Prof. Carol Brayne
What are the detailed effects of education? I think that is a very challenging question, because it could be argued that a poor education or low access to education, is itself a risk factor, and that maybe high education is separately a protective factor, and an average education is maybe the neutral state. I would argue that we probably don’t really know the answer to that question. There is the opportunity across the world to examine it because there are many populations in which access to education is very limited. And, of course, we’re talking about findings from a country in which education has been the norm for a long time. So we’re looking at variations in education, rather than no access, or absolutely minimal access. So I think we’ll understand a lot more about education in the years to come.
So the EClipSE Study is a grouping of three population based studies of dementia. One is of the 65 plus population; one is of the 75 plus population and one is of the 85 plus population and there are two in the UK and one in Finland. These studies have all studied dementia in the population. But what makes them stand out, is that they’ve also had a brain donation program associated with them. So in that research, we have gone out and asked people whether they were willing to consider donating their brains to medical research after they died, and their families as well, so we talk with their families. Between them those studies have collected a thousand donations. The reason why we brought them together was because, individually, each study is not powerful enough to look at the relationship between what you see in the brain and what you’ve measured during life, taking into account the various different factors. So we wanted to have the ability to look at what might be protective factors and compensatory factors in people’s lives that influence how they might or might not have had dementia.
In that study we explored the hypothesis that education is associated with less dementia. Now that’s a question that’s been addressed many times in ordinary cohort studies, in ordinary longitudinal studies, and we know that education is protective of later development of dementia, from a whole range of studies. What we wanted to do with this study was see what was the brain mechanism for that. And what we found was that if you have a certain amount of the changes associated with dementia in your brain, and if you have high education compared to low education, that the people in the high education group have less dementia during life. So just rephrasing that, if you hold the amount of neuropathology steady in a brain, whether you have more education or not influences whether you develop dementia during life or not. So that tells us that there are other things going on in the brain which allow us not to express dementia during life, even if we have say Alzheimer’s or vascular changes in our brain.
What we looked at was the dose of education and the dose of education seemed to be important. Not just the availability of education, so it’s not just confounded by other things. But it seems almost certain that there are a variety of ways in which the measure of education could be associated with protection from expression of dementia. So it could be having a bigger brain at the beginning. It could be higher IQ because there’s an association between those two. It could be higher access to educational exposure. And then it can be the things that a higher education then is associated with in later life. Because we also know that more intellectually stimulating occupations and later life engagement, also have a protective effect, and each of those, they’re associated with each other, but we know they also have independent effects.