Trauma can be repeated on behavioral, emotional, physiologic, and neuroendocrinologic levels. Repetition on these different levels causes a large variety of individual and social suffering. Anger directed against the self or others is always a central problem in the lives of people who have been violated and this is itself a repetitive re-enactment of real events from the past. People need a "safe base" for normal social and biologic development. Traumatization occurs when both internal and external resources are inadequate to cope with external threat. Uncontrollable disruptions or distortions of attachment bonds precede the development of post-traumatic stress syndromes. People seek increased attachment in the face of external danger. Adults, as well as children, may develop strong emotional ties with people who intermittently harass, beat, and threaten them. The persistence of these attachment bonds leads to confusion of pain and love. Assaults lead to hyperarousal states for which the memory can be state-dependent or dissociated, and this memory only returns fully during renewed terror. This interferes with good judgment about these relationships and allows longing for attachment to overcome realistic fears. All primates subjected to early abuse and deprivation are vulnerable to engage in violent relationships with peers as adults. Males tend to be hyperaggressive, and females fail to protect themselves and their offspring against danger. Chronic physiologic hyperarousal persists, particularly to stimuli reminiscent of the trauma. Later stresses tend to be experienced as somatic states, rather than as specific events that require specific means of coping. Thus, victims of trauma may respond to contemporary stimuli as a return of the trauma, without conscious awareness that past injury rather than current stress is the basis of their physiologic emergency responses. Hyperarousal interferes with the ability to make rational assessments and prevents resolution and integration of the trauma. Disturbances in the catecholamine, serotonin, and endogenous opioid systems have been implicated in this persistence of all-or-none responses. People who have been exposed to highly stressful stimuli develop long-term potentiation of memory tracts that are reactivated at times of subsequent arousal. This activation explains how current stress is experienced as a return of the trauma; it causes a return to earlier behavior patterns. Ordinarily, people will choose the most pleasant of two alternatives. High arousal causes people to engage in familiar behavior, regardless of the rewards. As novel stimuli are anxiety provoking, under stress, previously traumatized people tend return to familiar patterns, even if they cause pain.(ABSTRACT TRUNCATED AT 400 WORDS)