Alzheimer’s: How good is genetic analysis at home?

Es gibt bei solchen Gentests keine adäquate ärztliche Begleitung und Aufklärung des Patienten. Schon bevor man einen solchen Test durchführen lässt, sollte man wissen, was dabei herauskommen kann und was dieses Wissen für die eigene Zukunft bedeutet. Vielleicht überlegt man es sich danach noch einmal anders. Denn die Ergebnisse geben Wahrscheinlichkeiten an, beispielsweise ein 50-prozentig höheres Risiko, an einer Alzheimer-Demenz zu erkranken. Die wenigsten Patienten können einschätzen, was das bedeutet, sie werden aber mit ihrem Testergebnis alleingelassen. In Deutschland sind Gentests daher nur im Rahmen einer ärztlichen Behandlung und nur nach einer entsprechenden Beratung zulässig.

Which genes are examined in the tests?

Consumer genetic tests examine both classic hereditary diseases and risk genes. In classic hereditary diseases, mutations in certain genes lead to the disease with a very high probability (100 percent). Often, it is even possible to predict the onset of the disease. In Alzheimer’s disease, three genes can be affected. But these mutations are very rare; the disease begins between the ages of 40 and 45, and the disease is usually known in the family. The so-called risk genes are more relevant. In Alzheimer’s, this is essentially the gene for “apolipoprotein E”, or ApoE for short. Three variants of the ApoE gene are known. The most common form represents an average risk of Alzheimer’s, one of the two rarer variants represents a reduced risk, and the other, Epsilon 4, represents an increased risk. If you have one copy of the ApoE4 gene variant, you will develop the disease on average five years earlier; if you have two copies, one from your father and one from your mother, you will develop the disease ten years earlier.

What benefit do patients get from such a genetic test?

First of all, there is no direct one, because there are no preventive treatments. There is not much you can do about an increased risk, unless you make long-term lifestyle changes, such as doing more exercise, avoiding alcohol and cigarettes, keeping your blood pressure stable, paying attention to blood sugar and fat levels, and eating healthily. But these measures must begin in middle age.

Can Alzheimer’s really be prevented with a healthy lifestyle?

The onset of the disease can be delayed and, in the best case, prevented. A few weeks ago, the comprehensive “Lancet” report was published, according to which 45 percent of dementia cases could be prevented. This figure has been criticized because risk factors were simply added together and some factors interact with each other. Not all risk factors can be prevented, but they can be reduced. The figure is therefore certainly too high. But anyone who pays attention to and maintains a healthy lifestyle in middle age, i.e. around 45 to 50 years, has gained a lot. This is also the age at which the amyloid deposits that trigger Alzheimer’s disease begin to form. If you only start paying attention to the risk factors at the age of 70, it is too late.

If it now becomes apparent that prevention should be given greater importance in brain health, wouldn’t genetic tests that estimate the individual risk of disease make sense?

This is a difficult question that everyone should decide for themselves. It leads to the question of whether one should only live a healthy life if one has “bad” genes.