Alzheimer’s disease is a kind of dementia (AD)
Known medically as Alzheimer’s disease (AD), it is a neurological illness that often begins slowly and progresses over time.
It is the root cause of 60–70 percent of all instances of Alzheimer’s disease.
In the early stages, the most prevalent symptom is trouble recalling previous experiences.
The progression of the illness may include linguistic difficulties, disorientation (including the ability to get lost), mood fluctuations, a lack of motivation, self-neglect, and behavioral problems.
As a person’s health deteriorates, they are more likely to withdraw from family and society.
Gradually, physical functions begin to deteriorate, eventually resulting in death.
Despite the fact that the rate of progression might vary, the average life expectancy after diagnosis is three to nine years after diagnosis.
The exact causation of Alzheimer’s disease is still mostly unknown.
There are a variety of environmental and genetic risk factors that contribute to the development of the disease.
The most significant genetic risk factor is derived from an allele of the APOE gene.
Head injury history, severe depression, and high blood pressure are all risk factors to consider, as is being overweight.
It is believed that amyloid plaques, neurofibrillary tangles, and the loss of neuronal connections in the brain are the primary causes of Alzheimer’s disease.
In order to rule out other potential causes of the sickness, a likely diagnosis is made based on the history of the illness and cognitive testing, which may include include medical imaging and blood tests.
Initial symptoms are often confused for those associated with natural ageing.
It is necessary to examine brain tissue in order to make a definitive diagnosis, but this can only be done after the patient has died.
Good diet, physical exercise, and social engagement are all known to be beneficial in the ageing process, and these factors may also be beneficial in lowering the risk of cognitive decline and Alzheimer’s disease; in 2019, clinical studies were being conducted to investigate these possibilities.
There are currently no drugs or supplements that have been proved to reduce the chance of developing the condition.
There are no therapies that can halt or reverse the course of the disease, while some may temporarily alleviate symptoms.
Affected persons are more reliant on others for support, which places a significant load on those who care for them.
Pressures may come from a variety of sources, including social, psychological, physical, and economic factors.
Exercise programs may be good in terms of activities of daily living, and they may even be able to enhance results in certain cases.
When dementia causes behavioral issues or psychosis, antipsychotic medications are often used to treat the condition. However, this is not normally suggested since there is little benefit and an increased risk of early mortality.
By 2020, there will be around 50 million individuals living with Alzheimer’s disease across the globe.
Although it most often affects individuals in their late 60s and early 70s, it may affect those as young as their 30s and as old as they are.
It affects around 6% of adults over the age of 65, with women being affected more often than males.
Alois Alzheimer, a German psychiatrist and pathologist who first identified the illness in 1906, is credited with giving it its name.
Alzheimer’s disease has a significant financial impact on society, with an estimated worldwide yearly cost of US$1 trillion.
When abnormal amounts of amyloid beta (A) accumulate in the brain, either extracellularly as amyloid plaques and tau proteins or intracellularly as neurofibrillary tangles, it is thought to cause dementia. Amyloid beta (A) is thought to affect neuronal functioning and connectivity, resulting in a progressive loss of brain function.
In addition to being age-related, this reduced protein clearance capacity is also controlled by brain cholesterol and is connected with a variety of other neurodegenerative illnesses.
It is currently unclear what causes the majority of Alzheimer’s cases, with the exception of 1–2 percent of instances in which deterministic genetic abnormalities have been detected (see box).
Several conflicting ideas have been proposed in an effort to explain the underlying cause; the amyloid beta (A) hypothesis and the cholinergic theory are the two most widely accepted explanations.
A neurotransmitter called acetylcholine is thought to be responsible for Alzheimer’s disease, according to the cholinergic hypothesis.
This concept has been around for a long time and is the foundation for most pharmacological therapy today.
The loss of cholinergic neurons in the limbic system and cerebral cortex, which has been seen in Alzheimer’s patients, is a critical component of the disease’s course.
The amyloid hypothesis, first proposed in 1991, asserted that extracellular amyloid beta (A) deposits are the root cause of Alzheimer’s disease (AD).
