• Cameron M. Clark

Dementia in Decline

Updated: Jan 21

With the end of a year like 2020, we could all use some good news to start 2021 off right. Well, how about new scientific evidence that the incidence of dementia (that is, the number of new cases) is falling over time - at least in developed parts of the world. Stated differently, proportionately fewer people are being diagnosed with dementia today, compared to decades past. Stated differently again, your risk of developing dementia is lower than those born in the decades before you.


This is fantastic news, as dementia is a leading cause of dependence and disability worldwide - with an estimated 47 million people living with the disease currently, and another 100 million expected to develop it within the next 30 years. And of course even for those that do not develop dementia, worry and anxiety about the mere risk is significant. An estimated 50% of older adults report memory complaints of some kind, often causing decreased confidence in memory ability, and undue anxiety about declining cognition. Would you count yourself among those worried about cognitive decline and dementia?


Now to the science. Wolters and colleagues examined data from seven large cohort studies representing nearly 50,000 participants from six different countries across the last 25 years. What they found was rather surprising - a 13% reduction in dementia incidence per decade(!). The implications here are hard to overstate. This means that up to 15 million fewer people (in developed countries) may develop dementia by 2040 than previously thought, and up to 60 million fewer cases worldwide if the trend observed in the study holds for lower income populations.


Again, this is fantastic news, but it leads to the curious question of why dementia rates have been falling over the last several decades. The answer is instructive. Wolters and colleagues note: "...there have been many concurrent changes over time in possible key risk factors, including lifestyle education and health interventions such as blood pressure control and antithrombotic medication [drugs that reduces the formation of blood clots]". They continue: "while none of these have been specifically intended to halt cognitive decline, decades of cardiovascular risk management have likely had substantial effects on brain health, supported by reduction of small-vessel disease on brain imaging in more recent years".


There are two take home messages here - one about society at large, and one about you individually: 1) The risk of dementia is declining over time in the population; and 2) the choices you make about how you live your life (i.e. diet, exercise, sleep, stress, management of medical conditions etc.) have important implications for your brain health and cognitive functioning as you age. For more information on how lifestyle choices impact cognitive health, see this past newsletter: Our Future is Something we Make: Lifestyle Factors and Dementia Risk.


Finally, new for 2021 I'm going to end each newsletter with a question for you to think about (and maybe pose to others in your life to start a great conversation). This week's sharp question is:


If you met someone exactly like yourself - same resources, same experiences, same medical history, same current problems - what would you suggest they change about their lifestyle choices? And, how would you suggest they try to do it?


References:

Wolters, F. J., Chibnik, L. B., Waziry, R., Anderson, R., Berr, C., Beiser, A., … Hofman, A. (2020). Twenty-seven-year time trends in dementia incidence in Europe and the United States. Neurology, 95, e519–e531. https://doi.org/10.1212/WNL.0000000000010022

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