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Event Review: Is Dementia Inherited?

14 August 2017
Appeared in BioNews 913

After the annual Alzheimer's Association International Conference for scientific researchers was held in London this summer, and the subsequent flurry of media interest, the UK dementia charity Alzheimer's Society announced an event for the public to discuss the much asked question: is dementia inherited?

Attended by a mixed audience of those living with dementia, those who had friends and family with dementia, and professionals working in the field, the event was held on 20 July at University College London. It included talks by speakers working in Alzheimer's disease, an extended Q&A, and a chance to meet researchers over a glass of wine!

Dr Tim Shakespeare, research communications officer at the Alzheimer's Society, kicked off his talk by revealing that over 1000 people per week search Google looking for the answer to the question, 'is Alzheimer's disease inherited?', highlighting the worldwide fear of dementia.  This fear was also evident in the audience present, with a quick poll showing that the majority were concerned about the risk of developing dementia. This fear was however perhaps unfounded, given that most attendees, while seemingly aware of lifestyle-based risk, felt that they knew little about the role of genetics in the onset of dementia.

Following a brief introduction, Dr Shakespeare got straight to the heart of the matter – what are the risk factors for dementia and how much of a risk do they actually pose? He showed that the biggest risk factor is age – something which I think most of us tend to forget. What was most surprising was how low the prevalence of dementia is – even in older age groups. Only 6 percent of people between 75-79 years develop dementia, with this figure increasing to just 30 percent in those over 90 years.  He then discussed the role of genetics in dementia, ie. the 'heritable risk factor' and showed that genes, nominally the well-reported APOE-4 gene, were twice as likely to lead to dementia as lifestyle. Nevertheless, even with two copies of the APOE-4 gene, individual risk still remained relatively low. This means that the 6 percent likelihood of developing dementia between 75 and 79 years would increase to around 11 percent with one copy of the APOE-4 gene is present and 18 percent in those with two copies of the gene (a rarity!). In other words, even if you have the highest risk factor – two copies of the APOE-4 gene – you are still much more likely not to develop Alzheimer's disease.

Dr Alexandra Freeman from the Winton Centre for Risk and Evidence Communication picked up the idea of the way in which risk associated with dementia is misunderstood – owed due in no small part to misrepresentation of information by the media. Here, Dr Freeman highlighted the recent BBC coverage of the Lancet paper, which implied that tackling nine (mainly) lifestyle risk factors could reduce the risk of developing dementia.  This is essentially contrary to what was actually presented in The Lancet article, which simply highlighted a series of factors that correlated with dementia diagnosis. There was no mention of any of these factors 'causing' dementia; they were only potential risk factors.  Depression, for example, could be a cause of dementia, but could also be a symptom. The Winton Centre is currently working to ensure that scientific dementia-related information presented by the media is digestible, understandable and discusses risks with a more realistic perspective.

The final presentation by Dr Elizabeth Rosser of UCL changed direction -  looking not at risk and potential for developing dementia, but what to do when heritable Alzheimer's disease is present in families.  A rare form of dementia, familial Alzheimer's, has a 50 percent chance of being inherited and is identifiable via genetic testing. Using Huntington's disease (HD) as an example of a disease where genetic testing is routine, Dr Rosser talked about how taking a genetic test can influence life choices, particularly in younger gene-carriers who may, for example, wish to have children. Genetic counselling both before and after taking a genetic test is vital, and Dr Rosser mentioned a very interesting phenomenon, which as an HD researcher I had not previously considered: most people take a genetic test because they believe they do not have the disease. The importance of genetic counselling was further made clear by the fact that despite 90 percent of people saying they would take a genetic test for familial Alzheimer's, only 10 percent of people actually do.

In sum, the conference hit the right spot for the predominantly non-scientific attendees. Information regarding dementia and genetics was pitched at a level that was both enlightening and understandable. And as a professional, I learnt a great deal about the fantastic work that is being done by the Alzheimer's Society and the Winton Centre in improving the way dementia risk is perceived, and the perception of dementia itself.

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