Identifying the Differences: Normal Aging, Mild Cognitive Impairment and Alzheimer’s Disease
By Arline Kaplan © 2003 (All Rights Reserved)
Specific memory tests can help distinguish between normal age-related memory decline and mild cognitive impairment (MCI) as well as between MCI and Alzheimer’s disease, said Kirsten Fleming, Ph.D., assistant adjunct professor in the department of psychiatry and human behavior, at the University of California, Irvine.
Speaking at the 2003 Regional Alzheimer’s Disease Research Conference presented by UCI’s Institute of Brain Aging and Dementia and the Alzheimer’s Association of Orange County, Fleming discussed normal aging, explained some of the diagnostic differences between MCI and Alzheimer’s disease, and outlined treatment approaches.
“For a long time, people thought that memory stayed intact over the entire lifespan…that is not really the case,” said Fleming, who is also chief of neuropsychology at UCI. “There are different types of memory.”
Memories of experiences that happened long ago, such as in childhood, usually stay intact, even as people age. Rather, it is new learning that becomes a problem. Our ability to learn new information peaks at about age 25, she explained. From that age on, our memory generally starts to decline.
According to statistics, Fleming said about 70% of older adults report they have memory problems, but objective tests are needed to determine if they have mild cognitive impairment, which is also known as benign senescent forgetfulness, age-associated memory decline and early dementia.
“Mild cognitive impairment is basically a transitional stage between normal aging and Alzheimer’s disease. We are not really sure how prevalent it is; probably 17% to 34% of elderly people have MCI.”
For a diagnosis of MCI, an individual must not only think he or she has memory problems, but those memory problems must be verifiable through objective testing. What is important, Fleming said, is that the person needs to take specific memory tests administered by a psychologist or neuropsychologist working at a memory clinic or in private practice, since most general practitioners and internists are not trained to detect MCI.
“We have to score these [tests] very carefully, because depending on how old you are, how much education you have and your intelligence, there will be different expectations. So someone at 60 years of age should have a better memory than someone at 80, even if there is no a problem,” she added.
For MCI to be present, the individual must have a memory problem that is 1.5 standard deviations below the norm for age, education and IQ matched peers.
In 2001, the American Academy of Neurology published practice guidelines for the early detection of memory problems or mild cognitive impairment, Fleming said. The academy recommended the use of such general cognitive screening instruments as the Mini-Mental State Examination (MMSE).
“It is not enough to look just at the MMSE scores. I know a lot of people with early Alzheimer’s disease who score perfectly. What you need secondarily is neuropsychological testing with very good norms for specific ages,” she said. She also advocated for the use of brief cognitive instruments that focus on limited aspects of cognitive function, such as the individual’s ability to tell time and make a change, along with interviews of family members and others close to the memory-impaired individual.
Even though individuals with MCI may have memory problems, they still function well and can drive and continue their daily activities, Fleming said.
Before a diagnosis of MCI is given, the individual also should receive a good medical examination to rule out any medical, neurologic or psychiatric problems that could produce the memory deficits. According to Fleming, several medical conditions and other factors can cause memory problems in older adults, including urinary tract or respiratory infections, mini-strokes, vitamin B12 deficiencies, going under anesthesia and medication side effects or interactions.
Neuroimaging can aid in the identification of MCI. Magnetic resonance imaging (MRI) scans that look for structural abnormalities of the brain are always a good idea, Fleming said, because at least “they can show you whether you have had little strokes, and they can serve as the basis for further scans. And they are only a few hundred dollars.” Some of the MRI studies have shown that the shrinkage of the hippocampal formation system in the brain accurately predicts a decline to Alzheimer’s disease.
Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) that can identify functional abnormalities of the brain could be helpful if they are conducted at an imaging center with a large database of elderly subjects for comparison.
“If you do get a functional scan, do go to a center where they have a large database of elderly people the same age who don’t have any problems,” Fleming said. “In our study, we found that the people who progressed from MCI to Alzheimer’s disease did have reductions in posterior cingulate [regions of their brains]. But we could only see that because we have such a large-scale database for comparison.
Importance of MCI Diagnosis
It is important to learn about MCI, Fleming said, because over a three-year period, about half of those with MCI develop Alzheimer’s disease.
A number of studies have followed people from the time they were first diagnosed with MCI until their deaths. Researchers performing autopsies on their brains found the characteristic neurofibrillary tangles that are present in Alzheimer’s disease, Fleming said. She added that from age 30 on, our brains start accumulating the abnormal tissues called senile plaques and neurofibrillary tangles found in Alzheimer’s disease.
According to Fleming, if most of us live long enough, we will likely develop dementia, of which Alzheimer’s disease is the most prevalent form. By the time people reach age 85 years or older, nearly half have Alzheimer’s disease. Individuals with Alzheimer’s disease not only have severe memory problems, but also other cognitive problems involving language (e.g., finding and using the right word), attention, planning, and visuospatial skills. They also have difficulty performing daily activities, such as keeping a checkbook or driving.
Although most individuals with MCI go on to develop Alzheimer’s disease, about one quarter will not. They just continue to have memory problems. Researchers have been finding some clues to predict which patients will develop Alzheimer’s disease.
“If the person is disoriented to time or has problems with clock drawing (a test that involves drawing a clock face and setting the hands to 10:50), that person will more likely progress to Alzheimer’s disease. Also, the MCI patients who have vascular risk factors including uncontrolled high blood pressure or Parkinson’s symptoms convert more often,” Fleming said.
Depression also may be a possible prognostic factor.
“It is hard to tease out whether someone is depressed or has a memory problem, because if you are very depressed you can have a memory problem. However, it still looks as though depression is a part of early Alzheimer’s disease,” Fleming said. It is advisable, she added, for the physician to treat the depressed patient with a selective serotonin reuptake (SSRI) inhibitor and see if the patient’s memory gets better.
When asked what are some things people can do to prevent conversion to Alzheimer’s disease from MCI, Fleming recommended exercise; eating lots of fish and low-fat foods; drinking wine in moderation; and keeping the mind active (e.g., doing crossword puzzles).
Vitamin E has been shown to be pretty protective, but the amounts in multivitamins are not enough, Fleming added. The dose should be between 800 and 2,000 units per day.
The acetylcholinesterase inhibitors (donepezil [Aricept], rivastigmine [Exelon] and galantamine [Reminyl]) that have been approved for treatment of Alzheimer’s disease are being studied for their use in MCI.
Several large-scale trials are underway to determine whether specific vitamins, such as vitamin E, and the new acetylcholinesterase inhibitors can prevent people with MCI from progressing to Alzheimer’s disease, Fleming explained.
In the treatment of Alzheimer’s disease, the “new drugs really do help for a couple of years,” Fleming added. “They slow down the decline, but do not reverse it.”
“People’s expectations sometimes are too high,” she said. “They put family members on these medications and become frustrated because the family members are not getting better. What they don’t understand is that if they weren’t on the medication, they would be getting much worse.”
Fleming added that UCI is conducting a study on mild cognitive impairment:
“For the last four years, we have been following about 40 people who are elderly and who are worried about their memory, but they do not have dementia yet. Once the results of this trial are released, we will know much more.”
Alzheimer’s Association (2003), What is mild cognitive impairment. Question and answer column. Advances. The Alzheimer’s Association Newsletter. 23(1):8.
Petersen RC, Steven JC, Ganguli M et al. (2001), Practice parameter: early detection of dementia: mild cognitive impairment (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 56:1133-1142.
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