Alzheimer’s disease: amyloid plaques and neurofibrillary tangles

man with Alzheimer's being cared for
© iStock/KatarzynaBialasiewicz

Alzheimer’s disease causes degeneration and death of a person’s brain cells, meaning a sufferer will slowly and progressively lose their memory.

Guest writer, Holly Klamer, delves into the world of Alzheimer’s research and the need to find a cure to treat the disease.

In the later stages of Alzheimer’s, the patient may even face difficulty in carrying to basic and simple tasks. As a result, the person must depend on others for their day to day functions. The worst thing is that until now, no treatment can either reverse the effects or cure this disease completely.

Detecting the disease at the initial stage can be quite difficult. Early signs include failing to recall recent events and talks. With the progression of the disease, the memory losses get worse. The patient himself may fail to recognise the symptoms. A friend or a family member has a higher chance of noticing the symptoms.

A person who has Alzheimer’s disease faces following brain-related problems:

  • Memory;
  • Thinking and reasoning;
  • Taking decisions;
  • Performing routine tasks and;
  • Behavioural and personality change

Alzheimer patients need a lot of personal attention. Sometimes due to our busy schedules or job requirements, we are not able to give the needed attention to our loved ones suffering from Alzheimer’s diseases.

In such cases, it is advisable to take professional help. Numerous Alzheimer’s care facilities for seniors and senior assisted living homes and facilities are available for senior citizens who have Alzheimer’s disease. Various communities provide memory care facilities to provide a safe environment for Alzheimer’s patients. These facilities are well equipped with all the needed medical attention and assistance. They also provide emergency call systems, housekeeping and laundry services, meals, transportation facilities, and 24/7 supervision.

In most cases, Alzheimer’s disease is linked with two kinds of lesions throughout the cerebral cortex: Amyloid plaques- Present between the nerve cells/neurons and Neurofibrillary Tangles present inside the nerve cells/neurons.

Both the above lesions are a kind of protein build-ups. With the increasing age, individuals tend to develop these lesions. However, in Alzheimer’s patients, the quantity of these protein build-ups is very high.

1) Amyloid Plaques

Our body keeps on producing protein fragments as part of its normal function. These protein fragments are known as ‘amyloid,’ and these are present in the membrane surrounding the neurons. The protein segment which gets clipped from APP (Amyloid precursor protein) is known as Beta-amyloid. Chemically, the molecules of Beta-Amyloids are adhesive. As a result, they stick to each other. This results in the formation of plaque. Amyloid Plaques are insoluble and hard in nature.

In normal cases, these Beta-Amyloids get broken down and eliminated. In the case of the brain of an Alzheimer’s patient, these plaques are formed between the neurons and hamper the function of the neurons in the brain. Many researchers believe that a high concentration of Amyloid Plaques between the nerve cells can be highly toxic for the neurons.

As discussed earlier, Beta-Amyloids are small protein fragments that can easily be broken down in the fluid present between the neurons and are finally eliminated from the brain. But, the enzyme responsible for cutting Beta-Amyloid from App is not very accurate, and many a time, it cuts a longer strand, which cannot be broken down. These longer strands result in plaque formation.

2) Neurofibrillary Tangles

Neurofibrillary Tangles are also formed because of proteins becoming abnormal. However, unlike Amyloid plaques, they are formed inside the nerve cell.

In neurons, the transportation of organelles, nutrients, and other essential material are transferred from one part of the nerve cell to another, through a specialised filament known as microtubules. The protein which is responsible for holding these microtubules together and keeping them parallel is known as Tau protein.

In the case of an Alzheimer’s brain, the molecules of Tau protein disarrange into filaments, which further result in the formation of tangles. As a result, the microtubules fail to remain parallel and straight, and the entire structure collapses. Collapsing of the microtubule structure disrupts the transportation mechanism of the nerve cell, and this results in the degeneration of the cell. The first nerve endings that get degenerated are those that are present at the tip of the axon. This reduces the communication between the neurons, and once the entire nerve cell gets collapsed, the communication gets cut off completely.

Neurofibrillary tangles are formed when the molecules of Tau proteins misfold a very specific manner. In the case of an Alzheimer’s patient, a C-shape is formed in the centre of the tangle, and a loose end sticks out randomly. Whereas in the case of Pick’s disease, the tangle formed is in the shape of ‘J.’ Once, a tangle is formed, more tau tangles start attaching to it, hence, making it longer.

3) Effect on dementia

Various studies have suggested that changes in an Alzheimer’s brain may result from a complex relationship among beta-amyloid, tau protein, and various other aspects. The formation of plaque around the neuron may result in blocking of neuron-neuron synapsis communication. Also, plaque might result in the activation of an immune system in that area. Studies have also stated that the smaller groups of beta-amyloid may be more damaging as compared to the plaque.

Tau tangles within the nerve cell damage the transportation system in the neuron. Lack of flow of nutrients and other essential supplies interrupts the process of creation and recycling of proteins within the cell, which ultimately results in the death of the cell.  Tau tangles tend to accumulate in the memory area of the brain. As the plaque formation reaches a maximum limit, the tau tangles start spreading.

As Alzheimer’s disease keeps on progressing, neurofibrillary tangles and amyloid plaques spread in a predictable pattern, starting from the entorhinal cortex then spreading to the adjacent temporal and frontal parts of the brain. These parts are responsible for carrying out speech and other executive functions and finally covering the entire cerebral cortex. The progression rate varies from patient to patient.

4) Prevention

Various researches are going on to find a medicine to prevent neurofibrillary tangles and amyloid plaques but still, no such antibiotics have been found. However, regular exercise and a healthy diet are found to bound the formation of tangles and plaques.

In conclusion

Researchers are still working on finding a cure to treat Alzheimer’s disease. Current treatment might help in improving symptoms temporarily or slowing the rate of decline. However, studies have shown that by following some healthy habits, seniors may have a chance of preventing Alzheimer’s disease. This includes quitting smoking, taking a healthy diet, regular exercise, exercising the brain, and avoiding loneliness can be very helpful in preventing or slowing down the effects of this mental disorder.

 

About our guest contributor:
Holly Klamer is a seasoned writer who loves to create content related to ageing issues and everything to do with senior living. She is a frequent contributor to many top online publications including
Assisted Living Near Me, where she creates content that is specific to assisted living for older adults, as well as SeniorLivingFacilities.net, where she writes about common issues affecting senior citizens and provides senior living advice.

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