What Is Alzheimer's Disease? What Causes Alzheimer's Disease?

Editor's Choice
Main Category: Alzheimer's / Dementia
Also Included In: Psychology / Psychiatry;  Neurology / Neuroscience;  Seniors / Aging
Article Date: 31 Jul 2009 - 1:00 PST

email to a friend   printer friendly   opinions  

Alzheimer's disease is a progressive neurologic disease of the brain leading to the irreversible loss of neurons and the loss of intellectual abilities, including memory and reasoning, which become severe enough to impede social or occupational functioning. Alzheimer's disease is also known as simply Alzheimer's, and Senile Dementia of the Alzheimer Type (SDAT) .

During the course of the disease plaques and tangles develop within the structure of the brain. This causes brain cells to die. Patients with Alzheimer's also have a deficiency in the levels of some vital brain chemicals which are involved with the transmission of messages in the brain - neurotransmitters.

Alzheimer's disease is the most common form of dementia. The disease gets worse as it develops - it is a progressive disease. There is no current cure for Alzheimer's, although there are ways of slowing down its advance and helping patients with some of the symptoms. Alzheimer's is also a terminal disease - it is incurable and causes death.

According the National Institute on Aging, there are estimated to be between 2.4 million and 4.5 million Americans who have Alzheimer's. There are approximately 417,000 people in the UK with Alzheimer's, according to the Alzheimer's Society.

Why the name Alzheimer's disease?

Aloysius Alzheimer was a German neuropathologist and psychiatrist. He is credited with identifying the first published case of "presenile dementia" in 1906, which Kraepelin later identified as Alzheimer's disease - naming it after his colleague.

In 1901, while he worked at the city mental asylum in Frankfurt am Main, Germany, Dr. Alzheimer had a 51 year old patient called Mrs. Auguste Deter. The patient had distinct behavioral symptoms which did not fit any existing diagnoses - she had rapidly failing memory, disorientation, confusion, had trouble expressing her thoughts, and was suspicious about her family members and the hospital staff. Her symptoms progressed relentlessly. Dr. Alzheimer wrote that she once said to him "I have lost myself."

Over the coming years Auguste Deter would take up more and more of Dr. Alzheimer's time, to the point of almost becoming an obsession for him. The lady died in 1906 and Dr. Alzheimer, who was working at Kraepelin's lab in Munich, had her patient records and brain sent there.

Along with two Italian doctors, Dr. Alzheimer performed an autopsy. The autopsy revealed that her brain had shrunken dramatically, but there was no evidence of atherosclerosis (thickening and hardening of the walls of the arteries). He used a silver staining technique he had learnt from ex-colleague Franz Nissl which identified amyloid plaques and neurofribrillary tangles in the brain - two hallmarks of the disease.

In November, 1906 Dr. Alzheimer gave the first lecture ever that presented the pathology and the clinical symptoms of presenile dementia together. Kraepelin started using the term Alzheimer's disease, which by 1911 was being used throughout Europe and by European doctors when diagnosing patients in the USA.

Fairly recently, Dr. Alzheimer's findings were reevaluated when his original microscope preparations on which he based his description of the disease were rediscovered in Munich.

A researcher from Prague, Oskar Fischer, and a contemporary of Dr. Alzheimer's, may have described the pathology of dementia in greater depth than did Alzheimer himself, say Czech scientists who have been digging through historical archives in Prague.

What are the symptoms of Alzheimer's disease?

Doctors say Alzheimer's disease can sometimes be tricky to diagnose because each patient has unique signs and symptoms. Several of the signs and symptoms present in Alzheimer's disease also exist in other conditions and diseases.

Alzheimer's disease is classified into several stages. Some doctors use a 7-stage framework, while others may use a 4, 5 or 6-stage one.

A common framework includes 1. Pre-Dementia Stage. 2. Mild Alzheimer's Stage. 3. Moderate Alzheimer's Stage. 4. Severe Alzheimer's Stage. The example below is of a 7-stage framework.

The 7 stages of diagnostic framework

Most patients take from 8 to 10 years to progress through all the seven stages. However, some may live for 20 years after neuron changes first occur.

