Alzheimer’s is a progressive neurodegenerative disease that affects the brain. Alzheimer’s disease is the most prevalent cause of dementia as it accounts for 60-80% of dementia cases. Dementia is a medical term that refers to a set of symptoms associated with a progressive deterioration of brain functions. Alzheimer’s disease usually impairs memory, reasoning, rational thinking, and other mental capacities. It is characterized by memory loss, confusion, and disorientation. Alzheimer’s usually begins slowly and gradually worsens over time. There are no known cures for this disease, but there are treatments to manage its symptoms.
I wrong with the brain of patients with Alzheimer’s disease?
There are 100 billion nerve cells in the brain (neurons). these neurons are arranged in a form of a network to perform their functions of receiving, transferring, and interpreting electrical impulses. In these neural communication networks, each nerve cell links to many others. Aside from nerve cells, the brain contains cells that are responsible for supporting and providing nourishment to other cells.
Higher brain centers are concerned with conscious mental activities such as cognition, reasoning, behaving, learning, and memory. Other brain centers may be perceptional and help in seeing, hearing, and smelling while motor centers give orders of actions to the muscles. Brain cells function similarly to little factories. They receive supplies, create energy, build equipment, and dispose of cellular wastes.
In the case of Alzheimer’s disease, some brain cells are believed to be unable to get rid of certain proteins that build up forming plaques. Plaques are made of deposits of beta-amyloid protein fragments that accumulate extra-cellularly between nerve cells. Tangles are twisted protein fibers made of a protein called tau protein that accumulates intracellularly (inside nerve cells).
After further investigations and studying of the brain cells by autopsy (taking a sample of a tissue of a dead person). The autopsy revealed that most individuals produce some plaques and tangles as they age, those with Alzheimer’s develop far more and in a regular sequence, beginning in memory-related areas before spreading to other areas.
The exact mechanism of how plaques and tangles affect brain neurons in Alzheimer’s disease is still debatable and under research. Neurologists think they impair or prevent communication between nerve cells and disturb vital processes essential for these cells to survive. Memory loss, behavioral instability, personality alterations, difficulties carrying out everyday tasks, and other symptoms of Alzheimer’s disease are caused by the damage and death of nerve cells.
Types of Alzheimer’s disease
Alzheimer’s disease has two different types according to the age at which patients get diagnosed with AD. Both of them are presented with almost the same symptoms and signs. However, neurologists may suppose that each type is related to different etiologies (causes).
1. Late-onset Alzheimer’s disease: This is the most prevalent form of Alzheimer’s disease, it affects adults aged more than 65 years old. Neither the etiology nor the pattern of inheritance of late-onset Alzheimer’s disease is known. No one can tell for sure whether this type of AD runs in families or not. So far, researchers have not identified a specific gene that causes it. The medical community isn’t clearly sure why some individuals get it while others don’t.
2. Early-onset Alzheimer’s disease: This type affects persons aged less than 65. They are usually in their 40s or 50s when they are diagnosed with the condition. Early-onset AD is an uncommon disorder as it affects less than 10% of all Alzheimer’s patients. Early onset of AD is believed to be associated with another syndrome as people with Down syndrome are more likely to develop it. It is estimated that 30% of patients with down syndrome develop AD in their 50s and 60s. People who have this type of AD usually have other brain abnormalities associated with Alzheimer’s.
According to statistical studies, Early-onset Alzheimer’s differs from other types of dementia because it is found to occur in patients with a genetic predisposition. Early-onset familial Alzheimer’s disease is believed to be inherited in an autosomal dominant pattern, which means that only one copy of a faulty gene from your parent is enough to trigger the illness.
As with most autosomal dominant diseases, most affected patients inherit the mutated gene from one affected parent unless the parents are consanguineous. Because of the clear correlation between early-onset AD and genetic background, familial Alzheimer’s disease is a derived form of early-onset AD with a low prevalence not exceeding 1% of Alzheimer’s patients. Chromosomes 14, 21and 1 are accused of carrying the diseased gene of familial AD.
Causes and risk factors
What causes Alzheimer’s? There is no specific cause of Alzheimer’s, but it can be triggered by genetics or environmental factors such as certain infections or medications that damage the immune system. The risk of developing Alzheimer’s increases with following:
1. Age is the single most significant risk factor for Alzheimer’s disease. This irreversible process affects mostly those over the age of 65. Alzheimer’s disease affects one out of every nine persons in this age group, and approximately one-third of those aged 85 and older.
2. The defective genes you inherit from your parents don’t get you Alzheimer’s disease, but they can increase your susceptibility to acquiring Alzheimer’s disease later. However, Alzheimer’s disease could be caused by the inheritance of a single mutated gene in a few families, and in such a case the potential risk of developing AD by the next generations is significantly higher.
