What Typical Changes Occur In The Brain Of Alzheimers Patients
Autopsy studies reveal that several biochemical and cellular alterations take place in the brain of Alzheimers patients. The majority of these changes can only be visualized during microscopy performed after death and they include the following:
How Does Alzheimers Disease Affect The Brain
During normal, healthy aging, the brain does shrink somewhat, but it does not lose large numbers of neurons. In the early stages of Alzheimer’s, however, many neurons lose their synaptic connections, stop functioning, and die without being replaced.2
Losing a large number of neurons causes noticeable symptoms, prompting a primary doctor or caregiver to suspect Alzheimers or another type of dementia. The changes that occur may be related to one or more of these disease processes2:
- Vascular issues
- TREM2 gene
Alzheimer’s Stages And Progression
In the early stages of Alzheimers disease and dementia, neurons and their connections are destroyed in the areas of the brain which support memory. In later stages, brain functions involving language, reasoning, and regulating behavior become affected. In most cases, the patient will eventually lose their ability to safely live independently.
In the late stages of Alzheimers, as more neurons are lost, many areas of the brain shrink in size. This process is referred to as widespread brain atrophy, resulting in a significant loss of nerve tissue and severely impaired brain function2.
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Chemical Changes That Occur In The Brain
Our brains and bodies run on chemicals that tell our organs, nerves, muscles, and glands what to do and when to do it. These chemicals carry tiny electrical charges that trigger activity on a cellular level, triggering our ability to think, walk, speak, remember, and much more.
When someone has a dementia condition, this communication breaks down. This is thought to be caused by the presence of two proteins called beta-amyloid and tau. Were not sure why these proteins occur, but we can see how they damage the chemical interactions in the brain.
Beta-amyloid causes a type of plaque to form on the brains neurons. This plaque essentially covers the neurons up so that they cant communicate well with one another, creating a block between thoughts and movement. It also disrupts an important protein that communicates with the hippocampus, our center for creating new memories.
Tau works differently, creating twisted strands of protein that tangle through the cell and neuron networks. This works a bit like a strangling plant vine, cutting off supplies of oxygen and nutrients to the affected neurons and spreading throughout the brain killing cells in the process.
Causes Of Vascular Dementia
Vascular dementia is caused by reduced blood flow to the brain, which damages and eventually kills brain cells.
This can happen as a result of:
- narrowing and blockage of the small blood vessels inside the brain
- a single stroke, where the blood supply to part of the brain is suddenly cut off
- lots of “mini strokes” that cause tiny but widespread damage to the brain
Not everyone who has a stroke will go on to develop vascular dementia.
Read more about vascular dementia.
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Brain Imaging Can Aid Professionals
In most cases, brain imaging can assist professionals in diagnosing dementia, ruling out other possibilities with similar symptoms and verifying which stage a patient may be experiencing. Using scans to analyze signs of dementia can exclude the possibility of lesions that cause cognitive degeneration or impairment .
It can also help to determine which kind of dementia a patient is experiencing. For instance, vascular dementia may not show evidence of a cortical loss, whereas this qualifier could still allow a patient to have Alzheimer’s disease. Also, by undergoing frequent scans, neurologists can make a determination of how the disease is progressing. If a diagnosis is uncertain, follow-up scans taken after a few years can prove that degeneration is occurring. Finally, brain imaging can assist researchers in determining how each disease can affect a patient, and whether certain treatments are effective.
Dementia With Lewy Bodies
The brain of a person with dementia with Lewy bodies often shows less overall shrinkage than the brain of someone with Alzheimer’s or FTD. Instead, tiny deposits of protein are seen in the cerebral cortex, limbic system and brain stem.
In DLB, early damage is seen in the visual pathways and – in some studies – also in the frontal lobes. This may explain why problems with vision and attention are common early symptoms of DLB.
Similarly, Lewy bodies in the brain stem may be linked to the problems with movement, as also seen in Parkinson’s disease.
Dementia Connect support line
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Rarer Causes Of Dementia
There are many rarer diseases and conditions that can lead to dementia, or dementia-like symptoms.
These conditions account for only 5% of dementia cases in the UK.
- problems with planning and reasoning
These symptoms are not severe enough to cause problems in everyday life.
If the underlying illness is treated or managed, symptoms of MCI often disappear and cause no further problems.
But in some cases, people with MCI are at increased risk of going on to develop dementia, which is usually caused by Alzheimer’s disease.
Read more about how to prevent dementia.
What Is Mixed Dementia
It is common for people with dementia to have more than one form of dementia. For example, many people with dementia have both Alzheimer’s disease and vascular dementia.
