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Alzheimer’s Disease: Introduction & Pathology

Alzheimer’s disease is the most common form of dementia present among today’s population. It is a progressive disorder that affects the brain and memory. Alzheimer’s is known to rob individuals of their ability to connect with their family, friends, the environment, and themselves.

Unfortunately, this neurodegenerative disorder is irreversible, meaning that once the damage is done, it cannot be undone. In Alzheimer’s disease, the cells of the brain begin to die, and as a result there is loss of function.

Alzheimer’s Disease: Introduction & Pathology
Since there is no cure, current treatments aim at halting the progression rather than reversing it.

Most individuals who are diagnosed with Alzheimer’s Disease are older and it is very unusual to have this condition before the age of 60. A hallmark sign of Alzheimer’s disease is cognitive and/or behavioral impairment. This impairment often begins slowly and becomes worse over time. Eventually the disease will significantly interfere with the patient’s ability to live independently.

The progression of this disorder occurs in a stepwise fashion. In the early stages, the patient or patient’s family members may notice small differences in their loved one’s ability to remember certain items or complete certain tasks. Over time, the impairments become significantly more noticeable. In the final stages of this disorder, the patient will likely not be able to perform their daily activities by themselves, and in many instances, may not even recognize those closest to them.

Each patient is unique, and therefore a cookie cutter analysis of how the patient will progress and at what rate cannot be given. It is imperative that if the diagnosis is in question, then an appropriate physician who specializes in neurodegenerative diseases should be consulted – so that an individualized treatment plan can be initiated.

Pathology
Patients with Alzheimer’s will likely develop what are known as plaques within the Hippocampus of the brain. The Hippocampus is a specific area of the brain that encodes memories. When these plaques build up within the “memory” portion of the brain, the patient’s memories will begin to get affected.

Plaques may also develop in other areas of the brain that encode various cognitive and behavioral functions. Wherever the plaques occur within the brain, there will be resultant effects.

The hippocampus is a crucial brain structure that regulates emotions, and the ability to remember things that happened recently and form new memories. The memory for events that happened a long time ago, even years prior, are processed in a different part of the brain; and are therefore relatively spared in the early stages of Alzheimer’s Disease.

Most families will notice “short-term” memory loss, when bringing a loved one to medical attention for evaluation of Alzheimer’s Disease. When tested, people with symptoms of Alzheimer’s Disease will have difficulty remembering a set of three words a few minutes after having repeated them. As the Alzheimer’s Disease advances, patients with the disease will also have difficulty repeating the three words immediately after hearing them.

The exact mechanism that causes the development of Alzheimer’s disease is still unknown. There is still more research to be conducted in order to determine the exact pathophysiology of this disease. The one certainty about this disease is that the buildup of plaques does play a role in the development of the disease. It is not known whether the plaques themselves are what result in the disease, or if it is a by-product, but it is certain that plaques are involved in the disease process.

These plaques are composed of amyloid and have now been identified as neurofibrillary (tau) tangles. While the buildup of plaques is considered to be a hallmark of Alzheimer’s disease, there is another classic feature that is associated with this disease. That second classic feature commonly associated with Alzheimer’s disease is the loss of neuronal connections between neurons within the brain. Loss of these connections makes the brain unable to transfer important messages to other areas of the body. Which means the neurons have loss of function. In the final stages of the disease, because there has been so much cell death, the brain will be significantly smaller.

Unusual Types of Alzheimer’s Disease

  • Early Alzheimer’s Disease
    It is unusual to develop Alzheimer’s Disease before the age of 60. The term “early-onset” Alzheimer’s Disease is used to describe the rare cases wherein someone develops Alzheimer’s Disease before the age of 65. This is rare and can be due to an inherited risk or genetic risk. However, so rare is this that less than 1 in 100 cases of Alzheimer’s Disease are diagnosed in this fashion.
  • Primary Progressive Aphasia
    Primary Progressive Aphasia is a relatively rare disorder that causes very specific progressive difficulties with language. Memory, however, remains relatively good. The current science suggests that Primary Progressive Aphasia is not related to, or a type of Alzheimer’s Disease. However, when the brains of people with Primary Progressive Aphasia are looked during an autopsy, some have changes that are similar to the changes seen in the brains of people with Alzheimer’s Disease. Woody Durham, a well-known public figure and sports broadcaster in North Carolina, has recently been diagnosed with this condition. Having more awareness of this condition may help find better treatments.
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