11.3 Cognitive Development in Late Adulthood

What are cognitive changes in late adulthood?

There are many stereotypes regarding older adults– as forgetful and confused, but what does the research on memory and cognition in late adulthood reveal? Memory comes in many types, such as working, episodic, semantic, implicit, and prospective. There are also many processes involved in memory. Thus it should not be a surprise that there are declines in some types of memory and memory processes, while other areas of memory are maintained or even show some improvement with age.

In this section, we will focus on changes in memory, attention, problem-solving, intelligence, post-formal cognition, and wisdom in the elderly, including the effects of stereotypes that exaggerate these losses.

Cognitive Development and Memory in Late Adulthood

Brain Functioning

Research has demonstrated that the brain loses 5% to 10% of its weight between 20 and 90 years of age (Fjell & Walhovd, 2010). This decrease in brain volume appears to be due to the shrinkage of neurons, decreases in the number of synapses, and increasingly shorter axon lengths. According to Garrett (2015), normal declines in cognitive ability throughout the lifespan are associated with brain changes, including reduced activity of genes involved in memory storage, synaptic pruning, plasticity, and glutamate and GABA (neurotransmitters) receptors.

There is also a loss in white matter connections between brain areas. Without myelin, neurons demonstrate slower conduction and impede each other’s actions. A loss of synapses occurs in specific brain areas, including the hippocampus (involved in memory) and the basal forebrain region. Older individuals also activate larger regions of their attentional and executive networks, located in the parietal and prefrontal cortex, when they perform complex tasks. This increased activation coincides with reduced performance on both executive tasks and tests of working memory when compared to that of younger people (Kolb & Whishaw, 2011).

Continued Neurogenesis. Researchers at the University of Chicago found that new neurons continue to form in old age. Tobin et al. (2019) examined the post-mortem brain tissue of individuals between the ages of 79 and 99 (average age 90.6) and found evidence of neurogenesis in the hippocampus. Approximately 2000 neural progenitor cells and 150.000 developing neurons were found per brain, although the number of developing neurons was lower in people with cognitive impairments or Alzheimer’s disease. Tobin et al. hypothesized that the lower levels of neurogenesis in the hippocampus were associated with symptoms of cognitive decline and reduced synaptic plasticity.

The brain in late adulthood also exhibits considerable plasticity, and through practice and training, the brain can be modified to compensate for any age-related changes (Erber & Szuchman, 2015). Park and Reuter-Lorenz (2009) proposed the Scaffolding Theory of Aging and Cognition, which states that the brain adapts to neural atrophy (dying of brain cells) by building alternative connections, referred to as scaffolding. This scaffolding allows older brains to retain high levels of performance. Brain compensation is especially noted in the additional neural effort demonstrated by those individuals who are aging well. For example, older adults who performed just as well as younger adults on a memory task used both prefrontal areas, while only the right prefrontal cortex was used in younger participants (Cabeza, Anderson, Locantore, & McIntosh, 2002). Consequently, this decrease in brain lateralization appears to assist older adults with their cognitive skills.

Healthy Brain Functioning. In longitudinal studies, Cheng (2016) found that both physical activity and stimulating cognitive activity resulted in significant reductions in the risk of neurocognitive disorders. Physical activity, especially aerobic exercise, is associated with less age-related gray and white matter loss, as well as diminished neurotoxins in the bra

Overall, physical activity preserves the integrity of neurons and brain volume. Cognitive training improves the efficiency of the prefrontal cortex and executive functions, such as working memory, and strengthens the plasticity of neural circuits. Both activities support cognitive reserve, or “the structural and dynamic capacities of the brain that buffer against atrophies and lesions” (Cheng, 2016, p. 85). Although it is optimal to begin physical and cognitive activities earlier in life, it is never too late to start these programs to improve one’s cognitive health, even in late adulthood.

