Chronological age
Chronological age has been studied in 63 papers since 2016: 42 observational studies in people, 19 in animals; 5 in the past year. The newest paper, Jun 1, 2026: “Clinical Characteristics and Outcomes of Older Patients Admitted to the Cardiac Intensive Care Unit”.
63 papers study it91 findingsUpdated
Research on it is growing 32% faster than aging research as a whole: 640 papers in the latest year counted
“Age negatively correlated with AOT score (r = -0.11) and AOT-E score (r = -0.13).”
None of its findings points the other way.
- 36 independent labs in 19 countries
- Funders: National Institutes of Health and others
- 7 of 91 findings with company ties
- Humans42
- Animals14
- Model organisms5
- In silico2
What did studies of Chronological age find?
63Studies of Chronological age measured 63 outcomes; the most studied are desquamated endothelial cell count (1 study), RBC deformability index (1) and red blood cell aggregation (1).
Desquamated endothelial cell count
upin rats1
1 study
Desquamated endothelial cell count
upin rats1
Chronological age increases desquamated endothelial cell count in rats.
“an increase in desquamated endothelial cell count was observed in the blood plasma, indicating endothelial dysfunction”
Animalsblood plasma
Blood Rheological Properties in Rats of Different Ages
Journal of Evolutionary Biochemistry and Physiology
RBC deformability index
upin rats1
1 study
RBC deformability index
upin rats1
Chronological age increases RBC deformability index in rats.
“The RBC deformability index also significantly increases, indicating a decline in cell deformability.”
Animals
Blood Rheological Properties in Rats of Different Ages
Journal of Evolutionary Biochemistry and Physiology
Red blood cell aggregation
upin rats1
1 study
Red blood cell aggregation
upin rats1
Chronological age increases red blood cell aggregation in rats.
“the degree of RBC aggregation rises”
Animals
Blood Rheological Properties in Rats of Different Ages
Journal of Evolutionary Biochemistry and Physiology
Blood viscosity
upin rats1
1 study
Blood viscosity
upin rats1
Chronological age increases blood viscosity in rats.
“with age, hematocrit decreases, plasma and blood viscosity increase”
Animals
Blood Rheological Properties in Rats of Different Ages
Journal of Evolutionary Biochemistry and Physiology
Episodic memory
downin humans1
1 study
Episodic memory
downin humans1
Chronological age is linked with worse episodic memory in humans.
“had similar negative effects on episodic memory and executive functions”
Humansn = 232
Age-, sex-, and pathology-related variability in brain structure and cognition
Translational psychiatry
Adiposity
upin mice1
1 study
Adiposity
upin mice1
Chronological age increases adiposity in mice.
“middle-aged female mice showed increased adiposity”
Animalsfemales
Aging attenuates diurnal lipid uptake by brown adipose tissue
Aging
Lipoprotein lipase abundance in brown adipose tissue
downin mice1
1 study
Lipoprotein lipase abundance in brown adipose tissue
downin mice1
Chronological age decreases lipoprotein lipase abundance in brown adipose tissue in mice (at peak abundance).
“Peak abundance of lipoprotein lipase (LPL), a crucial regulator of FA uptake, was attenuated in BAT.”
Animalsat peak abundancebrown adipose tissue
Aging attenuates diurnal lipid uptake by brown adipose tissue
Aging
More on Lipoprotein lipase abundance in brown adipose tissue
Plasma triglycerides
upin mice1
1 study
Plasma triglycerides
upin mice1
Chronological age increases plasma triglycerides in mice (at onset of dark phase).
“This coincided with delayed plasma clearance of TG-rich lipoproteins and TG-depleted lipoprotein core remnants, and elevated plasma TGs at the same time point.”
Animalsat onset of dark phasefemales
Aging attenuates diurnal lipid uptake by brown adipose tissue
Aging
Body temperature
downin mice1
1 study
Body temperature
downin mice1
Chronological age decreases body temperature in mice.
“in middle-aged versus young mice body temperature is lower in both male and female mice”
Animalsmale and females
Aging attenuates diurnal lipid uptake by brown adipose tissue
Aging
Triglyceride-derived fatty acid uptake by brown adipose tissue
downin mice1
1 study
Triglyceride-derived fatty acid uptake by brown adipose tissue
downin mice1
Chronological age decreases triglyceride-derived fatty acid uptake by brown adipose tissue in mice (at onset of dark phase).
