http://goo.gl/urTHrc
Professor Jorge Manzanares explained that "an early disorder of the stress circuit caused by maltreatment affects how people receive situations." Also, Manzanares said that "the consumption of a substance in a problematic manner is due to an altered effect between a person's genetics and their environment. Thus, we know that people who come from an alcoholic parent and who are also mistreated have a higher vulnerability to developing substance use disorders."
Moreover, the psychiatrist Gabriel Rubio noted that "the abuse suffered during childhood predisposes adolescents to substance use because of the activation of mechanisms and brain circuits that motivates them to try more and to underestimate risk." Rubio explained that "the sequence of this process begins with the abuse which is to blame for activating the stress mechanisms and at the same time responsible for causing a change in brain circuits that predisposes adolescents to adopt consumer behaviour and ultimately be hooked".