In the first post of a two-part blog series, Dr Clare Walton, our Research Communications Manager discusses what we know and don’t know about dementia risk.
What causes dementia? Is dementia inherited? How can I prevent it?
Many of the questions that Alzheimer’s Society gets asked on a regular basis do not have easy or straightforward replies. This is in part because research does not yet have all the answers when it comes to dementia, but also because the answers often involve discussing the concept of risk.
Will I develop dementia or not?
We are making great strides in piecing together the complex causes of dementia, but we still don’t have the full picture. We know certain genes, lifestyle choices and other health conditions all contribute. But there is still a great deal of uncertainty about why some people develop dementia and some don’t.
For individual genes or lifestyle factors such as smoking, we can estimate how much your risk of developing dementia will change. However, our knowledge is not yet good enough for us to combine all these dementia risk factors together. For a given individual like you or me, we cannot accurately calculate how likely we are to develop dementia over our lifetime.
What things do increase my risk?
Inheriting a gene called ApoE4, being a woman and being of Southern Indian, African or African-Caribbean origin all increase the chances of dementia. Getting older does too – age is the risk factor with the largest effect. Of course we can’t stop ageing or change our genes but there are modifiable risk factors too. These include smoking cigarettes and being physically inactive as well as other health conditions such as high blood pressure and type 2 diabetes.
Things that keep our heart and blood vessels healthy will also promote brain health and may help to reduce your risk of getting dementia. Giving your brain a daily workout might help too – such as learning a new language or taking up a new hobby. Read our seven top tips for reducing your risk of dementia.
Dementia risk factors in the news
Risk can be a difficult concept to understand, especially when it is explained using probabilities, percentages or risk ratios. Newspaper headlines can make it harder still; often reporting that something causes dementia when there is no way to conclude that from the research that has been done.
Taking this headline as an example, you’d be mistaken for thinking that living close to a busy road had been discovered as a major risk factor for dementia. The researchers reported that people living within 50m of a major road were seven per cent more likely to have developed dementia over the course of the study than people living more than 300m away. Seven percent could sound fairly significant to some, but if the risk of developing dementia is already very low then a seven per cent difference will be very small indeed. Read about the research behind this headline.
Comparing risk factors for dementia
One way to see the relative importance of different risk factors is to compare them to one another. We’ve created an interactive tool to illustrate the effect of age, the ApoE4 gene, smoking and diabetes on dementia in a simple way. We’ve also included the busy roads study above so you can see how it compares. The figures it shows are an approximation of how the number of people with dementia would change in the presence of each of the risk factors.