Stage 1 - No impairment

Memory and cognitive abilities seem to be normal. During a medical interview a health care professional identifies no evidence of memory or cognitive problems.

Stage 2 - Minimal Impairment (Very Mild Cognitive Decline)

Could be normal age-related changes, or the earliest signs of Alzheimer's.

Friends, family and health care professionals hardly notice any memory lapses. Approximately 50% of people aged 65 and over start experiencing slight difficulties with recalling the occasional word and concentration. The person may feel there are occasional memory lapses, such as forgetting familiar words or the names, and perhaps where they left their keys, glasses or some other everyday object.

Stage 3 - Early Confusional (Mild Cognitive Decline). Duration - 2 to 7 years.

Early-stage Alzheimer's is sometimes diagnosed at this stage.

• The patient has slight difficulties which have some impact on certain everyday functions. In many cases the patient will try to conceal the problems.


• Problems include difficulties with word recall, organization, planning, mislaying things, failing to remember recently learned data which may cause problems at work and at home - family members and close associates become aware.


• Problem reading a passage and retaining information from it.


• The ability to learn new things may be affected.


• Problems with organization.


• Moodiness, anxiety, and in some cases depression.

Stage 4 - Moderate Cognitive Decline. (Mild or Early Stage Alzheimer's Disease). Duration - about 2 years

With these symptoms diagnosis is easy to confirm.

• Still identifies familiar people and is aware of self.


• Reduced memory of personal history.


• Problems with numbers which impact on family finance - managing bills, checkbooks, etc. Previously doable numerical exercises, such as counting backwards from 88 in lots of 6s become too difficult.


• Knowledge of recent occasions or current events is decreased.


• Sequential tasks become more difficult, including driving, cooking, planning dinner for guests, many domestic chores, shopping alone, and reading and then selecting what is in a menu at the restaurant.


• Withdraws from conversations, social situations, and mentally challenging situations.


• Denies there is a problem and becomes defensive.


• Requires help with some of the more complicated aspects of independent living.

Stage 5 - Moderately Severe Cognitive Decline (Moderate or Mid-stage Alzheimer's Disease). Duration - about 18 months

• Cognitive deterioration is more serious.


• Cannot survive independently in the community and requires some assistance with day-to-day activities.


• Cannot remember details about personal history, such as name of where they went to school, telephone numbers, personal address, etc.


• Confused about what day it is, month, year.


• Confused about where they are or where things are.


• Problems with numbers; mathematical abilities get worse.


• Easy prey for scammers.


• Require supervision and sometimes help when dressing, including selecting right clothing for the season or occasion.


• Require help carrying out some daily living tasks.


• Can still eat and go to the toilet unaided.


• Unable to recall current information consistently.


• Usually remember substantial amounts about themselves, such as their name, name of spouse and children.

Stage 6 - Severe Cognitive Decline (Moderately Severe Mid-stage Alzheimer's Disease). Duration - about 2½ years.

Memory continues to deteriorate. There is a considerable change in personality. Require all-round help with daily activities.

• Virtually totally unaware of present and most recent experiences.


• Cannot recall personal history very well.


• Can still usually recall their own name.


• Know family members are familiar but cannot recall their names.


• Can communicate pleasure and pain nonverbally.


• Ability to dress progressively deteriorates. Need help dressing and undressing.


• Ability to bathe and wash self progressively deteriorates.


• Fecal and/or urinary incontinence more likely.


• Need help when going to the toilet - flushing, wiping, disposing of tissues.


• Disruption of sleep patterns.


• Wander off and become lost.


• Suspicious, paranoid, aggressive. May believe caregiver is an impostor, devious, scheming, cunning, dishonest.


• Repeat words, phrases or repetitively utters sounds.


• Repetitive/compulsive behavior, such as tearing up tissues or wringing hands.


• Disturbed, agitated, especially later on in the day.


• Hallucinations, also more common later on in the day. May hear, smell or see things that are not there.


• Eventually need care and supervision, but can respond to non-verbal stimuli.

Stage 7 - Very Severe Cognitive Decline (Severe or Late-stage Alzheimer's Disease). Duration - 1 to 2½ years

During the last stage of Alzheimer's disease patients lose the ability to respond to their environment, they cannot speak, and eventually cannot control movement. The duration of this stage may depend on the quality of care the patient receives.