This hypothesis is supported by the fact that the gene for the amyloid precursor protein (APP) is located on chromosome 21, as well as the fact that people with trisomy 21 (Down syndrome), who have an extra gene copy, almost universally exhibit at least the earliest symptoms of Alzheimer’s disease by the age of 40 years.
APOE4, a particular variant of the apolipoprotein, is a key genetic risk factor for Alzheimer’s disease, according to recent research.
However, although apolipoproteins aid in the breakdown of beta amyloid, certain isoforms (such as APOE4) are less successful than others at this activity, resulting in an excess of amyloid building up in the brain.
Symptoms and signs to look out for
The progression of Alzheimer’s disease is commonly divided into three phases, each characterized by a gradual pattern of cognitive and functional decline.
Early or mild, middle or moderate, and late or severe are the terms used to define the three phases.
The hippocampus, which is involved with memory, is known to be targeted by the illness, and it is this that is responsible for the first signs of memory impairment.
The severity of memory impairment increases in tandem with the progression of the illness.
The first stage signs and symptoms
Alzheimer’s disease progression through the stages of atrophy.
The earliest signs and symptoms are often misattributed to the effects of age or stress.
It is possible to detect modest cognitive impairments up to eight years before a person meets the clinical criteria for Alzheimer’s disease diagnosis with detailed neuropsychological testing.
These early signs have the potential to interfere with even the most sophisticated routines of daily life.
The most evident weakness is short-term memory loss, which manifests itself as difficulties recalling previously acquired knowledge and an inability to learn new material in a timely manner.
Subtle difficulties with executive skills such as alertness, planning, flexibility, and abstract thinking, as well as deficits in semantic memory (memory of meanings and idea links) might also be a hallmark of Alzheimer’s disease in its early stages.
Symptoms like as apathy and despair may be seen at this stage, with apathy serving as the most consistent symptom throughout the progression of the illness.
Mild cognitive impairment is another phrase used to describe the preclinical stage of the illness (MCI).
In many cases, it has been shown that this is a transitional period between normal ageing and dementia.
There are many different symptoms associated with MCI, and when memory loss is the most prominent symptom, it is referred to as amnestic MCI.
Amnestic MCI is usually viewed as a prodromal stage of Alzheimer’s disease.
Alzheimer’s disease is very likely to be accompanied with amnestic MCI, which has a higher than 90% chance of occurring.
in its infancy
In persons with Alzheimer’s disease, the progressive deterioration of learning and memory finally leads to a formal diagnosis, which is called dementia.
Only a tiny fraction of people have more severe difficulty with language, executive processes, perceptual perception (agnosia), or movement execution (apraxia) than they do with memory disorders.
It is not true that Alzheimer’s disease affects all memory skills in the same way. In contrast to fresh facts or memories, older memories of the person’s life (episodic memory), facts learnt (semantic memory), and implicit memory (the memory of the body on how to perform tasks, such as using a fork to eat or drinking from a glass) are all influenced to a lesser extent.
Language issues are primarily defined by a reduction in vocabulary size and a loss in word fluency, which results in a general impoverishment of both oral and written communication skills.
At this stage, the individual suffering from Alzheimer’s disease is typically capable of articulating fundamental thoughts satisfactorily.
Several movement coordination and planning issues (apraxia) may be present when executing fine motor activities such as writing, sketching, or dressing; however, these difficulties are often not detected until the job is completed.
Individuals suffering with Alzheimer’s disease may frequently continue to execute many chores on their own as the condition develops, although they may need aid or supervision while performing the most cognitively demanding activities.
The middle stage
The gradual degradation of independence finally results in persons being unable to carry out the majority of their everyday tasks.
Speech problems become apparent as a result of a difficulty to retain language, which results in a high frequency of inaccurate word replacements (paraphasias).
A gradual loss of reading and writing abilities also occurs.
As time passes and Alzheimer’s disease worsens, complex motor sequences become less coordinated, increasing the likelihood of tripping and sustaining injuries.
During this stage, memory issues become more severe, and the individual may find it difficult to identify close relatives.
This results in the impairment of long-term memory, which was previously intact.
Behavioral and mental abnormalities become increasingly common as the disease progresses.
Some of the most common signs include restlessness and restlessness-related sobbing, as well as unplanned outbursts of hostility and resistance to caring.
It is possible to see the sun setting.
