Childhood abuse, whether it’s emotional, physical, or sexual, impacts a child’s psychological health into adulthood by altering the way their brain develops and later functions throughout their life. A child’s brain is still developing and extremely malleable, which is why early abuse can result in permanent developmental changes from a neurobiological standpoint. These anomalies can lead to a myriad of psychiatric problems, including Major Depressive Disorder (MDD), Borderline Personality Disorder (BPD), and Post-Traumatic Stress Disorder (PTSD). (Teicher M. H., 2000)
MDD is comprised of a multitude of symptoms including prolonged sadness or deflated mood, anhedonia, significant changes in weight or appetite, insomnia or hypersomnia, irritability, difficulty in concentration and memory, and even the consideration of suicide. (American Psychiatric Association, 2000)
BPD is most notably characterized by persistent emotional instability, especially within relationships, impulsive behavior, abnormal affect, chronic and extreme fear of abandonment, and frequently includes suicide gestures. Depression is also commonly experienced by patients with BPD. (American Psychiatric Association, 2000; Comer, 2011)
PTSD occurs only after a person suffers a severe trauma, which results in flashbacks, depression, anhedonia, flat affect or restriction of experienced emotion, anxiety, panic attacks, avoidance of possible triggers, nightmares, sleep disturbances, dissociation, irritability, difficulty with concentration and memory, and hyperarousal including a hypersensitive startle response. (American Psychiatric Association, 2000)
How does child abuse put a person at increased risk for developing MDD, BPD, or PTSD? One of the leading experts in the field on this subject, Dr. Martin H. Teicher, hypothesized that “the trauma of abuse induces a cascade of effects, including changes in hormones and neurotransmitters that mediate development of vulnerable brain regions.” (Teicher, 2000, p. 5 para. 3) His research, as well as many others, has found that several specific brain abnormalities repeatedly appear in patients with a history of abuse. These abnormalities include limbic irritability, inadequate development and differentiation of the left hemisphere, insufficient left-right hemisphere integration, and abnormal activity in the cerebellar vermin, all of which result in symptoms that correlate with MDD, BPD, and PTSD. (Spiers, et al., 1985; Ito Y., et al., 1993; Teicher, et al., 1993; Bremmer, et al., 1997; Stein, et al.; 1997; Ito Y., et al., 1998; Teicher M.H., 2000, van der Kolk, 2003) What the results of all this research have indicated is that their “belief that trauma causes brain damage” is not unfounded. (Teicher, 2000, p. 5, para. 4)
The limbic system, which is the part of the brain that controls much of our emotion, as well as our survival instincts, is damaged by childhood abuse, as evidenced from the findings of multiple studies. (Spiers, et al., 1985; Teicher, et al., 1993; Teicher, 2000) Compared to non-abused people, victims of childhood abuse have much higher rates of disturbances in their limbic system, referred to as limbic irritability, which has been found to be associated with seizures known as temporal lobe epilepsy (TLE) and significant EEG abnormalities. Signs of TLE are 38% greater in physically abused patients, 49% greater in sexually abused patients, and an alarming 113% greater in patients who were both physically and sexually abused. (Spiers, et al., 1985; Teicher, et al., 1993; Teicher, 2000) Further, if the abuse transpired before the age of 18, it had a much larger effect on the patient’s limbic system than abuse that occurred after the age of 18, which indicates that childhood is definitely a particularly sensitive time of development for the brain. Limbic irritability plays a key part in predisposing a person for PTSD later in life, as well as increasing their risk for developing dissociative and impaired memory symptoms. Further, neurochemical changes in these sections of the brain also result in a greater stress response and hypervigilance. Limbic irritability is also linked to chronic unhappiness, aggression, and violent tendencies toward oneself and others, which can also be linked both to MDD and BPD. (Teicher M. H., 2000)
With regard to EEG results, one study found that 54% of patients who experienced childhood abuse, as opposed to only 27% of patients with no history of abuse, had abnormal brain wave activity and that of those 54% of the abused patients, 43% had been psychologically abused, 60% had been abused physically, sexually, or both, and 72% had survived extreme forms of physical or sexual abuse. (Ito Y., et al., 1993; Teicher, 2000) These anomalies were usually present in the left hemisphere in abused patients and, very notably, they occurred in the left hemisphere 100% of the time in patients who had been psychologically abused. In fact, the abused patients had 6 times more left-sided abnormalities than right-sided abnormalities, and those who had suffered psychological abuse experienced left-hemisphere abnormalities 8 times more often than right-sided ones, which was especially significant even before comparing these results to the non-abused patients who had barely any left-hemisphere abnormalities at all, even though they were still twice as common as EEG anomalies in the right-hemisphere. Testing with EEG coherence, researchers further revealed that abused patients had significantly underdeveloped left cortexes, no matter what their diagnosis was, and were especially noticeable in the temporal region of the cortex, resulting in more difficulty processing and modifying electrical signals in the brain. (Ito Y., et al., 1993; Ito Y., et al., 1998; Teicher, 2000) These findings “corroborated [their] hypothesis that abuse is associated with an increased prevalence of left-sided EEG abnormalities and of left-hemisphere defects in neuropsychological testing.” (Teicher, 2000, p. 8, para. 1) This is interesting because the left hemisphere that is known for being more logical, keeping emotions under control, and for structure and planning, all of which could begin to explain some of the symptoms seen in patients with MDD, BPD, or PTSD who seem to have deficits in these areas.