Can we improve brain functioning? Many training programs have been created to improve brain functioning. ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly), a study conducted between 1999 and 2001 in which 2,802 individuals aged 65 to 94, suggests that the answer is “yes”. These racially diverse participants received 10 group training sessions and 4 follow-up sessions to work on tasks of memory, reasoning, and speed of processing. These mental workouts improved cognitive functioning even 5 years later. Many of the participants believed that this improvement could be seen in everyday tasks as well (Tennstedt et al., 2006).

However, programs for the elderly on memory, reading, and processing speed training demonstrate that there is improvement on the specific tasks trained, but there is no generalization to other abilities (Jarrett, 2015). Further, these programs have not been shown to delay or slow the progression of Alzheimer’s disease. Although these programs are not harmful, “physical exercise, learning new skills, and socializing remain the most effective ways to train your brain” (p. 207). These activities appear to build a reserve to minimize the effects of primary aging of the brain.

How does aging affect Information Processing?

Aging may cause small decrements in the sensitivity of the senses. To the extent that a person has a more difficult time hearing or seeing, that information will not be stored in memory. This is an important point because many older people assume that if they cannot remember something, it is because their memory is poor. In fact, it may be that the information was never seen or heard.

The Working Memory

Older people have more difficulty using memory strategies to recall details (Berk, 2007). Working memory is a cognitive system with a limited capacity responsible for temporarily holding information available for processing. It is the more active, effortful part of our memory system.

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 (Schwartz, 2011).

As we age, our working memory loses some capacity. This makes it more difficult to concentrate on more than one thing at a time or to remember details of an event. However, people often compensate for this by writing down information and avoiding situations where there is too much going on at once to focus on a particular cognitive task.

When an elderly person demonstrates difficulty with multi-step verbal information presented quickly, the person is exhibiting problems with working memory. Working memory is among the cognitive functions most sensitive to decline in old age. Several explanations have been offered for this decline in memory functioning; one is the processing speed theory of cognitive aging by Tim Salthouse. Drawing on the findings of the general slowing of cognitive processes as people grow older, Salthouse (1996) argues that slower processing causes working memory contents to decay, thus reducing effective capacity. For example, if an elderly person is watching a complicated action movie, they may not process the events quickly enough before the scene changes, or they may process the events of the second scene, which causes them to forget the first scene. The decline of working-memory capacity cannot be entirely attributed to cognitive slowing, however, because capacity declines more in old age than speed.

Another proposal is the inhibition hypothesis advanced by Lynn Hasher and Rose Zacks. This theory assumes a general deficit in old age in the ability to inhibit irrelevant information. Therefore, working memory tends to be cluttered with irrelevant content, which reduces the effective capacity for relevant content. The assumption of an inhibition deficit in old age has received much empirical support, but so far, it is not clear whether the decline in inhibitory ability fully explains the decline of working memory capacity.

Robert West (1996) proposed an explanation of the neural level of the decline of working memory and other cognitive functions in old age. Age-related decline in working memory can be briefly reversed using low-intensity transcranial stimulation, synchronizing rhythms in bilateral frontal and left temporal lobe areas.

The Long-Term Memory

Long-term memory involves the storage of information for long periods of time. It is divided into 

• Explicit (requires conscious effort to create and retrieve)
  • Semantic (knowledge of facts)
  • Episodic (memories of specific events)
• Implicit (stored procedural skills, classical conditioning, and priming)

Semantic and episodic memory is part of the explicit memory system, which requires conscious effort to create and retrieve. Several studies consistently reveal that episodic memory shows greater age-related declines than semantic memory (Schwartz, 2011; Spaniol, Madden, & Voss, 2006).

Retrieving such information depends on how well it was learned in the first place rather than how long it has been stored. If information is stored effectively, an older person may remember facts, events, names, and other types of information stored in long-term memory throughout life. The memory of adults of all ages seems to be similar when they are asked to recall the names of teachers or classmates. And older adults remember more about their early adulthood and adolescence than about middle adulthood (Berk, 2007).  Older adults retain semantic memory or the ability to remember vocabulary.

