Causes And Stages Of Alzeihmers Disease Biology Essay

Published: Last Edited:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

ABSTRACT : Alzheimer's Disease is a neurological disease majorly characterized by "decline in the brain function" and "memory loss".The disease involves mainly three stages.Different chemical factors and possibly genetic factors are responsible for causing the disease.Symptoms can be treated by provision of the sufficient supplements to reduce the risk of the disease.Techniques are also available for the treatment and detection which are being expected to be more advance in future.

KEYWORDS: Episodic memory,Beta-amyloidproteins,Pneumonia,Amyloid cascade hypothesis,Ab proteins,ApolipoproteinE(apoE),Hypertension,Omega-3 fattyacids,Dementia,Vitaminb12,Homocystein,Holotranscobalamin,MRI Techneques,Neurons,Risk markers.


"Alzheimer's disease is severly deliberating condition that affects thinking,learning and memory beginning with declines in the (1)episodic memory.

Alzheimer's disease (AD) is a slowly progressive disease of the brain that is characterized by impairment of memory and eventually by disturbances in reasoning, planning, language, and perception. Many scientists believe that Alzheimer's disease results from an increase in the production or accumulation of a specific protein(2)(beta-amyloid protein) in the brain that leads to nerve cell death.

The likelihood of having Alzheimer's disease increases substantially after the age of 70 around 50% of persons over the age of 85 may be affected by it. Nonetheless, Alzheimer's disease is not a normal part of aging and is not something that happens inevitably in later life.For example, many people live to over 100 years of age and never develop Alzheimer's disease.

Symptoms of Alzheimer's disease: Usually, the onset of Alzheimer's disease is gradual and it is slowly progressive.Most often,family members initially think memory problems as "a normal part of aging" but these problems noted by the family can be the first stages of Alzheimer's disease.When other problems along with memory problems also occur start to consistently affect the usual level of functioning;families begin to suspect that something more than "normal aging" is going on.

Commonly early memory problems in Alzheimer's disease are particularly characterized by "short-term memory".For example, the individual may, on repeated occasions, forget to turn off an iron or fail to recall which of the morning's medicines were taken.Early illness may show mild changes in personality such as less spontaneity,apathy and a tendency to withdraw from social interactions may occur. Problems in abstract thinking and in other intellectual functions also develop as the disease is progressed.The person may begin to face problems such as trouble with figures when working on bills, with understanding what is being read, or with organizing the day's work.This point of the disease may also show further disturbances in behavior and appearance, such as agitation, irritability, quarrelsomeness and a diminishing ability to dress appropriately.

Later in the course of the disorder, affected individuals may become confused or disoriented about what month or year it is, be unable to describe accurately where they live, or be unable to name a place being visited.Eventually,patients may wander, be unable to engage in conversation, erratic in mood, uncooperative and bladder and bowel control is lost. In late stages of the disease, persons may become totally incapable of caring for themselves.Cosequently,(3)pneumonia can occur which can lead to death or some other problem can occur due to severely deteriorated states of health.


There are three main stages of Alzheimer's disease.These stages are as follows:

Stage 1 (Mild): This stage can last from 2 to 4 years.Early in the illness, Alzheimer's patients tend to be less energetic and spontaneous.Minor memory loss and mood swings, slow learning and reaction are exhibited by them.They may become withdrawn,avoid people and new places and prefer the familiar.Confusion, difficulty in organizing and planning, getting lost easily and exercising poor judgment may also appear in affected individuals.They may have difficulty performing routine tasks, and have trouble communicating and understanding written material.If the person is employed, memory loss may begin to affect job performance. They can become angry and frustrated.

Some specific examples of behaviors that people exhibit in this mild stage include:

Getting lost

Difficulty managing money and paying bills

Repetitive questions and conversations

Taking longer than usual to finish routine daily tasks

Poor judgment

Losing things or misplacing them in odd places

Noticeable changes in personality or mood

Stage 2 (Moderate): This is the longest stage and can last 2 to10 years.In this stage,clear disability begins to appear in person with Alzheimer.Simple tasks can still be performed independently by the individuals,but assistance may be needed with more complicated activities.The patients forget recent events and their personal history, and more disoriention and disconnection from reality occurs in them.Memories of the distant past may be confused with the present, and cause difficulty for the affected person's to comprehend the current situation, date and time.There may be trouble in recognizing familiar people.Speech problems arise and understanding, reading and writing are more difficult, and the individual may invent words.They may no longer be safe alone and can wander. As Alzheimer's patients become aware of this loss of control, they may become depressed, irritable and restless or apathetic and withdrawn.They may experience sleep disturbances and have more trouble eating, grooming and dressing.

Stage 3 (Severe): This stage may last 1 to 3 years.During this final stage,lose of the ability to feed themselves, speak, recognize people and control bodily functions, such as swallowing or bowel and bladder control occur.The memory becomes worst and may become almost non-existent.More sleep and grunting or moaning can be common.Constant care is typically necessary.Other illnesses such as skin infections,and respiratory problems can also attack the patient in physically weakened state.

