Amnesias for some or all aspects of the trauma have been documented following a wide variety of traumas: natural disasters and accidents, combat, kidnapping, torture and concentration camp experiences, and in victims of physical and sexual abuse (van der Kolk and colleagues 1996). A general population study by Elliot and Briere (van der Kolk and colleagues 1996) reported complete or partial traumatic amnesia after virtually every form of traumatic experience, with childhood sexual abuse, witnessing the murder of a family member and combat exposure yielding the highest rates. Having a history of being in psychotherapy did not affect the rate of delayed recall of traumatic experiences (about 15% overall). Traumatic amnesias tend to be age- and dose-related: the younger the age at the time of the trauma, and the more prolonged the traumatic event, the greater the likelihood of significant amnesia (DSM-IV Field Trials for PTSD).

Thus, there is ample documentation of the fact that dissociative amnesia occurs in some traumatized adults. In recent years, however, doubts have been raised concerning the existence and reliability of recovered memories following childhood sexual abuse. This has fostered at least 12 prospective and retrospective studies of individuals who claim to have been sexually abused as children. All studies have found that a certain percentage of subjects suffered from total amnesia during some time in their lives (e.g., Loftus and coworkers).

The best available study on this subject was conducted by Linda Meyer Williams (1994, 1995) who reinterviewed a sample of 129 subjects who had been examined for documented sexual abuse experiences an average of 17 years before. Of these subjects, only 80 (62%) could recall the index sexual abuse. Even among the girls who had been between 7 and 15 years old at the time of the abuse, 30% reported no recall of the incident. Of the 62% of subjects who now remembered the index abuse, 16% reported having had total amnesia at some time in their lives. Memories of the subjects who reported total amnesia some time in the past were as accurate as those of the subjects who claimed they always remembered. However, the subjects who at some time had forgotten the abuse were more uncertain whether their memories were accurate or not (Williams 1995). The memories of all subjects in this study in essence reflected what had been documented 17 years before.

The official statement by the American Psychiatric Association on Memories of Sexual Abuse contains the following counsel, which we do well to heed: "It is not known how to distinguish, with complete accuracy, memories based on true events from those derived from other sources. Many individuals who have experienced sexual abuse have a history of not being believed by their parents, or others in whom they have put their trust. Expression of disbelief is likely to cause the patient further pain and decrease his/her willingness to seek needed psychiatric treatment. Similarly, clinicians should not exert pressure on patients to believe in events that may not have occurred, or to prematurely disrupt important relationships... Specialized knowledge and experience are necessary to properly evaluate and/or treat patients who report the emergence of memories."

For the past century-and-a-half, psychiatry as a profession has mirrored the intrusions, confusion and disbelief of our traumatized patients by periodically forgetting well-established knowledge about trauma, and ascribing the psychological impact of overwhelming experiences to constitutional or intrapsychic factors alone. From time to time, our profession gets fascinated by trauma, after which the pendulum swings in the direction of entirely disbelieving the relevance of our patients' stories.

Given the complexities of how people remember trauma, the issue of PTSD and memory should be approached with careful observation, attention to the facts, and compassion for the victims. Trauma invites people to assign blame, and to divide the world into simple paradigms of true and false, good and evil. This polarization has always colored our approach to victims, much to the detriment of our ability to help them overcome the effects of their traumatic experiences.