May 18, 2017

Hijacked :: CSA & the Developing Brain

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Martin Teicher and his colleagues of Harvard University are leaders in the area of sexual abuse research. The Child Welfare Information Gateway summarizes the specific long-term effects of abuse and neglect on the brain identified by Teicher and his team: (1) Diminished growth in the left hemisphere, which may increase the risk for depression; (2) irritability in the limbic system, setting the stage for the emergence of panic disorder PTSD and prolonged unhappiness; (3) smaller growth in the hippocampus and limbic abnormalities, which can increase the risk for dissociative disorders and memory impairments; and (4) impairment in the connection between the two brain hemispheres, which has been linked to symptoms of attention-deficit/hyperactivity disorder.[1]

Teicher’s research also indicates that a history of abuse is linked to (1) increased electrophysiological abnormalities[2]; (2) epileptic-like symptoms[3]; (3) EEG  abnormalities, which is the recording of electrical activity along the scalp[4]; (4) volume reduction in two areas of the hippocampus[5]; (5) volume reduction in the corpus callosum[6]; (6) impairment of the cerebellum vermis 6; (7) oddities in cortical size, symmetry, and neuronal density[7]; and (8) lateralized hemispheric responses to memory recall.[8] The remainder of this chapter will describe what these changes are along with their implications and the role of timing.

A study conducted by research scientists Akemi Tomoda, Carryl Navalta, Ann Polcari, Norihiro Sadato, and Martin Teicher of Harvard Medical School’s Department of Psychology examined the brains of 23 young women with histories of childhood sexual abuse (CSA). These 18 to 20-year-old women were selected based on age, outstanding hearing and visual perception, and the absence of any additional trauma(s). Furthermore, their selection was independent of psychological condition in order to avoid overestimating the effects. For example, if only those with PTSD were selected, the effects of abuse may have been confounded “disorder-related differences.” In other words, the researchers didn’t want the effects of the abuse itself to be hidden within the effects of possessing a certain disorder.

Detailed medical, psychiatric, developmental, family, and trauma histories were first collected for each of the subjects. Unaware of the emphasis on their histories with abuse, the subjects underwent Magnetic Resonance Imaging (MRI). A global Voxel-Based Morphometry (VBM) analytic approach (a technique used for assessing structural changes in the brain) was then used to assess the results.

Those with a history of CSA showed significant gray matter volume reduction in the brain, specifically in the left and right lingual and inferior occipital gyri. At the front end of the occipital lobe, the visual processing center, are the occipital gryi.[10] The lingual gyrus is associated with processing vision, especially vision related to letters. It’s believed that the lingual gyrus may also play a role in the examination of the order of events as well as encoding visual memories. Furthermore, De Bellis and his team have also shown that superior temporal gyrus gray matter volumes are larger in abused than non-abused girls.[11]

It’s possible that reduction in gray matter volume in certain areas of the brain may present a preference for alternative facial perceptions. This may explain “the tendency of some patients to interpret ambiguous facial expressions as angry.” Sleep disturbances such as nightmares are common in sexual assault survivors. Such disturbances may reduce blood flow to certain areas of the brain, thereby altering “its developmental trajectory.”

When the results are evaluated in conjunction with a previous study (conducted by Fennema-Notestine et al.), the findings suggest that “exposure to abuse affects visual cortex development but that vulnerability is limited to an early sensitive period. In other words, reduced gray matter in certain areas of the brain was significantly associated with abuse occurring before the age of 12 and not after.

The Developmental Traumatology Theory hold five main assumptions: (1) Stressors are infinite, whereas the brain and body’s reactions to stressors are finite; (2) maltreatment in childhood may cause developmental delays or deficits; (3) trauma in childhood may be more detrimental than trauma in adulthood; (4) interpersonal stress in childhood leaves one at a greater risk for developing PTSD; and (5) in the case where the CSA survivor knows the perpetrator, “the maltreatment is not only the act of maltreatment itself (e.g., sexual abuse) but also a dysfunctional and traumatized interpersonal relationship.” In other words, the compounded effects of also suffering from a traumatized interpersonal relationship leave the child at a much higher risk for developing PTSD.[12] According to De Bellis and his colleagues, “An important mission for the field of developmental traumatology is to unravel the complex interaction between an individual’s genetic constitution, unique psychosocial environment, and proposed critical periods of vulnerability for and resilience to maltreatment experiences.”