Researchers who have conducted autopsy studies have looked at the brains of people who had dementia, and have suggested that most people age 80 and older probably have mixed dementia caused by a combination of brain changes related to Alzheimer’s disease,vascular disease-related processes, or another condition that involves the loss of nerve cell function or structure and nerve cell death .
Scientists are investigating how the underlying disease processes in mixed dementia start and influence each other. Further knowledge gains in this area will help researchers better understand these conditions and develop more personalized prevention and treatment strategies.
Other conditions that cause dementia-like symptoms can be halted or even reversed with treatment. For example, normal pressure hydrocephalus, an abnormal buildup of cerebrospinal fluid in the brain, often resolves with treatment.
Researchers have also identified many other conditions that can cause dementia or dementia-like symptoms. These conditions include:
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Take Part In Dementia Research
There are many dementia research projects and clinical trials going on around the world, many of which are based in the UK.
If you have a dementia diagnosis or are worried about memory problems, you can help scientists understand more about it, and develop possible treatments, by taking part in research.
Carers can also take part, as there are studies into the best ways to care for someone with a dementia diagnosis.
Dementia Symptoms And Areas Of The Brain
Knowing how different types of dementia affect the brain helps explain why someone with dementia might behave in a certain way.
Dementia and the brain
Until recently, seeing changes in the brain relied on studying the brain after the person had died. But modern brain scans may show areas of reduced activity or loss of brain tissue while the person is alive. Doctors can study these brain scans while also looking at the symptoms that the person is experiencing.
The most common types of dementia each start with shrinkage of brain tissue that may be restricted to certain parts of the brain.
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How Dementia Affects The Brain
Dementia is not kind to the brain. However, most people believe dementia destroys the entire brain at once. Actually, dementia only focuses on three of the six major regions of the brain. To understand the destruction of dementia you must understand each of the lobes which could be affected and then the functions carried out by that portion of the brain. Different types of dementia damage specific regions of the brain while leaving other regions untouched. For example, Alzhemiers is a type of dementia but it usually only ravages the memory which is located in the temporal lobe.
The Brain Can Be Divided Into Two Major Parts: The Forebrain And The Brain Stem
- Cerebrum with its four lobes: frontal, parietal, occipital, and temporal
- Contains the hippocampus and amygdala, which are housed in the temporal lobe
- The corpus callosum that divides the brain into right and left hemispheres
The Brain Stem is Comprised of:
To set reasonable treatment expectations, we must have a clear understanding of the responsibilities of each part of the brain and how each one controls a residents ability to interact socially or perform daily self-care tasks.
Our minds should be spinning and wondering, Okay, now I know what part of the brain is under attack with dementia, and I know what abilities will be lost. But HOW does that relate to seating and positioning? Well, sit tight because that is precisely what we will discuss in next weeks blog. Stay tuned!
Ana Endsjo, MOTR/L, CLTClinical Education Manager LTC Division
Ana Endsjo has worked as an occupational therapist since 2001 in a variety of treatment settings. She has mainly worked with the geriatric population, dedicated to the betterment of the treatment of the elderly in LTC centers. Her focus has been on seating and positioning and contracture management of the nursing home resident. With this experience, her hope is to guide other therapists, rehab directors, nurses, and administrators through educational guides, blogs, webinars, and live courses in her role as Clinical Education Manager for the long term care division.
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What Are The Types Of Dementia
Dementias are often broken down into two main categories — Alzheimer type or non-Alzheimer type. Dementias of the Alzheimers disease type are defined by the symptoms of memory loss plus impairment in other brain functions, such as language function inability to move the muscles associated with speech or perception, visual or other inabilities to recognize speech or name objects .
Non-Alzheimer dementias include the frontotemporal lobar degenerations, which are further broken down into two main types. One type primarily affects speech. An example is primary progressive aphasia syndromes. The other type is defined by changes in behavior, including lack of feeling, emotion, interest or concern loss of a social filter personality change and loss of executive functions . In both of these frontotemporal lobe dementias, memory loss is relatively mild until later in the course of the disease.
Other non-Alzheimers disease dementias include vascular disorders , dementia with Lewy bodies, Parkinson’s dementia, and normal pressure hydrocephalus.
How Dementia Changes The Brain
Memory is tangible, so when someone has dementia or Alzheimers disease, changes begin to occur inside the brain that impacts the ability to recall events, names, and even skills correctly. These brain changes can be classified in two ways: structural and chemical. Our memory care specialists in Sussex County, NJ will go over both structural and chemical changes, what they mean and how they may affect your senior loved one with dementia.
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What Are The Different Types Of Dementia
Various disorders and factors contribute to the development of dementia. Neurodegenerative disorders result in a progressive and irreversible loss of neurons and brain functioning. Currently, there are no cures for these diseases.
