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Alzheimer's disease (AD), also known as Alzheimer's, accounts for 60% to 70% of cases of dementia. It is a chronic neurodegenerative disease that usually starts slowly and gets worse over time. The cause of Alzheimer's disease is not clear, but about 70% of the risk is believed to be genetic. Other risk factors include a history of head injuries, depression, or hypertension.
In 2015, there were approximately 48 million people worldwide with AD. It most often begins in people over 65 years of age, although 4% to 5% of cases are early-onset Alzheimer's which begin before this. It affects about 6% of people 65 years and older. In 2010, dementia resulted in about 486,000 deaths.
The most common early symptom is difficulty in remembering recent events (short-term memory loss). As the disease advances, symptoms can include:
- problems with language
- disorientation (including easily getting lost)
- mood swings
- loss of motivation
- not managing self care
- behavioral issues.
As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to nine years.
The disease process is associated with plaques and 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 ageing. Examination of brain tissue is needed for a definite diagnosis. Mental and physical exercise, and avoiding obesity may decrease the risk of AD. There are no medications or supplements that decrease risk or treatments to stop or reverse its progression, though some may temporarily improve symptoms.
Affected people increasingly rely on others for assistance, often placing a burden on the caregiver; the pressures can include social, psychological, physical, and economic elements. Exercise programmes are beneficial with respect to activities of daily living and can potentially improve outcomes. Treatment of behavioral problems or psychosis due to dementia with antipsychotics is common but not usually recommended due to there often being little benefit and an increased risk of early death.
Signs and symptoms
Early stage Alzheimer's
- Not remembering & episodes of forgetfulness
- Forgets names of family or friends
- Changes may only be noticed by close friends or relatives
- Some confusion in situations outside the familiar
Middle stage Alzheimer's
- Greater difficulty remembering recently learned information
- Deepening confusion in many circumstances
- Problems with sleep
- Trouble knowing where they are
- Poor ability to think
- Problems speaking
- Repeats same conversations
- More abusive, anxious, or paranoid
The disease course is divided into four stages, with a progressive pattern of cognitive and functional impairment.
The first symptoms are often mistakenly attributed to ageing or stress. Detailed neuropsychological testing can reveal mild cognitive difficulties up to eight years before a person fulfills the clinical criteria for diagnosis of AD. These early symptoms can affect the most complex daily living activities. The most noticeable deficit is short term memory loss, which shows up as difficulty in remembering recently learned facts and inability to acquire new information.
In people with AD, the increasing impairment of learning and memory eventually leads to a definitive diagnosis. In a small percentage, difficulties with language, executive functions, perception (agnosia), or execution of movements (apraxia) are more prominent than memory problems. AD does not affect all memory capacities equally. Older memories of the person's life (episodic memory), facts learned (semantic memory), and implicit memory (the memory of the body on how to do things, such as using a fork to eat) are affected to a lesser degree than new facts or memories.
Language problems are mainly characterized by a shrinking vocabulary and decreased word fluency, leading to a general impoverishment of oral and written language. In this stage, the person with Alzheimer's is usually capable of communicating basic ideas adequately. While performing fine motor tasks such as writing, drawing or dressing, certain movement coordination and planning difficulties (apraxia) may be present, but they are commonly unnoticed. As the disease progresses, people with AD can often continue to perform many tasks independently, but may need assistance or supervision with the most cognitively demanding activities.
Progressive deterioration eventually hinders independence, with subjects being unable to perform most common activities of daily living. Speech difficulties become evident due to an inability to recall vocabulary, which leads to frequent incorrect word substitutions (paraphasias). Reading and writing skills are also progressively lost. Complex motor sequences become less coordinated as time passes and AD progresses, so the risk of falling increases. During this phase, memory problems worsen, and the person may fail to recognize close relatives. Long-term memory, which was previously intact, becomes impaired.
Behavioral changes become more common, they include:
- unpremeditated aggression
- resistance to care giving
- Sun downing can also appear.
- Approximately 30% of people with AD develop illusionary misidentifications and other delusional symptoms.
- Subjects also lose insight of their disease process and limitations (anosognosia).
- Urinary incontinence can develop.
These symptoms create stress for relatives and carers, which can be reduced by moving the person from home care to other long-term care facilities
During the final stages, the patient is completely dependent upon caregivers. Language is reduced to simple phrases or even single words, eventually leading to complete loss of speech. Despite the loss of verbal language abilities, people can often understand and return emotional signals. Although aggressiveness can still be present, extreme apathy and exhaustion are much more common symptoms. People with Alzheimer's disease will ultimately not be able to perform even the simplest tasks independently; muscle mass and mobility deteriorate to the point where they are bedridden and unable to feed themselves. The cause of death is usually an external factor, such as infection of pressure ulcers or pneumonia, not the disease itself.
