By Makiko Tatebayashi and Keisei Takahashi / Yomiuri Shimbun Staff WritersMild cognitive impairment (MCI) that occurs during the early stages of dementia is drawing increased attention. According to results compiled by a research team at the National Center for Geriatrics and Gerontology of a four-year study that monitored elderly people diagnosed with MCI, 14 percent developed dementia, while 46 percent returned to normal cognitive function.
Opportunities are increasing for elderly people to receive checkups of their cognitive functions, and those diagnosed with MCI should remain optimistic and positively aim for healthy lifestyle habits.
MCI is a condition in which cognitive functions such as memory or concentration are reduced, but not to the extent of impeding everyday activities. It is an intermediate stage between dementia and normal cognitive function.
Ronald Petersen, a doctor of neurology in the United States, proposed the concept in 1996. It has recently generated great interest due to the aging of society and growing expectations that treating symptoms in their early stages can prevent dementia.
According to a government estimate, 4.62 million elderly people have dementia, and 4 million have MCI.
A cognitive function test is the primary method of diagnosing MCI. There are several commonly used methods, testing not only memory function but also the ability to draw a diagram as it appears or perform a task as instructed.
MCI is suspected when cognitive functions are lower than normal but not diminished enough to seriously impede everyday life and warrant a diagnosis of dementia.
Special medical institutions comprehensively determine MCI after interviewing those suspected of having the condition and their families. However, health checkups for local residents aimed at heightening health awareness or quick private examinations sometimes do not take the same careful approach to diagnosing MCI as special institutions.
Many unsolved mysteries
For four years starting in 2011, a study by the National Center for Geriatrics and Gerontology tracked about 4,200 residents of Obu, Aichi Prefecture, who were 65 years or older. A cognitive function test with about 150 problems initially determined that about 740 people, or 18 percent, had MCI. Four years later, 46 percent of these people had regained normal cognitive function.
On the other hand, 14 percent of those who were diagnosed with MCI developed dementia during that four-year period. Future studies will further analyze the characteristics of people who recovered from MCI.
Other reports have found that 10 percent of people diagnosed with MCI developed dementia within a year. However, the results of studies across the world on the development of MCI have varied, and many unanswered factors remain.
For example, the study by the National Center for Geriatrics and Gerontology found that 46 percent returned to normal cognitive function, but international studies have found recovery rates varying from a few percent to just under 60 percent.
Why is there such a wide gap?
Hiroyuki Shimada, chief of the preventive gerontology department at the National Center for Geriatrics and Gerontology, compiled the results. He explains: “MCI is a gray-zone concept. The degree varies widely, with some people having light cognitive impairment and others serious impairment. It is possible the rate of severe MCI cases differs according to how respondents are gathered.”
According to Shimada, people often visit medical institutions because they are aware something is wrong. Therefore, surveys targeting medical institutions have a greater chance of including people with relatively serious MCI. However, studies focusing on local residents are believed to include more people with milder cases.
The difference in the studies’ duration — from one year to more than eight years — also likely influences the results.
A statistical analysis of MCI recovery rates in 25 studies across the world found a rate of 14 percent for studies at medical institutions, and 31 percent for studies of local residents.
The National Center for Geriatrics and Gerontology’s study also demonstrates variations in the severity of MCI.
Those with sub-normal function in one of four categories — memory, concentration, processing speed and execution — returned to normal cognitive function at a rate of 39 to 57 percent. But those with functions lower than normal in multiple categories returned to normal cognitive function at a rate in the 20 percent range.
Those with sub-normal functions in multiple categories tend to recover at a lower rate.
More chances for checkups
The government is emphasizing measures against dementia, providing the elderly with more opportunities to undergo cognitive function tests.
Elderly people worried about dementia can receive hospital checkups, and some local governments conduct examinations for those who are interested. Businesses also conduct screenings over the phone.
However, there are no globally unified criteria for determining MCI. This has created fears that an increasing number of elderly people will receive a shock after being labeled as having “low cognitive function” or “suspected MCI.”
Shimada says: “In checkups with cognitive function tests focusing on residents, which have been increasing recently, people with light cognitive function disorder could possibly be diagnosed with MCI. The study at the National Center for Geriatrics and Gerontology showed that the risk of MCI developing into dementia is higher than the risk of normal cognitive function developing into dementia, but there were many cases of improvement. People determined to have MCI should not lose hope for improvement.”
Depression also heightens the risk of dementia. Those diagnosed with MCI seem to do best when they remain positive and strive to live a healthy life.
Activities to help stay sharp
How can the risk of developing dementia be reduced?
According to studies of elderly people overseas, people whose daily routine involves intellectual activities such as reading books or newspapers, participating in jobs or volunteer activities, or engaging in physical exercise have a lower risk of developing dementia.
One report found that healthy elderly people who continued aerobic exercise at least three times a week for a year had increased the volume of the brain’s hippocampus and improved memory.
The National Center for Geriatrics and Gerontology devised the concept of “cognicise,” which involves doing intellectual exercises such as calculations or word games while also engaging in full-body exercise. “Cognicise” was tested on about 300 people with MCI, and members of a group that practiced cognicise once a week showed improved cognitive function.
The exercise is gaining attention in South Korea as well as Singapore, and preparations for international joint research have been promoted.
Takao Suzuki, a professor of gerontology at J. F. Oberlin University who was involved in devising cognicise, said: “The important thing is to continue using your brain and body to preserve the functions of the brain. There is no rule that you must do something specific.”
According to Suzuki, human connections are important, but forcing yourself to think about post-retirement jobs in your local community is unnecessary. Instead, it is important to focus on what you can do, such as meeting people through hobbies or taking trips to temples.
The deterioration of cognitive function can also result from the side effects of medication.
According to Masahiro Akishita, a professor of the department of geriatric medicine at the Graduate School of Medicine of the University of Tokyo, medicines for frequent urination, some stomach medicines and medicine for hay fever can contribute to decreased function, and cognitive function will improve if use of the drugs is stopped.
Receiving treatment for diabetes or high blood pressure in middle age can reduce the risk of developing dementia. But for elderly people, the medicine may be too effective and result in low blood sugar or low blood pressure that leads to reduced cognitive function, Akishita said.
(Makiko Tatebayashi is a Yomiuri Shimbun senior writer.)