The five most common forms of dementia are:
- Alzheimers disease, the most common dementia diagnosis among older adults. It is caused by changes in the brain, including abnormal buildups of proteins, known as amyloid plaques and tau tangles.
- Frontotemporal dementia, a rare form of dementia that tends to occur in people younger than 60. It is associated with abnormal amounts or forms of the proteins tau and TDP-43.
- Lewy body dementia, a form of dementia caused by abnormal deposits of the protein alpha-synuclein, called Lewy bodies.
- Vascular dementia, a form of dementia caused by conditions that damage blood vessels in the brain or interrupt the flow of blood and oxygen to the brain.
- Mixed dementia, a combination of two or more types of dementia.
Causes Of Alzheimer’s Disease
Alzheimer’s disease is the most common type of dementia.
Alzheimer’s disease is thought to be caused by the abnormal build-up of 2 proteins called amyloid and tau.
Deposits of amyloid, called plaques, build up around brain cells. Deposits of tau form “tangles” within brain cells.
Researchers do not fully understand how amyloid and tau are involved in the loss of brain cells, but research into this is continuing.
As brain cells become affected in Alzheimer’s, there’s also a decrease in chemical messengers involved in sending messages, or signals, between brain cells.
Levels of 1 neurotransmitter, acetylcholine, are particularly low in the brains of people with Alzheimer’s disease.
Medicines like donepezil increase levels of acetylcholine, and improve brain function and symptoms.
These treatments are not a cure for Alzheimer’s disease, but they do help improve symptoms.
Read more about treatments for dementia.
The symptoms that people develop depend on the areas of the brain that have been damaged by the disease.
The hippocampus is often affected early on in Alzheimer’s disease. This area of the brain is responsible for laying down new memories. That’s why memory problems are one of the earliest symptoms in Alzheimer’s.
Unusual forms of Alzheimer’s disease can start with problems with vision or with language.
Read more about Alzheimer’s disease.
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What Part Of The Brain Does Alzheimers Affect
Alzheimers disease is a progressive disorder that starts and develops gradually in older people. As it progresses, the brain undergoes several changes, affecting memory, language, and thinking skills.
Brain shrinkage to a certain extent is normal in healthy aging but, surprisingly, the neurons are not lost in substantial numbers. In Alzheimers, however, the brain shrinks significantly due to extensive damage and neuron loss. The neurons lose the connections between them, stop functioning, and die since the disease obstructs their critical processes, including communication, metabolism, and repair.
Are There Medicines To Treat Dementia
There is no cure for dementia yet, but there are medicines that can help treat some of the symptoms of dementia. There are medications that may improve memory for a period of time. There are also medications that are effective for treating mood disorders, such as anxiety and depression, which commonly occur in people with dementia. It is also important that your provider carefully evaluates any medicine someone with dementia is taking, because some medications may make memory symptoms worse.
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Mri Analysis And Post
Two experienced observers, unaware of to whom the scans belonged, identified by consensus any pathological T2 hyperintensities on the hard copies from patients and controls. In order to limit the risk of including subjects with concomitant vascular pathology, subjects with one or more macroscopic T2-weighted abnormalities located in the deep white matter or more than five abnormalities located in periventricular regions were excluded from the analysis.
PGSE EPI images were first corrected for geometric distortion induced by eddy currents using an algorithm which maximizes mutual information between the diffusion-unweighted and -weighted images . Then, assuming a mono-exponential relationship between signal intensity and the product of the b matrix and diffusion tensor matrix components, the tensor was estimated statistically, using a multivariate linear regression model . D and FA maps were derived .
Location of the selected regions of interest in a patient with DLB. Internal capsule, putamen, thalamus, temporal and occipital lobes. Genu and splenium of the corpus callosum, anterior and posterior pericallosal areas and caudate nucleus. Frontal lobes. Parietal lobes. See text for further details.
Dementia: What Part Of The Brain Is Under Attack
Part 2 in our series on Dementia. Check out Part 1.
In the diagnosis list, dementia can be clearly stated or there may be other disorders highly linked to dementia, causing the resident to present with the same signs and symptoms. I want you to be able to recognize the types of dementia and the disorders linked to dementia so you can be adequately prepared to understand the residents needs and modify the treatment approach accordingly.
The Alzheimers Association recognizes these types of dementia:
- Alzheimers dementia: most common, 60-80% of known cases
- Vascular dementia: second most common, 10% of known cases
- Dementia with Lewy bodies
- Mixed dementia: commonly Alzheimers with Vascular dementia
- Frontotemporal dementia
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