Alzheimer's disease - a devastating brain disease which gradually ruins the , thinking skills, patient's memory and ultimately the ability to perform the simplest tasks of the daily life. Alzheimer's disease was named after Dr. Alois Alzheimer, a German physician . In 1906, he observed the variations in a dead women's brain tissues, who died due to a dementia(Alzheimer's disease). Dementia is a brain disorder which severely affects the patient's ability to even do the simple daily life activities. Alzheimer's disease (AD) is the most ordinary cause of the dementia in older people .
Alzheimer's damages & kills brain cells . The brain of the Alzheimer's patient diminishes in number & size compared to normal , healthy brain cells. It is distinguished by the development of amyloid plaques and neurofibrillary tangles . Amyloids are protein fragments that a healthy , normal body produces. In the normal brain , the fragments are broken down and eliminated . But in the brain of person carrying Alzheimer's disease, these fragments heap up to form hard, indissoluble plaques. Neurofibrillary tangles (NFT) are bundles of filaments in the neurons of the brain . NFT forms inside a cell and are made up of a protein called tau. Amyloid plaques and NFT are known as the hallmarks of the Alzheimer's disease .
Scientists' are still unsure what causes this disease . But it has became definite that the complex series of events that happens in the brain over a long period of time has a great part in the development of Alzheimer's disease . It's also probable that genetic factors , environmental factors , and lifestyle factors cooperates in developing this disease. Because everyone's lifestyle and genetic make-up differs from each other.
As the scientists learn more and more about Alzheimer's disease it's getting more clear that the genes play a crucial role in the development of the Alzheimer's disease. There are two types of Alzheimer's disease. First form of AD is early-onset Alzheimer's which is very rare. It occurs in the people ages 30-60 years . Most cases of the early-onset Alzheimer's are inherited, it's known as familial Alzheimer's disease (FAD). It can be caused by mutations on anyone gene of chromosomes 21 , 14 and 1 inherited from a parent. Mutations in anyone of the chromosomes causes abnormal proteins to form which disrupts the functions of the body and can leads to Alzheimer's .
Any mutations on chromosome 21 forms abnormal amyloid precursor protein (APP). An abnormal presenilin 1 is formed by the mutation on chromosome 14.And an abnormal presenilin 2 is formed by a mutation on chromosome 1.Presenilin is a protein in a cell membrane. These mutations take apart in the formation of harmful forms of amyloid plaques. If any parent or parents of a child carries a mutated gene for FAD. There is a 50/50 chance that a child will inherit the mutated gene .And if he gets it he will almost surely develop FAD.
The second form of the AD is late-onset Alzheimer's. In most people, late-onset Alzheimer's develops after the age of 60.The causes of late-onset AD is not yet fully understood . But it's almost definite that genetic, environmental and lifestyle factors influences a person's risk of developing a disease differently. For some people these factors might influence in decreasing the risk of developing a disease and for some people in increasing the risk of development of a disease. Unlike mutated genes on the chromosomes responsible for the early-onset AD , researcher didn't considered any genes on the chromosomes responsible for late-onset AD. Because they didn't found any specific gene other than APOE that can be considered responsible to cause late-onset AD. Despite, there is one genetic risk that seems to have a great risk of developing the disease. Apo lipoprotein E (APOE) gene on chromosome 19 has a great risk of developing the disease.
APOE carries all the instructions for making proteins that carries fats in the blood-stream. It comes in several different types or alleles. For instance, APOE e2 prevents the body from diseases. A person with this allele can develop Alzheimer's later in life than someone who carries a APOE e4 gene. And APOE e2 is very rarely found. Another form of APOE is APOE e3, it's a commonly found allele. This gene does not decrease or increase the risk of the development of a disease. Therefore, it's supposed to play a neutral role. APOE e4 is present in 25-30% people. And people carrying late-onset AD are mostly the ones who consists of APOE e4 gene. Many studies have proved that this APOE e4 allele increases the risk of developing AD. But it's not yet fully known that how does this process occurs including the APOE e4 allele. However, if a parent passes this gene on , it's very likely that the child will develop the early-onset AD. On the other hand, some people with this gene actually never got Alzheimer's disease which throws of the researcher studies.
Some of the symptoms that starts to appear are dreadful. For instance, short term memory loss , forgetting things done by themselves or can't identify their own relationships with the family members. And sometimes their mood changes in a moment if they were laughing a minute ago they will start crying badly and argue more often on even simple things. They start to believe false things are true , loss interest in conversation with someone but usually they just don't talk much because they have problem in speaking and they suddenly forgets what they were just talking about. As the disease progresses, they forget how to do the simplest tasks of daily routine. It extends to a worse position. For instance, they will routinely miss place things, they will put the keys in the fridge , wallet in the dishwasher and then will get furious that they can't find their things. Another example is that they often dress regardless of the weather. If it's snow outside they will wear shorts or sleeveless shirts and if it's blistering outside they will wear a heavy coat. These are some of the worse things a person can do to himself.
Alzheimer's disease is one of those confusing disease that scientists are still researching on to find the treatment for. Unfortunately, the exact treatment for Alzheimer's is not found yet. Because there are still many aspects of the disease that are either unknown or not completely researched. But researchers and scientists are trying to learn that how these symptoms occur. So, that they can find a drug or non-drug treatment for people affected by the devastating Alzheimer's disease. And the people in the clinical trials are helping scientists to test the safety , side effects , and effectiveness of a medication. Results of the clinical trials are actually used to improve prevention and treatment for the disease.
The life expectancy of someone affected by Alzheimer's differs from person to person. Everyone's life expectancy is different because it depends on the age the symptoms first begin to appear. As well as what other problems does the person's body experience including Alzheimer's .However, the average life expectancy of a patient with AD is approximately eight to ten years . Despite this, there were some people known who lived for almost twenty years or more.
A blood test can identify what APOE allele a person has but it's very unlikely to predict if a person have Alzheimer's or not. Because there are many other factors that can influence the advancement and progression of the disease. Despite, researchers can figure out that who have an increased or decreased risk of developing AD through APOE testing. The only accurate way of knowing if a person have AD is after their death . The doctors have to take out the brain of a patient and measure the size of it and compared to normal brain size during an autopsy. Because AD patient's brain diminishes in size as the disease progresses. Usually genetic testing is used in the clinics if people have a family history of early-onset Alzheimer's. If they have APOE e4 allele than they might have a higher risk of developing the disease. But it maybe probable that they never get Alzheimer's. So, it's not definitively confirmed yet.
Currently researchers are working on the aspects that are or might be related to Alzheimer's . They are looking forward to understand more about the basic genetics of the disease by answering some questions. Few of them are what makes the disease process begin? Why do people with other dementia develop Alzheimer's which other dementia develop Alzheimer's which other do not? How and when can this disease be prevented ? What treatments are needed? Other than this there are numerous other questions that need to be answered to prevent people from this disease.