Some Good News! Dementia is trending down.

We'll take it.

If it feels like a tsunami of bad news right now, I’m here to cheer you up with one trend that is moving in a positive direction.

KC Green Comic

TL;DR

While the total number of people with dementia is increasing because the population is getting older, the age-specific rate of dementia has decreased substantially.

Of all the potential health insults that come with aging, dementia is one that many of us fear the most. Alzheimer’s and other forms of dementia rob us of our memories and our ability to reason—the very essence of who we are.

With some family history of Alzheimer’s, in my twenties I was hopeful that we’d have a cure long before I had to worry. But while we have learned a lot (thanks in large part to NIH funding) about the proteins, plaques, and tangles in the brain that lead to dementia, we don’t yet have a treatment breakthrough.

While at age 50 I am ever hopeful about the future of scientific discoveries, I am comforted by the fact that dementia rates have declined steeply over the last decades even without effective treatment.

It could just be me, but I feel like this happy fact has flown a bit under the radar. We are often warned of the tsunami of dementia patients coming with an aging population (all those Baby Boomers). It’s true that an aging population will bring higher numbers of dementia cases, along with the emotional and financial toll for families. One study estimated the number of US adults living with dementia will rise from 5 million in 2019 to 10 million in 2050.

But within each cohort (people born around the same time), the percentage of people getting dementia is getting lower over time.

You can see this in the figure below. Back in 1984, around 30% of 85-89 year-olds in the US had dementia. By 2024, this has dropped to around 10% (Panel A). Age is still the strongest risk factor for dementia, so the rates increase steeply with age in each period. But the lines shift downward over time, so that the risk of having dementia at ages 80-84 in 2024 is more similar to the rate in 70–74-year-olds forty years ago.

Source: Stallard PJE, Ukraintseva SV, Doraiswamy PM. Changing Story of the Dementia Epidemic. JAMA, 2025.

Panel B shows this same data for birth cohorts, with the triangles representing people born in certain years but measured at different ages. This is another way of telling the same story—people born more recently have significantly lower rates of dementia at similar ages compared to people born longer ago.

These data are from the US, but similar trends have also been seen in European countries.

But why do we think dementia rates have declined so much, with no effective treatments? There are a lot of hypotheses, and with population trends over time, it’s hard to pinpoint cause and effect with certainty. But a few mechanisms are considered strong contenders:

• Increases in education: People with more education, on average, have a lower risk of dementia. While not going past primary school used to be the norm, access to higher education expanded dramatically for the cohorts now reaching older age. Besides having indirect effects on cognition through higher income and better living conditions, education rewires the brain with more neural connections. This “cognitive reserve” may provide a buffer against dementia allowing better cognitive functioning even at similar levels of damage in the brain (see figure below).

Theoretical Depiction of Cognitive Reserve: Source

• Better cardiovascular health: There’s a strong link between heart health and brain health. Improvements in managing blood pressure, cholesterol, and smoking cessation reduce vascular risks for dementia. Rates of cardiovascular disease have declined sharply over the last few decades, which may be paying dividends with lower rates of dementia.

• Better early life conditions: Compared to the early 1900s, improvements in nutrition, sanitation, maternal health, and infectious diseases (thank you vaccines!) may continue to show long-term benefits for brain health for those children born long ago but reaching older ages now.

Will this good news continue?

The news can’t be all good. There are a few concerning signs on the horizon:

“Generational Drift”: You may have heard that Americans in mid-life have seen increased mortality and worsening health compared to older born cohorts at the same age. This is from both drug deaths and increases in deaths from cardiovascular disease, possibly related to the obesity epidemic. Hints of these health reversals are cropping up in other countries including the UK. (I could write A LOT about this topic since it is my research bread and butter, so stay tuned). This “drifting” backwards in health may be showing up in cognitive health as well- a recent study found a significant slowing of improvements in the US compared to other countries.

The impact of COVID: COVID has been associated with brain fog and other cognitive symptoms. The social isolation of the pandemic likely also contributed to cognitive decline in older people. One study found that the incidence (new diagnoses) of dementia accelerated in 2020, bucking the trend of secular decline shown above. But this was followed by accelerating declines in dementia incidence in 2021. It will likely take more time to see whether COVID-19 has a long-term impact on dementia trends.

Social inequalities: Dementia is not an equal opportunity affliction. Besides the associations with educational attainment mentioned above, Black Americans have significantly higher rates of dementia, for reasons we don’t fully understand.

MacKenzie Isaac

recently brought home the sorrow of this reality in her beautiful story about her losing three of her grandparents to dementia. This is a reminder that even amid positive overall trends, there is still lots of work to do.

But let’s end with the GOOD NEWS:

The chances of being diagnosed with dementia at each age have declined dramatically over the last forty years. So even with a growing number of older people, that tsunami (or “tsoo-naw-mee!” as Victoria Ratliff from the White Lotus would say) will be a lot smaller than it could have been.

Stay well-

Jenn