Prospective memory refers to remembering things we need to do in the future, such as remembering a doctor’s appointment or taking medication before bedtime. It has been described as “the flip side of episodic memory” (Schwartz, 2011, p. 119). Episodic memories are the recall of events in our past, while the focus of prospective memories is on events in our future. In general, humans are fairly good at prospective memory if they have little else to do in the meantime. However, when there are competing tasks that also demand our attention, this type of memory rapidly declines. One explanation given for this phenomenon is that this form of memory draws on the central executive of working memory, and when this component of working memory is absorbed in other tasks, our ability to remember to do something else in the future is more likely to slip out of memory (Schwartz, 2011).

Implicit memory requires little conscious effort and often involves skills or more habitual patterns of behavior. This type of memory shows few declines with age. Many studies assessing implicit memory measure the effects of priming. Priming refers to changes in behavior as a result of frequent or recent experiences. for example, if you were shown pictures of food and asked to rate their appearance and then later were asked to complete words such as s_ _ p, you may be more likely to write “soup” than “soap” or “ship.” The images of food “primed” your memory for words connected to food. Does this type of memory and learning change with age? The answer is typically “no” for most older adults (Schacter, Church, & Osowiecki, 1994).

Younger adults rely more on mental rehearsal strategies to store and retrieve information. Older adults rely more on external cues such as familiarity and context to recall information and they are more likely to report the main idea of a story rather than all of the details (Berk, 2007).

A positive attitude about being able to learn and remember plays an important role in memory. When people are under stress (perhaps feeling stressed about memory loss), they have a more difficult time taking in information because they are preoccupied with anxieties. Many of the laboratory memory tests require comparing the performance of older and younger adults on timed memory tests in which older adults do not perform as well. However, few real-life situations require speedy responses to memory tasks. Older adults rely on more meaningful cues to remember facts and events without any impairment to everyday living.

Recall versus Recognition. Memory performance often depends on whether older adults are asked to simply recognize previously learned material or recall material on their own. Generally, for all humans, recognition tasks are easier because they require less cognitive energy. Older adults show roughly equivalent memory to young adults when assessed with a recognition task (Rhodes, Castel, & Jacoby, 2008). However, in recall tasks, older adults show memory deficits in comparison to younger adults. While the effect is initially not that large, starting at age 40, adults begin to show regular age-graded declines in recall memory compared to younger adults (Schwartz, 2011).

New Research on Aging and Cognition

Can the brain be trained in order to build cognitive reserve to reduce the effects of normal aging? ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly), a study conducted between 1999 and 2001 in which 2,802 individuals aged 65 to 94, suggests that the answer is “yes.” These participants received 10 group training sessions and 4 follow-up sessions to work on tasks of memory, reasoning, and speed of processing. These mental workouts improved cognitive functioning even 5 years later. Many of the participants believed that this improvement could be seen in everyday tasks as well. (Tennstedt et al., 2006). Learning new things, engaging in activities that are considered challenging, and being physically active at any age may build a reserve to minimize the effects of primary aging of the brain.

Changes in Attention and Problem Solving

Changes in Attention in Late Adulthood. Changes in sensory functioning and speed of processing information in late adulthood often translate into changes in attention (Jefferies et al., 2015).

Research has shown that older adults are less able to selectively focus on information while ignoring distractors (Jefferies et al., 2015; Wascher, Schneider, Hoffman, Beste, & Sänger, 2012), although Jefferies and her colleagues found that when given double time, older adults could perform at the same level as young adults. Other studies have also found that older adults have greater difficulty shifting their attention between objects or locations (Tales, Muir, Bayer, & Snowden, 2002).

For example, older adults show significant impairments in attentional tasks such as looking at a visual cue at the same time as listening to an auditory cue because it requires dividing or switching attention among multiple inputs. Deficits found in many tasks, such as the Stroop task, which measures selective attention, can be largely attributed to a general slowing of information processing in older adults rather than to selective attention deficits per se. They also are able to maintain concentration for an extended period of time. In general, older adults are not impaired on tasks that test sustained attention, such as watching a screen for an infrequent beep or symbol. The tasks on which older adults show impairments tend to be those that require flexible control of attention, a cognitive function associated with the frontal lobes. Importantly, these types of tasks appear to improve with training and can be strengthened (Glisky, 2007).

