Older adults tend to vary considerably when it comes to performance on certain mental tasks; some older individuals perform very well while others perform quite poorly. However, we know that a person’s cognitive performance in later life tends to be somewhat similar across various mental tasks, such that high performance in one cognitive domain tends to accompany high performance in others as well. Older people also vary widely to the extent that they are able to cope with the brain changes that are occurring during the aging process, and to what extent they impact upon behavioural performance. Aging research has therefore inferred that the extent of cognitive decline seen in aging is also determined by factors present before the onset of old age, a concept known as ‘brain reserve’. This concept is backed-up by research showing that people with higher levels of education show equal Alzheimer’s-related brain pathology as lesser-educated people. However, higher education is associated with less cognitive decline despite the presence of equal Alzheimer’s-related brain pathology.
If earlier factors (such as education) can help protect against cognitive decline in aging, then this suggests that in order to truly understand the brain aging process, we need to go further back in time. We at LCBC are among those who take this idea the furthest, arguing that the aging process needs to be considered against the backdrop of the entire lifespan, in which both development and aging are considered as one long, undivided and continual process. With this view, factors apparent very early in life (such as birth weight) should also impact upon brain aging.
In LCBC’s latest paper published in the prestigious scientific journal Proceedings of the National Academy of Sciences of the United States of America, the authors tested whether brain measurements that relate to one’s general cognitive ability (GCA) during development (i.e. at less than 12 years of age) could predict later changes in GCA from in later life, and whether early life factors could predict the life trajectory of brain-cognition relationships.
It was found that cognitive ability during development was associated with cortical area across much of the brain, lending support to the idea that general mental performance is made possible by the coordination of large-scale brain networks. Later brain changes for children scoring higher in GCA were then tested against those for lower-scoring children, revealing a parallel change trajectory for both groups (below figure). This suggests that early life factors may exhibit a continued influence on later brain changes. Further analyses revealed that one’s birth weight and the education level of one’s parents also predicts the trajectory of brain-cognition measurements occurring later in life.
In sum, the paper shows that the relationship between brain measurements and cognitive scores appears to be remarkably stable throughout life, and that factors apparent from birth impact upon the aging process.
Walhovd, K. B., Krogsrud, S. K., Amlien, I. K., Bartsch, H., Bjørnerud, A., Due-Tønnessen, P., … & Fjell, A. (2016)