There are particular stages in development where experience has the potential to affect an individual more significantly, the maximal effect occurring during sensitive periods and the essential occurring during critical periods.[13] Sensitive periods are evolutionary by nature. According to Oxford Dictionaries, a sensitive period can be thought of as “a time or stage in a person’s development when they are more responsive to certain stimuli and quicker to learn particular skills.”[14] In other words, sensitive periods permit experience to affect the development of neural circuits. Such alterations lead to variations in the way that information is perceived and processed, making it possible for the child to adapt to her environment. When acknowledging these sensitive periods, the question must be asked, are alterations in the brain indicative of damage, adaptive activity, or a combination of the two? Are the changes adaptive or maladaptive? The answer is not yet clear.[15] The hypothesis that these brain alterations serve an adaptive purpose has yet to be explored further.[16]

In a separate study, Tomada, Polcari, Teicher, and a second set of cohorts collected volumetric MRI scans from 26 women who endured repeated episodes of CSA (and 17 healthy, non-abused female subjects for comparison). A rather rigorous exclusion criterion was utilized when selecting the subjects. Differences in brain morphology that could obviously be attributed to CSA were actually excluded. This means that young women with neurological and medical disorders, past or present issues with alcohol or substances abuse, exposure to physical (non-sexual) abuse, etc. were purposefully omitted from the study. Reason being, these researchers aimed to uncover differences in brain structures that could widely be attributed to the occurrence of CSA occurring at specific developmental ages.

The scans were analyzed specifically for sensitive period effects on hippocampal and amygdala volume, frontal cortex gray matter volume, and corpus callosum area. What the study found, in short, is that the age of the individuals when the abuse incidents(s) occurred mattered significantly. The hippocampus plays a key role in memory merging and retrieval, and it is one of few areas of the brain that continue to produce cells after birth. Severe stress in childhood appears to affect this area.[17] Hippocampal volume reduction was mostly linked to CSA occurring between the ages of 3 and 5 and secondly between the ages of 11 and 13. Another study shows that adults who have suffered from CSA show deficits in short-term verbal memory.[18] Furthermore, CSA leading to PTSD, dissociative identity disorder, borderline personality disorder, or major depressive disorder has been linked to a reduction in hippocampal volume in adulthood.[19],[20] (People with dissociative identity disorder have “at least two seemingly separate people occupy the same body at different times, each with no knowledge of the other.”[21])

This research suggests that early abuse may have an effect on the brain that doesn’t emerge until well into adulthood. It’s important to note that PSTD and/or substance abuse are other factors that may lead to the size reduction; however, the “ticking time bomb effect” is worth studying. In other words, it seems most plausible that delayed effects of early abuse are cause for concern. And sexual abuse may not be the only means to the end. According to an article in The Guardian, Teicher’s findings indicate that key areas of the hippocampus were reduced by up to 6.5% in individuals who reported childhood maltreatment such as physical and even verbal abuse.[22]

The corpus callosum, a flat bundle of neural fibers that connects the right and left hemispheres of the brain, is also smaller in abused children. “We believe that a smaller corpus callosum leads to less integration of the two halves of the brain, and that this can result in dramatic shifts in mood and personality,” says Teicher. While this volume reduction in an integral portion of the brain is key to understanding the effects of sexual abuse on the brain, it’s important to note that this size reduction is seen in girls who have been sexually abused. In boys, however, such a reduction is associated with neglect. An interesting observation: A boy who experiences neglect is essentially subjected to a most severe loss of respect and worth, whereas a girl who experiences sexual abuse is left to face an attack on her feeling loved. Note that various forms of abuse and neglect tend to coexist, so it’s often difficult to tease out the effects. However, many scientific studies considering the effects of abuse take inventory of the subjects’ histories. Those with histories of neglect and other trauma are often not included in such studies.[23]

Teicher’s EEG research indicates that left-sided EEG abnormalities were more prevalent in CSA survivors, suggesting that the left hemisphere of abused children may not develop properly. It’s well-known that the dominant hemisphere is more developed, yet when Teicher and his colleague investigated the abnormalities in the left hemisphere of abuse survivors, they found that the right cortex was significantly more developed despite being right-handing. This anomaly was present regardless of the patient’s reported condition (PTSD, depression, anxiety, etc.). When tested further, individuals with a history of abuse appeared to use the left hemisphere when recalling neutral memories and the right when retrieving memories of disturbance. Individuals within the control group “had a more integrated bilateral response.” This reduction of development in the left hemisphere may increase one’s risk of developing depression.[24]

In the MRI scan study, corpus callosum volume reduction was linked to reported CSA occurring between the ages of 9 and 10. Furthermore, a weakened frontal cortex was observed subjects who endured CSA between the ages of 14 and 16 years. These results are consistent with the fact that the hippocampus has reached approximately 85% of adult volume by the age of 4, and functionality of the prefrontal cortex, the area of the brain responsible for planning complex cognitive behavior, the expression of personality, decision making, and moderating social behavior, may not develop until the onset of puberty. Finally, damage to the orbital frontal cortex can lead to hypersexuality, poor social interactions, compulsivity, substance abuse, and poor empathetic ability.

