Mechanisms
Biological pathways and processes that shape how we age, and which longevity interventions target.
Small human pilot studies or cohorts
AGE Formation (Advanced Glycation End-products)
Glucose reacts non-enzymatically with long-lived proteins such as collagen, creating cross-linked adducts that stiffen tissue and accumulate over decades.
Small human pilot studies or cohorts
AMPK Activation
AMP-activated protein kinase senses low cellular energy and switches on catabolic, autophagy-promoting programs; metformin's benefits are partly attributed to AMPK activation, though this is debated.
n=1 self-experiments or animal studies
Altered Intercellular Communication
Aging shifts how cells signal to each other, through hormones, the senescence-associated secretory phenotype (SASP), and extracellular vesicles, spreading inflammation and dysfunction across tissues.
n=1 self-experiments or animal studies
Autophagy
Autophagy is the cell's recycling system for damaged proteins and organelles, and its decline with age is one of the most consistently reversible hallmarks in animal models.
Medium human RCTs or systematic reviews
Cellular Bioenergetics (ATP Production Capacity)
How much ATP each mitochondrion actually makes, measured by 31P-MRS and respirometry, which falls with age faster than mitochondrial number does.
n=1 self-experiments or animal studies
DNA Damage Response and Genomic Instability
DNA sustains tens of thousands of damaging events per cell per day, and the repair machinery that fixes it becomes less efficient with age, allowing mutations and structural changes to accumulate.
Small human pilot studies or cohorts
Deregulated Nutrient Sensing
The body's core nutrient-sensing pathways (insulin/IGF-1, mTOR, AMPK, sirtuins) become less responsive with age, and dialing several of them down experimentally extends lifespan in every model organism tested.
Small human pilot studies or cohorts
Dysbiosis (Gut Microbiome Imbalance)
Age-related shifts in gut bacterial composition that leak inflammatory signals into the circulation, named the twelfth hallmark of aging in 2023.
Small human pilot studies or cohorts
AGE Formation (Advanced Glycation End-products)
Glucose reacts non-enzymatically with long-lived proteins such as collagen, creating cross-linked adducts that stiffen tissue and accumulate over decades.
Small human pilot studies or cohorts
AMPK Activation
AMP-activated protein kinase senses low cellular energy and switches on catabolic, autophagy-promoting programs; metformin's benefits are partly attributed to AMPK activation, though this is debated.
n=1 self-experiments or animal studies
Altered Intercellular Communication
Aging shifts how cells signal to each other, through hormones, the senescence-associated secretory phenotype (SASP), and extracellular vesicles, spreading inflammation and dysfunction across tissues.
n=1 self-experiments or animal studies
Autophagy
Autophagy is the cell's recycling system for damaged proteins and organelles, and its decline with age is one of the most consistently reversible hallmarks in animal models.
Medium human RCTs or systematic reviews
Cellular Bioenergetics (ATP Production Capacity)
How much ATP each mitochondrion actually makes, measured by 31P-MRS and respirometry, which falls with age faster than mitochondrial number does.
n=1 self-experiments or animal studies
DNA Damage Response and Genomic Instability
DNA sustains tens of thousands of damaging events per cell per day, and the repair machinery that fixes it becomes less efficient with age, allowing mutations and structural changes to accumulate.
Small human pilot studies or cohorts
Deregulated Nutrient Sensing
The body's core nutrient-sensing pathways (insulin/IGF-1, mTOR, AMPK, sirtuins) become less responsive with age, and dialing several of them down experimentally extends lifespan in every model organism tested.
Small human pilot studies or cohorts
Dysbiosis (Gut Microbiome Imbalance)
Age-related shifts in gut bacterial composition that leak inflammatory signals into the circulation, named the twelfth hallmark of aging in 2023.
Small human pilot studies or cohorts
Epigenetic Drift
DNA methylation patterns become progressively noisier and less predictable with age, and this drift is the basis for epigenetic clocks like Horvath's and GrimAge.
