These two paragraphs give the background:
Cognitive reserve was originally defined as the extra protection against cognitive decline afforded to people with greater intellectual enrichment (see Stern et al., 2012). Given the same amount of brain pathology, people with a higher cognitive reserve (often measured as a great number of years of formal education) were found to be less susceptible to cognitive decline than people with a lesser reserve. Viewed from a different angle, others reported that given the same level of cognitive performance, people with higher reserves tended to have more brain pathology, indicating that their mental acuity was somehow shielded from the encroaching pathology (see Nov 2008 news).
However, some recent studies have suggested that cognitive reserves may do something even better—prevent pathology from occurring in the first place. For example, William Jagust’s group at the University of California, Berkeley, reported that AD biomarker signatures in the cerebrospinal fluid developed more slowly in people with higher cognitive reserves, and that ApoE4 carriers with higher cognitive reserves had less Aβ accumulation in their brains (see Lo et al., 2013, and Wirth et al., 2014). However, others have failed to find such a relationship (see Vemuri et al., 2012).
And this is the thought-provoking conclusion of the article:
Yaakov Stern of Columbia University in New York, one of the early proponents of the theory of cognitive reserve, said that he had originally never considered the idea that such reserves could alter brain pathology; rather, they could boost resistance to it. Now, the idea that lifestyle factors such as cognitive stimulation or even exercise could also dynamically influence brain pathology is gaining traction, he said. He added that Okonkwo’s study sample was relatively small and did not parse out the contributions of other factors associated with education. However, he said the results raise the interesting possibility that the people with higher cognitive reserves in the study may be spared not only from elevated CSF biomarkers, but also from the onslaught of dementia.
My own initial thought is that this is a fascinating area of study. If cognitive reserve can either give some protection against cognitive decline or even prevent the brain changes that are associated with dementia that might be great news for those who are fortunate enough to have some cognitive reserve but not much consolation to your average person.
The most interesting finding for me is explained in the passage in red above. Here we have people performing better than their brain pathology would suggest. Forget for the moment the uncertainty about what exactly is responsible for this positive for these people. Once again it seems clear that people with the same degree of 'brain damage' (in the simplistic jargon) perform very differently, i.e. people with the same amount of 'brain damage' can have significantly different levels of cognitive decline. It reminds me very much of the nuns study* and it's something that deserves to be much more widely investigated.
*I've blogged about this exciting research and you can read these posts by putting 'nuns study' into the search box (top left).