Alzheimer's disease is usually diagnosed based on the person's medical history, history from relatives, and behavioral observations. The presence of characteristic neurological and neuropsychological features and the absence of alternative conditions is supportive.Advanced medical imaging with computed tomography (CT) or magnetic resonance imaging (MRI), and with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) can be used to help exclude other cerebral pathology or subtypes of dementia. Moreover, it may predict conversion from prodromal stages (mild cognitive impairment) to Alzheimer's disease.
Assessment of intellectual functioning including memory testing can further characterize the state of the disease. Medical organizations have created diagnostic criteria to ease and standardize the diagnostic process for practicing physicians. The diagnosis can be confirmed with very high accuracy post-mortem when brain material is available and can be examined histologically.
Further neurological examinations are crucial in the differential diagnosis of AD and other diseases. Supplemental testing provides extra information on some features of the disease or is used to rule out other diagnoses. Blood tests can identify other causes for dementia than AD, causes which may, in rare cases, be reversible. It is common to perform thyroid function tests, assess B12, rule out syphilis, rule out metabolic problems (including tests for kidney function, electrolyte levels and for diabetes), assess levels of heavy metals (e.g. lead, mercury) and anemia. (It is also necessary to rule out delirium).
Individuals with Down Syndrome have an extra gene copy, they almost universally exhibit at least the earliest symptoms of AD by 40 years of age.
Studies using MRI and PET have documented reductions in the size of specific brain regions in people with AD as they progressed from mild cognitive impairment to Alzheimer's disease, and in comparison with similar images from healthy older adults.
At present, there is no definitive evidence to support that any particular measure is effective in preventing AD, but people who engage in intellectual activities such as reading, playing board games, completing crossword puzzles, playing musical instruments, or regular social interaction have shown a reduced risk for Alzheimer's disease. Education delays the onset of AD syndrome, Learning a second language even later in life seems to delay getting Alzheimer disease. Physical activity is also associated with a reduced risk of AD.
Stimulation-oriented treatments include art, music and pet therapies, exercise, and any other kind of recreational activities. Stimulation has modest support for improving behaviour, mood, and, to a lesser extent, function. Nevertheless, as important as these effects are, the main support for the use of stimulation therapies is the change in the person's routine.
Conclusions on dietary components have at times been difficult to ascertain as results have differed between population groups, but:
- People who eat a healthy, Japanese, or Mediterranean diet have a lower risk of AD.
- A Mediterranean diet may improve outcomes in those with the disease.
- Those who eat a diet high in saturated fats and simple carbohydrates (mono- and disaccharide) have a higher risk.
- Light to moderate use of alcohol, particularly red wine, is associated with lower risk of AD.
- A number of foods high in flavonoids such as cocoa, red wine, and tea may decrease the risk of AD.
Since Alzheimer's has no cure and it gradually renders people incapable of tending for their own needs, caregiving essentially is the treatment and must be carefully managed over the course of the disease.
During the early and moderate stages, modifications to the living environment and lifestyle can increase patient safety and reduce caretaker burden.
Examples of such modifications are:
- the adherence to simplified routines
- the placing of safety locks
- the labelling of household items to cue the person with the disease or the use of modified daily life objects.
- If eating becomes problematic, food will need to be prepared in smaller pieces or even pureed.
- When swallowing difficulties arise, the use of feeding tubes may be required. In such cases, the medical efficacy and ethics of continuing feeding is an important consideration of the caregivers and family members.
- The use of physical restraints is rarely indicated in any stage of the disease, although there are situations when they are necessary to prevent harm to the person with AD or their caregivers.
When People with Alzheimer's develop problems with eating, due to difficulties in swallowing, reduced appetite or the inability to recognise food. Their carers and families often request they have some form of feeding tube. However, there is no evidence that this helps people with advanced Alzheimer's to gain weight, regain strength or improve their quality of life. In fact, their use might carry an increased risk of aspiration pneumonia. Use of physical restraints can increase the risk of pressure ulcers.
As the disease progresses, different medical issues can appear, such as:
- oral and dental disease
- pressure ulcers
- hygiene problems
- respiratory, skin, or eye infections.
Careful management can prevent them, while professional treatment is needed when they do arise. During the final stages of the disease, treatment is centred on relieving discomfort until death, often with the help of hospice.
The role of the main caregiver is often taken by the spouse or a close relative. Alzheimer's disease is known for placing a great burden on caregivers which includes social, psychological, physical or economic aspects. Home care is usually preferred by people with AD and their families. This option also delays or eliminates the need for more professional and costly levels of care. Nevertheless, two-thirds of nursing home residents have dementias.
Dementia caregivers are subject to high rates of physical and mental disorders. Factors associated with greater psychosocial problems of the primary caregivers include having an affected person at home, the carer being a spouse, demanding behaviours of the cared person such as depression, behavioural disturbances, hallucinations, sleep problems or walking disruptions and social isolation. Regarding economic problems, family caregivers often give up time from work to spend 47 hours per week on average with the person with AD, while the costs of caring for them are high.