Consider the implication of these attentional changes for older adults.  How does maintenance or loss of cognitive ability affect older adults’ everyday lives?

An important conclusion from research on changes in cognitive function as we age is that attentional deficits can have a significant impact on an older person’s ability to function adequately and independently in everyday life. One important aspect of daily functioning impacted by attentional problems is driving. This is an activity that, for many older people, is essential to independence. Driving requires a constant switching of attention in response to environmental contingencies. Attention must be divided between driving, monitoring the environment, and sorting out relevant from irrelevant stimuli in a cluttered visual array. Research has shown that divided attention impairments are significantly associated with increased automobile accidents in older adults (McDowd & Shaw, 2000).  Therefore, practice and extended training on driving simulators under divided attention conditions may be an important remedial activity for older people (Park & Gutchess, 2000). 

Problem Solving. Declines with age are found on problem-solving tasks that require processing non-meaningful information quickly– a kind of task that might be part of a laboratory experiment on mental processes. However, many real-life challenges facing older adults do not rely on the speed of processing or making choices on one’s own. Older adults resolve everyday problems by relying on input from others, such as family and friends. They are also less likely than younger adults to delay making decisions on important matters, such as medical care (Strough, Hicks, Swenson, Cheng & Barnes, 2003; Meegan & Berg, 2002).

What might explain these deficits as we age?

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. This slowing of processing speed may explain age differences in a variety of cognitive tasks. For instance, as we age, working memory becomes less efficient (Craik & Bialystok, 2006). Older adults also need longer time to complete mental tasks or make decisions. Yet, when given sufficient time (to compensate for declines in speed), older adults perform as competently as young adults (Salthouse, 1996). Thus, when speed is not imperative to the task, healthy older adults generally do not show cognitive decline.

In contrast, inhibition theory argues that older adults have difficulty with tasks that require inhibitory functioning or the ability to focus on certain information while suppressing attention to less pertinent information (Hasher & Zacks, 1988). Evidence comes from directed forgetting research. In directed forgetting people are asked to forget or ignore some information, but not other information. For example, you might be asked to memorize a list of words but are then told that the researcher made a mistake and gave you the wrong list and asks you to “forget” this list. You are then given a second list to memorize. While most people do well at forgetting the first list, older adults are more likely to recall more words from the “directed-to-forget” list than younger adults (Andrés, Van der Linden, & Parmentier, 2004).

Do aging stereotypes exaggerate cognitive losses?

While there are information processing losses in late adulthood, many argue that research exaggerates normative losses in cognitive functioning during old age  (Garrett, 2015). One explanation is that the types of tasks that people are tested on tend to be meaningless. For example, older individuals are not motivated to remember a random list of words in a study; they are motivated for more meaningful material related to their lives and consequently perform better on those tests.

Another reason is that researchers often estimate age declines from age differences found in cross-sectional studies. However, when age comparisons are conducted longitudinally (thus removing cohort differences from age comparisons), the extent of loss is much smaller (Schaie, 1994).

A third possibility is that losses may be due to the disuse of various skills. When older adults are given structured opportunities to practice skills, they perform as well as they had previously. Although diminished speed is especially noteworthy during late adulthood, Schaie (1994) found that when the effects of speed are statistically removed, fewer and smaller declines are found in other aspects of an individual’s cognitive performance. In fact, Salthouse and Babcock (1991) demonstrated that processing speed accounted for all but 1% of age-related differences in working memory when testing individuals from ages  18 to 82. Finally, it is well established that hearing and vision decline as we age. Longitudinal research has found that deficits in sensory functioning explain age differences in a variety of cognitive abilities (Baltes & Lindenberger, 1997). Not surprisingly, more years of education, higher income, and better health care (which go together) are associated with higher levels of cognitive performance and slower cognitive decline (Zahodne, Stern, & Manly, 2015).

