Who hasn’t struggled occasionally to come up with a desired word or the name of someone near and dear? I was still in my 40s when one day the first name of my stepmother of 30-odd years suddenly escaped me. I had to introduce her to a friend as “Mrs. Brody.”
But for millions of Americans with a neurological condition called mild cognitive impairment, lapses in word-finding and name recall are often common, along with other challenges like remembering appointments, difficulty paying bills or losing one’s train of thought in the middle of a conversation.
Though not as severe as full-blown Alzheimer’s disease or other forms of dementia, mild cognitive impairment is often a portent of these mind-robbing disorders. Dr. Barry Reisberg, professor of psychiatry at New York University School of Medicine, who in 1982 described the seven stages of Alzheimer’s disease, calls the milder disorder Stage 3, a condition of subtle deficits in cognitive function that nonetheless allow most people to live independently and participate in normal activities.
One of Dr. Reisberg’s patients is a typical example. In the two and a half years since her diagnosis of mild cognitive impairment at age 78, the woman learned to use the subway, piloted an airplane for the first time (with an instructor) and continued to enjoy vacations and family visits. But she also paid some of the same bills twice and spends hours shuffling papers.
Dr. Ronald C. Petersen, a neurologist at the Mayo Clinic College of Medicine in Rochester, Minn., described mild cognitive impairment as “an intermediate state of cognitive function,” somewhere between the changes seen normally as people age and the severe deficits associated with dementia.
While most people experience a gradual cognitive decline as they get older (only about one in 100 lives long without cognitive loss), others experience more extreme changes in cognitive function, the neurologist wrote in The New England Journal of Medicine in June. In population-based studies, mild cognitive impairment has been found in 10 percent to 20 percent of people older than 65, he noted.
Dr. Petersen described two “subtypes” of the condition, amnestic and nonamnestic, that have different trajectories. The more common amnestic type is associated with significant memory problems, and within 5 to 10 years usually — but not always — progresses to full-blown Alzheimer’s disease, he said in an interview.
“Subtle forgetfulness, such as misplacing objects and having difficulty recalling words, can plague persons as they age and probably represents normal aging,” he wrote. “The memory loss that occurs in persons with amnestic mild cognitive impairment is more prominent. Typically, they start to forget important information that they previously would have remembered easily, such as appointments, telephone conversations or recent events that would normally interest them,” like the outcome of a ballgame would a sports fan.
The forgetfulness is often obvious to those who are affected and to people close to them, but not to casual observers.
The less common nonamnestic type, which is associated with difficulty making decisions, finding the right words, multitasking, visual-spatial tasks and navigating, can be a forerunner of other kinds of dementia, Dr. Petersen said.
In general, Dr. Reisberg said, “mild cognitive impairment lasts about seven years before it begins to interfere with the activities of daily life.”
The Correct Diagnosis
Distinguishing mild cognitive impairment from the effects of normal aging can be challenging. Typically, new patients take a short test of mental status, provide a thorough medical history and are checked for conditions that may be reversible causes of impaired cognition. Problems like depression, medication side effects, vitamin B12 deficiency or an underactive thyroid can mimic the symptoms of mild cognitive impairment.
Other tests, like an M.R.I. or CT scan of the brain, can look for evidence of a stroke, brain tumor or leaky blood vessel that may be impairing brain function.
It is natural, Dr. Petersen said, for patients and their families to want to know whether and how quickly the disorder might progress. While patients decline by about 10 percent each year, on average, certain factors are associated with more rapid progression. Among these are the presence of a gene called APOE e4, more common among patients with Alzheimer’s disease; a reduced hippocampus, a region of the brain important to memory; and a low metabolic rate in the temporal and parietal regions of the brain.
Amyloid plaques in the brain, while a hallmark of Alzheimer’s disease and a predictor of progression, have also been found at autopsy in people with perfectly normal cognitive function.
Preserving Cognitive Function
Despite a number of clinical trials that tested various medications, no drug to treat mild cognitive impairment has been approved by the Food and Drug Administration. But experts like Dr. Reisberg and Dr. Petersen suggest several approaches that may slow the decline in cognitive function.
Although studies did not show that medications like donepezil (brand name Aricept) and memantine (Namenda), both used to treat Alzheimer’s disease, change the ultimate course of mild cognitive impairment, Dr. Reisberg said they can be useful temporary treatments that may stabilize patients for a few years.
Although the drugs are not approved for this condition, licensed physicians can prescribe approved medications “off label.” “Clinicians have to work with what we have,” Dr. Reisberg said.
There are people who think they are having memory problems, but tests do not show anything definitive. Some may be in Stage 1 of Alzheimer’s disease, Dr. Reisberg said, and perhaps could benefit from early treatment with the drugs.
It is also important to reduce cardiovascular risk factors like smoking, elevated cholesterol and high blood pressure; keep blood sugar at normal levels; minimize stress (which in animal studies can cause the hippocampus to shrink); and avoid anticholinergic drugs that can interfere with brain chemicals important to memory. These include Demerol to treat pain, Detrol to treat a leaky bladder, tricyclic antidepressants, Valium, and over-the-counter medications with Benadryl (diphenhydramine), like Tylenol PM, Dr. Petersen said.
Some cognitive rehabilitation exercises, like computer games that enhance focus, may be helpful, Dr. Petersen said, but there have been few good studies to demonstrate a benefit. Compensatory techniques, like taking notes, creating mnemonics and making structured schedules, can be useful aids, he added.
But most promising is regular physical exercise, which in animal studies was found to reduce the accumulation of amyloid in the brain. An Australian study in patients with memory problems showed that brisk walking for 150 minutes a week improved cognitive function.
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