The Study
Blood and cerebrospinal fluid neurofilament light differentially detect neurodegeneration in early Alzheimer’s disease
This study looked at a protein in people’s spinal fluid and blood to see how it changes as Alzheimer’s starts. It found that when the brain starts getting damaged, the protein shows up more in spinal fluid before it shows up in blood — but it doesn’t prove that the protein causes the damage. It just shows they happen together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists compared two ways to measure brain damage in Alzheimer’s: a spinal fluid test and a blood test. They found the spinal fluid test spots trouble much earlier.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means you can detect brain damage from Alzheimer’s years before symptoms appear — but only with a spinal tap, not a simple blood test.
- 2In people with no symptoms but early Alzheimer’s brain changes, spinal fluid NfL was 1.3–1.7x higher, but blood NfL stayed normal.
- 3Blood NfL only rose when people had memory problems.
- 4In mice, spinal fluid NfL rose at 2 months, blood at 4 months.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Neurobiology of Aging
Year
2020
Authors
E. Andersson, S. Janelidze, B. Lampinen, M. Nilsson, A. Leuzy, E. Stomrud, K. Blennow, H. Zetterberg, O. Hansson
Related Content
Claims (6)
Blood levels of neurofilament light chain rise 9 to 10 years before a person is diagnosed with Alzheimer's disease, indicating that nerve cell damage is already occurring.
In people without cognitive impairment, higher levels of neurofilament light in cerebrospinal fluid are linked to measurable damage in white matter fibers of the brain, while similar levels in blood show no such link.
People with mild cognitive impairment or Alzheimer’s dementia have higher levels of neurofilament light protein in their spinal fluid and blood than people without cognitive impairment. Blood levels of this protein rise significantly only when symptoms are present, reflecting more advanced nerve damage.
In people with Alzheimer’s disease, the level of neurofilament light in cerebrospinal fluid is more closely linked to the amount of amyloid-beta plaques in the brain than the level of neurofilament light in blood, making cerebrospinal fluid NfL a more sensitive indicator of nerve damage caused by amyloid-beta.
In older adults without cognitive impairment, higher levels of neurofilament light in spinal fluid are found when amyloid-beta plaques are present, but blood levels of neurofilament light remain the same, showing that spinal fluid measurements detect early brain changes better than blood tests.
In mice genetically engineered to develop Alzheimer’s-like brain changes, neurofilament light protein appears in the cerebrospinal fluid at 2 months after pathology begins, and only later at 4 months in the blood.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.