About two in 10 people over the age of 65 have mild cognitive impairment, such as marked changes in memory, problem-solving abilities, or attention.

This setback is partly due to the same brain changes that occur in dementia.

While mild cognitive impairment often has little effect on a person’s lifestyle, between 5% and 10% of those with it will develop dementia.

Why some people with mild cognitive impairment develop dementia and others has not been a mystery for long.

But a recent study from Columbia University in New York identified several factors that determine whether a person is more or less likely to develop mild cognitive impairment.

These findings could give us clues about who is most likely to develop dementia.

The researchers looked at 2,903 people aged 65 and over and tracked their brain function for nine years.

To detect cognitive impairment, it was observed whether participants who were not diagnosed with dementia had problems with memory exercises or whether they had reported difficulties with certain daily tasks (such as using the phone).

At the start of the study, all participants had normal brain function. After six years, 1,805 participants had normal cognitive function, 752 had mild cognitive impairment, and 301 had dementia.

The researchers then followed the cognitive impairment group for three years.

Because some participants were “lost to follow-up”, the researchers were only able to observe 480 people from the original group with mild cognitive impairment.

While 142 still had mild cognitive impairment, they found that 62 people in this cohort now had dementia.

The researchers also found that 276 people no longer met the criteria for mild cognitive impairment, showing us that mild cognitive impairment does not always lead to dementia and is not always permanent.

Let’s first look at the factors associated with a lower risk of developing mild cognitive impairment.

Lower risk

1. Education

Time spent on education is a factor that reduces the risk of mild cognitive impairment.

People who had studied for an average of 11.5 years were 5% less likely to develop mild cognitive impairment than those who had studied for 10 years.

This study did not distinguish between types of education (primary school or higher education).

One theory for this relationship is that longer time in education is associated with higher socioeconomic status, which could mean that a person has access to a healthier lifestyle and better health care.

Another theory is that education helps the brain build more neurons and connections. This can help the brain compensate for any changes that occur from mild cognitive impairment, such as memory loss.

2. Exercise and recreational activities

People who are more physically or socially active have a slightly lower risk of mild cognitive impairment.

To measure how social or active the participants were, they filled out questionnaires about the type and frequency of activities they did, such as walking or going to the movies.

The researchers gave the participants a maximum score of 13. The higher the score, the more active the participants were.

Those without mild cognitive impairment scored an average of 7.5, while those with mild cognitive impairment scored slightly lower, 7.4.

People with dementia scored 5.8.

Previous studies have also shown that moderate-intensity physical activity (such as swimming) during middle age or old age can reduce the risk of mild cognitive impairment.

The protective effects of exercise can be explained by the beneficial structural changes that occur in our brains as a result of physical activity. There is also growing evidence that participating in social activities can help maintain brain health and reduce the risk of premature death.

3. Sign in

People who earn more than $36,000 a year are 20% less likely to have mild cognitive impairment compared to those who earn less than $9,000 a year.

Income may be associated with a lower risk of cognitive decline for reasons similar to education. People with higher incomes are more likely to pay for better health care and have healthier diets and lifestyles.

They can also live in areas where environmental factors, such as pollution, have little effect on them.

This is important, as there is growing evidence that contamination may be linked to conditions such as Alzheimer’s and Parkinson’s.

Higher risk

Researchers at Columbia University also identified several factors associated with an increased risk of developing mild cognitive impairment.

These factors include:

1. Genetics

The presence of the AP0E E4 allele (one of two or more versions of the gene) was found to increase the risk of developing mild cognitive impairment by 18%.

This finding is consistent with previous evidence which also suggests that this allele may increase the risk of dementia.

People with AP0E E4 are about three times more likely to develop Alzheimer’s disease than those with a different variant of the AP0E gene.

The reason, scientists believe, is that this variant makes people more likely to accumulate toxic protein deposits in the brain, a hallmark of Alzheimer’s disease.

Researchers also believe that this gene only causes damage in old age.

2. Underlying health problems

People with one or more chronic health conditions, such as heart disease, depression or diabetes, had a 9% higher risk of mild cognitive impairment, according to researchers from Columbia University.

The increased burden of various health conditions can cause a person to become less involved in daily activities or social life. Both behavioral changes can accelerate the decline in brain health.

Other conditions, such as heart disease, are also known to increase the risk of cognitive decline.

“Our brain is dynamic”

This study reminds us that mild cognitive impairment is not necessarily a precursor to dementia.

In fact, some study participants with mild cognitive impairment returned to normal brain function.

Not entirely sure why, but it could be due to lifestyle changes after diagnosis (such as exercising more) that might have improved the results.

It is also possible that some participants were misdiagnosed at the start of the study, but this is unlikely given the various tools used to confirm their diagnosis.

Our brain is dynamic and keeping it active throughout our lives is important for maintaining good brain function.

While there are some risk factors, such as our genes, that we cannot change, staying active and leading a healthy lifestyle can be one way to reduce the risk of mild cognitive impairment and dementia.

* This article was originally published in The Conversation. You can read the original version and see links to all the scientific studies mentioned here.

Mark Dallas is Associate Professor of Cellular Neuroscience at the University of Reading in the UK.

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