• Severely limited cognitive ability.


• Patients lose their ability to recognize speech, but may utter short words or moans to communicate.


• Usually the ability to walk unaided is lost first, then the ability to sit unaided, plus the ability to smile, and eventually the ability to hold the head up.


• Body systems start to fail and health deteriorates.


• Swallowing becomes increasingly more difficult. Chocking when eating/drinking becomes more common.


• Reflexes become abnormal.


• Seizures are possible.


• Muscles grow rigid.


• Generally bedridden.


• Spends more time asleep.


• Require round-the-clock care.

Alzheimer's disease and life expectancy

The main reason Alzheimer's disease shortens people's life expectancy is not usually the disease itself, but complications that result from it. As patients become less able to look after themselves, any illnesses they develop, such as an infection, are more likely to rapidly get worse. Caregivers will find it harder and harder to identify complications because the patient becomes progressively less able to tell if he/she is unwell, uncomfortable, or in pain. Pneumonia and pressure ulcers are examples of common complications which may lead to death for people with severe Alzheimer's disease.

What are the causes or risk factors of Alzheimer's Disease?

Although a great deal of research has been done and is currently being done on the possible causes of Alzheimer's, experts are still not sure why the brain cells deteriorate. However, there are several factors which are known to be linked to a higher risk of developing the disease. These include:

• Age
  
  After the age of 65 the risk of developing Alzheimer's doubles every five years. Although Alzheimer's is predominantly a disease that develops during old age, some younger people may also develop the condition. According to the Canadian Medical Association Journal the risk of developing Alzheimer's is as follows:
  
  • Ages 65-74, 1 in 100
  • Ages 75-84, 1 in 14
  • Age over 85, 1 in 4.
• Family history
  
  People who have a close family member who developed Alzheimer's have a slightly higher risk of developing it themselves - just a slightly higher risk, not a significantly higher risk. Only about 7% of all cases are associated with genes that cause the early onset inherited familial form of the disease. Among those who do inherit the condition, it may start at an earlier age.


• Down's syndrome
  
  People with Down's syndrome have an extra copy of chromosome 21, which contains a protein that exists in the brain of people with Alzheimer's. As people with Down's syndrome have a larger amount of this protein than others, their risk of developing the disease is greater.


• Whiplash and head injuries
  
  Some studies have identified a link between whiplash and head injuries and a higher risk of developing Alzheimer's.


• Aluminum (UK/Ireland/Australia: Aluminium)
  
  The link here is a theory which most scientists have discarded. Aluminum exists in the plaques and tangles in the brains of Alzheimer's patients. Some have suggested that aluminum absorption by humans could increase the risk. However, studies have failed to find a link. Aluminum exists in some foods and plants. It is found in some cooking pans, medications and packaging. Scientists doubt there is a link because our bodies absorb minimum amounts and our bodies eliminate it through the urine.


• Gender
  
  A higher percentage of women develop Alzheimer's than men. As women live longer than men, and Alzheimer's risk grows with age, this may partly explain the reason.


• Mild cognitive impairment
  
  A person who has just mild cognitive impairment has memory problems but not Alzheimer's. His/her memory is worse than other healthy people's of the same age. A higher percentage of people with mild cognitive impairment develop Alzheimer's, compared to other people. Some people say that this is not a risk factor, because those with mild cognitive impairment just had a very, very early Alzheimer's stage which was not diagnosed. Others disagree with this. Surprisingly, a UK study showed that people with mild cognitive impairment are less at risk of developing dementia than previously thought.


• Atrial firbrillation
  
  A study of more than 37,000 patients showed a strong relationship between atrial fibrillation and the development of Alzheimer's disease.


• Heart disease risk-factors
  
  People with the risk factors of heart disease - high blood pressure (hypertension), high cholesterol, and poorly controlled diabetes - also have a higher risk of developing Alzheimer's. If your high-blood pressure, high cholesterol, and or poorly controlled diabetes type 2 is a result of lifestyle, it is called a lifestyle factor. Eating a well balanced diet, doing plenty of exercise, aiming for your ideal bodyweight, and sleeping between 7 to 8 hours each night will probably eliminate these factors. If you cannot eliminate your diabetes 2, good diabetes control will help.
  
