Brain Health Research: Interpreting Mainstream Media Coverage
Animal studiesWas a study carried out with humans or lab animals? Performing laboratory experiments with animals (typically mice or rats) is extremely important for understanding fundamental disease pathways and for testing scientific ideas under experimental conditions that we could never do directly in humans. As useful as they are however, humans are not mice. And mice don’t naturally get Alzheimer’s. These studies will often use animal models which attempt to recreate Alzheimer’s pathology on the animal, for example through genetic manipulation. So if something has been shown to have an effect in mice, it can provide a valuable promising avenue of investigation for future human studies, but we need to be wary about how much we can extrapolate mouse findings directly to a human population.
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Understanding Brain Health: Preventing Dementia
Correlation not causationWe can often find associations between two things, but does it prove one causes the other? Even if we do find that people who eat a lot of blueberries are less likely to develop dementia we can’t conclude on this evidence alone that the blueberries are causing a reduction in dementia risk. There could be many other related factors at play. For example can you think of other traits that we could speculate might be more common amongst the blueberry eaters as a group? Maybe people who eat a lot of blueberries are more likely to have healthier diets overall? Possibly they are more likely to exercise more? Perhaps less likely to smoke? We need to keep in mind all these associated factors when evaluating research findings. Often the only way to truly know if one factor is causing an effect is to run a randomised controlled trial – which we’ll cover in week three of this course.
Relative risk vs absolute riskAsk the question – an increase in risk from what to what? Let’s imagine another newspaper headline on links between blueberries and dementia risk. This time the story describes a study which looked at the health records of 5000 adults aged between 60-65 and found that those adults who did not eat blueberries are twice as likely to develop dementia. Sounds pretty convincing. The problem with reporting things as ‘twice as likely’ is that when we have a low rate to begin with things can sound a lot more dramatic than they truly are. We know that, in this age range, we would expect only around 1% of people to have dementia. Therefore if our study finds a doubling of risk, this implies we see that 2% of the non-blueberry-eaters developed dementia. So although the relative risk increase is 100% (the numbers have doubled), the absolute risk increase is only 1%. Another way of putting this is that from the blueberry eating group, 1 out of 100 people developed dementia while from the non-blueberry eating group 2 out of 100 developed dementia. So maybe not quite as alarming as the headline first sounds. Knowing a relative risk can often be very informative but when reading reported risks it’s important for context to always try to get to the bottom of what the absolute risk increase or decrease is too. Visit the RealRisk calculator for a fantastic online tool that will help you determine real risk from reported figures. Have a look at some of their examples or try entering your own data from a news report of scientific publication.
Thinking criticallyAs we progress through this course we’ll start to uncover the complexities of conditions like Alzheimer’s disease and appreciate that we should be extremely wary of anything that appears to offer a ‘quick fix’. Using the tools we’ve discussed here, we should be well placed to critically appraise stories we see in the media. There can often be some interesting science behind the headline which is valuable to prompt further areas of investigation. We just need not to get carried away with the hype and to realise things are not always as simple as they first seem. There is not, and never will be, ‘one simple trick to avoid Alzheimer’s’. Only though more research and more collaborative efforts can we begin to unravel the complicated disease processes at play and to design multi-pronged approaches to prevention of disease. Why not take a look at the following examples of newspaper headlines and, with the critical tools we’ve developed here, think of any areas you might want more information on before you come to a conclusion.
- Drinking three glasses of champagne per week could help stave off dementia
- Eat curry to beat Alzheimer’s
- This popular drink may help reduce the risk of dementia
Understanding Brain Health: Preventing Dementia
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