A new study from Columbia University suggests that signs of Alzheimer’s disease may begin affecting the brain much earlier in life than previously thought—even as early as age 24.
Researchers found that several known risk factors and blood-based biomarkers linked to Alzheimer’s are already connected to how well people think and remember, even in their 20s and 30s.
The study, led by Dr. Allison Aiello from the Columbia Mailman School of Public Health and the Butler Aging Center, is the first to examine Alzheimer’s risk in a large group of mostly healthy younger and middle-aged adults in the United States. The results were published in The Lancet Regional Health – Americas.
Past research focused mainly on people over age 50, but this new study shows that the early signs of risk can be detected long before that. Dr. Aiello explained that understanding these early links can help doctors and researchers predict long-term brain health and design better ways to prevent decline.
The research team used a tool called the CAIDE score, which looks at things like age, education level, sex, blood pressure, cholesterol, weight, exercise habits, and whether someone has a certain gene (APOE ε4) linked to Alzheimer’s.
They studied information from the National Longitudinal Study of Adolescent to Adult Health (Add Health), which has followed a large group of Americans since the mid-1990s.
The team focused on data from two time points. In Wave IV, researchers collected information from over 11,000 people aged 24 to 34. About 4,500 of them gave blood samples and completed cognitive tests.
In Wave V, 1,112 people aged 34 to 44 participated in interviews and completed memory and thinking tasks, like recalling words and repeating numbers backward. Genetic testing was also done.
The researchers found that higher CAIDE scores—indicating more risk factors—were linked to poorer performance on cognitive tasks.
This connection appeared well before age 50. They also found that several biological markers in the blood, including those known as amyloid (A), tau (T), and neurodegeneration (N)—or ATN—were tied to changes in brain function.
These ATN markers, along with certain immune system markers, have been used in older adults to predict Alzheimer’s risk. But now they seem to matter earlier in life, too. Interestingly, one genetic risk factor, APOE ε4, didn’t show a strong effect in this younger age group. Researchers think it may not influence brain health until later in life.
Dr. Aiello said the results are important because they show that warning signs of Alzheimer’s disease can appear decades before any symptoms are noticed. By identifying these early clues, healthcare providers can work on ways to prevent or slow the disease before it starts.
The study supports the idea that protecting brain health should start early, and that future efforts to fight Alzheimer’s disease will benefit from paying attention to younger adults—not just seniors.
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The study is published in The Lancet Regional Health – Americas.