If your siblings or other members of your family have had dementia over the generations, especially at a young age, you may need to seek genetic counseling for further investigations and guidance. Doctors always ask people with a family history of Alzheimer’s to see a neurologist to know more about their risks of having Alzheimer’s disease as they become older.
3. It has long been recognized that excessive alcohol use causes injury to the nerve cells and brain disturbances. Several extensive research and reviews revealed a relationship between excessive alcohol intake and an increased risk of dementia, particularly early-onset dementia. Unlike other types of dementia, alcohol-induced dementia is believed to be reversible in its early stage.
4. Serious head trauma and concussions could result in Alzheimer’s disease. Recent studies reported that patients aged 50 and over who experienced a traumatic brain injury (TBI) at some point throughout their life had a higher incidence of dementia and Alzheimer’s disease. People with more severe and multiple TBIs are at a higher risk. Trauma-induced AD could occur six months to 3 years after the trauma. Some neurologists still doubt the causation between trauma and AD.
5. An unhealthy lifestyle and poor sleep patterns are found to increase the risk of developing AD. False habits such as smoking, and lack of exercise could lead to different health issues including Alzheimer’s disease. Patients with Improper management of hypertension and type 2 diabetes are more exposed to getting late-onset AD. Fortunately, these factors are easily modifiable and could significantly reduce the probability of getting Alzheimer’s disease.
Alzheimer’s disease Symptoms
Unfortunately, Alzheimer’s disease has a progressive course as its symptoms usually get worsen by getting older. The rate of progression of the disease varies according to the age at which the patient is diagnosed, his general health, and the provided medical and psychological care. Subsequently, the prognosis of AD is variable as well as the life expectancy of the patients. Patients with AD are often classified according to the severity of their symptoms into three stages that we will discuss in detail.
1) Early stage
AD patients may function independently in the early stages of the disease. they can practice their daily activities such as working, driving a vehicle, and participating in social events. At this stage, Alzheimer’s disease is manifested insidiously as experiencing memory lapses, such as forgetting common phrases or misplacing items. meanwhile, only close friends and family members can notice patients’ unfamiliar behavior. It could be quite hard for the neurologists to diagnose Alzheimer’s disease at this stage because its symptoms are often misinterpreted as physiological age-related lack of concentration. AD Symptoms at this stage include:
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- Difficulties coming up with the correct term or recalling names.
- Forgetting recent conversations and phone calls.
- Forgetting what they’ve just read.
- Misplacing or losing a valuable item.
- Poor judgment and trouble making decisions as the patients may have poor and irrational choices.
- Having difficulty planning or arranging.
- Asking the same question more than once.
2) Middle stage
Middle-stage Alzheimer’s is typically the stage in which patients get diagnosed. The duration of this stage is the longest and last for a couple of years before progressing into a later stage. BY this stage, Alzheimer’s patients may not be able to carry out simple tasks, therefore they need frequent care and assistance with their daily activities. The psychological impact of Alzheimer’s in this stage is significant. Family members may notice their patient is socially withdrawn or moody most of the day. Patients’ inability to express themselves well or carry out daily routine tasks may get them frustrated, impatient, and bizarrely behaving. Common AD Symptoms at this stage may include:
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- Frequent mood swings and attacks of anxiety.
- Forgetfulness of not only recent events but also personal data such as full name, age, and phone number.
- Disorientation of person, place, and time resulting in getting lost. it is found that almost half of AD patients wander and get confused about their location.
- Repetitive, obsessive, and impulsive actions.
- Impaired ability to control urination.
- Disturbed sleep patterns.
- Delusions are reported to be a common symptom for patients with Alzheimer’s.
- Hallucinations are less commonly reported than the previously mentioned symptoms.
- Increased difficulty to recall and remember names.
3) Late-stage AD
The symptoms of Alzheimer’s disease get progressively severe in the later stages, which can be distressing and overwhelming for the patients, as well as their caregivers, friends, and family. Patients in the last stages of Alzheimer’s disease lose the capacity to respond to their surroundings and carry out daily tasks. AD patients may have impaired speech and subsequent communication with their relatives and friends. Marked disturbed behavior and delusions may get worse as the disease progress. patients can rarely still express themselves, as memory and cognitive skills deteriorate severely affecting communication skills. Not all AD patients progress to this stage of the disease but if so, they need intensive assistance with everyday tasks. Patients at this stage may show:
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- Marked confusion and disorientation of time and person.
- A greater vulnerability to infections especially pneumonia (lung inflammation).
- Significant recalling of short-term and long-term memories.
- Marked impairment of urination and bowels.
- Difficulty in eating and swallowing (dysphagia) which will eventually lead to significant loss of weight.
- Inability to identify objects.
How is Alzheimer’s disease diagnosed?
