Roughly 55 to 57 million people worldwide are living with dementia, and Alzheimer’s disease accounts for 60 to 70 percent of those cases. That puts the global Alzheimer’s count somewhere around 33 to 40 million people. In the United States alone, an estimated 7.4 million Americans age 65 and older have Alzheimer’s, and that number is climbing fast as the population ages.
How Risk Increases With Age
Alzheimer’s is not an inevitable part of aging, but age is by far the strongest risk factor. The numbers shift dramatically with each decade of life: about 5 percent of people aged 65 to 74 have Alzheimer’s, 13.1 percent of those aged 75 to 84, and a full third of people 85 and older. That steep curve explains why population aging is the single biggest driver of rising case counts around the world.
Most people picture Alzheimer’s as a disease of the elderly, but it can strike earlier. Globally, an estimated 13 million people under age 70 are living with dementia, a number that has more than doubled since 1990. These younger-onset cases are rarer, harder to recognize, and often misdiagnosed as depression, stress, or burnout before the correct diagnosis is made.
Who Is Most Affected
Women make up a disproportionate share of Alzheimer’s cases. Part of that gap is straightforward: women live longer on average, so more of them reach the ages where risk is highest. But longevity alone doesn’t fully explain the difference, and researchers continue to investigate biological and hormonal factors that may contribute.
Race and ethnicity also play a significant role. Black Americans are roughly twice as likely as white Americans to develop Alzheimer’s, and Hispanic Americans are about 1.5 times as likely. These disparities reflect a tangle of factors, including higher rates of cardiovascular disease, less access to preventive healthcare, and socioeconomic conditions that affect brain health over a lifetime.
Most Cases Go Undiagnosed
The numbers above are estimates, and the real totals are almost certainly higher. An estimated 75 percent of people with dementia worldwide have never been formally diagnosed. That means roughly 41 million people are living with the disease without knowing it or without access to care. In low- and middle-income countries, the undiagnosed rate reaches as high as 90 percent.
Even in wealthier countries, diagnosis rates hover around 25 percent. Early symptoms like forgetting recent conversations, losing track of dates, or struggling to follow a recipe are easy to dismiss as normal aging. Many people don’t seek evaluation until the disease has progressed to a moderate stage, which narrows the window for treatments that work best early on.
Alzheimer’s as a Cause of Death
Alzheimer’s is the sixth leading cause of death in the United States, responsible for over 116,000 deaths per year. Unlike heart disease or cancer, there is no treatment that stops or reverses its progression. Death typically results from complications like pneumonia, infections, or falls that become increasingly dangerous as the brain loses its ability to coordinate basic body functions.
Because death certificates often list those complications rather than Alzheimer’s itself, the true death toll is likely undercounted. Many experts believe the disease’s actual impact on mortality is significantly higher than official statistics reflect.
Where the Numbers Are Headed
Global dementia cases are projected to nearly triple, reaching an estimated 153 million people by 2050. Population growth and longer lifespans in developing countries are the primary drivers. In the United States, the aging of the baby boomer generation is already accelerating case counts, and the trend will continue for decades.
These projections assume current prevention and treatment trends hold steady. Reducing risk factors like high blood pressure, physical inactivity, hearing loss, social isolation, and smoking could slow the rise. A 2020 Lancet Commission estimated that up to 40 percent of dementia cases worldwide are linked to modifiable risk factors, meaning lifestyle and public health interventions have real potential to bend the curve, even without a breakthrough drug.