Dementia has long been considered a disease of old age. 

In general, about one in 14 people develop Alzheimer’s disease, the most common form, by age 65. By 85, it strikes one in three. 

Most patients are still of retirement age or older, but doctors warn the disease is striking Americans younger than ever before. 

The incidence of dementia in individuals under 65 has increased significantly, more than doubling between 1990 and 2021. According to the latest studies, there is a more than 40 percent risk of developing dementia after the age of 55.

Less commonly known forms of the condition, such as frontotemporal dementia, which can affect people as young as 40, have also seen a rise in recent years.

During the world’s largest dementia conference in July, neurologists told the Daily Mail that they are observing an increasing number of younger patients struggling with basic tasks like keeping track of appointments or remembering the location of their belongings.

They said part of this surge in early-onset dementia could be due to young people getting tested earlier than their parents and grandparents, especially if they have a family history.  

However, they also sounded the alarm about chronic diseases and other lifestyle factors increasingly plaguing young people such as diabetes, obesity, depression and stress.

In one of the most tragic early-onset dementia cases, Robin Williams was found to have been suffering from Lewy body dementia after dying by suicide in 2014 at age 63. He is pictured here with actress Zelda Williams in 2009

Dr Adrian Owen, a professor of cognitive neuroscience and imaging at the University of Western Ontario in Canada and chief scientific officer at dementia detection company Creyos, told Daily Mail: ‘We’re seeing people younger, and we’re seeing people with different types of dementia.

‘In the last 15 or 20 years, we’ve sort of gone from the focus being squarely on Alzheimer’s disease, that’s all people used to talk about, to now broad recognition of frontotemporal dementia, vascular dementia, Lewy body dementia, many different types of dementia, and they present in sometimes subtly different ways.’

Dementia is an umbrella term used to describe a range of progressive neurological disorders that impact memory, thinking and behavior. 

Common symptoms include memory loss, poor judgment, confusion, repeating questions, difficulty communicating, taking longer to complete normal daily tasks, acting impulsively, and mobility issues. 

Alzheimer’s disease, which affects about 7million Americans, is the most common form, and it typically affects those over 65, with the risk increasing with age. But around 200,000 have early-onset Alzheimer’s, the latest research shows.  

Dr Joel Salinas, adjunct professor of neurology at NYU Langone in New York City and Chief Medical Officer of telehealth platform Isaac Health, told Daily Mail that while most people with dementia are diagnosed after age 65, the disease often strikes much earlier before patients realize.

He told this website: ‘We know that these conditions start to develop 10 or even 20 years before you even obviously notice symptoms, and these symptoms are present in a continuum where the earliest symptoms may be really subtle.

‘We want to get better at detecting things where they’re in that subtle range.’ 

Both doctors told Daily Mail that younger patients who come into their clinics are less likely to come in with stereotypical signs like wandering or forgetting who their loved ones are. 

Wendy Williams was diagnosed in 2023 frontotemporal dementia and aphasia at age 59

Dr Salinas said: ‘Anxiety can give an early presentation. Social isolation can be an early presentation. 

‘I think we’re still figuring out whether those symptoms are either tied to having cognitive deficits that are suddenly getting worse, like having difficulty remembering so I’m getting anxious about it, or they’re manifestations of the disease in the brain itself.’

Younger patients may also notice trouble staying organized at work or around the house, which shows a decline in working memory. Obsessive behaviors are also common

Dr Salinas also pointed to the example of a writer having trouble coming up with a typical word they would use in a piece and that difficulty worsening over time. 

He said: ‘If I have a harder time reaching those words, and that’s getting worse over time, that actually would be a red flag, kind of like forgetting keys, or walking to a room and not remembering why I walked into the room.

‘But the key is actually to see are these changes that are persistent and getting worse slowly over time over like six months to a year or two years. Then I would consider that as something that really is a red flag that should be addressed.’

While much is unknown about why dementia is increasingly affecting younger Americans, lifestyle factors likely play a significant role. 

Last year, a Lancet Commission study found about 40 percent of Alzheimer’s cases could be tied to 14 modifiable risk factors, including high cholesterol, diabetes, obesity and depression. 

And a study unveiled at the Alzheimer’s Association International Conference (AAIC) in July of 2,000 Americans at risk of dementia found that strict diet and exercise regimens helped them perform significantly better at cognitive tests.

Many of these risk factors are on the rise across America, including in young people. CDC data shows the prevalence of obesity, for example, has doubled in adults from 1990 to 2021, and 40 percent of adults are now considered obese. 

The above chart shows changes in cognitive scores over time among people who implemented structured changes and those who implemented self-guided ones in the US POINTER study

Diabetes prevalence has also increased from about 10 percent in 2000 to 14 percent in 2023, and prevalence among people under 44 has increased about 20 percent in 2024 compared to 2017. 

These conditions trigger inflammation throughout the body, including in the brain, that damages cells and promotes the accumulation of toxic proteins that kill brain cells. 

Dr Owen said: ‘I think in the past, dementia was always a really mysterious illness that seemed to just hit some people randomly and not other people.

‘Now you’re seeing more people with cognitive changes and potentially dementia at a younger age. It’s almost a byproduct of the fact that younger people are developing diabetes, younger people are getting obese, younger people have anxiety and depression. There are increased levels of mental health challenges that tend to affect young people.’

Mental health is another key factor, he emphasized. 

CDC data shows the percentage of adults with anxiety symptoms has increased from 16 percent in 2019 to 18 percent in 2022. Meanwhile, depression is up from 10.5 percent in 2015 to about 18 percent in 2025.

Dr Owen said: ‘There are many other factors in today’s world that young people are that are contributing to this sort of cognitive mental health crisis is probably better than epidemic, but I think one of them is anxiety and stress.

‘No question, young people are more stress.

‘People are worried about their futures. They’re worried about their employment. They’re worried about their health earlier on. We know stress has detrimental effect on brain functions.’

Dr Salinas also noted that while lifestyle factors and mental health are at play, he has seen more patients get evaluated for dementia as a precaution.

He said: ‘I would say we are seeing more and more people who are coming to get evaluated at a younger age, partly because I think [there are] cultural changes around the importance of addressing these issues early.’

Dr Owen urged younger Americans who notice issues like trouble focusing, personality changes, issues remembering words and other subtle signs to seek medical care, as early intervention opens the doors for more effective treatments and getting into clinical trials.

He told this website: ‘Early detection is so crucially important. The earlier you get in, the more effective it’s going to be.’