Physiological and Clinical Changes of Aging

1. Physiological and Clinical Changes of Aging Pio L. Oliverio, MD Fellow, Geriatrics SVCMC, Jamaica, NY

2. OBJECTIVES • To describe basic concepts of physiologic changes with aging • To describe the effect of aging on body processes/ systems

3. DEFINITION of TERMS • Aging – the process of growing old, specially by failure of replacement cells in sufficient number to maintain full functional capacity (Stedman’s Med Dictionary 2000)

4. DEFINITION of TERMS • Aging – the gradualdeterioration of a mature organism resulting from time-dependent, irreversible changes in structure that are intrinsic to the particular species, and that eventually lead to decreased ability to cope with the stresses of the environment thereby increasing the probability of death (Stedman’s Med Dictionary 2000)

5. DEFINITION of TERMS • Aging – is a process that converts healthy adults into frail ones with diminished reserves in most physiologic systems and exponentially increasing vulnerability to most diseases and to death (W. Hazzard, Principles of Geriatric Medicine & Gerontology 2003)

6. DEFINITION of TERMS • Gerontology – the scientific study of the process and problems of aging. • Geriatrics – the branch of medicine concerned with the medical problems and care of the aged

7. DEFINITIONS of Life Span • A lifetime • The average or maximum length of time an organism or object can be expected to survive or last • The maximum number of years that a person has been known to live, currently around 115 years • Frequently confused with life expectancy

8. DEFINITION of Life Expectancy • length of time that a person on the average is expected to live • average number of years of life remaining to a person at a particular age and is based on a given set of age-specific death rates • Also Average Life Span or Mean Life Span • Can change over life cycle • Based on statistical probabilities

9. Average Life Expectancy (In years) 61 – developing countries 74 – developed countries

10. VARIATIONS in life expectancy WORLD WIDE • Causes: differences in public health medicine and nutrition from country to country USA + other developed countries • Variation in ethnicity and gender

11. Genetic disorder Exercise Smoking Excessive drug and alcohol use FACTORS affecting life expectancy • Poverty • Air pollution • Occupation • Diet • Access to health care

12. Fundamental Considerations • Aging is developmental • Old age is a gift of 20th century technology and scientific advancement • The effects of normal aging vs. pathologic aging must be differentiated • There is no universally accepted theory of aging

13. Theories of Aging Oxidative stress (free radical) Theory • Tissue damage is caused by free radicals (super oxide or hydroxyl radicals) through lipid peroxidation • Specific form of wear and tear theory • Accumulation of aging pigments (lipofuscin) in lysosomes

14. Theories of Aging Rate of Living Theory (Metabolic Rate Theory) • The higher the basal metabolic rate (the rate, at which the body at rest, uses energy), the shorter the life span

15. Theories of Aging Error Catastrophe Theory • DNA errors promote senescence, programmed cell death (apoptosis) • Aging results from gene interference with the ability of the cells to reproduce

16. Theories of Aging Error Catastrophe Theory Redundant DNATheory • Biologic age changes are a result of errors accumulating in functioning genes • Lifespan may be a degree of repeated genetic sequences • Fails to explain other possible aging factors

17. Theories of Aging Hayflick Limit Theory • Functional changes within cells are responsible for aging • Cumulative effect of improper functioning of cells and eventual loss of cells in organs and tissues

18. Cardiovascular System Morphology: • Elongation and tortuosity, stiffening of arteries including aorta • Increase intimal thickening of arteries • Increased fibrosis of media of arteries • Sclerosis of heart valves

19. Cardiovascular System • Cardiac Hypertrophy with aging • Inotropic and chronotropic responses to catecholamines sympathetic nervous system are impaired • Both systolic and diastolic blood pressures increase with age • Blood pressure regulation: older patients are at high risk for orthostatic hypotension

20. Decreased Cardiac output Heart rate response to stress Compliance of peripheral blood vessels Cardiovascular System

21. Decreased Lung elasticity Activity of cilia Cough reflex Respiratory drive Respiratory System

22. Lower… Respiratory muscle strength & endurance Diffusing capacity (oxygen uptake) PO2, O2 saturation due to V/Q mismatch (but no change in PcO2 ) Respiratory System

23. Lower Maximal expiratory flows: FEV1, FEV1/FVC VC Increased FRC and RV Respiratory System • Stable • TLC

24. Decreased Number of nephrons Kidney weight and volume Lean body mass Maximum urine osmolality Renal System

25. Decreased Renal blood flow Creatinine clearance Renin response to volume depletion or salt restriction Renal System

26. Renal System Impaired: • Hydroxylation of Vitamin D • Metabolism of PTH, calcitonin and glucagon Unchanged: • Erythropoietin production

27. Decrease in: Muscle mass strength of grip/ contractile force stability of neuromuscular innervation Bone substance (osteoporosis) Height and Weight Musculoskeletal System Most common disability cause in > 65 years old

28. Gastrointestinal System • Decreased: • Hydrochloric acid production • Taste buds • Intestinal motility • Swallowing coordination • Vitamin K-Dependent factor synthesis

29. Gastrointestinal System Increased: • Lithogenic index of bile composition (cholesterol gallstones) Functional Changes (Large Intestine): • Slowed transit • Altered coordination of contraction • Increased opioid receptors (drug induced constipation)

30. Endocrine System • Decreased: • Free testosterone • Triiodothyronine • Cortisol production • Hypothalamic-pituitary-adrenal axis sensitivity to glucocorticoid feedback

31. Endocrine System • Increased: • Insulin • Norepinephrine • Parathoromone • Vasopressin

32. Immune System • Impaired thermal regulation • Afebrile infection common • Total lymphocyte counts do not change with age • TNF-alpha increased but not interleukin-1

33. Immune System Decreased: • Humoral antibody-mediated response • Antibody response to vaccines • Production of thymic hormones • Mass of thymus • Production of lymphocytes • T-cell activity

34. Vision • Retina becomes thinner • Changes in lens and iris = presbyopia • Cataract formation: • Lens yellows and accumulation of insoluble protein in center…

35. Lacrimal gland function Tear production Goblet cell function Acuity Accomodation Color sensitivity Depth perception Pupil size Aqueous humor production Vision • Decreased:

36. Hearing • External auditory canal atrophies • Cerumen becomes drier Hearing Loss caused by: • Loss of hair cells in the organ of Corti • Loss of cochlear neurons • Stiffening of the basilar membrane • Calcification of auditory mechanism • Degeneration of spiral ligament

37. Thermoregulation • Increased susceptibility to hypo/hyperthermia • Impaired vasoconstrictor response to cooling • Impaired ability to conserve heat • Impaired skin vasodilatation response • Decreased sweat production

38. Sexual Function • Slower arousal phase • Increased ability to stay at plateau levels of arousal • Estrogen loss reduces acidity of vaginal secretions, causes atrophic vaginitis and hot flashes

39. Sexual Function • In men, a longer refractory period • In older men, erectile dysfunction impotence. There is no such thing as male menopause

40. THANK YOU! for your attention and your time