A large study has confirmed the significant role of prevention in dementia-related diseases, demonstrating that millions of cases could be avoided by addressing influential factors such as smoking and pollution. However, it is noted that prevention is not beneficial in many cases. The study, published on Wednesday in the journal "The Lancet," states that "the potential for dementia prevention is substantial." This study compiles the latest knowledge on the subject to serve as a reference, following a previous report published in 2020 that emphasized the importance of prevention.
Researchers highlighted at that time that 40% of dementia cases were associated with about 12 diverse risk factors, including low education levels, hearing problems, smoking, obesity, air pollution, depression, isolation, head trauma, and high blood pressure. In light of the latest research, two new risk factors have been added: vision loss and high cholesterol levels. The study's authors confirmed the possibility of preventing almost half of dementia cases by being mindful of the fourteen risk factors.
This focus on prevention comes at a time when there is still no effective drug treatment for dementia, despite decades of research on the matter. Since last year, two Alzheimer’s drugs have been approved in the United States: "Lecanemab" from Biogen and "Donanemab" from Eli Lilly. These medications combat the formation of amyloid plaques in the brain, which are considered one of the main mechanisms of the disease. However, their effects remain modest compared to their high costs and dangerous side effects. Unlike U.S. health authorities, the European Union last week refused to allow the sale of "Lecanemab," while regulatory processes related to "Donanemab" are still pending.
While some researchers hope that "Lecanemab" and "Donanemab" will pave the way for more effective treatments, others prefer to focus on prevention rather than waiting for treatments. Neurologist Massoud Hussein explained in an interview with the Science Media Centre in the UK that combating risk factors "might be much more rewarding than developing topical treatments that, at this stage, prove to be disappointing." Neurologists, who often do not discuss prevention extensively, received the study published in "The Lancet" positively, with some calling for consideration of the possibility of addressing half of dementia cases through early measures.
Some methodological points raise caution. Initially, the study's authors themselves acknowledge that it cannot be definitively stated that these risk factors directly cause dementia, questioning "Could dementia, for example, cause depression?" It is also difficult to separate certain factors from others, even though the authors attempted to incorporate this idea into their calculations. For instance, there is a reciprocal relationship between depression and isolation, or between tobacco use and high blood pressure.
The study also addressed the integration of individual recommendations, such as wearing a helmet while biking, and collective ones, such as broader access to education. Additionally, some researchers warn—without dismissing the study published in "The Lancet"—about the potential misinterpretation of results that may lead some patients to feel guilty, believing they are responsible for their dementia.
It is noteworthy that tens of millions of people worldwide suffer from dementia, with Alzheimer's being the most common and widespread type, generally causing a permanent decline in patients' memory and ability to speak.
