8.8: Cognitive Function in Late Adulthood

Learning Outcomes

• Describe abnormal memory loss due to Alzheimer’s disease, delirium, and dementia

Abnormal Loss of Cognitive Functioning During Late Adulthood

Dementia is the umbrella category use to describe the general long-term and often gradual decrease in the ability to think and remember that affects a person’s daily functioning. The manual used to help classify and diagnose mental disorders, the Diagnostic and Statistical Manual of Mental Disorders, or DSM-V -TR, classifies dementia as “major neurocognitive disorder, with milder symptoms classified as “mild cognitive impairment,” although the term dementia is still in common use. 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 which 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, 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.^[1]

The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing self care, and behavioral issues. In the early stages, memory loss is mild, but with late-stage Alzheimer’s, individuals lose the ability to carry on a conversation and respond to their environment.

Figure 1. Alzheimer’s disease is not simply part of the aging process. It is a disease with physiological symptoms and decay in the brain.

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).^[2]

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 and 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.

Parkinson’s Disease

Parkinson’s disease (PD) is a long-term degenerative disorder of the central nervous system which mainly affects the motor system, although as the disease worsens, non-motor symptoms become increasingly common. Early in the disease, the most obvious symptoms are shaking, rigidity, slowness of movement, and difficulty with walking, but thinking and behavioral problems may also occur. Dementia becomes common in the advanced stages of the disease, and depression and anxiety also occur in more than a third of people with PD.

The cause of Parkinson’s disease is generally unknown, but believed to involve both genetic and environmental factors. Those with a family member affected are more likely to get the disease themselves. There is also an increased risk in people exposed to certain pesticides and among those who have had prior head injuries, while there is a reduced risk in tobacco smokers (though smokers are at a substantially greater risk of stroke) and those who drink coffee or tea. The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain, which results in not enough dopamine in these areas. The reason for this cell death is poorly understood, but involves the build-up of proteins into Lewy bodies in the neurons.

In 2015, PD affected 6.2 million people and resulted in about 117,400 deaths globally. Parkinson’s disease typically occurs in people over the age of 60, of which about one percent are affected. Males are more often affected than females at a ratio of around 3:2. The average life expectancy following diagnosis is between 7 and 14 years. People with Parkinson’s who have increased the public’s awareness of the condition include actor Michael J. Fox, Olympic cyclist Davis Phinney, and professional boxer Muhammad Ali.

Watch It

This Ted-Ed video explains some of the history and biological diagnosis of Alzheimer’s.

Access at https://youtu.be/yJXTXN4xrI8

You can view the transcript for “What is Alzheimer’s disease? – Ivan Seah Yu Jun” here (opens in new window).

 

Link to Learning

Samuel Cohen researches Alzheimer’s disease and other neurodegenerative disorders. Listen to Cohen’s TED Talk on Alzheimer’s disease to learn more.

Try It

https://assess.lumenlearning.com/practice/41dad9c7-3d91-4eb7-9d7b-a2bb858d3703

 

Glossary

Alzheimer’s disease:
an irreversible, progressive brain disorder that slowly destroys memory and thinking skills, and eventually the ability to carry out the simplest tasks

delirium:
an abrupt change in the brain that causes mental confusion and emotional disruption. It makes it difficult to think, remember, sleep, pay attention, and more

dementia:
a cause of neurocognitive disorder, characterized by progressive and gradual cognitive deficits due to severe cerebral atrophy

Parkinson’s disease:
long-term degenerative disorder of the central nervous system which mainly affects the motor system, first characterized by shaking, rigidity, slowness of movement, and difficulty with walking, but thinking and behavioral problems may also occur

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1. What is Alzheimer's? Alzheimer's Association. Retrieved from https://www.alz.org/alzheimers-dementia/what-is-alzheimers↵
2. What is Alzheimer's? Alzheimer's Association. Retrieved from https://www.alz.org/alzheimers-dementia/what-is-alzheimers. ↵

Contributors and Attributions

CC licensed content, Original

• Modification, adaptation, and original content. Authored by: Sonja Ann Miller for Lumen Learning. Provided by: Lumen Learning. License: CC BY: Attribution

CC licensed content, Shared previously

• Psyc 200 Lifespan Psychology. Authored by: Laura Overstreet. Located at: http://opencourselibrary.org/econ-201/. License: CC BY: Attribution
• Alzheimer's Disease. Provided by: Wikipedia. Located at: https://en.Wikipedia.org/wiki/Alzheimer%27s_disease. License: CC BY-SA: Attribution-ShareAlike
• Delirium. Provided by: Wikipedia. Located at: https://en.Wikipedia.org/wiki/Delirium. License: CC BY-SA: Attribution-ShareAlike

All rights reserved content

• What is Alzheimer's. Provided by: Ted-Ed. Located at: https://www.youtube.com/watch?v=yJXTXN4xrI8. License: All Rights Reserved

Public domain content

• Alzheimer's disease brain comparison.jpg. Authored by: Garrando. Provided by: Wikipedia. Located at: https://en.Wikipedia.org/wiki/Dementia#/media/File:Alzheimer%27s_disease_brain_comparison.jpg. License: Public Domain: No Known Copyright