Nervous system: Alzheimer’s Disease and Strokes

Learning Objectives

Know what Strokes and Alzheimer’s Disease are and how the affect a person’s brain and behavior.

Alzheimer’s Disease

Alzheimer’s disease is a progressive disorder which causes brain cells, also known as neurons, to slowly degenerate. The disease is marked by a buildup of plaque in the brain due to changes in brain chemistry. Typically, degeneration begins in brain regions responsible for memory, like the hippocampus. It then slowly begins to spread across the brain. This occurs through a series of stages. I outline three here, but I have seen as many as seven indicated. The resulting symptoms are memory loss and general confusion. Personality changes and a decreased ability to concentrate have also occurred. These symptoms often lead people to confuse Alzheimer’s disease with dementia, which is actually an umbrella term for diseases involving cognitive decline. Therefore, Alzheimer’s disease is actually a type of dementia. Many research labs are making progress on treatments and prospective cures. So far, earlier detection and medication to improve cognitive function have been the largest accomplishments for these labs. In addition to these findings, exercising the mind and body also appear to slow symptoms.

The image depicts a healthy brain on the left. This brain is plump and voluminous. On the right, the image depicts the brain of someone with severe Alzheimer's Disease. This brain is significantly smaller and shriveled. If the left side was a grape, the right side would be a raisin.
Fig. 1 Comparison of a healthy brain and a brain with severe Alzheimer’s Disease
  1. Early or Mild:
    The beginning stages of Alzheimer’s disease are marked by general forgetfulness and minor memory lapses. At this point, patients are still independent but may need reminders about dates or where they last left their keys. Later on loved ones may begin to notice more struggles with communication. For example, patients may repeat the same question or struggle to find the right word.
  2. Middle or Moderate:
    This stage sees the worsening of the symptoms from the early or mild stage (problems with memory, speech, and reasoning). During this stage, patients are more likely to become disoriented and lost ,as they may forget where they are or are going. In addition, they may begin to forget details about their life such as their loved ones’ names. Although, they still do remember who they are. Memories from early life tend to be the strongest at this time. Patients may become more dependent on caregivers during this time, but they do not need around the clock care.
  3. Late or Severe:
    This is the final stage of the disease where patients often need 24 hour care and are completely dependent on caregivers. At this point, patients may not remember how to walk, eat, or sit up on their own. Speech and communication is very limited, and they may no longer remember loved ones.



The cartoon is separated into two rows. The top depicts a stroke occurring due to a blood clot. On the left, a blood vessel in the brain is shown. They then zoom in on the vein to show a blood clot. On the right, the area affected by the blood clot is indicated by darkening about 1/6 of the brain. On the bottom the same outline is used to depict a stroke caused by a burst blood vessel. On the left, the zoomed in image shows a blood vessel where there is a tear in the top side. On the right, the area affected is depicted with a red blob indicating where the blood has leaked into the brain.
The top half of the image shows an ischemic stroke where a blood clot starves part of the brain from its oxygen supply (the grey area in 2a). The bottom shows a hemorrhagic stroke where a burst blood vessel is causing internal bleeding. The area affected is indicated in 2b.

A stroke results from an impairment in blood circulation in the brain. The onset is sudden and can be described as a brain attack. A stroke can either be ischemic which involves a blood clot or hemorrhagic which involves a burst blood vessel. There is about a 70% and 30% split between ischemic and hemorrhagic strokes. Additionally, transient ischemic attacks, described as ministrokes, are temporary blockages in blood flow which resolve themselves. These attacks are considered warnings because they often precede larger strokes. Note: the likelihood of a second stroke greatly increases after having one stroke. The good news is there are many things to do to prevent and treat strokes. If you are experiencing an ischemic attack, clot busting medications like tPA can effectively treat a stroke if administered within three hours. In addition, making healthy lifestyle changes in diet and activity can also lower the risk of having a stroke in the first place. Other medications like blood thinners can also prevent an ischemic stroke. In the rare case of a hemorrhagic stroke, patients may need surgery. After suffering from a stroke, many patients receive occupational and physical therapy to strengthen the area of the brain where the stroke occurred.

Know the sudden signs of strokes. If you see anyone experiencing these signs of stroke, call 911 immediately. Getting treatment within 60 minutes can prevent disability. The signs are: trouble walking, trouble seeing, weakness on one side, and trouble speaking.

Strokes can occur in any region of the brain which means the symptoms can widely vary. Small areas of the brain or entire hemispheres of the brain can be affected. Strokes often have clear physical symptoms such as weakness, numbness, facial drooping, decreased vision, impaired speech, dizziness, mental confusion, the inability to understand and more. These symptoms vary based on the location of the stroke as each area of the brain has specific functions. In some cases the location of the stroke results in no noticeable symptoms; these are called silent strokes. A good way to remember the major symptoms is to be fast.

Balance – sudden loss of coordination or balance
Eyes – sudden double vision or loss of vision

Face – facial drooping
Arms – numbness or weakness in the arms or legs
Speech – sudden difficulty speaking
Time – If you notice these symptoms, it is TIME to call 911.

Authored by: Kori Skrypek Provided by: University of Minnesota License: CC BY 4.0


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