Alzheimer’s disease cannot be diagnosed with a single reliable test. If a doctor suspects the presence of the illness, he or she may question the patient, their family members, friends, and even coworkers about their symptoms, recent behavior, and medical history. A GP (general practitioner) usually conducts simple blood work and simple tests to rule out any other underlying disease.
If necessary, general practitioners might refer you to a specialist, a neurologist for instance, for evaluation and further investigations. Specialists will evaluate your cognitive functions, memory, and other mental abilities. If the mental functions revealed Impaired short-term memory and cognitive functions, it may be an indication for brain imaging to exclude brain occupying lesions.
MRI and CT of Alzheimer’s patients may show shrinkage of regions of the cerebrum, but they should be free of masses, otherwise, Alzheimer’s disease will not be at the top of the list of the differential diagnosis. Tau pet scan and amyloid pet scan are a type of brain imaging technique used to assess the amount of beta-amyloid protein and tau tangles deposited in the brain tissue.
Evidence of elevated tau and amyloid protein consistent with a history of Alzheimer’s symptoms is a hallmark of Alzheimer’s disease. Tau pet scan is also used in follow-up to assess the progression of the disease. Pet scan in addition to positive medical history provides high accuracy in the diagnosis of AD, yet pet scan isn’t available at all health facilities.
CSF (the fluid in which the brain and spinal cord are swimming) is believed to carry some chemicals that are called biomarkers by which doctors could diagnose Alzheimer’s disease. To obtain CSF, doctors perform a lumbar puncture, often known as a spinal tap.
The most commonly used CSF biomarkers for Alzheimer’s disease measure beta-amyloid (the main component of amyloid plaques in the brain), tau, and phospho-tau (primary components of tau tangles present in the brain tissue of Alzheimer’s patients). CSF biomarkers are employed in clinical practice to help in diagnosing Alzheimer’s disease or other neurodegenerative disorders. The accuracy of CSF biomarkers in diagnosing early dementia is arguable.
Treatment & social support
Treatment of Alzheimer’s disease is divided into symptoms-relieving medication and psychological support. Unfortunately, there isn’t a definitive cure for Alzheimer’s disease.
Symptomatic treatments available for AD include:
● Acetylcholinesterase inhibitor (ACHE) is a class of medications that increase the level of acetylcholine (neurotransmitter) in the brain tissue. Elevation of acetylcholine will enhance communication between the nerve cell in the brain and subsequently improve its function. Donepezil, galantamine, and rivastigmine are the most widely used ACHE in Alzheimer’s disease. The efficacy of these medications varies from one patient to another. ACHEs are believed to alleviate symptoms temporarily, yet they may not delay or prevent the brain changes that accompany Alzheimer’s.
● Memantine does not work as an ACHE inhibitor, but it works by preventing the action of a neurotransmitter in the brain known as glutamate. Memantine is approved by the FDA as a symptomatic treatment for moderate to severe Alzheimer’s disease in 2003. Memantine is effective for patients who cannot use or tolerate ACHE inhibitors.
● The Food and Drug Administration (FDA) approved aducanumab (Aduhelm) for the treatment of certain types of Alzheimer’s disease in June 2021. Aducanumab (Aduhelm) is used to delay the course of Alzheimer’s disease. It is administered slowly as an intravenous infusion once per month. Each dose takes one to three hours to administer. Aducanumab simply reaches the brain tissue, binds to deposits of amyloid protein, and then removes it. Unfortunately, aducanumab clinical studies are limited which made its FDA approval controversial. Aduhelm is also quite expensive costing around 55,000 US dollars per year.
● Anti-psychotic drugs could be prescribed to control delusions and hallucinations. A psychiatrist could also prescribe anti-depressants in case of social withdrawal and isolation.
Psychological care
There are different strategies to help someone with dementia practice his life normally. The main goal of psychological support for AD patients is to keep them as independent as possible and cope with impairments such as memory loss. Creating and reinforcing habitual habits, as well as reducing memory-demanding activities, may make life considerably simpler.
Keeping cognitively, physically, and socially active by attending cognitive rehabilitation or cognitive stimulation therapy can have a significant effect on patients suffering from Alzheimer’s disease. It is recommended for Alzheimer’s patients to keep up with activities they enjoy as well as participation in social events. If patients experience attacks of anxiety or depression their caregivers can deal with it by identifying what triggered these attacks and avoiding them.
Prevention
Alzheimer’s disease is the fifth cause of death among people aging 65 or older, therefore it is important to care about our mental health as well as our physical health to avoid its occurrence. There aren’t specific preventive measures that should be taken to avoid AD, yet enhancing daily routines and following a healthy lifestyle surely would help.
Some neurologists claim to keep mentally active throughout your life reduces your risks of developing Alzheimer’s disease.