  Sometimes these factors have nothing to do with lifestyle, i.e. if you have high blood pressure for another reason, have diabetes type 1, or are susceptible to high blood cholesterol despite being the right weight, exercising, etc., good control and treatment of the condition helps minimize the risk of developing Alzheimer's (and heart disease).


• Academic level
  
  There is some data showing a higher risk of developing Alzheimer's among people with lower educational qualifications, compared to highly qualified individuals . However, nobody really knows why.


• Processed foods and fertilizers (nitrates)
  
  A study carried out by researchers at Rhode Island Hospital found a significant link between increased levels of nitrates in our environment and food, with increased deaths from diseases, including Alzheimer's, diabetes and Parkinson's. The study looked at progressive increases in human exposure to nitrates, nitrites and nitrosamines through processed and preserved foods as well as fertilizers.


• Some other diseases and conditions
  
  The following diseases and conditions have been linked to a higher risk of developing Alzheimer's.
  
  • Some chronic inflammatory conditions
  • A history of episodes of clinical depression
  • Strokes and/or ministrokes
  • Obesity

How is Alzheimer's diagnosed?

A doctor can diagnose most cases of Alzheimer's. However, nobody can be 100% sure until after death, when a microscopic examination of the brain detects plaques and tangles. There is no basic testing, such as a blood test, urine test, biopsy, or image scan for diagnosing Alzheimer's disease. A brain scan may help identify changes in the brain.

Ruling out other conditions

Doctors will usually carry out some tests to rule out other conditions which typically have symptoms that are also present in Alzheimer's. Below are some examples of diseases and conditions that need to be ruled out:

• Anxiety
• Brain tumor
• Depression
• Infection
• Thyroid problems
• Vitamin deficiency

The following tests may be ordered:

• Blood tests - to see if the patient has a thyroid disorder or vitamin deficiency.


• Neuropsychological testing - this involves an extensive assessment of cognitive (thinking) and memory skills. It can take several hours. These types of tests are extremely useful in detecting Alzheimer's as well as other dementias early on.


• MRI (magnetic resonance imaging) scan - A powerful magnetic field is created by passing an electric current through the wire loops. Meanwhile, other coils in the magnet send and receive radio waves. This triggers protons in the body to align themselves. Once aligned, radio waves are absorbed by the protons, which stimulate spinning. Energy is released after "exciting" the molecules, which in turn emits energy signals that are picked up by the coil. This information is then sent to a computer which processes all the signals and generates it into an image. The final product is a 3-D image representation of the area being examined; which in this case would be the brain.


• PET (positron emission tomography) scan - uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. It is very useful in helping the doctor diagnose Alzheimer's disease. A PET scan that measures uptake of sugar in the brain significantly improves the accuracy of diagnosing a type of dementia often mistaken for Alzheimer's disease, a study revealed.


• CT (computerized tomography) scan - this device uses digital geometry processing to generate a 3-dimensional (3-D) image of the inside of an object. The 3-D image is made after many 2-dimensional X-ray images are taken around a single axis of rotation - in other words, many pictures of the same area are taken from many angles and then placed together to produce a 3-D image.


• What is difference between a PET, CT or MRI scan? A CT or MRI scan can assess the size and shape of body organs and tissue. However, they cannot assess function. A PET scan looks at function. In other words, MRI or CT scans tell you what it looks like, while a PET scan can tell you how it is working.

What is the treatment for Alzheimer's disease?

Alzheimer's is a terminal disease. This means it has no cure and will end in death. However, there are various medications which can help slow down the progression of the disease, and others that can improve the signs and symptoms, such as sleeplessness, wandering, depression, anxiety and agitation.

The doctor may prescribe the following medications to help slow down the disease:

Neurotransmitters - A neurotransmitter is a chemical that transmits neurologic information from one cell to another. Without neurotransmitters our nervous system, which includes the brain, would not work. We would be paralyzed, blind, with no thoughts, no movement - we would be dead.

