Chapter 9 - Late Adulthood

• Lifespan or Maximum Lifespan is referred to as the greatest age reached by any member of a given population (or species). For humans, the lifespan is currently between 120 and 125.
• Life expectancy is defined as the average number of years that members of a population (or species) live.
• When looking at large populations, the WHO (2019) measures how many equivalent years of full health on average a newborn baby is expected to have. This age takes into account current age-specific mortality, morbidity, and disability risks and is referred to as The Healthy Life Expectancy. 
• According to Jin (2010), modern biological theories of human aging involve two categories. The first is Programmed Theories that follow a biological timetable, possibly a continuation of childhood development. This timetable would depend on “changes in gene expression that affect the systems responsible for maintenance, repair, and defense responses,”
• The second category includes Damage or Error Theories which emphasize environmental factors that cause cumulative damage in organisms. Examples from each of these categories will be discussed. 
• At the end of each chromosomal strand is a sequence of DNA that does not code for any particular protein, but protects the rest of the chromosome, which is called a telomere. 
• With each replication, the telomere gets shorter. Once it becomes too short the cell does one of three things. It can stop replicating by turning itself off, called cellular senescence. It can stop replicating by dying, called apoptosis.
• Damage to mitochondrial DNA can lead to a decaying of the mitochondria, which is a cell organelle that uses oxygen to produce energy from food. 
• The free radicals are missing an electron and create instability in surrounding molecules by taking electrons from them. 
• When gerontologists study stress, they are not just considering major life events, such as unemployment, death of a loved one, or the birth of a child. They are also including metabolic stress, the life sustaining activities of the body, such as circulating the blood, eliminating waste, controlling body temperature, and neuronal firing in the brain.
• The innate immune system is made up of the skin, mucous membranes, cough reflex, stomach acid, and specialized cells that alert the body of an impending threat. With age these cells lose their ability to communicate as effectively, making it harder for the body to mobilize its defenses. 
• The adaptive immune system includes the tonsils, spleen, bone marrow, thymus, circulatory system and the lymphatic system that work to produce and transport T cells.
• Hormonal Stress Theory, also known as Neuroendocrine Theory of Aging, suggests that as we age the ability of the hypothalamus to regulate hormones in the body begins to decline leading to metabolic problems.
• Sarcopenia is the loss of muscle tissue as a natural part of aging. Sarcopenia is most noticeable in men, and physically inactive people can lose as much as 3% to 5% of their muscle mass each decade after age 30, but even when active muscle loss still occurs.
• Cataracts are a clouding of the lens of the eye. The lens of the eye is made up of mostly water and protein. 
• Older adults are also more likely to develop age-related macular degeneration, which is the loss of clarity in the center field of vision, due to the deterioration of the macula, the center of the retina.
• A third vision problem that increases with age is glaucoma, which is the loss of peripheral vision, frequently due to a buildup of fluid in the eye that damages the optic nerve.
• Presbycusis is a common form of hearing loss in late adulthood that results in a gradual loss of hearing. It runs in families and affects hearing in both ears (NIA, 2015c). Older adults may also notice tinnitus, a ringing, hissing, or roaring sound in the ears.
• loss of smell due to aging is called presbyosmia.
• Total loss of smell, or anosmia, is extremely rare.
• osteoporosis is a disease that thins and weakens bones to the point that they become fragile and break easily. 
• As bones weaken in the spine, adults gradually lose height and their posture becomes hunched over, which is called Kyphosis.
• Chronic obstructive pulmonary disease (COPD) is a progressive lung disease in which the airways become damaged making it difficult to breathe.
• the excess of the AAT protein can lead to cirrhosis, which is a disease in which the liver becomes scarred and does not function properly
• cognitive reserve, or “the structural and dynamic capacities of the brain that buffer against atrophies and lesions” 
• Parkinson’s disease is characterized by motor tremors, loss of balance, poor coordination, rigidity, and difficulty moving.
• Similar to other adults, older adults need between 7 to 9 hours of sleep per night, but they tend to go to sleep earlier and get up earlier than those younger. This pattern is called advanced sleep phase syndrome and is based on changes in circadian rhythms. 
• There are sleep problems in older adults, and insomnia is the most common problem in those 60 and older (NIA, 2016). People with insomnia have trouble falling asleep and staying asleep.
• Sleep apnea refers to repeated short pauses in breathing, while an individual sleeps, that can lead to reduced oxygen in the blood. Snoring is a common symptom of sleep apnea and it often worsens with age.
• Restless legs syndrome feels like there is tingling, crawling, or pins and needles in one or both legs, and this feeling is worse at night. 
• Periodic limb movement disorder causes people to jerk and kick their legs every 20 to 40 seconds during sleep. 
• Rapid eye movement sleep behavior disorder occurs when one’s muscles can move during REM sleep and sleep is disrupted.
• Working memory is composed of three major systems: 

  The phonological loop that maintains information about auditory stimuli, 

  the visuospatial sketchpad, that maintains information about visual stimuli, 

  and the central executive, that oversees working memory, allocating resources where needed and monitoring whether cognitive strategies are being effective
• older adults do find that they experience more “blocks'' at retrieving information that they know. In other words, they experience more tip-of the-tongue (TOT) events than do younger adults
• Priming refers to changes in behavior as a result of frequent or recent experiences.
• Prospective memory refers to remembering things we need to do in the future, such as remembering a doctor’s appointment next week, or to take medication before bedtime
• prospective memories are often divided into time-based prospective memories, such as having to remember to do something at a future time, or 
• event-based prospective memories, such as having to remember to do something when a certain event occurs.
• The processing speed theory, proposed by Salthouse (1996, 2004), suggests that as the nervous system slows with advanced age our ability to process information declines. 
• In contrast, inhibition theory argues that older adults have difficulty with inhibitory functioning, or the ability to focus on certain information while suppressing attention to less pertinent information tasks. Evidence comes from directed forgetting research.