“uptake of triglyceride (TG)-derived fatty acids (FAs) by BAT, reflecting metabolic activity, is attenuated at its peak at the onset of the dark (wakeful) phase in female mice.”
Animalsat onset of dark phasebrown adipose tissuefemales
Aging attenuates diurnal lipid uptake by brown adipose tissue
Aging
More on Triglyceride-derived fatty acid uptake by brown adipose tissue
All 63Fewer
What is Chronological age linked with?
28Studies link Chronological age with 28 measures, most often Mitochondrial dysfunction (1 study), differentially expressed genes (1) and CD28 expression on T cells (1).
Mitochondrial dysfunction
upin chickens1
1 study
Mitochondrial dysfunction
upin chickens1
Chronological age is associated with mitochondrial dysfunction in chickens.
“Mitochondrial dysfunction was observed in both groups”
Animalsovarian folliclen = 15
Poultry science
Differentially expressed genes
upin chickens1
1 study
Differentially expressed genes
upin chickens1
Chronological age is associated with differentially expressed genes in chickens (118 DEGs at 67 weeks; 180 DEGs at 87 weeks).
“This analysis revealed 118 DEGs in the 67-week group and 180 DEGs in the 87-week group.”
Animalsovarian folliclen = 15
Poultry science
CD28 expression on T cells
downin humans1
1 study
CD28 expression on T cells
downin humans1
Chronological age is associated with CD28 expression on T cells in humans.
“The loss of CD28 expression on T cells and the transverse trend of activated CD38 and HLA-DR were also related to the increased age”
Humansperipheral bloodn = 150
Aging
Memory CD4+ or CD8+ T cells
upin humans1
1 study
Memory CD4+ or CD8+ T cells
upin humans1
Chronological age is associated with memory CD4+ or CD8+ T cells in humans.
“Age was associated with decreased CD4+CD45RA+CD62L+ T cells, decreased CD4+CD45RA+CD31+ T cells, and increased memory CD4+ or CD8+ T cells”
Humansperipheral bloodn = 150
Aging
CD4+CD45RA+CD62L+ T cells
downin humans1
1 study
CD4+CD45RA+CD62L+ T cells
downin humans1
Chronological age is associated with CD4+CD45RA+CD62L+ T cells in humans.
“Age was associated with decreased CD4+CD45RA+CD62L+ T cells, decreased CD4+CD45RA+CD31+ T cells, and increased memory CD4+ or CD8+ T cells”
Humansperipheral bloodn = 150
Aging
CD8+Ki-67+ T cells
upin humans1
1 study
CD8+Ki-67+ T cells
upin humans1
Chronological age is associated with CD8+Ki-67+ T cells in males.
“the percentage of CD8+ki-67+ also showed an increasing trend, with significant differences between the young group and other elderly groups in males”
Humansin malesperipheral bloodmalesn = 150
Aging
PD-1+ T cells
upin humans1
1 study
PD-1+ T cells
upin humans1
Chronological age is associated with PD-1+ T cells in men.
“age was positively associated with PD-1+ T cells and showed significant age-related variability in men”
Humansin menperipheral bloodmalesn = 150
Aging
Cerebellar tonsil position
downin humans1
1 study
Cerebellar tonsil position
downin humans1
Chronological age is associated with cerebellar tonsil position in humans (normal adults) (r=-0.334).
“Correlation analysis showed that age was negatively correlated with AB, BC, CD, DA, BE, ∠α, and MN ( r=-0.375, P=0.001; r=-0.417, P=0.001; r=-0.046, P=0.001; r=-0.244, P=0.001; r=-0.326, P=0.001; r=-0.320, P=0.001; r=-0.334, P=0.001).”
Humansnormal adultscerebellar tonsiln = 180
Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery
Posterior cranial fossa linear volume
downin humans1
1 study
Posterior cranial fossa linear volume
downin humans1
Chronological age is associated with posterior cranial fossa linear volume in humans (normal adults) (r=-0.046 to -0.417).
“Correlation analysis showed that age was negatively correlated with AB, BC, CD, DA, BE, ∠α, and MN”
Humansnormal adultsposterior cranial fossan = 180
Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery
Distance prime
mixedin humans1
1 study
Distance prime
mixedin humans1
Chronological age is associated with distance prime in humans (cross-sectional analysis; decreases from 35 to 70 yr then increases) (R2 = 0.45).
“D' also changed in a curvilinear manner with age (R2 = 0.45, P < 0.001, n = 103)”
Humanscross-sectional analysis; decreases from 35 to 70 yr then increasesn = 103
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