Recent findings from a large population-based study suggest that Alzheimer’s disease (AD) may be more widespread in certain age groups than previously estimated. By using blood-based biomarkers rather than relying solely on clinical symptoms, researchers are gaining a clearer picture of how common Alzheimer’s pathology truly is across different stages of aging.

A New Way to Measure Alzheimer’s Risk

Traditionally, Alzheimer’s disease has been diagnosed based on cognitive symptoms, neuroimaging, and cerebrospinal fluid tests—methods that are often costly, invasive, or applied late in the disease process. In contrast, this new study used blood tests capable of detecting biomarkers associated with Alzheimer’s pathology, such as amyloid-beta and tau proteins.

Because blood testing can be applied more broadly in the general population, researchers were able to estimate the prevalence of Alzheimer’s disease across different age groups more accurately than before.

Higher Rates of Alzheimer’s Dementia in Older Adults

The study found that Alzheimer’s dementia is significantly more common in older adults than earlier estimates suggested. Among people aged 70 and older, rates of Alzheimer’s dementia were notably higher, indicating that a substantial portion of this population may already have progressed beyond the preclinical stage of the disease.

These findings reinforce the idea that Alzheimer’s disease is not a rare condition of extreme old age, but rather a widespread public health challenge that grows rapidly with aging.

Lower Preclinical Alzheimer’s in Younger Groups

Interestingly, the researchers observed lower rates of preclinical Alzheimer’s disease—defined as the presence of Alzheimer’s biomarkers without cognitive symptoms—among younger adults. This suggests that widespread early pathology may not be as common in midlife as previously feared.

However, the transition from preclinical disease to symptomatic dementia appears to accelerate later in life, underscoring the importance of monitoring cognitive health as people age.

More Than 1 in 10 Older Adults May Be Eligible for Treatment

One of the most striking findings of the study is its implication for treatment eligibility. The researchers estimated that more than 1 in 10 people over the age of 70 may meet the biological criteria for monoclonal antibody therapies designed to slow cognitive decline.

These therapies, which target amyloid pathology in the brain, have recently gained regulatory approval in several countries. While they do not cure Alzheimer’s disease, they may help slow disease progression in selected patients—particularly those diagnosed early.

Implications for Public Health and Clinical Practice

The study highlights several important implications:

• Alzheimer’s disease may be underdiagnosed, especially in older adults who have not undergone biomarker testing.

• Blood-based screening tools could transform early detection and population-level risk assessment.

• Healthcare systems may face increasing demand for diagnostic services, specialist care, and disease-modifying therapies.

• Early identification could allow more patients to benefit from treatments that slow cognitive decline rather than only managing symptoms.

Looking Ahead

As blood tests for Alzheimer’s disease become more accessible and accurate, our understanding of how common the disease truly is will continue to evolve. This study suggests that Alzheimer’s disease may affect a larger segment of the aging population than previously thought—particularly among those over 70.

Early detection, combined with emerging therapies, offers hope for changing the trajectory of Alzheimer’s disease. However, it also calls for careful planning, ethical considerations, and equitable access to testing and treatment as this new era of Alzheimer’s care unfolds.