When analyzing the questionnaires that each of the subjects completed, depression was associated only with CSA occurring between the ages of 3 and 5, whereas PTSD symptoms were only linked to CSA occurring between the ages of 9 and 10.[25]

These results suggest evidence that various brain regions have distinct periods during development when they are especially vulnerable to the effects of traumatic stress such as CSA. These results echo the findings of related studies. According to researchers Kristen Brunson and her colleagues of the Department of Anatomy Neurobiology and Pediatrics at the University of California, early exposure of an immature hippocampus to corticotropin-releasing factor (CRF), both a hormone that stimulates other hormone (ACTH) secretion and a neurotransmitter involved in stress response, may result in long-term memory deficits and selective loss of hippocampal neurons.[26]

The team of researchers led by Martin Teicher has also studied around 200 individuals ages 18-25. (The original article was published in the Proceedings of the National Academy of Sciences.) They were told that they were participating in a study on memories of childhood. Those who had been maltreated showed volume reductions of approximately 6% (on average) in two areas of the hippocampus and 4% in the subiculum (which “helps determine both behavioral and biochemical responses to stress”) and presubiculum when compared to those who hadn’t been abused. Since previous studies haven’t supported these findings, the research suggests that such changes may not arise until after puberty. According to neuroscience journalist Maia Szalavitz, “High levels of stress hormones can lead to cell death in the very regions that are supposed to tell the system to stop production.” This means that one who has been abused may wind up with a stress system that’s always on high alert.

Hormones such as norepinephrine, serotonin, and dopamine are released as part of the stress response. The hormone serotonin stimulates certain circuits that create and lessen anxiety. It plays an important role in controlling mood, aggression, and impulsivity.[27] Chronic stress is known to lead to decreased serotonin levels in the prefrontal cortex. These low serotonin levels are linked to suicidal behavior, depression, anxious depression, and aggression. Dopamine, on the other hand, is overproduced as a result of chronic stress. During stress, dopamine pokes the prefrontal cortex, which can increase one’s likelihood of becoming extra vigilant, even paranoid or psychotic. Furthermore, research confirms that reported CSA is associated with low serotonin transporter binding (5-HTT BPP) in major depressive disorder.[28] In other words, CSA is linked to an inability to “recycle” serotonin, leading to misregulation, even depletion. [29]

As children abuse survivors are more distractible and have more difficulty maintaining focus. They have a more difficult time restraining themselves from certain behaviors.[30] For teens who have been abused, impulsivity may be more apparent than your average teen. These teens may be much more drawn to taking risks, which may include something like experimenting with drugs.[31]

At the 2007 joint conference sponsored by both the Massachusetts Adolescent Sexual Offender Coalition and the Association for the Treatment of Sexual Abusers, Teicher presented on Childhood Abuse, Brain Development and Impulsivity. Practically speaking, poor impulse control can be displayed as addictive, self-destructive, and abusive behaviors due to a decrease in judgment, reason, fear, and inhibition. This increase in impulsivity appears to be the result of diminished hemisphere integration, meaning abused children may act out of emotion as opposed to reason and logic in response to stress. Early stress trains the body to have a more exaggerated and prolonged reaction to future stressors. As a result, accelerated aging often takes place as a result of chronic stress. In other words, early abuse trains the body and the brain to survive in “what it predicts will be a malevolent world.”[32]

The amygdala reacts to the release of norepinephrine, serotonin, and dopamine. In turn, the hypothalamus releases CRF, which leads to increased ACTH secretion, another hormone. The chain of events eventually leads to elevated cortisol levels. If this process occurs frequently, CRF and cortisol levels remain elevated and disrupt the feedback loop. In other words, the result is an imbalance of hormones and deregulation of them. Research on CSA survivors supports this: “Elevated resting levels of CRF have been found in the spinal fluid of abuse victims.”[33] Practically speaking, this individual may experience anxiety, fear, lack of pleasure, which may lead to negative habits such as alcoholism if not properly addressed.