• Cholinesterase inhibitors
  
  These improve the levels of neurotransmitters in the brain. The medication contains a chemical that inhibits the cholinesterase enzyme from breaking down the neurotransmitter acetylcholine - resulting in an increase in both the neurotransmitter's level and duration of action.
  
  Cholinesterase inhibitors are prescribed to treat problems related to memory, thinking, language, judgment and other thought processes.
  
  Clinical trials showed that about half of all patients did not get any benefit from this type of drug. Experts believe cholinesterase inhibitors may delay or slow worsening symptoms by about six to twelve months. However, some patients experience longer periods of delay.
  
  Examples of cholinesterase inhibitors include:
  
  
  • donepezil (Aricept) - approved in the USA to treat all stages.
  • galantamine (Razadyne) - approved in the USA to treat mild to moderate stages.
  • rivastigmine (Exelon) - approved in the USA to treat mild to moderate stages.
  
  Cholinesterase inhibitors are generally well tolerated (side effects minimal).
  
  Side effects may include:
  
  
  • Diarrhea
  • Nausea
  • Vomiting
  • Loss of appetite


• Memantine
  
  This medication protects brain cells from damage caused by glutamate, a chemical messenger. It is used to treat moderate to severe stages of Alzheimer's. Some doctors prescribe memantine along with a cholinesterase inhibitor. Examples include Axura, Akatinol, Namenda, Ebixa and Abixa, and Memox.
  
  Memantine is prescribed to improve memory, language, reason, attention, and the ability to carry out simple tasks.
  
  A clinical trial showed that patients taking memantine showed a small, but statistically significant improvement in mental function and their ability to carry out daily activities.
  
  Memantine is generally well tolerated (minimal side effects)
  
  Side effects include:
  
  
  • Dizziness
  • Drowsiness
  • Headache
  • Insomnia
  • Constipation
  • Agitation and delusional behavior in some patients.


• ACE Inhibitors - researchers from the Wake Forest School of Medicine found that ACE inhibitors that affect the brain by crossing the blood-brain barrier, may reduce inflammation that could contribute to the development of Alzheimer's disease.


• Stem cells - scientists at UC Irvine showed that neural stem cells can rescue memory in mice with advanced Alzheimer's disease, raising hopes of a potential treatment for humans.


• Insulin - Insulin could protect against damage to brain cells key to memory, according to researchers from Northwestern University in the US and the University of Rio de Janeiro in Brazil. They claim that treating Alzheimer's disease with insulin, or with drugs to boost its effect, may help people with the condition.

What are the complications of Alzheimer's disease?

People with Alzheimer's disease progressively lose the ability to care for themselves. This makes them more susceptible to accidents and health problems:

• Pneumonia - this becomes a significant risk when patients start losing their ability to swallow properly. Food and drink often go down the wrong way - down the air passages into the lungs, rather than into the digestive system. If food or drink gets into the lung there is a risk of pneumonia.


• Urinary tract infection - when the patient becomes incontinent it may be necessary to place a urinary catheter. This increases the risk of urinary tract infections. Urinary tract infections can become very serious and life threatening.


• Injuries - disorientation and wandering are common symptoms of Alzheimer's. Patients are much more likely to fall and fracture a bone or sustain a head injury. The risk is greater if they have sleeping problems and get up in the night and wander about while others are asleep.

The caregiver (UK/Ireland/Australia: carer)

If the caregiver is a close relative, which is usually the case, he/she will go through the sense of grief and loss about the diagnosis. Then they will witness the gradual deterioration of the person they love. They will watch the person they love slowly lose their personality and abilities.

A lone caregiver has to undergo a radical change of lifestyle to look after somebody with Alzheimer's.

Caring for a person with Alzheimer's at home is a challenging task. It is often overwhelming, tiring, and frustrating.

A study led by Johns Hopkins and Utah State University researchers suggests that a particularly close relationship with caregivers may give people with Alzheimer's disease a marked edge over those without one in retaining mind and brain function over time. The researchers reported that the benefit for the patient in slowing cognitive decline was on a par with some medications used to treat the disease.

It is crucial that the caregiver receive support, not just for the patient, but also for himself/herself.

Written by Christian Nordqvist


Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

• Additional
• References
• Citations