present (Tarullo & Gunnar, 2006). In a vicious cycle, these high levels are thought to result in further damage to the hippocampus and subsequent mental and physical health problems (Jaffee & Christian, 2014).

The second hypothesis regarding how early maltreatment alters HPA axis functioning poses the opposite process, namely that early stress leads to insufficient glucocorticoid production in response to threat or to a loss in responsivity of the glucocorticoid receptors, either of which would result in low cortisol levels and a failure to turn off the HPA axis in response to threat (Jaffee & Christian, 2014; Lupien et al., 2009). This hypothesis is supported by findings that individuals with a history of physical abuse exhibit lower cortisol reactivity in response to stressful tasks in the laboratory than do individuals without such histories (Carpenter, Shattuck, Tyrka, Geracioti, & Price, 2011; Trickett, Gordis, Peckins, & Susman, 2014). However, another study found no relationship between severity of physical abuse and cortisol levels (Bruce, Fisher, Pears, & Levine, 2009).

Research is ongoing to understand these mechanisms and to determine whether these competing processes occur differentially across individuals or within individuals but in different circumstances or at different periods of development (Jaffee & Christian, 2014).

Implications for Future Research, Practice, and Policy

The hypothesis that physical punishment constitutes a toxic stressor in the lives of children is consistent with the existing literature on toxic stress, physical punishment, and physical abuse, but it is far from being proven. Much more research is needed to fully understand the stress processes activated by physical punishment. Key to understanding these processes will be prospective longitudinal studies that measure physical punishment and abuse in childhood and then measure changes in brain structure and functioning as children develop. The key study (Tomoda et al., 2009) to date that links physical punishment with brain changes used a retrospective design with young adults. Prospective designs that measure physical punishment in childhood and link it with changes in brain structure and functioning over time would provide much stronger evidence.

More research is also needed to explicitly test the hypothesized mediational pathway from physical punishment → permanent changes in children’s brains → chronic mental, behavioral, cognitive, and physical problems (Shonkoff et al., 2012). One example of the type of research needed is a recent study that found the link between children’s life stress, which included physical abuse history, and their behavior problems was mediated by differences in hippocampal volume, with physically abused children having smaller hippocampal volume (Hanson et al., 2015). Similarly, the study by Bugental and colleagues (2003) described earlier, which linked toddlers’ experiences with physical punishment to their levels of cortisol in response to a stressful situation, could be repeated with older children. As research in this area progresses, it will also be important to rule out third variables that may account for the observed associations among physical punishment or abuse, brain development, and health outcomes, or that may moderate the linkages among them. Primary candidates are family structure, parents’ relationship quality, economic status, parent education, parent depression, and other forms of life stress. Indeed, children from families with low socioeconomic status tend to have heightened stress-response systems (Shonkoff et al., 2009) and to have higher rates of physical punishment (Regalado, Sareen, Inkelas, Wissow, & Halfon, 2004), physical abuse (Sedlak et al., 2010), and detrimental child outcomes (Yoshikawa, Aber, & Beardslee, 2012). Future research will need to rule out family socioeconomic characteristics in trying to isolate the potential impact of physical punishment or abuse on children’s brains and health.

There are practice implications of the findings as well. As I noted at the outset, both physical punishment and physical abuse have been linked with short- and long-term harm to children. It now appears that part of how they may have such effects is by altering children’s brains. These findings give added urgency to the need to prevent parents from engaging in acts that may result in abuse, and possibly from engaging in physical punishment altogether. Indeed, given the connections between physical abuse and physical punishment, preventing physical punishment is an important, and perhaps even necessary, step in preventing most cases of physical abuse (Klevens & Whitaker, 2007). A variety of interventions have been found to reduce parents’ use of physical punishment and, in doing so, to reduce negative outcomes for children, including interventions delivered through parenting groups (Beauchaine, Webster-Stratton, & Reid, 2005), preschool settings (Gershoff, Ansari, Purtell, & Sexton, 2015), and community education (Prinz, Sanders, Shapiro, Whitaker, & Lutzker, 2009). An evaluation of the Triple P parenting program implemented in communities across South Carolina found that the message of reducing physical punishment of children conveyed through public service announcements and billboards translated into reductions in county-level child maltreatment rates (Prinz et al., 2009).

Although prevention of physical harm to children is preferred, treatment of children who have been harmed through physical abuse or physical punishment is possible and necessary. Thankfully, the harm to children’s brains resulting from physical abuse is not irreversible; children’s brains show remarkable neural plasticity and can rebound if adequate treatment and rehabilitation are administered (Kleim & Jones, 2008). For example, when foster parents were trained to provide consistent discipline and positive reinforcement, the previously maltreated children in their care experience a normalization of their cortisol levels and a reduction in their behavior problems (Fisher, Gunnar, Chamberlain, & Reid, 2000). A variety of trauma-focused interventions have also been shown to be effective with child victims of physical abuse, including cognitive behavioral therapy, play therapy, multisystemic therapy, and parent–child interaction therapy (Saunders, Berliner, & Hanson, 2004).

The idea that physical abuse and physical punishment constitute toxic stressors in the lives of children has implications for policy as well. The American Academy of Pediatrics has called for public policies and programs designed to reduce exposure to toxic stress, including physical abuse (Shonkoff et al., 2012). Physical abuse is, of course, already illegal throughout the United States (Child Welfare Information Gateway, 2014), but these laws have done little to stop it from occurring (Finkelhor & Jones, 2012). The prevention of physical abuse must be a public health priority that involves evidence-based parenting education efforts (Saul et al., 2014).

Given the harm that has been linked to parents’ use of physical punishment, reducing physical punishment should be a public health goal in its own right. Upon finding a link between hostile parenting and reduced hippocampal volume, Luby and colleagues (2013) called for early caregiving intervention to be a “focused public health target” (p. 1135). Forty-eight countries around the world have agreed and have banned all physical punishment of children, including that by parents (Global Initiative to End All Corporal Punishment of Children, 2015). Given our national reluctance for government to be involved in the everyday interactions of families, it is unlikely the United States will ban physical punishment outright (Gershoff & Bitensky, 2007). However, we can do more as a society to change norms about hitting children and to educate parents about the harms associated with physical punishment and thereby reduce parents’ use of physical punishment in the long term.

Conclusion

Toxic stress is a relatively new concept that has been used to understand how physical abuse may affect children’s emotional, cognitive, and physical health by changing their brain structure and functioning. In this article I have made the case that physical punishment should also be considered a potential source of toxic stress that harms children’s overall development by harming their brains. Although there is consistent research linking physical abuse to change in children’s brain structure and functioning, only preliminary efforts have been made to understand how physical punishment affects children’s brain development. Given their strong similarities in genesis and in outcomes, it seems likely that future research will bear out the conclusion that physical punishment, like physical abuse, hurts children’s brains as well as their bodies.

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