The University of Southern California teamed with the Cincinnati Children’s Hospital Medical Center back in 1987 to begin a study on 80 diverse girls with histories of CSA, some who were abused as early as age 2. The girls were anywhere from 6 to 16 at the start of the study. On average, the girls were sexually abused for approximately 2 years before child protective services got involved. The researchers assessed them (along with a control group) 6 times over the next 23 years. Unfortunately, there’s some truth to much of the stigma that’s historically been associated with sexual assault victims. The researchers found higher rates of depression and obesity and issues with chemical regulations in the brain. These CSA survivors were “more likely to become sexually active at younger ages, have lower education status, and have more mental health problems.” As children they had higher levels of cortisol, a hormone released in response to stress, yet by age 15 cortisol levels were lower than the control group, meaning the bodies of the abused children may have become increasingly unable to deal with the stress. “That [low levels of cortisol] tell us their stress response system is burned out,” says Dr. Frank Putnam, study co-author. Low levels of cortisol have been linked to a number of problems including obesity, depression, and PTSD.

Researchers at the University of Minnesota and the University of Rochester also investigated cortisol. The impact of sexual abuse occurring with the first 5 years of a child’s life was investigated by obtaining saliva samples from the children twice a day over a period of several days. The samples analyzed indicated an atypical flattening of cortisol production throughout the day in CSA survivors experiencing high internalizing symptoms. Upon further investigation, the researchers found that early onset of physical or sexual abuse was predictive of this phenomenon. In fact, factors such as type of perpetrator and recency could not explain the observations. This suggests that these children may be more likely to experience a lack of cortisol regulation in adulthood. However, it’s important to note that more may be at play. Physical and sexual abuse often occurs in the presence of neglect and emotional abuse.[34]

Some studies suggest that survivors may more easily perceive genital pain, meaning any touch in that area results in pain instead of pleasure. Research seems to support this. Dr. Charles Nemeroff and his colleagues from the University of Miami in Florida have found that “early life trauma was related to a much thinner somatosensory cortex, smaller hippocampal volume, and neurocognitive deficits,” which all may relate to genital sensation.[35]

Abused children may live in a persistent fear state. This constant response to stress and fear can “create permanent memories that shape the child’s perception and response to the environment.” The response can linger, even if the environment improves. This is where the term trigger originates. These memories may trigger responses apart from conscious thought. These children may become consumed with the need to monitor their surroundings for fear of encountering another threat. This is also known as hypervigilance. And because of the trauma of such memories, children may dissociate from them. This explains post-abuse amnesia and long-term memory loss. Perhaps to preserve the attachment process, my brain smothered the memories of my abuse until the triggers were too overwhelming. My memories of early abuse were buried until another incident “reminded” me of all that had happened.[36]

J. Douglas Bremner and his colleagues at the Emory University School of Medicine in Atlanta, Georgia have gleaned the following from their research: Relative to a control group, female PTSD patients with reported CSA “had increased left amygdala activation with fear acquisition, and decreased anterior cingulate function during extinction.” The amygdala is a part of the brain associated with distressing emotions such as fear. The anterior cingulate is thought to operate as a regulator for a wide range of reflex-like functions like adjusting heart rate and blood pressure. It’s also involved in logic processes, such as empathy, impulse control, emotion, and decision-making. The amygdala lights up at the onset of fear, whereas the anterior cingulate loses function as fear is eliminated. This suggests that one’s response to fear is somewhat anticipated, yet the post-fear effects may linger. Other researchers support this as abuse has been linked to Attention Deficit Hyperactivity Disorder (ADHD) behavioral problems.[37] Women with abuse-related PTSD may have bodies that struggle with returning to normal, pre-fear conditions. And in fact, “an inability to extinguish the effects of fear is a characteristic of PTSD patients.[38] Other characteristics include nightmares, sleep disturbances, flashbacks, intrusive thoughts, hypervigilance, and changes in memory.

It was another layer of unrelated trauma that taught me an even more intense level of fear. And today? Behind the shower curtains and in the corners of a dark garage—that’s where the malicious individuals typically lurk, or so I think. No matter how irrational, implausible even, I anticipate these people, these things, harming me. My mind and my body convince me. I can explain this to myself a million times over, but only when I flip on the lights can I truly calm the stress response solidly seen in the wideness of my eyes, the rapidness in my heart beat, and the sweating that soaks my lower back.

