Declining memory tests can be an early indicator of future onset of Mild Cognitive Impairment (MCI)

Wednesday, April 05, 2006

SCOTTSDALE, Ariz. — For many people who will eventually develop Alzheimer's disease, low memory scores can be an early indicator of future Mild Cognitive Impairment (MCI). On April 1-8, 2006, Mayo Clinic physicians from Arizona will present their findings on MCI at the 58th Annual Meeting of the American Academy of Neurology in San Diego.

Alzheimer's disease is a progressive brain disorder that gradually destroys a person's memory and ability to learn, reason, make judgments, communicate and carry out daily activities. An estimated 4.5 million Americans have Alzheimer's disease. Memory loss is the most common presenting feature of Alzheimer's disease.

Mild Cognitive Impairment (MCI) is a transition stage between the cognitive changes of normal aging and the more serious problems caused by Alzheimer's disease. While mild cognitive impairment can affect many areas of cognition — such as language, attention, critical thinking, reading and writing — most research has focused on its effects on memory. The disorder can be divided into two broad subtypes. One subtype, amnestic MCI, significantly affects memory. The other type, nonamnestic MCI, does not. Other functions, such as language, attention and visuospatial skills, may be impaired in either type.

The results of a study lead by Richard J. Caselli, M.D., Chair of Neurology, Mayo Clinic, indicated that memory declines earlier and more selectively than other cognitive domains in the vast majority of individuals who develop MCI. "When we looked at the patients scores before they were diagnosed with MCI and compared them to the rest of our study population (who didn't develop MCI) we observed that memory scores, were lower in the MCI-to-be group. This finding suggests, that even before a patient is symptomatic or objectively impaired, they are performing less well than their peers," said Dr. Caselli.

Among those who were eventually diagnosed with MCI, cognitive functions that declined over the two years between the "pre-MCI epoch" and the "MCI epoch" were limited to verbal and visual memory tests. Executive skills, language and visual spatial skills remained stable during this symptomatic transitional period for this group, but differences were noted between the MCI converters and those who did not develop MCI during both the pre-MCI and the MCI epochs.

The exact prevalence of mild cognitive impairment in the population is difficult to determine, but some estimates are as high as 20 percent of the nondemented population over age 65. Only about a third of those cases, however, have the amnestic variety that has been linked to Alzheimer's. Amnestic (memory-related) MCI converts to Alzheimer's at a rate of 10 percent to 15 percent a year. Researchers hope to find a treatment that will delay this conversion, or perhaps even prevent it.

Mayo Clinic is a private group practice of medicine dedicated to providing diagnosis and treatment of patient illnesses through a systematic focus on individual patient needs. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 208-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

###

To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. MayoClinic.com is available as a resource for your health stories.