Aging changes

Last updated: September 2, 2023

Summarytoggle arrow icon

Aging is the time-related progressive functional decline that affects all organ systems. It is believed to be caused by the accumulation of DNA damage, hormonal changes, and internally programmed cellular changes. Effects of aging include stiffening of the arteries and calcification of valves (cardiovascular system), osteoporosis and increased risk of fracture (musculoskeletal system), decreased chest wall compliance and increased ventilation-perfusion mismatch (respiratory system), susceptibility to recurrent infections and malignancies (immune system), and decline in cognitive function and changes in sleep patterns (nervous system).

Overviewtoggle arrow icon

All cells and all organ systems are subject to the natural processes of aging that ultimately lead to progressive functional decline. Aging is characterized by cellular degradation combined with a diminished capacity for biosynthetic processes and cellular repair mechanisms.

Effects of aging on repair and regeneration

A number of factors are associated with reduced regenerative ability during aging and contribute to the aging process, e.g.: [1]

  • Genomic instability
  • Telomere shortening: Each cell cycle leads to a progressive decrease of telomere length; if telomere length falls beneath a certain threshold, cellular apoptosis or senescence is signalled.
  • Epigenetic modifications: Research suggests that epigenetic changes (e.g., posttranslational histone modification, DNA methylation) can contribute to a decreased regenerative ability.
  • Disrupted protein homeostasis: Decreased efficiency of pathways controlling proteostasis (e.g., autophagy, ubiquitin-proteasome degradation system) results in protein dysfunction and cellular damage, which in turn contributes to cellular dysfunction.
  • Metabolic changes: Age-related changes in pathways responsible for nutrient sensing (e.g., mTOR pathway, mitochondrial dysfunction) can negatively impact cellular function.
  • Changes in stem cell microenvironment: Aging is associated with a dysregulation of molecular mediators in the microenvironment that are necessary for proper stem cell regeneration (e.g., in muscle, intestine, CNS).

Bones, muscles, and jointstoggle arrow icon

Regular exercise and a diet rich in protein, vitamin D, creatine, and omega-3 fatty acids are essential to ensure muscle growth and help prevent sarcopenia.

Skintoggle arrow icon

Intrinsic aging

There is an increased incidence of:

Extrinsic aging

  • Solar elastosis
    • Age-related cutaneous change characterized by the development of diffusely thickened and wrinkled skin, sometimes with yellow discoloration
    • Caused by the accumulation of damaged collagen and elastic tissue as a result of chronic sun exposure (photoaging), especially with UVA light

Nails and hairtoggle arrow icon

Cardiovascular systemtoggle arrow icon

Respiratory systemtoggle arrow icon

Overview of aging changes in the respiratory system
Bodily changes Pathophysiology [3] Consequences
Weaker chest wall muscles
  • ↑ Chest wall stiffness → ↓ chest wall compliance
Calcification of costochondral junctions
Osteoporosis-induced kyphosis
Decreased elastin in pulmonary parenchyma
  • ↓ Elastic recoil → lung compliance
Weakened baroreceptor/chemoreceptor response
  • Poor ventilatory response to ↓ O2 and ↑ CO2 levels
Weakened respiratory muscles
Weakened immune system
  • ↑ Susceptibility to infection

Genitourinary systemtoggle arrow icon

Immune systemtoggle arrow icon


Endocrine systemtoggle arrow icon

Gastrointestinal systemtoggle arrow icon

Nervous systemtoggle arrow icon

  • Hearing impairments: presbycusis
  • Visual impairments
  • Decreased sense of smell and taste
  • Reduced ability to detect vibration, touch, temperature, and pressure changes (increased risk of pressure ulcers, hypothermia, and burns)
  • Decreased/absent deep tendon reflexes (e.g., ankle jerk reflex)
  • Decline in balance and gait stability (e.g., slow speed, reduced tandem gait ability) leading to increased risk of falls in older adults
  • Lower-extremity weakness
    • Delay in the onset of muscle activation due to a greater contraction of antagonistic muscles
    • Decline in the ability to develop joint torque using lower extremity muscles (e.g., compromised balance recovery during a postural disturbance)
    • Decline in physical function due to increased muscle tone, decreased muscle mass and increased muscle adiposity
  • Decreased cerebral blood flow and brain volume (due to neuronal loss)
  • Fluid intelligence declines, whereas crystallized intelligence increases.
  • Altered sleep patterns in older adults: early morning awakening, later sleep onset, decreased REM, and decreased slow-wave sleep
  • Psychomotor slowing
    • A state characterized by decreased and decelerated physical movements, speech, and mental processes (i.e., decline in executive function, working memory, processing speed, and attention span)
    • In most cases, no clinically significant impairment in social or occupational functioning
  • Increased suicide risk in individuals with physical illness, mental illness (particularly depression), functional impairment, and stressful life events (e.g., loss of a partner)

Referencestoggle arrow icon

  1. John D. Furber. Extracellular Glycation Crosslinks: Prospects for Removal. Rejuvenation Research. 2006; 9 (2): p.274-278.doi: 10.1089/rej.2006.9.274 . | Open in Read by QxMD
  2. Sharma G, Goodwin J. Effect of aging on respiratory system physiology and immunology.. Clinical interventions in aging. 2006; 1 (3): p.253-60.
  3. Watad A, Bragazzi NL, Adawi M, et al. Autoimmunity in the elderly: Insights from basic science and clinics - A mini-review. Gerontology. 2017; 63 (6): p.515-523.doi: 10.1159/000478012 . | Open in Read by QxMD
  4. Eisen HN. Affinity enhancement of antibodies: How low-affinity antibodies produced early in immune responses are followed by high-affinity antibodies later and in memory B-cell responses. Cancer Immunol Res. 2014; 2 (5): p.381-392.doi: 10.1158/2326-6066.cir-14-0029 . | Open in Read by QxMD
  5. Montecino-Rodriguez E, Berent-Maoz B, Dorshkind K. Causes, consequences, and reversal of immune system aging. J Clin Invest. 2013; 123 (3): p.958-965.doi: 10.1172/jci64096 . | Open in Read by QxMD
  6. Mehr R, Melamed D. Reversing B cell aging. Aging. 2011; 3 (4): p.438-443.doi: 10.18632/aging.100313 . | Open in Read by QxMD
  7. Bulati M, Caruso C, Colonna-Romano G. From lymphopoiesis to plasma cells differentiation, the age-related modifications of B cell compartment are influenced by “inflamm-ageing”. Ageing Res Rev. 2017; 36: p.125-136.doi: 10.1016/j.arr.2017.04.001 . | Open in Read by QxMD
  8. Kogut I, Scholz JL, Cancro MP, Cambier JC. B cell maintenance and function in aging. Semin Immunol. 2012; 24 (5): p.342-349.doi: 10.1016/j.smim.2012.04.004 . | Open in Read by QxMD
  9. Seraji-Bzorgzad N, Paulson H, Heidebrink J. Neurologic examination in the elderly. Elsevier ; 2019: p. 73-88
  10. Hiroaki Oguro, Kazunori Okada, Nobuo Suyama, Kazuya Yamashita, Shuhei Yamaguchi, Shotai Kobayashi. Decline of vertical gaze and convergence with aging. Gerontology. 2004.
  11. Yun M. Changes in Regenerative Capacity through Lifespan. International Journal of Molecular Sciences. 2015; 16 (10): p.25392-25432.doi: 10.3390/ijms161025392 . | Open in Read by QxMD

Icon of a lock3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer