Diabetes, stroke, colon cancer, dementia: These are just some of the diseases associated with old age, so why are these conditions appearing decades earlier than they used to? An alarming trend of young people developing what most consider "old people" diseases is causing concern across the medical field.
‘Old People’ Diseases Now Prevalent in Youth
Growing old used to be the biggest risk factor for developing diseases like colon cancer, stroke, fatty liver disease, dementia, and Type 2 diabetes. Colorectal cancer is now one of the leading cancer killers of adults under 50, strokes are increasing among younger populations, and researchers are documenting rises in everything from fatty liver disease to appendix cancer among Millennials and Generation X.
Colon Cancer
The Cancer Research Institute reported that “1 in 5 diagnoses [of colon cancer] occurs in someone under the age of 55 – and it has become a leading cause of cancer-related death in young people.”
The American Cancer Society estimated there will be 158,850 new cases of colorectal cancer this year, and 55,230 people in the US will die from it. This disease is rising 3% per year in those 30 to 49 years old and 0.4% in those aged 50 to 64. Additionally, “Nearly half (45%) of new colorectal cancer cases are now occurring in adults under 65, up from 27% in 1995, signaling a major shift toward younger generations.”
While there are no known proven reasons for this shift to younger generations, doctors speculate it has to do with the modern lifestyle of eating fatty and processed foods and a sedentary lifestyle.
Appendiceal Cancer
Appendiceal or appendix cancer is – or, rather, it was – rare. But now it’s suddenly showing up in millennials. A study published in the Annals of Internal Medicine revealed that this disease tripled for Americans born between 1976 and 1984 and quadrupled for those born between 1981 and 1989.
Although this type of cancer is uncommon, with about 3,000 new cases diagnosed each year in the US, there is a growing concern about what the trend of younger people getting it means. “As incidence rates in younger generations are often indicative of future disease burden, these results support the need for histology-specific investigations of appendiceal adenocarcinoma, as well as increased education and awareness of appendiceal adenocarcinomas among health care providers and the public,” the study stated.
Young Onset Dementia
Most people think of dementia as something that affects seniors, but researchers have increasingly focused on young-onset dementia occurring before age 65. A study published in Nature found that young-onset dementia rose a whopping 210% worldwide between 1990 and 2021, from around 1.8 million people in 1990 to 3.8 million in 2021.
A 2024 study by the University of Eastern Finland, the University of Oulu, and Neurocenter Finland, published in Science Daily, estimates that around 370,000 people in Europe are living with young-onset dementia, affecting about 119 out of every 100,000 adults.
High Blood Pressure, Cholesterol, and Blood Sugar
High blood pressure and cholesterol levels are usually associated with older people’s diseases, but these, too, are rising in younger adults and kids. Metabolic syndrome is a condition where there’s a cluster of obesity, high blood pressure, abnormal cholesterol, and high blood sugar. It used to be considered an issue for middle age and beyond, but now researchers are viewing this syndrome as a young adult health crisis that is also linked to dementia risk later in life.
About 1 in 3 American adults have metabolic syndrome, according to the National Heart, Blood, and Lung Institute. “Metabolic syndrome involves having at least 3 out of 5 health conditions that increase your risk of cardiovascular disease, stroke, and Type 2 diabetes,” the Cleveland Clinic explained.
Nearly one in four adults ages 18–39 already has hypertension, one of the diseases associated with Metabolic syndrome, according to the American Heart Association. Obesity is another factor, and as the CDC pointed out, over 40% of US adults are obese.
Strokes
Strokes are another one of those diseases associated with older people. However, at the International Stroke Conference 2026, Emily R. Fisher, MD, a medical resident and Neurology and Rehabilitation fellow at the University of Cincinnati College of Medicine, said strokes among adults between 30 and 54 years old nearly doubled between 1993 and 2020, while rates for strokes in older adults declined. The CDC found a 14.6% increase in strokes among people ages 18–44 from 2020 to 2022. The National Library of Medicine explained that approximately 10-15% of all strokes occur in adults aged 18 to 50 years.
Why Are Younger Generations Getting Sick Earlier in Life?
Across the board for each of these diseases, medical experts list the same reasons for why younger generations are getting illnesses that used to be reserved for the elderly. The answer is simple: lifestyle. In today’s technological world, where everything is within a fingertip’s touch away, people are becoming more sedentary. They don’t have to walk five miles uphill each way to the store or go out and garden for their vegetables. The foods available today are filled with unhealthy fats and preservatives. Ultra-processed foods are also a contributing factor.
One of the biggest causes is obesity. So many adults are overweight, adding to their risk of various diseases. Other lifestyle choices influence health as well, such as smoking and drinking. Taking all of these into consideration, experts speculate that old people’s diseases will continue to affect younger adults in future generations if the trend continues.
The idea that diseases like dementia, stroke, colon cancer, and metabolic disorders are showing up in younger adults would have sounded unbelievable just a few decades ago. Yet researchers are increasingly warning that modern lifestyles may be accelerating the body’s wear and tear far earlier than previous generations experienced. While medical advances continue to improve treatment options, the growing rise of these old people's diseases in younger populations raises a troubling question: If people are getting sick earlier in life, what will health in America look like another 20 or 30 years from now?