Causes of Alzheimer's disease:The cause(s) of Alzheimer's disease is (are) unknown.The most widely discussed and researched hypothes is about the cause of Alzheimer's disease is"amyloid cascade hypothesis.Early-onset inherited (genetic) Alzheimer's disease the strongest data supporting the (4)amyloid cascade hypothesis.Mutations associated with Alzheimer's disease have been found in about half of the patients with early-onset disease.In all of these patients, the mutation lead to excess production of a specific form of a small protein fragment called ABeta (Aβ)in brain.It is the believe of many scientists that there is too little removal of this (5)Aβ protein rather than too much production in majority of sporadic (for example, non-inherited) cases of Alzheimer's disease (these make up the vast majority of all cases of Alzheimer's disease).In any case, much of the research in finding ways to prevent or slow down. Alzheimer's disease has focused on ways to decrease the amount of Aβ in the brain.

Risk factors for Alzheimer's disease: Increased age is the main risk factor for Alzheimer's disease.The frequency of Alzheimer's disease continues to increase with the aging of the population.Ten percent of people over 65 years of age and 50% of those over 85 years of age have Alzheimer's disease. The number of individuals with Alzheimer's disease in the United States is expected to be 14 million by the year 2050 unless new treatments are developed to decrease the likelihood of developing Alzheimer's disease.

There are also genetic risk factors for Alzheimer's disease. A relatively common form of a gene located on chromosome 19 is associated with late onset Alzheimer's disease.In the majority of Alzheimer's disease cases, however, no specific genetic risks have yet been identified.

Risks of developing Alzheimer's disease are increased by these common forms of certain genes,but these genes do not invariably cause Alzheimer's disease.Gene that encodes(6)apolipoprotein E (apoE) is the best-studied "risk".The apoE gene has three different forms (alleles) -- apoE2, apoE3, and apoE4.In most (but not all) populations studied,apoE4 form of gene is considered to be the significant risk factor for Alzheimer's disease.The frequency of the apoE4 version of the gene in the general population varies,but is always less than 30% and frequently 8%-15%.The risk of developing Alzheimer's disease is increased two to three fold in Persons with one copy of the E4 gene.Persons with two copies of the E4 gene (usually around 1% of the population) have about a nine-fold increase in risk.Nonetheless,even persons with two copies of the E4 gene don't always get Alzheimer's disease.40% of patients with sporadic or late-onset Alzheimer's disease were found to have at least one copy of the E4 gene.

This means that in majority of patients with Alzheimer's disease, no genetic risk factor has yet been found. since there is no treatment for Alzheimer's disease,most experts do not recommend that adult children of patients with Alzheimer's disease should have genetic testing for the apoE4 gene.Genetic testing may be recommended for adult children of patients with Alzheimer's disease when medical treatments that prevent or decrease the risk of developing Alzheimer's disease become available.Other risk factors for Alzheimer's disease include:


Coronary artery disease,


Elevated blood cholesterol.

also have There can also be increased risk for Alzheimer's disease in individuals who have completed less than eight years of education,but by no means do they mean that Alzheimer's disease is inevitable in persons with these factors.


(1)Effect of 0mega-3 fatty acids: FISH is rich in (8)omega-3 fatty acids, so eating of fish can protect against "Alzheimer's Disease".Omega-3 Fatty acids slow down the process of aging but the results are not positive at the advanced stage of the disease.It is also found that when diatery source of Omega-3 Fatty acids (Fish) is consumed,there is only "reduction" in the risk of cognitive decline or dementia.

Related Treatment: DHA-Fish oil preparations are generally recommended by physicians and they are more effective when given initially to the patients who do not have over (9)dementia.

(2)Effect of vitamin B12: (10)VitaminB12 acts as a "marker" for the detection of Alzheimer's disease.Low levels of vitaminB12 are responsible to cause aging so,the risks of the "memory loss" are likely to reduce by sufficient supplements of vitaminB12.It is found that increased amounts of (11)homocystein increase the risk of Alzheimer's disease by 16% whearas the risk is "decreased"(by2%) when there is picomolar increase in the concentration of (12)holotranscobalamin which is the active form of vitaminB12.

Related Treatment: Usually,vitaminB12 shots are practised.There is only 1% absorption of vitaminB12 if it is given in tablet form and currently,there is oral solid formulation which brings absorption of about 7-30%.

Advances in the treatment in future: It is also being expected that in the future the researchers will be able to monitor the process of aging by using(13)MRI techniques and the measurement of the levels of "lactic acid" will also become possible lactate levels can act as an indicator of the aging process as these levels increase with the age.Gene that governs the normal and pathological aging of (14)neurons have also been discovered.In the future,clinical studies may be free from the organisms who don't possess(15)risk markers.Patients who are really at the risk zone of Alzheimer's disease should be studied and these studies are simple and correct.

It is not safe to use the individuals for experimentation who are not at the risk.These patients may have no effect of medication but they may undergo some harm due to the drug side-effects.