Despite earlier projections of a doubling of dementia cases by 2050, more recent analyses suggest a more modest increase of around 25-30% globally, even as the overall number of cases will rise due to a larger and older population. This revised outlook is driven by a significant decline in the age-specific risk of developing dementia for successive birth cohorts. Researchers have observed that an 85-year-old today has only one-third the dementia risk compared to an 85-year-old in 1984, representing a two-thirds drop over 40 years. This hopeful trend is more pronounced in women, particularly in Europe and England.
Several factors are hypothesized to contribute to this reduction in risk. These include improved education, a decline in smoking rates, better medical treatments for conditions like heart disease, diabetes, and hearing loss, as well as increased physical activity and better management of high blood pressure and obesity. A 2024 Lancet commission identified 14 modifiable risk factors that, if addressed, could prevent or delay up to 45% of dementia cases, emphasizing the importance of midlife interventions (ages 18-65).
Additionally, some studies suggest a potential link between the shingles vaccine and a lower risk of dementia. Observational studies in Wales and Canada found that older adults who received the shingles vaccine were less likely to develop dementia. A 2025 analysis of the Welsh data even indicated that the vaccine might slow the disease's progression and reduce dementia-related deaths, although conclusive evidence from randomized trials is still needed. While the global number of people living with dementia is projected to increase to 78 million by 2030 and 139 million by 2050, especially in low- and middle-income countries, the individual risk reduction for younger generations offers a more optimistic future.