Intelligence and Wisdom

When looking at scores on traditional intelligence tests, tasks measuring verbal skills show minimal or no age-related declines, while scores on performance tests, which measure solving problems quickly, decline with age (Botwinick, 1984). This profile mirrors crystallized and fluid intelligence. As you recall from the section on middle adulthood, crystallized intelligence encompasses abilities that draw upon experience and knowledge. Measures of crystallized intelligence include vocabulary tests, solving number problems, and understanding texts. Fluid intelligence refers to information processing abilities, such as logical reasoning, remembering lists, spatial ability, and reaction time.

Baltes (1993) introduced two additional types of intelligence to reflect cognitive changes in aging. Pragmatics of intelligence is cultural exposure to facts and procedures that are maintained as one age and are similar to crystallized intelligence. Mechanics of intelligence are dependent on brain functioning and decline with age, similar to fluid intelligence. Baltes indicated that pragmatics of intelligence show a little decline and typically increase with age, whereas mechanics decline steadily, starting at a relatively young age. Additionally, the pragmatics of intelligence may compensate for the declines that occur with the mechanics of intelligence. In summary, global cognitive declines are not typical as one age, and individuals typically compensate for some cognitive declines, especially processing speed.

Wisdom has been defined as “expert knowledge in the fundamental pragmatics of life that permits exceptional insight, judgment, and advice about complex and uncertain matters” (Baltes & Smith, 1990). A wise person is insightful and has knowledge that can be used to overcome obstacles in living. Does aging bring wisdom? While living longer brings experience, it does not always bring wisdom. Paul Baltes and his colleagues (Baltes & Kunzmann, 2004; Baltes & Staudinger, 2000) suggest that wisdom is rare. In addition, the emergence of wisdom can be seen in late adolescence and young adulthood, with there being few gains in wisdom over the course of adulthood (Staudinger & Gluck, 2011). This would suggest that factors other than age are stronger determinants of wisdom. Occupations and experiences that emphasize others rather than the self, along with personality characteristics such as openness to experience and generativity, are more likely to provide the building blocks of wisdom (Baltes & Kunzmann, 2004). Age combined with certain types of experience and/or personality brings wisdom.

Sleep

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 (National Sleep Foundation, 2009).  There are sleep problems in older adults, and insomnia is the most common problem in those 60 and older (National Institute on Aging, 2016). A good night’s sleep. https://www.nia.nih.gov/health/publication/good- nights-sleep[/footnote] People with insomnia have trouble falling asleep and staying asleep. There are many reasons why older people may have insomnia, including certain medications, being in pain, having a medical or psychiatric condition, and even worrying before bedtime about not being able to sleep. Using over-the-counter sleep aids or medication may only work when used for a short time. Consequently, sleep problems should be discussed with a healthcare professional.

Also common in older adults are sleep disorders, including sleep apnea, restless legs syndrome, periodic limb movement disorder, and rapid eye movement sleep behavior disorder (National Institute on Aging, 2016).

• Sleep apnea refers to repeated short pauses in breathing while an individual sleeps, which can lead to reduced oxygen in the blood. Snoring is a common symptom of sleep apnea, and it often worsens with age. Untreated sleep apnea can lead to impaired daytime functioning, high blood pressure, headaches, stroke, and memory loss.
• 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. 

According to the National Sleep Foundation (2009), there are many medical conditions that affect sleep, including gastroesophageal reflux disease, diabetes mellitus, renal failure, respiratory diseases such as asthma, and immune disorders. Diseases such as Parkinson’s disease and multiple sclerosis also commonly cause problems sleeping. Lastly, Alzheimer’s disease can interfere with sleeping patterns. Individuals may wake up many times during the night, wander when up, and yell, which can alter the amount of time they sleep. Both minor and significant sleep problems in older adults can lead to an increased risk of accidents, falls, chronic fatigue, decreased quality of life, cognitive decline, reduced immune function, and depression (Buman, 2013).