Within the temporal lobe is the hippocampus, which also seems to be underdeveloped in patients with a history of child abuse, but only on the left side again, and commensurate with the severity of the patient’s symptoms. (Bremmer, et al., 1997; Stein, et al., 1997; Teicher, 2000, van der Kolk, 2003) The stunted development of the hippocampus observed in victims of child abuse can be linked to exposure to high levels of cortisol, which is toxic to the hippocampus and results in atrophy. Since the hippocampus is involved in controlling emotions and memory, as well as regulating the body’s stress hormones, it makes sense that this specific brain abnormality is repeatedly found in those suffering from MDD, PTSD, or BPD. (Teicher M. H., 2000) It also makes sense that all the abnormalities seem to be in the left hemisphere since that side develops at a much swifter rate during early childhood than does the right hemisphere, thus putting it at higher risk for brain damage caused by abuse sustained during those formative years. Researchers have proposed that reduced activity in left frontal lobes results in MDD, linking the left hemisphere to one of the psychological disorders that can result from child abuse and, as suggested before, left-hemisphere anomalies may be responsible for inadequate maintenance of the negative emotions and impulses for which the right hemisphere is known, again giving insight as to how child abuse may increase the risk for all three mental illnesses, MDD, BPD, and PTSD. (Teicher M. H., 2000)
Research has also indicated that patients who have been abused in early life have difficulty with integrated bilateral responses and use their left hemisphere when recalling memories of a non-traumatic nature, and their right hemisphere when recalling negative memories. The right hemisphere is responsible for processing and expressing negative emotions, whereas the left is the side that keeps emotions in check. (Schiffer, et al., 1995; Teicher, 2000) If the right hemisphere is more developed than the left, it could in part possibly explain why rumination on negative thoughts or feelings occurs with abuse victims who have MDD, BPD, or PTSD. Additionally, the reason why these individuals may have difficulty using both hemispheres in a more integrated fashion as non-abused people do is explained by the findings that abused individuals have significantly smaller middle portions of their corpus collosum, which is the primary pathway connecting the two sides of the brain. (Teicher M. H., 2000) This explains why someone with MDD or PTSD may have difficulty with emotional regulation, and especially why those with BPD may go from putting someone on a pedestal to being overcritical of the same person, seeing things and people in black and white terms, rather than in a more integrated point of view that both bad and good can exist within one person or situation. When using the left side of their brain, people seem glowingly positive to the individual, and when using the right side of their brain, those same people are completely negative. (Teicher M. H., 2000)
Anomalies in the cerebellar vermis also appear in those who have been abused, which may be linked to depression, among other disorders. This part of the brain, which is also thought to play a key role in managing one’s emotions and attention, as well as in calming the electrical irritability associated with the limbic system, is also extremely sensitive to stress hormones which can alter its usual development and leave it impaired with regard to carrying out the previously mentioned functions. This again would explain certain symptoms of MDD, PTSD, and BPD in victims of child abuse with regard to emotional stability and attention. (Teicher, 2000; van der Kolk, 2003)
Neglect has specifically been found to interfere with thyroid hormone production, which results in a domino effect of lower levels of serotonin within the hippocampus, the stunted development of glucocorticoid receptors, and finally an increased risk of hyper-reactive stress hormone response, leaving the individual in heightened fear and adrenaline responses when faced with external stressors and negative situations in life, again setting the stage for psychological disorders such as MDD, BPD, PTSD, all of which are also linked to lowered serotonin levels. This further leads to neuronal instability, and back to where we started with an increased likelihood of seizures, which are associated with limbic irritability.
However, the neurobiological effects of neglect don’t stop there. Child abuse can result in a permanent increased levels of vasopressin, a stress hormone associated with sexual arousal, and lowered levels of oxytocin, a critical hormone in maintaining monogamous relationships, which could in theory explain why BPD patients may be predisposed to have such turbulent relationships that are often short lived and intense in nature. (Teicher M. H., 2000) As Bessel A. van der Kolk notes, child abuse can affect the “neuroendocrine system, including the hypothalamic-pituitary-adrenal (HPA) axis, and every conceivable neurotransmitter system.” (van der Kolk, 2003) Dysfunction within the HPA axis can actually be tied to all three disorders, MDD, BPD, and PTSD, as can various neurotransmitters. (van der Kolk, 2003; Anda, et al., 2006; Carvalho Fernandoa, et al., 2012, American Psychiatric Association, 2000)
All of these findings support that specific types of permanent brain damage can result from child abuse which can set an individual up to become more moody, irrational, hyper vigilant, easily startled, and to display dissociative symptoms, lower levels of judgment, impaired memory, poor control of affect and impulses, and more. (Teicher, 2000; van der Kolk, 2003) It is because of the neurobiological effects of child abuse that survivors are at greater risk for developing MDD, BPD, and PTSD.
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Budding Into Fullness: From Broken Pieces to Masterpieces 
