A new study has highlighted the complex emotions and ethical dilemmas of knowing the future risk of suffering from Alzheimer’s disease. Among the 274 healthy participants of the US investigation of 65 years or more, 40% refused to receive their personal risk estimates, despite having initially expressed interest in doing so.
These risk estimates were based on demographic data, brain images and blood biomarkers, which offers an 82 to 84% accuracy in the prediction of the probability of developing Alzheimer’s disease within five years. In comparison, age alone can predict this risk with 79% precision.
Therefore, the value of these tests is modest in people without any cognitive symptom, and there are potential risks when disseminating them. The people who are told that they have a higher risk of dementia describe how this can feel like a disease in itself, or be in limbo between health and disease, and cause anguish.
Participants who did not want to test the uncertainty of the result, the burden of knowledge and their negative experiences in witnessing Alzheimer’s disease in other people. Those with a family history of Alzheimer’s were less likely to want to know their results, perhaps due to greater exposure to these negative experiences.
Black participants were also less likely to want to know, what researchers suggest that it could relate to greater experiences of stress, stigma and discrimination, which makes the perspective of a positive result in the test feel more threatening.
Perhaps the question here is not why more people did not want to know the results, but if the researchers should offer them routinely, given the lack of certainty of the results and the potential of anguish.
Another problem is its limited usefulness for asymptomatic people. Addressing lifestyle risk factors, such as eating a healthy diet and exercising regularly, can reduce cognitive deterioration, a message that the public is increasingly aware. But knowing your risk does not change the advice.
Unlike areas such as breast cancer, where people at high risk of disease can be offered preventive measures, such as medications, surgery or improved detection tests, there are no comparable interventions to reduce the risk of dementia in people without symptoms.
The authors of the new study explain that researchers used to be cautious when sharing the results of the tests with the participants in the studies on Alzheimer’s. But now there is a growing expectation that people will receive their results. A “rights declaration” for participants in dementia research includes the right to obtain their results and to be explained clearly.
It is difficult to explain how uncertain these results can be. People often care about contracting in general, not only Alzheimer’s disease, which represents approximately two thirds of all cases. Some people who are told that they have a low risk of suffering from Alzheimer’s can develop another form of dementia, such as vascular dementia.
The widest science that produced these estimates of future risk has allowed the development of new unimaginable diagnostic technologies ten years ago. Similar blood analysis can detect the pathology of Alzheimer’s disease in people with cognitive symptoms with an accuracy of more than 90%, which could allow more precise and timely dementia diagnoses.
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Blood test
Two important research programs in the United Kingdom are testing these blood tests in the NHS to support the most precise diagnoses of some forms of dementia, including Alzheimer’s disease. Improved and early detection is necessary: a third of people with dementia in England and Northern Ireland are never diagnosed.
The benefits of the first drugs to delay the progression of Alzheimer’s disease are modest. In the United Kingdom, the National Institute for Health and Excellence is not yet convinced that these medications are worth the NHS.
Some might question the approach to identifying future dementia risks before having good treatments. But the development of better treatments depends on the new scientific discoveries that are helping us detect Alzheimer’s earlier. Finding a treatment for a disease requires a detailed understanding of how that disease develops.
We are closer to offering a precise detection of Alzheimer’s disease than of healing treatment. This presents a dilemma of how much to know about personal risk. Rights -based approaches place this dilemma in the participant, who decides whether or not, and instead of the investigators decide whether they tell it.
For researchers, disseminating the results in a compassionate and clear way is difficult and, for some, knowledge will cause anguish, however well it is transmitted. The option to receive results must come with warnings.
*Claudia Cooper is a psychological medicine professor at Queen Mary University in London
This article was originally published in The Conversation/Reuters
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