9.5 Alzheimer’s Disease
Dementia is a general term that refers to a decline in cognitive ability severe enough to interfere with a person’s ability to complete their activities of daily living. Alzheimer’s disease (AD) is the most common type of dementia, accounting for at least two thirds of cases of dementia in people aged 65 and older. AD is a neurodegenerative disease that causes progressive and disabling impairment of cognitive functions, including memory, comprehension, language, attention, reasoning, and judgment. An estimated 6.7 million Americans are living with AD.[1]
Family members commonly function as unpaid caregivers to support individuals with AD who continue to live at home, including assistance with activities of daily living (ADLs), paying bills, shopping, and preparing meals. Caregivers also provide emotional support, help manage health conditions, and ensure safety at home. Caregiving is time-intensive and can be physically and emotionally exhausting, causing declines in the caregiver’s health.[2] Nurses often address caregiver health when caring for clients with AD.
Pathophysiology
The brain of an older adult experiences normal physiological changes associated with aging, such as increased size of the ventricles. However, with Alzheimer’s disease and other forms of dementia, these changes occur at a much more rapid pace, along with significant atrophy of the cerebral cortex and degeneration of neurons.
The hallmark microscopic changes of AD consist of neurofibrillary tangles and neuritic plaques. Neurofibrillary tangles consist of fibrous tissue that impair the transmission of impulses from neuron to neuron. Neuronal transmission is further hindered by neuritic plaques, composed of abnormal proteins called beta amyloid and tau, that damage the neurons. See Figure 9.14[5] for an illustration of neurodegeneration caused by these abnormal proteins.
Initial neuron damage occurs in the parts of the brain responsible for memory, language, and thinking, so initial symptoms of Alzheimer’s disease are short-term memory loss and language and thinking problems. Brain changes that cause these symptoms are thought to begin 20 years or more before symptoms start.[6]
Imbalanced neurotransmitter levels are also associated with Alzheimer’s disease. For example, decreased levels of acetylcholine (ACh), norepinephrine, dopamine, and serotonin can further contribute to impaired cognition, loss of short-term/recent memory, and ability to retain new memories.
Risk Factors
The cause of Alzheimer’s disease is not certain. However, age, gender, and genetics are three major risk factors linked to AD, with increasing age being the greatest risk factor. The percentage of people with AD increases dramatically with age, with 33% of people aged 85 or older having AD. Females over 65 years old are more likely to develop AD than men, and having a first-degree relative with AD also increases one’s risk. There is also an increased incidence of AD in people wh