**5.1 Brain development**

Most recent scientific studies on brain development reveal the fact that early experiences shape the architecture of a child's brain having a long-term impact on a child's social and emotional well-being [1]. A child's social, cognitive, and emotional development is heavily dependent on the quality of interaction between child and "significant" adult (e.g., mother, father. Caregiver. whoever s/he is bonded with). Neurodevelopmental studies claim that bonding problems and parenting inconsistencies might cause long-term mental health problems [75]. Although, the first years are critical for life-long success and healthy physical and mental development for the rest of their life, having a baby makes a significant change in the lives of parents. Lower stress of families is associated with lower stress levels and normal brain development in children [76].

Neurological development of the brain does not take place in a vacuum nor by itself. It is highly dependent on external stimulations and interactions. In other words, a child's early experiences shape the brain architecture from the beginning [1] and leave footprints that last a lifetime. Brain developmental functions also have critical moments providing "windows of opportunities" or challenges for specific developmental pathways (**Figure 3**).

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

**Figure 3.** *Human brain development [1].*

#### **Figure 4.**

*Sensitive periods in early brain development [77].*

Among all critical and sensitive periods, the first 3 years of life seem to be the most critical for emotional control responding to positive as well as adverse experiences as demonstrated in **Figure 4** [77].

Human brain development takes more years to reach maturity compared to other species. Although this long way to maturity is adaptive for the human species, the adolescent period is the second most important part of this journey of maturity because of its adaptive values of plasticity [78]. Therefore, the adolescent period is also sensitive and critical for stress factors. According to research about brain development, it claimed that exposure time to stress plays an important role in brain structure, the adolescent stage is more vulnerable to stress compared to the adulthood stage of development.
