Mission


Alzheimer's disease predictors

Dr. Donald Royall

by Jan Elkins

How does Alzheimer's disease disable its victims? How can a physician differentiate between Alzheimer's and other diseases that mimic it? These questions are being answered by Donald R. Royall, MD, associate professor in the departments of psychiatry, medicine and clinical pharmacology at the Health Science Center and director of the university's geriatric psychiatry program.

Dr. Royall believes that the disability associated with Alzheimer's disease is explained by the loss of what he calls "executive control functions." The executive functions control the execution of complex, goal-directed activities.

Past research has focused on the memory loss and language impairments of Alzheimer's disease patients. These skills are associated with the brain's temporal lobes. In contrast, executive functions are associated with the frontal lobes, explained Dr. Royall. Thus, frontal lobe Alzheimer's disease pathology is a stronger predictor of disability in Alzheimer's disease than temporal lobe pathology, he said.

Dr. Royall became interested in executive functions in the brain while observing schizophrenics during his psychiatry training at the Johns Hopkins University School of Medicine. Schizophrenics are disabled, he explained, but unlike Alzheimer's patients they have little memory loss. Dr. Royall has since shown that Alzheimer's patients are just as disabled as schizophrenics when matched in the quality of their executive skills.

For physicians to be able to predict disability and problem behavior in Alzheimer's patients, they would have to know how to measure the extent of someone's executive function impairment. Dr. Royall found a way. He developed practical, bedside tests to determine executive function impairment and distinguish Alzheimer's from other conditions. These simple tests allow physicians, social workers, nurses and other health care providers to determine the patient's executive function in as little as 20 minutes.

"Drawing a clock is a good way to demonstrate how executive functions control complex, goal-directed behaviors," Dr. Royall said. "If a patient with a frontal lobe disorder is told to draw the face of a clock on a blank sheet of paper--and not instructed where to place the clock, or the type of clock to draw, or how big to make it--the patient can't complete the task, because the drawing requires the use of executive functions. But when the same patient is told to copy a drawing of a clock, the need for executive skill is removed, and the assignment can be completed."

Dr. Royall believes testing for executive skill impairment will help health care providers predict the level of supervision a patient will require. "Our next step is to teach physicians, nurses, nurse practitioners and other care givers to use executive function tests to recognize impairment," he said. "Then a library of manuals and videotapes can be created featuring people with executive impairment, and its symptoms can be described. Once this has been accomplished, workshops can be held to spread the knowledge of executive function to a broader audience."

Executive skill impairment also helps explain a patient's problem behavior, according to the researcher. "When a patient has a mental disorder, his behavior is caused by those portions of the brain that still function," Dr. Royall said.

"In Alzheimer's disease the cortex of the brain is affected--impacting executive control, language and memory--but the brain's deeper structures that are responsible for personality and habitual behavior are not affected. Thus, an Alzheimer's patient's personality remains intact."

In patients with executive impairment, habits are triggered by familiar cues, according to Dr. Royall. Extending his hand while turning his head aside, he explained, "I'm giving you a cue that goes with a familiar habit--a handshake. Because I'm not making eye contact, the cue is unusual and you hesitate. The frontal lobes inhibit the habit because it is not clearly appropriate to shake hands under these conditions. If I give you a new rule--'Don't shake my hand.'--you remember and cooperate with the rule.

"When executive control is intact, the spontaneous urges to act are controlled by the rule," he said. "When a person has Alzheimer's, though, the executive function doesn't work--the cue triggers a response since there is no control." Eliminating some cues for patients with the disease may help stop some problem behaviors. "Patients with Alzheimer's disease often wander," Dr. Royall said, "but they aren't planning to go anywhere. Instead, they leave the room because there is a knob on the door. This doorknob is a cue linked to door-opening behavior." At home, he suggested, doorknobs can be hidden by covering them with a small box.

The fact that Alzheimer's disease affects the entire cortex of the brain, including the frontal lobes, explains why patients seem to regress. "The frontal lobes, representing approximately 40 percent of the brain's cortical surface, are the last part of the brain to develop. They control behaviors that distinguish children from adults," Dr. Royall explained. "Many actions requiring supervision in childhood are the very same actions that require supervision in Alzheimer's patients."

Dr. Royall is studying patients with Alzheimer's disease in conjunction with The Freedom House, an Alzheimer's care facility located at Air Force Village II in San Antonio. He is also conducting research on the early detection of dementia in a group of 700 well elderly volunteers at the Air Force Villages.

His work extends also to the South Texas Veterans Health Care System (STVHCS) and its Geriatric Research, Education and Clinical Center (GRECC). The Health Science Center's affiliation with the veterans facilities provides researchers a larger patient base. The Audie L. Murphy Memorial Veterans Hospital in San Antonio, a division of STVHCS, houses a 90-patient nursing home facility which is a part of the system's extended care programs.

"A significant portion of the older veterans population has dementia and/or Alzheimer's, and this patient base benefits from Dr. Royall's extensive research," commented Michael S. Katz, MD, professor and chief of the department of medicine's division of geriatrics & gerontology at the Health Science Center and director of the GRECC. In addition to inpatient programs, the Audie Murphy facility has an adult day care program for patients directed by Laura K. Chiodo, MD, clinical associate professor of medicine. About 10 percent of those patients have Alzehimer's.


Arrow Return to "Fading Memories"

Arrow Return to index--Fall 1998