Medium human RCTs or systematic reviews
FOXO Longevity Transcription Factors
FOXO transcription factors switch on stress-resistance and repair genes when insulin/IGF-1 signaling drops, and a common FOXO3 gene variant is among the most replicated human longevity genes known.
In vitro or mechanistic only
Hallmarks of Aging
A framework of twelve interconnected cellular processes, first proposed in 2013 and expanded in 2023, that researchers use to organize what drives biological aging.
Medium human RCTs or systematic reviews
Immunosenescence
Age-related remodelling of adaptive immunity: the thymus shrinks, naive T cells run out, CD8 cells expand, and vaccine responses fall.
Medium human RCTs or systematic reviews
Inflammaging
Chronic, low-grade inflammation rises with age even without infection, and it is now recognized as one of the twelve hallmarks of aging with hs-CRP and IL-6 as its main blood markers.
Medium human RCTs or systematic reviews
Insulin/IGF-1 Signaling in Aging
The insulin/IGF-1 signaling pathway couples nutrient availability to growth and metabolism, and reduced signaling through this pathway is one of the most reproducible lifespan-extension findings across species.
Small human pilot studies or cohorts
Klotho Signaling
Alpha-Klotho is a kidney-derived protein whose loss in mice produces a compressed aging syndrome, and whose low blood level predicts death in older humans.
Small human pilot studies or cohorts
Lipid Peroxidation
Reactive oxygen species attack polyunsaturated fatty acids in membranes and lipoproteins, producing malondialdehyde and 4-hydroxynonenal, which then modify proteins and DNA.
Large human RCTs or meta-analyses
Mitochondrial Biogenesis
PGC-1alpha-driven mitochondrial biogenesis declines with age, and exercise remains the most reliably effective way to reverse it in humans.
Small human pilot studies or cohorts
NAD+ Decline
Nicotinamide adenine dinucleotide (NAD+) levels fall with age in animal tissue, driving supplement interest in NMN and NR, but a 2025 human study found no age or lifestyle association with whole-blood NAD+.
Medium human RCTs or systematic reviews
NLRP3 Inflammasome Activation
A cytosolic sensor complex that cleaves and releases IL-1 beta, driving the sterile inflammation that accumulates with age.
Medium human RCTs or systematic reviews
Oxidative Stress and the Free Radical Theory
Reactive oxygen species damage cellular components with age, but the once-dominant free radical theory of aging has lost support after antioxidant supplement trials repeatedly failed to extend human lifespan.
n=1 self-experiments or animal studies
Proteostasis Collapse
The cellular quality-control systems that fold, refold, and clear proteins lose capacity with age, letting misfolded and aggregated proteins accumulate.
Small human pilot studies or cohorts
Senescence Clearance
Senescent cells stop dividing but refuse to die, secrete inflammatory signals, and clearing them with senolytic drugs extends healthy lifespan in mice.
n=1 self-experiments or animal studies
Sirtuin Activation
Sirtuins are NAD-dependent deacetylases that link nutrient status to DNA repair, mitochondrial function, and lifespan in lower organisms, with human relevance still unproven.
n=1 self-experiments or animal studies
Stem Cell Exhaustion
Adult stem cell pools shrink and lose regenerative capacity with age, slowing tissue repair in blood, muscle, and gut.
Medium human RCTs or systematic reviews
Telomere Attrition
Telomeres, the repetitive DNA caps on chromosomes, shorten with each cell division, and while short telomeres predict some disease risk, telomere length has repeatedly underperformed as a personal aging biomarker.
Small human pilot studies or cohorts
mTOR Signaling
Mechanistic target of rapamycin (mTOR) couples nutrient and growth-factor signals to cell growth, and inhibiting it extends lifespan in every model organism tested so far.
Small human pilot studies or cohorts
p53 Tumor Suppressor Pathway
p53 stops damaged cells from dividing to prevent cancer, but constitutively active p53 accelerates aging in mice, making it a textbook case of cancer-versus-aging trade-off.