Child mental health is an important public safety issue. Under adverse environmental conditions, children may develop delinquent behavior and aggression, which in turn may lead to serious criminal acts. Studies have found that various gene-environment interactions contribute to behavioral difficulties, including delinquent behavior and crime. In psychology, as in other sciences, like public security, there has been a debate for a long time about the extent to which the environment influences various health disorders and the extent to which it is innate. In the analysis of child development disorders, in recent years, the view is increasingly taken that both the child's innate characteristics (such as genes) and thechild's immediate or distant environment affect the child's mental development in one way or another. It also emphasizes not only these two factors - the child himself and his environment, but also the importance of their mutual interaction (Brofenbrenner, 1979, Boyce, 2007; Ellis et.al., 2011; Rende, 2012). Therefore, the purpose of this article is to discuss and analyse theories of the influence of adverse environmental factors on children's mental health and development. From a methodological point of view, the article applies the synthesis of theoretical literature. The importance of analysing the impact of adverse environmental factors on children's mental health is also shown by the fact that research results show that approximately 2.4 - 18.2 percent of children have anxiety disorders and impulse control disorders - 1 - 6.8 percent, etc. (Demyttenaere et al., 2004). Although many and various studies are conducted every year analysing the causes, treatment, correction, and prevention of children's behaviour, cognitive, and emotional disorders, the number of disorders is increasing every year. Therefore, it is extremely important to systematically analyse the factors related to the child's mental health. The article analyses three currently prevailing theories related to child development. Thus, the main objects of this study are to reveal the patterns of adverse environmental influences on children's mental health:
1. Reveal the stress-diathesis model
2. To analyse the theoretical model of different receptivity
3. To analyse the theoretical model of biological sensitivity to context
4. Compare these three models, distinguishing essential similarities and differences.
The stress-diathesis model posits that some individuals, due to heightened sensitivity, which may
be behavioural (e.g., difficult temperament), physiological/endophenotypic (e.g., increased biological reactivity to stress), or genetic (e.g., having true gene alleles) are disproportionately more vulnerable to environmental stressors than others. Different susceptibility theory (DST) primarily raised the question not of how experience affects development, but why it should affect it at all. Children also differ in their sensitivity to environmental influences. It is also necessary to survive. Biological sensitivity to context theory (BSCT) states that children with low reactivity reacted almost equally to both strongly negative and low negative environments. Boyce and Ellis (2005) defined neurobiological susceptibility to both negative and positive environmental influences. Existing sensitivity increases developmental sensitivity to the environment, i.e. more sensitive individuals are more likely to experience long-term developmental change than just short-term developmental changes in response to environmental exposures. Sensitivity to environmental influences is neurobiological. So, it can be said that all three theories have a fundamental similarity – i.e. all talk about a person's sensitivity to environmental influences. However, they differ in that the stress-diathesis model analyses only how a bad environment affects development, while the theory of differential susceptibility and biological sensitivity to context states that sensitivity is not only related to the reaction to negative environmental effects but also to positive ones. The most important recommendation arising from these theories is that when raising children, it is important to recognize whether the child is sensitive to environmental influences or not. Taking this into account, it is necessary to plan child-rearing, children's schooling, and other important aspects of the child's life depending on his sensitivity. If the child is extremely sensitive to the effects of the environment, efforts should be made to reduce the negative effects of the environment as much as possible. It should also be considered that the child will be more sensitive to e.g. sounds, and light, so the child's environment should be created accordingly so that he feels good and grows in a suitable environment. Sensitive individuals appear to be more receptive to treatment than non-sensitive individuals, and therapists should take this into account when providing their services. Various interventions should change the immediate environment of susceptible individuals, i.e., for example, improving the parenting skills of parents. Also, interventions could be related to increasing stress resistance. Finally, when planning help for children to prevent relapse, it should be considered that vulnerable individuals are more likely to be damaged by an inappropriate environment and to relapse.