US seniors ‘smarter’ by 10 years than their English peers

Despite their greater risk of developing memory-hampering cardiovascular issues, United States (US) seniors performed significantly better than their English counterparts on standard tests of memory and cognitive function, a new study found.

In fact, the difference in “mental ageing” between seniors in the two countries seemed to be about 10 years, in favor of the Americans, according to a report published in the British medical journal BMC Geriatrics.

The study is the first known international comparison of cognitive function in nationally representative samples of older adults in the US and England.

“The better cognitive performance of US adults was surprising, since United States adults had a higher prevalence of cardiovascular risk factors, which are generally associated with cognitive decline and poorer mental function,” says University of Michigan researcher, Dr Kenneth Langa, lead author of the study.

For the study, Dr Langa and colleagues compared data on 8,299 Americans age 65 and older with 5,276 British seniors in the same age bracketing. The same cognitive tests were administered to the two groups in the same year.

The US advantage in “brain health” was greatest for the oldest of the old, those age 85 and older. On a population level, the overall difference in cognitive performance between the two countries was quite large, approaching the magnitude associated with about 10 years of ageing.

In other words, the cognitive performance of 75 year-olds in the US was as good, on average, as that of 65-year-olds in England.

Data on the US population came from the Health and Retirement Study, conducted by the University of Michigan Institute for Social Research. Data on the UK study was from the English Longitudinal Study of Ageing.

Both are nationally representative, population based studies designed to facilitate direct comparisons of health, wealth and well-being among older men and women.

Older adults in both countries took tests of immediate and delayed recall of 10 common nouns.

Higher levels of education and net worth in the US accounted for some of the better cognitive performance of US adults, according to Dr Langa.

The research team also examined data on participant health conditions, risk factors and treatments for stroke, diabetes, heart disease, hypertension, lung disease and cancer.

They also collected data on recent symptoms of depression, and on smoking status, alcohol consumption, and limitations in performing common activities of daily living, including dressing, bathing, taking medications and managing money.

US adults reported significantly lower levels of depression symptoms than English adults, and according to Dr Langa, this may have accounted for some of the US advantage in brain health, since depression is linked with worse cognitive function.

The researchers also found significant differences in alcohol consumption between the US and English seniors. More than 50% of US seniors reported no alcohol use, compared to only 15.5% of their English peers. Previous research has shown that moderate alcohol consumption, compared to abstinence, is linked with better cognition among those aged 50 and over.

Finally, Dr Langa noted, while US adults reported a higher prevalence of high blood pressure, or hypertension, they also were more likely to be taking medications to treat the condition. A number of studies have shown a link between untreated hypertension and an increased risk for cognitive impairment.

“The fact that the greatest cognitive advantage for US adults was among the oldest-old may support the hypothesis that more aggressive diagnosis and treatment of hypertension, and possibly other cardiovascular risks, leads to less cognitive decline,” Dr Langa said.