Because of sleep problems experienced by those in late adulthood, research has looked into whether exercise can improve their quality of sleep. Results show that 150 minutes per week of exercise can improve sleep quality (Buman, 2013). This amount of exercise is also recommended to improve other health areas, including lowering the risk for heart disease, diabetes, and some cancers. Aerobic activity, weight training, and balance programs are all recommended. For those who live in assisted living facilities, even light exercise, such as stretching and short walks, can improve sleep. High-intensity activity is not necessary to see improvements. Overall, the effects of exercise on sleep may actually be even larger for older adults since their sleep quality may not be ideal to start.

Abnormal Loss of Cognitive Functioning During Late Adulthood

Parkinson’s disease

Parkinson’s disease is characterized by motor tremors, loss of balance, poor coordination, rigidity, and difficulty moving. (Garrett, 2015). Parkinson’s affects approximately 1% of those over the age of 60, and it appears more frequently in family members in a little less than 10% of cases. Twenty-eight chromosomal areas have been implicated in Parkinson’s disease, but environmental factors have also been identified, including brain injury. Being knocked unconscious once increases the risk by 32%, and being knocked out several times increases the risk by 174% (Garrett, 2015). Other environmental influences include toxins, industrial chemicals, carbon monoxide, herbicides, and pesticides (Olanow & Tatton, 1999). The symptoms are due to the deterioration of the substantia nigra, an area in the midbrain whose neurons send dopamine-releasing axons to the basal ganglia, which affect motor activity. Treatment typically includes the medication levodopa (L-dopa), which crosses the blood-brain barrier and is converted into dopamine in the brain. Deep brain stimulation, which involves inserting an electrode into the brain that provides electrical stimulation, has resulted in improved motor functioning. (Garrett, 2015).

Dementia

Historically, the term dementia was used to refer to an individual experiencing difficulties with memory, language, abstract thinking, reasoning, decision-making, and problem-solving (Erber & Szuchman, 2015). While the term is still in common use, it has been replaced by neurocognitive disorder in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) (American Psychiatric Association, 2013).

A Major Neurocognitive Disorder is diagnosed as a significant cognitive decline from a previous level of performance in one or more cognitive domains and interferes with independent functioning.

A Minor Neurocognitive Disorder is diagnosed as a modest cognitive decline from a previous level of performance in one of more cognitive domains and does not interfere with independent functioning.

There are several different neurocognitive disorders that are typically demonstrated in late adulthood, and determining the exact type can be difficult because the symptoms may overlap with each other. Diagnosis often includes a medical history, physical exam, laboratory tests, and changes noted in behavior.

Common symptoms of dementia include emotional problems, difficulties with language, and a decrease in motivation. A person’s consciousness is usually not affected. Globally, dementia affected about 46 million people in 2015. About 10% of people develop the disorder at some point in their lives, and it becomes more common with age. About 3% of people between the ages of 65–74 have dementia, 19% between 75 and 84, and nearly half of those over 85 years of age. In 2015, dementia resulted in about 1.9 million deaths, up from 0.8 million in 1990. As more people are living longer, dementia is becoming more common in the population as a whole.

Dementia generally refers to severely impaired judgment, memory, or problem-solving ability. It can occur before old age and is not an inevitable development, even among the very old. Dementia can be caused by numerous diseases and circumstances, all of which result in similar general symptoms of impaired judgment, etc. Alzheimer’s disease is the most common form of dementia and is incurable, but there are also nonorganic causes of dementia that can be prevented. Malnutrition, alcoholism, depression, and mixing medications can also result in symptoms of dementia. If these causes are properly identified, they can be treated. Cerebral vascular disease can also reduce cognitive functioning.

Delirium

Delirium, also known as acute confusional state, is an organically caused decline from a previous baseline level of mental function that develops over a short period of time, typically hours to days. It is more common in older adults but can easily be confused with a number of psychiatric disorders or chronic organic brain syndromes because of many overlapping signs and symptoms in common with dementia, depression, psychosis, etc. Delirium may manifest from a baseline of existing mental illness, baseline intellectual disability, or dementia without being due to any of these problems.

