US Seniors are Smarter than Their British Counterparts

The focus today on ‘mild cognitive impairment’, with its threat of progression to Alzheimer’s, draws attention to the possible causes of loss of cognitive function under different circumstances. Comparing results from different cultures is one approach that may show up important causative factors.

A study reported in the journal BMC Geriatrics describes the results of cognitive performance tests in people over 65 living in Great Britain or the USA. These results were drawn from surveys conducted simultaneously in the two countries, which included the same test of cognitive function. It was a basic word-recall exercise. Participants were given lists of nouns and asked to repeat them immediately, and then again five minutes later after they had answered other survey questions.

After adjustment for age and gender the delayed recall test showed a 24% difference between the countries. The average scores were 4.3 and 3.3 for the 8,300-odd USA and the 5,250 British participants, respectively. Results for the immediate recall test were closer – 5.3 vs. 4.8 – but still significantly different. This translates into a 10-year difference in cognitive ability between the two countries – a 75-year-old US resident has memory skills equivalent to a 65-year-old British resident.

Why did the USA seniors do better than the Brits? Several reasons were put forward by the researchers. The Americans had a higher burden of cardiovascular disease and diabetes, but this may have been trumped by their more intensive treatment of high blood pressure, compared with that in the British participants. Depression was more frequently reported in the British group, which could have influenced the results. And the Americans were, on average, slightly better (or longer?) educated, and had somewhat more wealthy participants.

A major problem was a difference in methodology between the tests in each country. In Britain, the tests were all conducted in person, whereas in the USA study both telephone and face-to-face contact was used. The phone-conducted tests could have allowed the participants to write down the word list, for example.

I think we should await further confirmation of these findings before getting too excited about differences between old USA-ers and old Brits. But the results make it important to look at the relative control of high blood pressure in the two countries. . .