ALZHEIMER'S DISEASES

Alzheimer's disease (AD), also called Alzheimer disease, Senile Dementia of the Alzheimer Type (SDAT) or simply Alzheimer's, is the most common form of dementia. This incurable, degenerative, and terminal disease was first described by German psychiatrist and neuropathologist Alois Alzheimer in 1906 and was named after him.[1] Generally, it is diagnosed in people over 65 years of age,[2] although the less-prevalent early-onset Alzheimer's can occur much earlier. As of September 2009, this number is reported to be 35 million-plus worldwide.[3] The prevalence of Alzheimer's is thought to reach approximately 107 million people by 2050.[4]
Although the course of Alzheimer's disease is unique for every individual, there are many common symptoms.[5] The earliest observable symptoms are often mistakenly thought to be 'age-related' concerns, or manifestations of stress.[6] In the early stages, the most commonly recognised symptom is memory loss, such as difficulty in remembering recently learned facts. When a doctor or physician has been notified, and AD is suspected, the diagnosis is usually confirmed with behavioural assessments and cognitive tests, often followed by a brain scan if available.[7] As the disease advances, symptoms include confusion, irritability and aggression, mood swings, language breakdown, long-term memory loss, and the general withdrawal of the sufferer as their senses decline.[6][8] Gradually, bodily functions are lost, ultimately leading to death.[9] Individual prognosis is difficult to assess, as the duration of the disease varies. AD develops for an indeterminate period of time before becoming fully apparent, and it can progress undiagnosed for years. The mean life expectancy following diagnosis is approximately seven years.[10] Fewer than three percent of individuals live more than fourteen years after diagnosis.[11]
The cause and progression of Alzheimer's disease are not well understood. Research indicates that the disease is associated with plaques and tangles in the brain.[12] Currently used treatments offer a small symptomatic benefit; no treatments to delay or halt the progression of the disease are as yet available. As of 2008, more than 500 clinical trials have been conducted for identification of a possible treatment for AD, but it is unknown if any of the tested intervention strategies will show promising results.[13] A number of non-invasive, life-style habits have been suggested for the prevention of Alzheimer's disease, but there is a lack of adequate evidence for a link between these recommendations and reduced degeneration. Mental stimulation, exercise, and a balanced diet are suggested, as both a possible prevention and a sensible way of managing the disease.[14] In people with AD the increasing impairment of learning and memory eventually leads to a definitive diagnosis. In a small proportion of them, difficulties with language, executive functions, perception (agnosia), or execution of movements (apraxia) are more prominent than memory problems.[26] 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.[27][28] Language problems are mainly characterised by a shrinking vocabulary and decreased word fluency, which lead to a general impoverishment of oral and written language.[26][29] In this stage, the person with Alzheimer's is usually capable of adequately communicating basic ideas.[26][29][30] 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.[26] 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.[26]Progressive deterioration eventually hinders independence; with subjects being unable to perform most common activities of daily living.[26] 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.[26][30] Complex motor sequences become less coordinated as time passes and AD progresses, so the risk of falling increases.[26] During this phase, memory problems worsen, and the person may fail to recognise close relatives.[26] Long-term memory, which was previously intact, becomes impaired.[26] Behavioural and neuropsychiatric changes become more prevalent. Common manifestations are wandering, irritability and labile affect, leading to crying, outbursts of unpremeditated aggression, or resistance to caregiving.[26] Sundowning can also appear.[31] Approximately 30% of patients develop illusionary misidentifications and other delusional symptoms.[26] Subjects also lose insight of their disease process and limitations (Anosognosia).[26] Urinary incontinence can develop.[26] These symptoms create stress for relatives and caretakers, which can be reduced by moving the person from home care to other long-term care facilities.[26][32]
During this last stage of AD, the patient is completely dependent upon caregivers.[26] Language is reduced to simple phrases or even single words, eventually leading to complete loss of speech.[26][30] Despite the loss of verbal language abilities, patients can often understand and return emotional signals.[26] Although aggressiveness can still be present, extreme apathy and exhaustion are much more common results.[26] Patients will ultimately not be able to perform even the most simple tasks without assistance.[26] Muscle mass and mobility deteriorate to the point where they are bedridden, and they lose the ability to feed themselves.[26] AD is a terminal illness with the cause of death typically being an external factor such as infection of pressure ulcers or pneumonia, not by the disease itself.[26]