October 30, 2019

expert reaction to study on association between cognitive abilities in childhood and at seventy years old

Research, published in the journal Neurology, reports on the relationship between cognitive ability in childhood and in late life. 

Dr Matthew Iveson, Senior Data Scientist, University of Edinburgh, said:

“As far as I can understand the purpose of the study was primarily to assess the associations between particular brain pathologies and performance on a particular battery of cognitive tests in older age. The press release seems to focus on the finding that childhood thinking skills predict older-age thinking skills, which is not the main focus of the paper. Note that the study doesn’t say anything about ‘change with age’ as suggested by the press release. This is because the paper looks at associations between thinking skills at only two time points (childhood and older age). As such, it can’t make any conclusions about ageing, as it can’t capture the change in thinking skills that older adults experience. Notably, larger studies – such as the Lothian Birth Cohort 1936 – have shown that childhood thinking skills predict later-life thinking skills, but that they not as good at predicting the rate at which thinking skills decline in later-life as part of healthy ageing. The paper also highlights that early-life thinking skills are only part of the puzzle, and that other factors such as education, socioeconomic position and specific brain pathologies may also help to predict thinking skills in later life. Again, this has been shown in previous, larger studies.

“The paper does a good job at acknowledging its limitations regarding a small and selective (in terms of socioeconomic background, ethnicity, etc.) sample.

“The paper doesn’t directly say anything about dementia risk, nor does it attempt to follow-up the individuals to see who actually developed dementia. It just looks at performance on a battery of cognitive tests that may help to detect the subtle cognitive decline that precedes dementia. The study does not claim that those performing poorly on the tests have, or will get dementia. It also does not speculate about implications for the detection or treatment of dementia. Again, it focuses much more on the correlational (i.e., not causal) associations between brain pathologies and thinking skills in older age.”

Dr Ashok Jansari, Lecturer in Psychology, Goldsmiths, University of London, said:

“The results are impressive given the size of the study and large number of variables. However, it is important to note that these results do not show any relationship between a child’s cognitive skills and their risk of developing dementia. The press release specifically states “However the presence of these plaques was not associated with sex, childhood cognitive skills, education or socioeconomic status.” Given that the plaques are the only current biological marker of Alzheimer’s, there is no relationship at all to be found here. Further, in this study, there was no statistical difference in the scores of the adults who did show the plaques and who didn’t. Therefore, while the study shows a number of very important strengths, it is important not to overstate or confuse the main findings.”

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“It is difficult to measure the extent to which individual lifestyle factors contribute to our overall dementia risk, but participants in the Insight 46 study offer a unique opportunity to find out more. This study sheds more light on the complex relationship between memory and thinking skills in early life and our cognitive ability as we get older.

“One explanation for this relationship is cognitive reserve, the idea that the memory and thinking skills we acquire during our lives can make us more resilient to the symptoms of dementia in older age, but more research is needed to better understand this link.

“Research shows up to a third of dementia risk may be within our power to change, with evidence suggesting that eating a balanced diet, staying physically and mentally active, keeping blood pressure and cholesterol in check and not smoking are all ways to keep our brains healthy.”

‘Cognition at 70’ by Kirsty Lu et al. was published in Neurology at 20:00 UK time on Wednesday 30th October. 

Declared interests

Dr Matthew Iveson: I’m affiliated with the Lothian Birth Cohort 1936 research team.

Dr Ashok Jansari: No conflicts of interest.

None others received.