Amnestic Syndrome Presenting as Malingering in a Man With Developmental Disability

Multiple factors in this case made it difficult to arrive at a correct diagnosis and treatment plan.

Diagnostic overshadowing (2,3,4) was one factor. Overshadowing occurs when a patient's problematic behaviors are attributed to mental retardation, and no attempt is made to search for the root causes of the problem. Ferreting out the underlying causes can be even more challenging because it is sometimes difficult for individuals with mental retardation to communicate effectively. Problem-solving skills and coping skills are often limited. In this situation the onus of eliciting information and developing management strategies clearly falls on the professional.

Another factor was Mr. G's memory deficit. Amnestic disorder is characterized by an inability, in the absence of other significant cognitive impairments, to learn new information. Memories acquired before the etiologic insult are intact. As described in DSM-IV, the memory disturbance causes a significant impairment in social or occupational functioning and represents a significant decline from a previous level of functioning (5). Amnestic disorder should be differentiated from situations in which memory impairment occurs in association with other cognitive dysfunction such as dementia and delirium.

The development of amnestic syndrome could be attributed to a number of factors in this case: poor nutrition, alcoholism (with secondary thiamine deficiency), treatment with vitamin B, head trauma, hypoperfusion during cardiac bypass surgery, and infarction of the posterior cerebral artery. Vascular insults can selectively damage areas of the brain in which memory is stored, such as mamillary bodies, hippocampus, and fornix (5,6). However, the most likely factor is related to events surrounding cardiac bypass surgery, particularly when the patient's previous level of functioning and his functioning after treatment are taken into consideration (7).

Memory deficits are not characteristic of mental retardation. Patients with mild mental retardation, in the IQ range of 55 to 70, are capable of self-support and independent community living (5). Mr. G should not have had any problems remembering specific episodes, particularly those with a strong emotional overtones, such as a hospitalization, an arrest for loitering, or confrontations with emergency room staff. His history clearly indicated that before cardiac surgery his episodic memory was relatively intact.

There was little reason to attribute Mr. G's behavior to malingering. He was not motivated by medicolegal gain, did not exaggerate his symptoms, and did not intentionally fail to cooperate with evaluation and treatment. No evidence of an antisocial personality disorder was found (5,8,9,10). His emergency room visits were prompted by chronic pain. Although his developmental disability may have impaired his ability to explain his concerns adequately, his frequent emergency room visits were clearly related to his inability to remember. In fact, a malingerer would be extremely unlikely to return to the emergency room once he was admitted to the hospital, and Mr. G sometimes wandered from the hospital unit where he was placed back to the emergency room.

Although the health care and social service agencies dealing with Mr. G expended considerable time, energy, and funds, they had not been successful in reducing his utilization of emergency rooms or in providing effective management. After he was hospitalized, a detailed evaluation was able to identify the etiology of his chest pain and the severity of his amnestic syndrome. Only then could appropriate interventions be developed. It is not surprising, given his memory impairment and inability to read, that Mr. G forgot follow-up visits. Emergency room personnel are not usually in a position to explore this kind of complex medical-psychosocial situation, and his random interactions with different health care organizations made it difficult for the emergency room staff to appreciate the full picture.

Physicians need to be aware of the organization of other service systems and to have resources within the emergency room to contact relevant agencies. Most individuals with mental retardation require case management assistance to meet their day-to-day needs. The case manager typically knows the person's biopsychosocial history and thus can provide a critical link between physical and mental health systems and the developmental disability system. For Mr. G, successful intervention occurred through a coordinated effort and redefinition of the problem.

Individuals with mental retardation can be a challenging group to serve successfully, particularly in the rapid-paced setting of the emergency room. When an individual with mental retardation presents with significant psychiatric symptoms, attributing them to mental retardation results in prematurely closing avenues worthy of exploration. Emergency room personnel will find it extremely helpful to join forces with agencies serving persons with developmental disabilities. Such agencies may be unfamiliar to medical personnel, but they represent an important resource, particularly when dealing with a "problem" patient. Neither the medical system nor the developmental disability system has the knowledge or the resources to provide needed care for these patients, and coordination is thus essential.

The authors thank Kytja Voeller, M.D., for helpful comments.

Dr. Sundheim and Dr. Ryan are in private practice with the Community Circle, 1556 Williams Street, Denver, Colorado 80218 (e-mail, suzannebille.sundheim@ worldnet.att.net).