Fear and anxiety tend to provoke people towards further harm. Individuals often turn to drugs, alcohol, sedatives, and sleep to relieve their anxieties, yet even sleep, which may seem harmless, can make matters worse. Sleep tends to establish and fuse traumatic memories together. For example, the Israeli army advises against sleep post-combat. Instead, soldiers are encouraged to stay awake and engage in sincere human interactions in order to mitigate the risk of PTSD. Studies show that the more “support, altruism and connection people share, the lower the risk for the disorder and the easier the recovery.” [39]

A study distinguishing the PTSD that abused children may experience from the PTSD that’s caused by other types of trauma (in adults) was published in the Proceedings of the National Academy of Sciences. This particular study is unique compared to many other CSA studies, the reason being that the team of researchers studied African American women in their late 30s to mid-40s who had been exposed to various types of trauma which may have included CSA and/or being held at gun-point. Of the 169 individuals evaluated, 108 were resilient, meaning they never developed PTSD. (PTSD symptoms are normal responses to stress, yet the symptoms typically fade in the first three months post-trauma.[40]) Out of the ones that did (61), 32 had been sexually abused as children. The researchers examined the blood cells of these women, specifically looking for genetic changes. Such genetic alterations are chemical changes that don’t actually affect the DNA itself but rather how the genes are made into proteins. “In PTSD with a history of child abuse, we found a 12-fold higher [level] of epigenetic changes,” says postdoctoral student Divya Mehta of the Max Planck Institute of Psychiatry in Munich Germany. Those who experienced trauma later in life exhibited genetic effects that tended to be short-lived and didn’t permanently affect the functioning of the genes. [41]

Luckily around 80 percent of people exposed to trauma will never develop PTSD, but those who do may have a long battle ahead. According to Bruce Perry, Senior Fellow of the ChildTrauma Academy, “When people are terrorized, the smartest parts of our brain tend to shut down.” Due to the need for rapid responses, our normal pathways get short-circuited when exposed to terror. According to Bremner, imaging studies have shown alterations in a circuit within the brain including the prefrontal cortex, hippocampus, and amygdala. Terror teaches us to see everything as a threat in order to protect us. “But once the immediate threat has passed, this style of thinking can become a hindrance, not a help.” Bremner says that early treatments don’t always help. In fact, immediate treatment such as Critical Incident Stress Debriefing (CISD), a specific, 7-phase, small group, supportive crisis intervention process, may actually lead to a worsening of the symptoms compared to no treatment at all. Instead, he advocates for the use of antidepressants for chronic PTSD: “Antidepressants have effects on the hippocampus that counteract the effects of stress.” What’s even more encouraging is remedies that are effective in treating PTSD appear to promote neurogenesis in animal studies. In other words, a mechanism that’s most active during pre-natal development—the populating of a growing brain with neurons—is stimulated as a result of treatment. Treatment also appears to result in increased memory and hippocampal volume.[42]

This doesn’t mean, however, that CSA survivors are doomed to a life of destitution. The differences between the sexually abused girls and the control group are significant, but that doesn’t mean that each survivor experienced these hardships. In fact, many are resilient and never develop conditions like PTSD. I’d argue the variation within the abused group may be an area for further study. Why is it that many of the CSA survivors experienced these difficulties while others did not? Moreover, can various treatments prevent these conditions from developing and/or reverse the effects? Researchers are currently unable to answer such questions with confidence. Lead author Penelope Trickett, psychologist and professor of Social Work, says, “What is clear here is that abuse is not something that’s a one-time fix.”[43]

The cerebellum vermis—a part of the brain that develops slowly and continues to grow new neurons after birth—is instrumental in the body’s sense of touch, spatial positions, and movements. The vermis also has an emotional stabilizing function, which may be impaired in sexually abused children due to limited blood flow to the area. According to Teicher, the vermis is more strongly influenced by environment versus genetic factors. Other researchers support this by explain that it has a high density of stress hormone receptors, “so exposure to such hormones can markedly affect its development.” [44] Though to date no statistical evidence to support this exists, Teicher and his colleagues believe that exercise may stimulate the vermis, thereby expanding attention span and combating hyperactivity. Even rocking and simple movements can have calming effects. The hypothesis is intuitive, for blowing off extra steam is known to help calm one down.[45]

Children’s brains that have suffered CSA and/or intense deprivation may actually permanently lose the ability to properly use serotonin, a neurotransmitter that assists in emotional stability.[46] Teicher has asked the question, “Does abuse modify a brain to cope with what it predicts will be a malevolent world?” Does one enter into a semi-permanent survival mode? Does what seems to be a hindrance instead aid the individual down the road? Teicher and his team are considering testing such questions with lab animals. They hope to determine if, for example, lab rats that are exposed to severe stress at an early age react better in particular situations compared to rats that enjoy an easy-going life early on.[47] If this hypothesis is true, perhaps experiencing hardship in childhood equips one to better deal with other hardships throughout her life.

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[43] Raymond, Joan (2011): Effects of sexual abuse last for decades, study finds; Levels of so-called stress hormone are altered for years, sometimes causing physical and mental problems, researchers find. NBC News. <msnbc.com>.
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