Basic of Geriatrics and Internal Medicine for Physiotherapist by Rasheedy D - HTML preview

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Ageing Process

Definition of ageing:

img3.png Physiological ageing (normal ageing): is a complex process of progressive reduction in the function of all body organs. This process may be summarized in the expression “homeostenosis”. It reflects alteration of organ structure and function with time alone and in the absence of supervening disease processes.

img3.png Physiological ageing is an inevitable changes can be explained from both biologic and psychosocial perspectives.

img3.png Processes influencing ageing include gene variations and differences in expression and environmental factors.

img3.png Age and disease are closely associated phenomena. Secondary ageing then refers to those aspects of the aged state that are attributable to disease.

Fig 1: Predictors of the Ageing process

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Characters of the ageing process:

Aging is characterized by being Universal, Cumulative, Unidirectional, Heterogeneity, Intrinsic, and Deleterious.

Characters of ageing process

Universal

All humans age

Cumulative

the effects of aging are irreversible and accumulate over time

Unidirectional

For example, a postmenopausal woman cannot become ovulatory again.

Heterogeneity

occurs at different rates among individuals and within individuals

Intrinsic

Because even under the best environmental conditions an individual ages, aging is intrinsic to the organism.

Deleterious

aging is harmful, resulting in decreased vitality and an increased vulnerability to disease and environmental stresses

Ageing is different from Cellular senescence is the process by which a cell loses its ability to divide, grow, and function, ultimately leading to cell death.

Theories of ageing (biological)

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Fig 2: examples of biological theories of ageing

Cellular senescence/ telomere theory:

img3.png Replicative senescence is a specific type of cellular senescence that ultimately results from loss of telomeres (specialized structures composed of a repeating DNA sequence and located at the ends of each linear chromosome).With each cell division, a small amount of DNA is lost at each chromosome end, resulting in shorter telomeres, altered telomere structure, and eventual replicative senescence.

img3.png Activation of the telomerase enzyme will regenerate telomeres, prevent replicative senescence, and immortalize human primary cell cultures

Free Radical theory:

img3.png Free radicals are reactive oxygen species (ROS) are highly reactive molecules that can damage all sorts of cellular components.

img3.png ROS can originate from exogenous sources such as ultraviolet (UV) and ionizing radiations or from several intracellular sources: (phagocytosis, fatty acid degradation, drug detoxification by liver, ATP utilization).

img3.png Toxic accumulation of ROS interfere with cell communication, disturb DNA, RNA and protein synthesis, lower energy levels and generally impede vital chemical processes.

img3.png To protect against oxidation there are many different types of antioxidants, from vitamins C and E selenium, CoQ10 and lipoic acid to enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase. Briefly, antioxidant enzymes are capable of degrading ROS into inert compounds through a series of chemical reactions.

The Neuro-endocrine Theory

img3.png Hypothalamo-pituitary-adrenal (HPA) axis is the master regulator that control the onset and termination of each life stage. It is also responsible for the maintenance of the internal “homeostasis” (steady state) despite the continuing changes in the environment.

img3.png During life span, chronic exposure to severe stress from a multitude of physical, biological, or emotional stimuli may exhaust or weaken the capacity to adapt and lead to the so-called “diseases of adaptation” and death . Aging would then result from “a decreasing ability to survive stress.

img3.png Evidence to this theory: the cortisol hormone which is considered to be responsible for stress is one of the few hormones that increases with age.

The immunosenescence theory:

img3.png The immune system must control and eliminate foreign organisms and substances in the host body while at the same time recognizing and therefore sparing from destruction the molecules (cells and tissues) from oneself. In most elderly humans, immunosenescence is characterized by a decreased resistance to infectious diseases, a decreased protection against cancer, and an increased failure to recognize self (hence, autoimmune pathology.

The disposable soma

img3.png The somatic cells are only preserved to maintain reproductive functions. After reproduction somatic cells become disposable.

Antagonistic pleiotropy

img3.png The theory of antagonistic pleiotropy is based on two assumptions. First, it is assumed that a particular gene may have an effect not on one trait only but on several traits of an organism (pleiotropy). The second assumption is that these pleiotropic effects may affect individual fitness in opposite (antagonistic) ways.

img3.png Such genes will be maintained in the population due to their positive effect on reproduction at young ages despite their negative effects at old age (their negative effects in later life will look exactly like the aging process)

Error catastrophe

img3.png Gene expression accuracy diminishes with age. This culminates in a higher proportion of abnormal proteins.

img3.png There is a certain rate of error tolerance of a cell, exceeding which the cell fails in its ability to sustain and function normally.

img3.png Thus, accumulation of errors in the genomic replication machinery beyond a certain threshold might lead to erroneous dysregulation of the protein synthesis, folding and expression mechanisms which ultimately might bring about deterioration in the functionality of the cell.

Types of Ageing:

Chronological

The number of years a person has lived since birth.

Biological

age changes in physical structures and functions that affect either ability to survive or appearance

Social

How a person perceives the aging process and how it relates to the society in which they live

Psychological

age changes in mental processes and behavior

The elderly are special population with special needs:

img3.png Physiological Changes in the Elderly (Normal Aging is not a disease)

img3.png Multiple comorbidities and multiple medications: The incidence of chronic diseases increases with ageing e.g. dementia, Parkinsonism, stroke, heart diseases leading to polypharmacy.

img3.png Overlapping Variables (physiological, social, psychological, environmental variables) &multiple diseases): heterogeneous Population: Need for Individualized Treatment:

img3.png Atypical presentations of diseases

img3.png They need different assessment approach (see comprehensive geriatric assessment) through Multidimensional, Interdisciplinary, Geriatric team

img3.png The goal of elderly care is maintaining function &quality of life:" To add life to years NOT only years to life

Age related physiological changes:

img3.png Aging and disease are not synonymous. Although the aging process makes individuals more vulnerable to illness and disease, pathology is not inevitable with age. Aging alone generally does not cause symptoms.

img3.png The major age-related biologic change is a diminished reserve capacity and the inability to maintain homeostasis in the face of stressors such as a disease or adverse environmental factors such as excessive heat.

Body system

Physiological change

Clinical implications

General body composition

The percent of body water (TBW)

decreases with aging

↑risk of dehydration