Biological Theories of Aging

Four Criteria on Biological Theories on Aging  Universal process: all members of a species must experience it  Process must result in physiological decline  Process must be gradual and progressive over time  Losses cannot be corrected by the organism

Biological Theories of Aging  Wear and Tear Theory The body simply wears out over time Each species has a biological ‘clock’  Cellular aging Cells are programmed to follow a biological ‘clock’ and stop replicating over time  Immunological theory The body’s immune system becomes defective over time (T cells and telomeres)

Biological Theories (continued)  Free radical or oxidative stress Progressive and irreversible accumulation of oxidative damage to cells explains the age-related loss of physiological function  Mitochondrial DNA mutation theory Aging may be due to errors made during the cell’s attempt to repair or replicate damaged DNA in the mitochondria

Biological Aging is a Gradual Process  Our systems have built in redundency  Frailty is defined as a clinical syndrome in which three or more of the following criteria were present: unintentional weight loss (10 lbs in past year), self-reported exhaustion, weakness (grip strength), slow walking speed, and low physical activity

Physiologic Changes With Aging  Increased dysregulation of physiologic systems  Frail people have higher risks of poor outcomes: disability, falls, mortality  Early stage frailty can be prevented through physical activity and nutrition

Intellectual Changes With Aging  Cognitive impairment increases with age Only 5-10% of elderly have dementia Alzheimer’s disease is most prevalent type of dementia  Some cognitive functions decline with age, while others are stable or improve Greater knowledge base

disease“damage” impairment limits to function increased dependence Sources: Nagi (1965); Verbrugge & Jette (1994); World Health Organization (1999) Other Factors: things individuals can do (e.g., behavior, control) Other Factors: things outside the individual (e.g., medical care, environment) Disablement Process

diabetes retinopathylimited vision can’t pay bills arthritis joint damage limited mobility can’t provide own meals Alzheimer’s disease dementiageographic disorientation restricted environment disease “damage” limits to function increased dependence Examples

PH Goals for Aging Society  Compression of morbidity Active life expectancy Support healthy conditions for people of all ages Ensure effective PH and preventive approaches (all levels) for older people  Provide community and home-based supports  Effective care systems and competent work force to support healthy aging