Humans are puzzled together from wearing parts. Over the years, the body wears out, bones become brittle, and the brain deteriorates. The older we get, the more likely it is that forgetting will set in at some point. In Germany alone, around 1.8 million people are currently suffering from dementia. It is not curable. However, each individual can influence the likelihood of developing dementia to some extent, or at least slow down its progression. Studies show that prevention is possible.

“We now know that preventative measures, taking risk factors into account, can have a positive effect on the progression of the disease and reduce the individual risk of dementia,” says the head of the Cologne Alzheimer’s Prevention Center, Frank Jessen. “It is thought that a healthy, active lifestyle accounts for up to 40 percent of the risk of developing dementia or not.”

In 2020, an international research group (The Lancet Commission on Dementia and Prevention) listed twelve risk factors that increase the risk of Alzheimer’s disease. In early life, this includes poor education. In middle age, hearing loss, high blood pressure, traumatic brain injuries, harmful alcohol consumption and obesity are associated with a higher risk. In older age, smoking, depression, social isolation, physical inactivity, diabetes and air pollution increase the likelihood.

The list is based on epidemiological data. As an instruction manual for the individual, it is only of limited use, says prevention researcher Jochen René Thyrian from the German Center for Neurodegenerative Diseases (DZNE) in Greifswald. On the one hand, not all factors can be influenced – an accident with a head injury cannot be corrected afterwards. On the other hand, it is not always clear how the connection comes about: social withdrawal, for example, could be a consequence of dementia as well as contribute to its development.

“But there are also factors that are clearly and unequivocally proven – and they can be influenced,” says Thyrian. These include, above all, a healthy diet, exercise, not being overweight and not smoking. What certainly has a positive effect is cognitive stimulation. These could be crossword puzzles or Sudokus, but this means any form of “cultural interaction” from reading to watching television to conversations.

“What is increasingly coming into focus in Alzheimer’s prevention is the topic of social activity,” says Thyrian. The Corona pandemic has provided evidence of this: Due to the strict Corona rules in old people’s homes, the dementia of many residents has worsened: “The lack of social activities and emotional contacts has led to a serious deterioration in cognitive performance and health.”

The Cologne expert Jessen highlights three factors that are particularly important – and explains the connection. One thing is good hearing. “The brain needs input,” says the psychiatrist. Those who have difficulty hearing receive less input and have a higher risk of Alzheimer’s disease. It should be just as natural to buy glasses when you have poor eyesight, so it should be a hearing aid.

A second point is good sleep. A chronic sleep disorder increases the risk of dementia, says Jessen. Cleansing processes take place in the brain during sleep. This would also break down amyloid plaques, which are involved in the development of Alzheimer’s dementia.

When it comes to head injuries, Jessen explains that it’s not just serious injuries like those in a car accident, but also common and minor injuries like those that occur in some sports. “Professional footballers who train a lot of headers, but also boxers, have an increased risk of dementia,” says Jessen.

Avoiding risk factors can protect against dementia – but it’s all about statistical probabilities, says Thyrian. The concrete consequences for an individual are a different matter, “humans are too complex for that.” “There are hardly any studies that depict this complex event in such a way that one can get clear evidence.”

In addition, the individual risk of illness is influenced by many factors. Only rare forms of dementia, such as familial Alzheimer’s disease, are inherited genetically. “In other dementias, genetics is rarely the sole trigger, although it can occur in close relatives,” explains Thyrian. However, the reason for this is not that family members have similar genetic predispositions. Rather, they shared a social background, such as similar lifestyles.

From an epidemiological point of view, many cases of Alzheimer’s and other forms of dementia could actually be prevented by avoiding the risk factors. This is suggested by the so-called Finger Study from Finland, in which a group of old people received nutritional and health advice as well as physical and mental training for two years. In contrast to the control group, the researchers saw “small but significant positive effects.”

Ten years after the finger study, the Agewell study wants to examine the results in Germany. “The study is explicitly designed so that, if successful, recommendations are made for implementation in the regular care landscape,” write the initiators led by Steffi Riedel-Heller from the University of Leipzig. 1,152 older people with an increased risk of dementia were recruited in Leipzig, Greifswald, Munich and Kiel. Results are expected later this year.

According to estimates by the World Health Organization (WHO), around 1.8 million people over the age of 65 were suffering from dementia in Germany in 2021. How much this number increases also depends on how the risk factors develop in the population. DZNE researcher Iris Blotenberg and colleagues calculated this. “Our calculations show a prevention potential of 38 percent,” they wrote in the “Deutsches Ärzteblatt International”. “That means, assuming a causal relationship, more than one in three cases of dementia can be traced back to the risk factors under consideration.”

According to the model calculation, if it were possible to reduce the risk factors that can be influenced by 15 percent, around 138,000 of the expected two million cases of illness in 2033 could theoretically be delayed or avoided. At 30 percent there would even be 265,000 cases. “These figures make it clear that greater efforts to prevent dementia can be worthwhile,” it says.

While general advice like “Live healthy!” Often fizzled out in earlier phases of life, some people try to counteract the first symptoms of dementia with “brain jogging” and hours of Sudoku solving. In principle that is correct, says Jessen.

Prophylaxis becomes relevant in the phase when the first symptoms appear: slight memory problems, initial uncertainties with orientation, difficulties with complex tasks – while independence is not yet impaired. “Cognitive activation is particularly important after leaving work,” says the prophylaxis expert.