Ultimately, the destruction and death of neurons in AD leads to the macropathology of brain atrophy. Significant shrinkage of the hippocampus and surrounding cortex occurs as the disease progresses, and with the atrophy of the cortex, the ventricles appear larger. Although there is some variability in the clinical
course of AD, symptoms appear to develop through the same general stages. The time from diagnosis to death varies and can be as short as 3 years or as long as 20 years, with average survival after diagnosis being 4 to 8 years (Alzheimer’s Association, 2018a).
STAGES OF ALZHEIMER’S DISEASE
● Trouble handling money and paying bills. ● Poor judgment leading to bad decisions. ● Loss of spontaneity and sense of initiative. ● Mood and personality changes. ● Increased anxiety. ● Beginning to abandon hobbies and interests.
The brain changes that occur in AD are associated with distinct symptoms and behavior changes that progress throughout the course of the disease. Behavior is the result of complex brain processes. In AD, the disturbance of many of these processes is the basis for distressing or inappropriate behaviors. For example, an individual with AD may angrily refuse to take a bath or get dressed because he or she does not understand or forgets what the caregiver has asked. The anger is a mask for confusion and anxiety. Another individual with AD may constantly follow his or her spouse and display heightened anxiety when the person is out of sight. To an individual who cannot remember the past or anticipate the future, the world can be strange and frightening. Sticking close to a trusted and familiar caregiver may be the only thing that makes sense and provides security. Taking off clothes may seem reasonable to a person with AD who feels hot and does not understand or remember that undressing in public is not acceptable. Clinical staging can include three or seven stages of disease. The seven-stage model is based on the work of Barry Reisberg (Reisberg, Ferris, & Franssen, 1985) and is a useful framework for education on the progression of the disease and categorizing function for rehabilitation studies. The seven stages are: 1. No impairment (normal function). 2. Very mild cognitive impairment (may be normal changes of aging, e.g., subjective difficulty in word finding, forgetfulness). 3. Mild cognitive decline (may be incipient AD, e.g., difficulty in a challenging work environment). 4. Moderate cognitive decline (mild or early-stage AD, e.g., difficulty in complex tasks such as balancing a checkbook, planning a party). 5. Moderately severe cognitive decline (moderate or midstage AD, e.g., requires assistance choosing appropriate clothing). 6. Severe cognitive decline (moderately severe or late midstage AD, e.g., requires assistance with acts of dressing, bathing, toileting). 7. Very severe cognitive decline (severe or end-stage AD, e.g., loss of ability to communicate, ambulate, interact). A widely used, more simplified model identifies three major stages of disease: mild, moderate, and severe. The first noticeable signs of memory loss and decreased cognitive abilities mark the mild stage. The growing number of plaques and tangles first damage areas of the brain that control memory and, to a lesser extent, language and reasoning. Obvious physical problems are not clinically apparent at this stage, although subclinical gait and balance deficits are likely present. This leads to a situation in mild AD in which a person seems to be healthy but is actually having increasing trouble making sense of the world. The realization that something is wrong often comes gradually because the early signs may be confused with normal aging. Accepting these signs and deciding to go for diagnostic tests can be difficult for patients and families to face. The clinical diagnosis of AD is usually made during this mild stage. The signs and symptoms of mild AD can include: ● Memory loss. ● Confusion about the location of familiar places (getting lost begins to occur). ● Taking longer to accomplish normal daily tasks and may need prompting.
By the moderate stage of AD, the damage has spread to the areas of the cerebral cortex that control language, reasoning, sensory processing, and conscious thought. Affected regions continue to atrophy, and signs and symptoms become more pronounced and widespread. Behavior problems such as wandering and agitation can occur. More intensive supervision and care of the person – which can be difficult for many spouses and families – become necessary. The signs and symptoms of moderate-stage AD can include: ● Increasing memory loss and confusion. ● Shortened attention span. ● Problems recognizing friends and family members. ● Difficulty with language. ● Problems with reading, writing, and working with numbers. ● Difficulty organizing thoughts and thinking logically. ● Inability to learn new things or to cope with new or unexpected situations. ● Restlessness, agitation, anxiety, tearfulness, and wandering – especially in the late afternoon or at night (sundowning). ● Repetitive statements or movements. ● Hallucinations, delusions, suspiciousness or paranoia, and irritability. ● Loss of impulse control (e.g., sloppy table manners, undressing at inappropriate times or places, use of profanity). ● Perceptual-motor problems (e.g., trouble with self-care skills or chores, such as setting the table). In the severe stage of AD, plaques and tangles are widespread throughout the brain, and areas of the brain have atrophied significantly. At this stage, individuals with AD generally cannot recognize family and loved ones or communicate in any meaningful way, and the sense of self seems to vanish; these individuals are completely dependent on others for care. Multiorgan system complications of immobility abound. Other signs and symptoms of the severe stage can include: ● Accelerating weight loss. ● Dysphagia. ● Seizures. ● Groaning, moaning, or grunting. ● Increased sleeping. ● Lack of bladder and bowel control. During the final stage, patients may be in bed much or all of the time. AD can be the primary cause of death (i.e., brain function can no longer support the living being), but more often, individuals with AD die from a secondary illness or event, likely related to immobility and/or decreased function caused by AD. Common causes of death include aspiration pneumonia, sepsis (from urinary tract infection or decubitus ulcer), and malnutrition (related to dysphagia). Individuals with AD are likely to spend the final stages of the disease in a nursing home; an estimated 75% of people with AD will be admitted into a nursing home by age 80 years, compared to 4% of the general population (Alzheimer’s Association, 2018a).
ETIOLOGY OF ALZHEIMER’S DISEASE
The exact cause of AD is not known; however, it is clear that the disease develops because of a complex series of events that take place in the brain over a long period of time. Current
research into the causes of AD focuses on a variety of factors, including genetics, neurotransmitters, beta-amyloid, tau, and neurofibrillary tangles. The discovery that early-onset AD
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