Aging changes

Last updated: February 8, 2022

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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).

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) 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).

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!

There is an increased incidence of:

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

References:[4][5][6][7][8][9]

  • 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)
  • 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
  • Fluid intelligence declines, whereas crystallized intelligence increases
  • Altered sleep patterns in the elderly: 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)

Falls in elderly individuals

  • Identification of risk factors: The risk for falls in elderly individuals is often multifactorial.
  • Individual risk assessment: Individuals who have fallen or with gait and balance deficits should undergo a risk assessment.
    • Past medical history; (e.g., history of previous falls, circumstances of the falls, current medication)
    • Physical examination including postural vital signs, visual acuity, cognitive, neurological, musculoskeletal, and hearing function tests
    • Postural stability tests
      • Timed Up and Go test
        • The individual is asked to get up from a chair, walk a certain distance, turn around, walk back, and sit down again.
        • Used to assess musculoskeletal function and postural stability in a patient who has fallen.
      • Performance-oriented mobility assessment
        • Evaluates an individual's balance abilities in a chair, standing, and dynamic balance during gait (e.g., gait initiation, step continuity and path deviation when asked to walk, trunk position, ability to maintain balance when someone slightly pulls on the individual)
        • Used to assess balance and gait
  • Preventive measures
    • Minimize the number of medications that may contribute to falls (See “Beers criteria” for details).
    • Physical therapy
    • Elimination of potential hazards in the individual's home environment
  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

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