There are in the region of 55 million people living with dementia, in all its protean forms, across the world and that number is projected to rise three-fold by 2050 largely as a result of improvements in longevity.1
This global increase represents a significant challenge, not only for the individuals themselves, but also for families, social policy and national economies. Providing care in years to come is likely to be more difficult due to declining birth rates – there will be fewer young people to support the elderly both practically and economically.
How good quality, dignified care is to be provided in an affordable way remains a conundrum for which the UK has yet to find and implement a sustainable solution, despite the application of much thought, lobbying and effort on many fronts.2 Insurers have been inventive in attempting to provide solutions in this area despite often being hampered by a lack of clear strategies from the public sector.
One of the few pieces of good news about dementia in the early 2000s was that the incidence declined in many high-income countries, providing some offset against the increasingly ageing population.3
These findings were widespread, if not universal. Where demonstrated, they were impressive, with decreases ranging between 12% and 35% per decade. These changes were largely driven by improvements in cardiovascular risk management.
Most of this data came from a population series that ended in 2010, with subsequent predictions emerging from databases which could not guarantee consistent diagnostic practice and depended on dementia awareness to collect cases.
There are significant methodological problems in carrying out this work, born from the sheer practicality of managing large, long-term follow‑up studies that have the potential to introduced bias into the findings.
A recent exercise by Chen et al. (2023) sought to update our understanding of the temporal change of dementia incidence by using the tried and tested methodology of the English Longitudinal Study of Ageing (ELSA). The authors also looked to make predictions about the likely numbers of those experiencing dementia by 2040. They studied the successive waves of representative samples of adults aged over 50 between 2002 and 2019.4
The data revealed a decline in the rate of new cases of dementia between 2002 and 2010 (from 10.7 to 8.6 per 1,000 person years), replicating earlier findings. From 2010 onwards however the rate increased again, from 8.6 to 11.3 per 1,000 person years. It was of note that the decline was largest, and the subsequent rate of increase slowest, in people with the highest educational achievements.
Using the central estimate for this recent upward trend, the authors concluded that the number of people with dementia in England and Wales will increase to 1.7 million by 2040, approximately twice the number today. It was recognised that this finding might be due to chance, but it happened when the increase in life expectancy in the UK stalled, accompanied by a rapid rise in obesity – particularly in the most socially disadvantaged groups.5
This can perhaps be seen as a failure to communicate the message that around 40% of dementia cases are preventable by modifying 12 risk factors (Table 1).