**5.2 PTSD as a result of adverse childhood experiences (ACE)**

Adverse childhood experiences (ACE), as demonstrated in **Figure 5**, can disrupt neurodevelopment causing social, emotional, and cognitive impairment in children that lead to the adoption of health-risk behavior leading to adulthood illnesses including cardiovascular diseases, sleep disorders, obesity, and the like [79].

Toxic stress is known as one of the most ACE in leaving almost irreversible damage in a child's brain as given in **Figure 6**.

Weems's model, based on evolutionary presentative, emphasizes that the stress may lead to delay, accelerate, or prolonged developmental process according to the adaptive importance of these changes. According to the model, the developmental

#### **Figure 5.**

*Mechanisms by which ACE influences health and well-being throughout the lifespan [79].*

**Figure 6.**

*Persistent stress changes brain architecture [15].*

#### *New Diagnosis and Treatment Approaches to Post-Traumatic Stress Disorder DOI: http://dx.doi.org/10.5772/intechopen.104098*

timing of stress exposure plays an important role in how the brain responds to the stressor, also they claimed that age and maturation are critical for amygdala volumes, which are responsible for emotion regulation [80]. Also, it is known that the prefrontal cortex and amygdala connection develop through childhood to adulthood and become stronger [79].

Coping with stress, if the stress is moderate level, is important for the healthy development of children and adolescents. In contrast, if the stress level is high, long term, and hard to cope with it, may cause damage to brain structural development, which is called toxic stress. Toxic stress defines as the activation of the human body's stress reaction system frequently and hardly reacting to long-term stressful stimuli or long-term activation of stress response to a stressful event with a failure of the human body. Toxic stress may cause prolonged physiologic and psychologic abnormalities, such as organ dysfunction or brain functional abnormalities. Abuse, violence, neglect, food scarcity are common types of toxic stress sources All these sources can also be considered as risk factors in the development of PTSD.

Toxic stress also negatively affects the neuroendocrine-immune system. Such abnormalities on cortisol levels might also be observed. Moreover, toxic stress preventing neural connections can have an adverse impact on brain architecture that impacts planning, reasoning, emotional and behavioral control areas. It is also claimed that these responses may play a role in psychopathological disorders including psychosis, depression, and PTSD [81].

Parenting style is considered as one of the major factors having an impact on the psycho-social development of young children as well as adolescents. It is known that parenting style plays an important role in the etiology of psychopathology in children and adolescents, both as a genetic factor and an environmental factor from a transgenerational perspective [82]. Parenting style can also be a protective factor when it has a positive role, whereas when it has a negative role, it is considered as a risk factor for the development of psychopathologies, such as depression, anxiety, obsessive-compulsive disorder, and schizophrenia. Also, according to evocative gene-environment correlations, symptoms of adolescent psychological disorders may affect parental psychological status [83]. Further, some studies have found that attachment styles are associated with both psychopathological and cognitive problems in adolescents, such as psychosomatic complaints, anxiety, verbal aggression, attention-seeking behavior, and thinking problems [84]. In conclusion, exposure to the traumatic event, negative parenting attitudes, or negative attachments may also have a negative effect on brain development.

All these developmental risk factors, evaluated from an evolutionary perspective, adaptational sensitivity in both young children and adolescents, from the perspective of toxic stress, exposure to toxic stress in the early developmental period, from the perspective of family attitudes, children growing up in an overprotective or authoritarian and inconsistent family structure, when faced with traumatic stress, are all considered risk factors for developing PTSD.

Developmental models of PTSD argue that an individual's biological, cognitive, and psycho-social characteristics are more decisive factors than the traumatic event itself in the emergence of PTSD. Such PTSD models, pointing to the importance of developmental processes of each individual argue that the brain will be affected by the traumatic event in a neurodevelopmental state. Likewise, it is thought that the neurodevelopmental state of the individual's brain is an important determinant in the development of PTSD reacting to the traumatic event.

According to neurodevelopmental research, the duration, intensity, timing of a traumatic event is important on how the brain and development will affect the event. Also, genetic vulnerabilities may affect the damage size, such as a genetically vulnerable child may develop psychopathology while a hardier child may not [73].

Preventing, early intervention and rehabilitation techniques are important for protecting the child from PTSD effects, especially neurodevelopmental damages. If possible, preventing children from possible traumatic experiences should be the first step. Later, for children who have been exposed to the traumatic event, early intervention and immediate action to remove the child from the traumatic environment should be the second step, finally, rehabilitation, such as psycho-social support mechanisms and programs, plays an important role in preventing neurodevelopmental damages. As a promising research Nelson et al. [85], studied with 136 abandoned children to examine their brain development, cognitive functioning, social and physical growth with 12 years' study. According to results, compared with children in foster care, the institutionalized children showed severe impairment in IQ and brain development, along with psychological disorders [85]. This study confirms that even if the child is exposed to a traumatic event, immediate action to remove the child from the traumatic environment afterward supports the reduction of traumatic effects and abnormal brain development.
