The incidence of dementia has declined by 13% every 10 years for the past 25 years. A conclusion that calls for further studies to better understand this phenomenon.
Despite the lack of treatments and preventive strategies, Europeans and North Americans are suffering less and less from dementia, according to a scientific study published Monday in the American scientific journal Neurology. This publication, endorsed by the scientific reading committee, followed for 25 years the incidence of this disease according to age and sex for 25 years on a cohort of 49 2020 individuals living in the United States, France, the United Kingdom. United, the Netherlands, Sweden and Iceland.
They conclude that a person’s risk of developing this disease has declined by 13% every 10 years over the past 25 years. “In 1995, a 75-year-old man had a 25% chance of developing dementia in his remaining time. Now the same man’s risk is 18%,” Dr. Albert Hofman, chairman of the epidemiology department at Harvard University’s school of public health and a senior editor of the study, told The New York Times.
A decline which can be observed among all age groups but which has experienced large disparities in incidence between generations. Thus, this study estimates that today 4 people in 1000 would develop dementia between 65 and 69 years, against 65 for 85 to 89 years. However, even if the decline in risk is more marked in men than in women, the risk of developing this decline in the brain is also important for both sexes. A result which may surprise at first glance but which can be explained by the large proportion of women among the elderly.
Scientists are still wondering about the reasons for the phenomenon. “We need to identify the critical factors among a variety of actors such as blood pressure, cholesterol, and inflammation that may have contributed to this decline,” suggests the report. Improving access and educational services is another major change of the last century and may explain the decrease in the incidence rate over time.”
Despite this good news, the number of people with dementia is expected to increase further in the next few years, or even double within 30 years in Europe, according to the World Health Organization. Main reason: the aging of the population. Another indication in this direction, the study worries that the incidence of dementia is stable or increasing in Japan, China and Nigeria. The authors of the study call for the need for further studies, especially on non-European populations, which “do not represent more than 16% of the world population” they write.