GFAP and NfL: Two Blood Proteins That Predict Dementia Death 5-6 Years in Advance

Early diagnosis of dementia has always been a challenge. Until today, most cases are detected only after symptoms are already clear, and that is too late for some treatments. But a massive study published in Neurology, based on 30,239 participants, shows that a simple blood test of 4 proteins can predict dementia risk and death years in advance. This is the critical step that brings us closer to the era of early diagnosis.

The Problem: Diagnosis Too Late

Alzheimer's and other dementias are diseases that develop slowly. Brain changes begin 15-20 years before symptoms. By the time diagnosis occurs, damage is already extensive and treatments are limited.

Existing methods for early diagnosis:

• Brain PET scan: Expensive ($3,000-5,000), radiation exposure
• Spinal fluid test: Invasive, painful, low risk of complications
• Advanced MRI: Expensive, not always available

None of these are suitable for mass screening. Something simpler is needed. A blood test.

The Trial: REGARDS, 30,239 Participants

The team used data from REGARDS (REasons for Geographic and Racial Differences in Stroke), one of the largest medical databases in the US. The study has followed 30,239 Black and White individuals across the US since 2003. The team measured 4 proteins in plasma from a random sample:

• NfL (Neurofilament Light Chain): A protein released from damaged neurons
• Total Tau: Tau protein, linked to Alzheimer's
• GFAP (Glial Fibrillary Acidic Protein): A protein from glial cells (brain support cells)
• UCH-L1: A protein from neurons

They then followed all deaths and specific dementia for 15 years.

The Findings: GFAP and NfL Are the Strongest Predictors

Only two proteins showed a significant association:

GFAP - The Strongest Predictor

• People with high levels of GFAP in the blood showed a 5.66 times higher risk of death from specific dementia
• The association remained after adjusting for age, sex, race, BMI, diabetes, blood pressure
• Also increased risk of death from heart causes

NfL - Also Strong

• 2.72 times higher risk of death from dementia
• Also associated with increased risk of death from any cause
• Rises long before official dementia diagnosis

Tau and UCH-L1 - Less Strong

Total Tau showed only a weak association. UCH-L1 showed no significant association. This is interesting because it means not every biomarker is equal. GFAP and NfL are the strong representatives.

"This is not just an association. It is a strong predictor. A person with high GFAP has a 5-6 times higher chance of dying from dementia in the next 15 years."

Why Is GFAP So Strong?

GFAP expresses "astrogliosis" - a response of glial cells to damage. When the brain begins to be damaged (even if not visible on MRI), glial cells wake up and start "responding." They release GFAP into the blood. This is a very early signal that something is wrong in the brain, even before symptoms appear.

NfL is the opposite - it is released only when neurons are physically damaged. Therefore, it is strong as a marker of existing damage, but less strong as an early marker.

Practical Implications

The test is already available in several labs in the US, and is coming to Israel following expansion in 2025-2026. The price is still relatively high ($300-600 for a full test), but it is decreasing.

Who is recommended?

1. Family history of Alzheimer's: If a parent or sibling was diagnosed, your risk is increased. Testing every 2-3 years from age 50+ is reasonable
2. Mild symptoms of cognitive decline: Frequent word forgetting, waking up often at night, face recognition issues. The test can help distinguish between normal aging and early Alzheimer's
3. People with head injury (sports impacts, accidents): NfL especially tracks neuronal damage
4. Adults aged 65+ who want to know where they stand

The Limitations

It is important to clarify:

• This is not a diagnostic map. High markers do not mean "you have dementia." They mean "increased risk"
• Other factors can raise them: Infections, autoimmune diseases, age
• Need to track over time: A single test is not enough. Two tests a year apart provide information on trends
• Must be interpreted with a doctor: Do not interpret alone

What to Do If Markers Are High?

If a test showed high GFAP or NfL, it is not a disaster but an opportunity. Common interventions for Alzheimer's and brain vascular diseases are:

1. Blood pressure control: Blood pressure above 130/80 accelerates brain damage
2. Diabetes management: Diabetes is linked to a 50%+ increase in dementia risk
3. Physical activity: 150+ minutes per week reduces risk by 30%
4. Mediterranean/MIND diet: Reduces risk by 25%
5. Quality sleep: 7-8 hours, without interruptions
6. Maintaining social connections: Loneliness adds to risk
7. Managing depression/anxiety: Proven risk factors

If risk is very high, there are now new drugs (lecanemab, donanemab) that slow Alzheimer's progression in its early stages. They are expensive and have side effects, but they are available.

The Next Step: Universal Tests?

The expectation is that by 2030, GFAP and NfL testing will be a routine part of periodic blood tests for adults over 60. Just as cholesterol became standard after 1980, neurological markers will become standard in the coming decade. This study is the step that brings us closer to that.

The Bottom Line

Early diagnosis of dementia has been a complex idea for decades. Now, with a blood test of 4 proteins, we can predict risk 15 years in advance. This changes how we approach dementia: from a disease treated when it breaks out, to a disease prevented throughout life. The tools are here. The question is only to use them.