Delirium is a syndrome encompassing disturbances in attention, consciousness, and cognition. It may also involve other neurological deficits, such as psychomotor disturbances (e.g., hyperactive, hypoactive, or mixed), impaired sleep-wake cycle, emotional disturbances, and perceptual disturbances (e.g., hallucinations and delusions), although these features are not required for diagnosis. Among older adults, delirium occurs in 15-53% of post-surgical patients, 70-87% of those in the ICU, and up to 60% of those in nursing homes or post-acute care settings. Among those requiring critical care, delirium is a risk for death within the next year.

Alzheimer’s Disease

Alzheimer’s disease (AD), also referred to simply as Alzheimer’s, is the most common cause of dementia, accounting for 60-70% of its cases. Alzheimer’s is a progressive disease causing problems with memory, thinking, and behavior. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks (Alzheimer’s Association, n.d.).

Alzheimer’s disease is probably the most well-known and most common neurocognitive disorder for older individuals. In 2016, an estimated 5.4 million Americans were diagnosed with Alzheimer’s disease (Alzheimer’s Association, 2016), which was approximately one in nine aged 65 and over. By 2050, the number of people age 65 and older with Alzheimer’s disease is projected to be 13.8 million if there are no medical breakthroughs to prevent or cure the disease. Alzheimer’s disease is the 6th leading cause of death in the United States but the 5th leading cause for those 65 and older. Among the top 10 causes of death in America, Alzheimer’s disease is the only one that cannot be prevented, cured, or even slowed. Current estimates indicate that Alzheimer’s disease affects approximately 50% of those identified with a neurocognitive disorder (Cohen & Eisdorfer, 2011).

Alzheimer’s disease has a gradual onset with subtle personality changes and memory loss that differs from normal age-related memory problems occurring first. Confusion, difficulty with change, and deterioration in language, problem-solving skills, and personality become evident next. In the later stages, the individual loses physical coordination and is unable to complete everyday tasks, including self-care and personal hygiene (Erber & Szuchman, 2015). Lastly, individuals lose the ability to respond to their environment, to carry on a conversation, and eventually to control movement (Alzheimer’s Association, 2016). The disease course often depends on the individual’s age and whether they have other health conditions.

Alzheimer’s is the sixth-leading cause of death in the United States. On average, a person with Alzheimer’s lives four to eight years after diagnosis but can live as long as 20 years, depending on other factors. Alzheimer’s is not a normal part of aging. The greatest known risk factor is increasing age, and the majority of people with Alzheimer’s are 65 and older. But Alzheimer’s is not just a disease of old age. Approximately 200,000 Americans under the age of 65 have younger-onset Alzheimer’s disease (also known as early-onset Alzheimer’s).

The cause of Alzheimer’s disease is poorly understood. About 70% of the risk is believed to be inherited from a person’s parents with many genes usually involved. Other risk factors include a history of head injuries, depression, and hypertension. The disease process is associated with plaques and neurofibrillary tangles in the brain. A probable diagnosis is based on the history of the illness and cognitive testing with medical imaging and blood tests to rule out other possible causes. Initial symptoms are often mistaken for normal aging, but examination of brain tissue, specifically of structures called plaques and tangles, is needed for a definite diagnosis. Though qualified physicians can be up to 90% certain of a correct diagnosis of Alzheimer’s, currently, the only way to make a 100% definitive diagnosis is by performing an autopsy of the person and examining the brain tissue. In 2015, there were approximately 29.8 million people worldwide with AD. In developed countries, AD is one of the most financially costly diseases.

Attributions

Human Growth and Development by Ryan Newton is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License,

Individual and Family Development, Health, and Well-being by Diana Lang, Nick Cone; Laura Overstreet, Stephanie Loalada; Suzanne Valentine-French, Martha Lally; Julie Lazzara, and Jamie Skow is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License,

Human Development by Human Development Teaching & Learning Group under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License,

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