Dementia, vaccines and gene editing. The good news that doesn’t make the headlines

There is a category of news stories you are unlikely to find at the start of a television news programme: disasters that never happened, diseases that affect fewer people, lives saved without anyone being able to put a name and a face to each one. Science often improves the world in precisely this way: without spectacular images, without a specific moment in which to declare victory, through a succession of small advances that only become visible when someone stops to take stock.

The case of dementia is extraordinary. For decades, we have regarded the ageing of societies as the prelude to an uncontrollable epidemic of Alzheimer’s and other cognitive disorders. Yet the data tell a different story. Forty years ago, in the United States, around three in ten people aged between 85 and 89 suffered from dementia. By 2024, this had fallen to one in ten. Across six European and North American countries, the incidence has fallen by an average of 13 per cent every decade; the Framingham Heart Study recorded a decline in new cases of nearly 20 per cent per decade. This does not mean that dementia has been defeated. We are living longer and the number of older people is increasing, so the overall number of people with the condition may continue to rise. It does mean, however, that, for people of the same age, the risk today is much lower than it was for previous generations. The most encouraging finding concerns the causes. The reduction does not appear to be down to a miracle drug, but to many seemingly ordinary improvements: higher levels of education, less smoking, better control of blood pressure, cholesterol and diabetes, fewer strokes, physical activity, hearing care and a more active social life. Dementia is not merely a misfortune that befalls old age at random: it is often the culmination of a process that began decades earlier and which individuals and public policy can influence. The Lancet Commission estimates that up to 45 per cent of cases could be delayed or prevented by addressing fourteen modifiable risk factors. Treating hearing loss and high cholesterol – two common but often overlooked problems – could, on its own, reduce the overall number of cases by 14 per cent. Even those carrying the ApoE4 genetic variant, which is associated with a much higher risk of Alzheimer’s, appear to derive particularly significant benefits from lifestyle interventions. In short, genes influence our destiny without necessarily determining it.

Then there is a surprising discovery: the herpes zoster vaccine. A natural experiment in Wales has shown that vaccination reduced the risk of developing dementia by around 20 per cent over the following seven years. Studies in Australia and Canada have produced similar results, and new research suggests that the vaccine may also slow the progression of an existing condition. This is not yet definitive proof of a cure, but it is the sort of clue that opens up a completely new avenue: preventing an infection could also protect the brain. The same cautious optimism applies to other areas. Malaria vaccines are now part of paediatric programmes in 25 African countries and aim to reach over ten million children each year. In the first countries to adopt them – Ghana, Kenya and Malawi – a four-year evaluation estimated that approximately one in every eight child deaths was prevented among children who received the vaccination.

Malaria remains a tragedy: in 2024, it caused around 610,000 deaths. However, new vaccines, insecticide-treated bed nets and preventive treatments helped to prevent 170 million cases and one million deaths in the same year. Forty-seven countries and one territory are now certified as malaria-free. This progress has not eliminated the problem; it has shown that eliminating it is no longer a pipe dream. Meanwhile, gene editing is ceasing to be a science-fiction promise. In a 2026 study on sickle cell anaemia, an inherited condition that causes excruciating crises and organ damage, 27 out of 28 patients experienced no further vaso-occlusive episodes following treatment. Another technique, base editing, modifies specific letters in DNA with greater precision and has produced equally encouraging initial results. These therapies are not yet simple, cheap or risk-free, but they demonstrate that certain genetic diseases can be corrected at their root rather than merely managed. In 2025, the US Food and Drug Administration authorised 46 entirely new medicines; between 2025 and 2026, the first gene and cell therapies became available for certain rare and extremely serious diseases, ranging from Wiskott-Aldrich syndrome to severe LAD-I immunodeficiency. These are conditions that affect very few people and, for that very reason, rarely make the news. For those families, however, the difference between ‘incurable’ and ‘there is a treatment’ amounts to a complete transformation of their world. Scientific optimism does not mean denying failures. New drugs for Alzheimer’s currently offer only modest benefits and can cause serious side effects. Gene therapies are expensive, complex and accessible to only a few. Malaria continues to kill hundreds of thousands of people. But pessimism makes the opposite mistake: it portrays every tragedy as if the world were standing still. Genuine progress rarely proclaims: ‘As of today, the problem is solved.’ Rather, it says: today, one in ten people fall ill, whereas yesterday it was three; today, a vaccine prevents some of the deaths; today, twenty-seven patients have not had a seizure; today, for the first time, a very rare disease has a cure. These are less sensational stories than emergencies. But it is these that, taken together, truly change the world.