07 / RESEARCH AREAS
Methods & evidence
The tools of careful inquiry. Study design, causal reasoning and uncertainty.
QUESTIONS WE WANT TO UNDERSTAND
Does the study design answer the question being asked?
How do measurement choices and assumptions shape a result?
What distinguishes a repeatable calculation from a supported conclusion?
These questions describe the scope of this area. They are not findings or a list of active studies.
Research in this area
Newest published first
1–12 of 22 articles
Does a Younger “Vascular Age” Mean Improved Vascular Structure?
Vascular readings can carry health information, but a lower predicted age, a changed arterial wall, and fewer future clinical events are separate results. We reanalyzed a public dataset of 36,223…
- Cross-sectional age and algorithmsModerate
- Pressure and mechanical conditionsStrong
- Acute human tone and vessel sitesLimited
- Clinical prognosisModerate
- Management trial and surrogacyNot yet determinable
Does daily regularity have independent value, or reflect activity and health?
Regularity can describe behavior beyond movement volume, but measurement, prognosis and intervention value are separate questions. In our NHANES reanalysis, RA retains a favorable mortality…
- Measurement and finite identificationStrong
- Conditional mortality associationsModerate
- External prognostic evidenceModerate
- Short interventions and physiologyLimited
- Healthspan and clinical prescriptionsNot yet determinable
At the same weight loss, does losing visceral fat offer greater benefits?
Weight alone does not describe fat distribution or metabolic change. Randomized lifestyle trials support different visceral fat reductions with different intervention bundles, even when average…
- Randomized lifestyle bundles and fat distributionModerate
- Long-term metabolic and diabetes associationsLimited
- Fatty-acid/inflammatory pathways and selective removalLimited
- Causal extra benefit at fixed weight lossNot yet determinable
- Healthspan and routine imaging decisionsNot yet determinable
Protein accumulation in the aging brain: made locally or acquired from other cells?
Mouse experiments support the presence of neuron-derived protein material in microglia, with higher associated labeling signals in aged microglial samples. Some labeled proteins also disappear more…
- Mouse cellular origin and recipient materialModerate
- Effective persistence in selected brain regionsModerate
- Routes, intrinsic rates and functional attributionLimited
- Normal-human aging and intervention benefitNot yet determinable
Do two longevity drugs add their benefits, or act synergistically?
A 2025 mouse experiment supports longer survival with rapamycin plus trametinib than with either drug alone under the tested strain, doses and schedule. Exceeding a single treatment, exceeding a…
- Joint survival benefit in the specified mouse regimenLimited
- Lifespan interaction and mechanistic attributionNot yet determinable
- Mouse function and molecular changesLimited
- Combined benefit in normally aging humansNot supported
How much of lifespan is heritable—and why do estimates differ so much?
There is no universal percentage of an individual's lifespan that is “decided by genes.” Heritability describes variation within a specified population, environment and measurement scale. Estimates…
- Genetic differences in lifespanModerate
- Conditional estimates in historical pedigreesLimited
- Intrinsic lifespan under zero external mortalityLimited
- An individual’s modifiable lifespan or healthspan fractionNot supported
Does Shingles Vaccination Reduce Dementia Risk?
The evidence supports a signal worth testing seriously: eligibility for live shingles vaccination is associated with fewer recorded dementia diagnoses, and birth-date discontinuities make this…
- Live-vaccine eligibility policyModerate
- Receipt and relative efficacyLimited
- Recombinant vaccination in humansLimited
- Disease-mortality signalLimited
- Mechanism, onset and lifespanNot yet determinable
Matrix fragments: drivers of aging, or echoes of tissue injury?
Elastin fragments can participate in immune signaling, and mouse interventions provide causal clues. Higher circulating concentrations can also reflect tissue injury, increased release or slower…
- Circulating levels and originsLimited
- Animal signaling mechanismsModerate
- Naturally aged lifespanLimited
- Specificity and safetyLimited
- Human causality and healthspanNot yet determinable
Hepatic immune signals: new T cells, or expansion of existing cells?
A mouse study temporarily supplied three immune-support signals from the liver and improved some vaccine and antitumor responses in aged animals. Evidence for thymic involvement matters, but larger…
- Thymus-related processesModerate
- Repertoire depth and originsLimited
- Animal function and withdrawalModerate
- Model safetyLimited
- Human protection and healthspanNot yet determinable
Why can aging muscle become more oxidative while function declines? Cardiolipin and compensation
An oxidative shift can compensate for mitochondrial damage without improving muscle function. A 2026 cardiolipin-depletion study demonstrates that separation: some muscles gain mitochondrial-content…
- Measurements and denominatorsModerate
- Depletion and cellular mechanismModerate
- Animal function and recoveryLimited
- Antioxidants and net effectsLimited
- Human function and healthspanNot yet determinable
Longer lipids with age: a causal change or a shift in lipid composition?
These source tables show relative remodeling within lipid classes in some tissues, which cannot be explained entirely by replacement between classes. But “longer species become relatively favored,”…
- Definitions and samplesModerate
- Age/intervention remodelingModerate
- Animal mechanism/lifespanLimited
- Genetics and membrane physicsLimited
- Human healthspan/applicationsNot yet determinable
Which senescent cells are we actually identifying? Do different markers describe the same state?
Measurements can complement one another, but “p16-positive,” “p21-positive,” “high senescence-signature score” and “harmful cells worth clearing” remain different descriptions. Our analysis of a…
- Detection definitionsModerate
- Multimodal predictionLimited
- External-study signature associationLimited
- State and functional referencesModerate
- Human clearance applicationsNot yet determinable