DBT posits that borderline patients possess a genetic/biological vulnerability to emotional over-reactivity. This view hypothesizes that the limbic system, the part of the brain most closely associated with emotional responses, is hyperactive in the borderline. The second contributing factor, according to DBT practitioners, is an invalidating environment; that is, others dismiss, contradict, or reject the developing individual’s emotions. Confronted with such interactions, the individual is unable to trust others or her own reactions. Emotions are uncontrolled and volatile.