About one-third of Alzheimer’s patients have illusionary misidentifications and other delusional symptoms, according to the Alzheimer’s Association.
Subjects also lose awareness of the progression of their sickness and their limits (anosognosia).
It is possible to develop urinary incontinence.
Towards the end stage
During the last stage, which is also known as the late-stage or severe stage, the patient is completely reliant on others for support.
Simple phrases or even single words are used instead of complex sentences, ultimately leading to the full loss of ability to speak.
Despite the loss of vocal language skills, individuals are generally able to recognize and respond to emotional cues via nonverbal communication.
Alzheimer’s disease (AD) is related with an increased risk of onset and deteriorated course when certain cardiovascular risk factors are present.
These risk factors include hypercholesterolemia, hypertension, diabetes, and smoking.
The use of statins to decrease cholesterol levels may be beneficial in the treatment of Alzheimer’s disease.
Individuals without overt cognitive impairment who use antihypertensive and antidiabetic drugs may have a lower risk of dementia because these medications have an effect on cerebrovascular pathology.
The association with Alzheimer’s disease in particular requires more investigation; clarification of the direct impact drugs play in comparison to other concurrent lifestyle modifications (diet, exercise and smoking) is required.
Alzheimer’s disease is connected with depression, and treating depression with antidepressants may be a useful prophylactic strategy in certain cases.
In the past, it was believed that long-term use of non-steroidal anti-inflammatory medicines (NSAIDs) might lower the risk of acquiring Alzheimer’s disease because they decrease inflammation; however, NSAIDs do not seem to be effective as a therapy for the condition.
As a result of the fact that women have a greater prevalence of Alzheimer’s disease than males, it was formerly believed that oestrogen insufficiency following menopause constituted a risk factor.
Although there is some evidence to suggest that hormone replacement treatment (HRT) during menopause reduces the risk of cognitive impairment, further research is needed.
The risk of developing Alzheimer’s disease may be influenced by certain lifestyle factors such as physical and cognitive exercises, higher education and occupational attainment, cigarette smoking, stress, sleep, and the management of other comorbid conditions such as diabetes, hypertension, and depression.
Physical activity is related with a lower incidence of dementia and is useful in lowering symptom severity in persons suffering from Alzheimer’s disease.
Aerobic workouts, such as brisk walking for forty minutes three times per week, may help to enhance memory and cognitive functioning.
It may also have the additional effect of increasing neuroplasticity in the brain.
It has been shown that engaging in mental activities such as reading, crossword puzzles, and chess may be beneficial in the prevention of depression.
Higher levels of education and vocational accomplishment, as well as engagement in leisure activities, all contribute to a lower chance of getting Alzheimer’s disease or to delaying the emergence of symptoms of Alzheimer’s disease.
Interestingly, this is consistent with the cognitive reserve hypothesis, which claims that some life events result in more efficient neuronal functioning, allowing the person to accumulate a cognitive reserve that delays the development of dementia symptoms.
Education may help to postpone the start of Alzheimer’s disease symptoms without altering the length of time that the illness will last.
Smoking cessation may lower the chance of acquiring Alzheimer’s disease, particularly in people who have the APOE 4 allele.
Inflammatory and neurodegenerative processes are triggered by the increased oxidative stress generated by smoking, and these processes may raise the likelihood of developing Alzheimer’s disease.
Avoidance of smoking, counselling, and pharmacotherapies to help people stop smoking are all encouraged, as is staying away from places where tobacco smoke is present.
However, the exact nature of the association between Alzheimer’s disease and sleep disturbances remains unknown.
Once upon a time, it was believed that as individuals get older, their chance of acquiring sleep problems and Alzheimer’s disease increased separately.
However, new study is investigating if sleep disorders may enhance the incidence of Alzheimer’s disease.
One explanation holds that during sleep, the systems that accelerate elimination of hazardous chemicals, including A, are in full operation.
With less sleep, a person’s A production increases while A clearance decreases, resulting in a buildup of A in the body.
Receiving proper sleep (about 7–8 hours each night) has emerged as a promising lifestyle intervention for the prevention of the development of Alzheimer’s disease (AD).
Alzheimer’s disease is associated with stress, which is a risk factor for the disease.