“I knew it — I’m getting stupider,” was my first response when I saw the major new study on “cognitive decline” just out in the BMJ (formerly known as the British Medical Journal.)
“Cognitive decline can begin as early as age 45, warn experts,” was the headline of the press release. It began: “The brain’s capacity for memory, reasoning and comprehension skills (cognitive function) can start to deteriorate from age 45, finds research published on bmj.com today. Previous research suggests that cognitive decline does not begin before the age of 60, but this view is not universally accepted.”
Not a pleasant prospect — early senility. But I feel much better now that I’ve spoken with Dr. Francine Grodstein, an associate professor of medicine at Brigham and Women’s Hospital who studies aging. She wrote a BMJ editorial that accompanied the study, and I turned to her for a reality check. Tell me it ain’t so, I begged; is there real cognitive decline in our forties?
“It depends on what ‘real’ means,” she replied. “They did demonstrate in this study that there was ‘measurable’ cognitive decline in people in their mid-40s. So ‘measurable’ is probably a better word than real. But it still was quite a small amount and though it’s not data-driven, I would say those 40-year-olds who had measurable cognitive decline aren’t feeling anything. So it’s probably a small enough amount that in terms of their day-to-day life, it does not mean very much in the present.
The bigger question is really whether a small amount of measurable decline that the [BMJ] Whitehall study could see in the forties does predict dementia 20-30-40 years down the line. And if it does, then the translation in a day-to-day message for people in their forties is, ‘Start living healthy now, because if you put it off for 40 years, it may be too late.’”
It’s good to hear the early decline is slight, but I still find it depressing…
It’s not depressing! The amount of decline that was measured here was tiny. It doesn’t mean you’re demented when you’re 50. This is a long, long way from anything that has clinical relevance. People are more sensitive about memory, but it’s no different from other things: cancer, cardiovascular disease — the same thing is true: These are very long-term processes and the fact that you have some early signs of it in mid-life shouldn’t be something that depresses you, it should be something that inspires you. It should get you to say, ‘If I want to prevent something bad from happening in 30 years, I need to start doing more healthy things today.’ These findings in no way mean that at 50, there are more people with dementia than we previously thought.”
But doesn’t it imply that we’re getting stupider?
First of all, ‘cognitive function’ is mainly memory, so intelligence and memory are not the same thing. And again, the extent of the decline seen in this study was small; it’s not an extent that is noticeable to an individual. Across an entire population on average, there were some small change happening at younger ages. On an individual level, none of those people are noticing any change in their daily function. This does not translate to their forgetting their keys more than they used to because of a pathological problem in their brains.
So what does this landmark study mean for future research?
This is just one study demonstrating a small amount of decline, but I think the research implications are the most important thing about this study. It does mean that we have to start learning more about cognitive function at much younger ages than we thought about previously, since we really don’t know anything about cognitive decline in people at younger ages and what might prevent or accelerate it.
There is no evidence-based medicine in terms of what people can do to prevent it. There has not been a study in terms of lifestyle determinants of cognitive function in the forties. It’s possible that it’s identical to people in their seventies but it’s possible that it’s not. So the primary message is that we need to do more research to learn about the determinants of cognitive function in people at young ages. But if we were to assume that the determinants at young ages are the same as at older ages, then what people typically think of as living a healthier lifestyle presumably could help preserve their brains as well.
So all the usual advice? Diet, exercise, quit smoking?
Yes. A simple way to think about it is that cardiovascular disease and brain health really seem to share a lot of risk factors. So most of the things we think about in terms of heart health probably work for brain health as well: Diet, exercise, things people have been telling you about for years.
So what are you imagining in terms of the research that could be done?
I think it would be very similar research to what is already happening in older people, it’s just that researchers need to start applying this work to younger people. As I talked about in the editorial, the challenge is that given that the levels of cognitive decline on average are so much smaller in younger than older people, it is going to involve much, much bigger studies. The current studies in older people tend to be very resource-intensive, so if you’ve got to do it in much bigger populations, it’s just going to be prohibitively expensive.
Is there a cheap and easy model?
People are already experimenting with cognitive assessments that can be done by computer. But in order for this to work, you have to track people over time, and keep people in the study.
If and when you’ve got an online assessment ready for public consumption, sign me up…