Does childhood cognition predict dementia risk later in life?
To what extent do factors such as education and socioeconomic position affect our thinking skills and memory over time? Not as much as one might think, a new study suggests.
The study set out to investigate what influences a person's cognitive ability — that is, their ability to think, reason, and remember — over a lifetime.
The researchers hoped that by getting an insight into what impacts people's cognitive ability, they might be able to shed some light on factors that lead to cognitive decline in later life, including Alzheimer's disease and other forms of dementia.
Dementia, which affects around 5.8 million people in the United States, can cause a decline in a person's ability to solve problems, remember, speak, and think. In its most severe form, dementia has a significant impact on a person's ability to carry out daily tasks.
But what if there was a way to understand the factors that may affect cognitive decline? Predicting what may influence cognitive health in later life could help stave off cognitive impairment.
The results of the study now appear in the journal Neurology. Its authors set out to compare the results of thinking and memory tests in people at 8 years old and 70 years old.
The researchers looked at 502 people who had all been born in the same week in 1946. They had all taken cognitive tests at age 8 and again at ages 69–71.
The researchers behind the new study were looking for factors that might serve to predict thinking and memory performance later in life, such as education level and socioeconomic status.
"Finding these predictors is important," says study author Jonathan M. Schott, of University College London in the United Kingdom.
"If we can understand what influences an individual's cognitive performance in later life, we can determine which aspects might be modifiable by education or lifestyle changes like exercise, diet, or sleep, which may, in turn, slow the development of cognitive decline."
Children who performed highly did so at 70
The participants took a number of tests that measured skills such as memory, language, orientation, and concentration. In one test, for example — which was similar to one they had taken as children — they had to look at geometric shapes and spot the missing piece out of five options.
The researchers looked at sex, childhood ability, education, and socioeconomic status, which they determined by the participants' occupation at age 53.
They found that the ability to think as a child tallied with the scores they achieved over 60 years later. Those who performed in the top 25% as children, for example, were likely to hold their position in the top 25% at 70 years of age.
Not only that, but women outperformed men when it came to thinking speed and tests of memory.
Education also had an effect. Those with a college degree, for example, scored around 16% higher than those who had left school before age 16.
Higher socioeconomic status did not have a significant impact on cognitive performance. Those who had been professionals, for example, recalled an average of 12 details from a story, while those who had had manual jobs remembered 11 details, on average.
The participants also underwent detailed MRI scans and PET scans to look for beta-amyloid plaques in the brain. These are markers of Alzheimer's disease. Alzheimer's is the most common form of dementia, accounting for 60–80% of all dementia cases.
The researchers found that the participants with beta-amyloid plaques scored lower on the tests. For example, on a missing pieces test, these participants scored 8% lower, on average.
They found no link between the presence of plaques and childhood cognitive ability, socioeconomic status, education, or sex.
"Our study found that small differences in thinking and memory associated with amyloid plaques in the brain are detectable in older adults even at an age when those who are destined to develop dementia are still likely to be many years away from having symptoms."
-Jonathan M. Schott
"Continued follow-up of these individuals and future studies are needed to determine how to best use these findings to more accurately predict how a person's thinking and memory will change as they age."
The study was limited in that all participants were white. For this reason, it is difficult to say whether or not the findings will apply to other populations.