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What Part Of The Brain Is Affected By Alzheimer’s

What Is Known About Alzheimers Disease

What is dementia? Alzheimer’s Research UK

Scientists do not yet fully understand what causes Alzheimers disease. There likely is not a single cause but rather several factors that can affect each person differently.

  • Age is the best known risk factor for Alzheimers disease.
  • Family historyresearchers believe that genetics may play a role in developing Alzheimers disease. However, genes do not equal destiny. A healthy lifestyle may help reduce your risk of developing Alzheimers disease. Two large, long term studies indicate that adequate physical activity, a nutritious diet, limited alcohol consumption, and not smoking may help people. To learn more about the study, you can listen to a short podcast.
  • Changes in the brain can begin years before the first symptoms appear.
  • Researchers are studying whether education, diet, and environment play a role in developing Alzheimers disease.
  • There is growing scientific evidence that healthy behaviors, which have been shown to prevent cancer, diabetes, and heart disease, may also reduce risk for subjective cognitive decline. Heres 8 ways.

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Prevention Of Alzheimer Disease

Some research tentatively suggests certain measures that may help prevent Alzheimer disease:

  • Controlling cholesterol levels: Some evidence suggests that having high cholesterol levels may be related to developing Alzheimer disease. Thus, people may benefit from a diet low in saturated fats and, if needed, drugs to lower cholesterol and other fats .

  • Controlling high blood pressure: High blood pressure may damage blood vessels that carry blood to the brain and thus reduce the brains oxygen supply, possibly disrupting connections between nerve cells.

  • Exercising: Exercising helps the heart function better and, for unclear reasons, may help the brain function better.

  • Keeping mentally active: People are encouraged to continue doing activities that challenge the mind, such as learning new skills, doing crossword puzzles, and reading the newspaper. These activities may promote the growth of new connections between nerve cells and thus help delay dementia.

  • Drinking alcohol in modest amounts: In modest amounts , alcohol may help lower cholesterol and maintain blood flow. Alcohol may even help with thinking and memory by stimulating the release of acetylcholine and causing other changes in nerve cells in the brain. However, there is no convincing evidence that people who do not drink alcohol should start drinking to prevent Alzheimer disease. Once dementia develops, abstaining from alcohol is usually best because it can make symptoms of dementia worse.

How The Finding Encourages Alzheimers Prevention Methods

In addition to helping researchers learn more about the progression of Alzheimers, scientists hope their discovery will encourage prevention measures. The research team believes that norepinephrine can help slow brain decline. Norepinephrine is released when the brain feels challenged, leading researchers to encourage engaging the brain in complex activities, like completing crosswords or even having a complicated job.

Professor Mara Mather, expert in aging and cognition and author of the study, said, Education and engaging careers produce late-life cognitive reserve, or effective brain performance, despite encroaching pathology. Activation of the locus coeruleus-norepinephrine system by novelty and mental challenge throughout ones life may contribute to cognitive reserve.

Dr. Rosa Sancho of Alzheimers Research UK, is optimistic about the teams findings, stating:

Its important that researchers around the world investigate the initial stages of Alzheimers and explore why some parts of the brain are more vulnerable to damage than others, as this will help in the hunt for new treatments.

What do you think about the area of the brain where Alzheimers begins? Are you optimistic about the discoverys impact on disease prevention methods? Share your thoughts with us in the comments below.

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Common Forms Of Dementia

There are many different forms of dementia. Alzheimer’s disease is the most common form and may contribute to 6070% of cases. Other major forms include vascular dementia, dementia with Lewy bodies , and a group of diseases that contribute to frontotemporal dementia . The boundaries between different forms of dementia are indistinct and mixed forms often co-exist.

Cholinergic Neurotransmission And Alzheimer Disease

Areas of the Brain Affected by Alzheimer

The cholinergic system is involved in memory function, and cholinergic deficiency has been implicated in the cognitive decline and behavioral changes of AD. Activity of the synthetic enzyme choline acetyltransferase and the catabolic enzyme acetylcholinesterase are significantly reduced in the cerebral cortex, hippocampus, and amygdala in patients with AD.

The nucleus basalis of Meynert and diagonal band of Broca provide the main cholinergic input to the hippocampus, amygdala, and neocortex, which are lost in patients with AD. Loss of cortical CAT and decline in acetylcholine synthesis in biopsy specimens have been found to correlate with cognitive impairment and reaction-time performance. Because cholinergic dysfunction may contribute to the symptoms of patients with AD, enhancing cholinergic neurotransmission constitutes a rational basis for symptomatic treatment.

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More Information About Alzheimer Disease

The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

  • Alzheimer’s Association: This web site provides information about Alzheimer disease, including statistics, causes, risk factors, and symptoms. It also provides resources for support, including information about daily care of people with Alzheimer disease, care for the caregiver, and support groups.

  • The Alzheimer’s Society: This web site provides a guide to dementia , a guide for caregivers, and information about types of dementia, symptoms, diagnosis, treatments, risk factors, and prevention.

  • Institute of Neurological Disorders and Stroke Alzheimer’s Disease Information Page: This web site defines Alzheimer disease and provides information about treatment, prognosis, and available clinical trials and links to other organizations focused on Alzheimer disease.

New Research Sheds Light On How Alzheimer’s Progresses In The Brain

Alzheimers disease and other types of dementia affect more than 55 million people worldwide. But the development of effective treatments and cures is progressing slowly. To some extent, this is because we still dont understand enough about what causes the disease and drives its progression.

Myself and my colleagues most recent work, published in Science Advances, presents a new approach using ideas from other areas of science to analyse data from Alzheimers patients. In this way, weve been able to build a better understanding of the processes that control the progression of Alzheimers disease in the brain.

By way of background, in Alzheimers disease and many other neurodegenerative diseases, like Parkinsons disease, proteins that are normally part of healthy brain cells start sticking together in microscopic clumps. These clumps of protein, called aggregates, form in patients brains, killing off brain cells and leading to symptoms such as memory loss.

As the number of aggregates increases, the disease worsens and eventually leads to death, often many years after the first mild symptoms. Several processes likely contribute to the formation of aggregates, but scientists are yet to understand how aggregates form in detail, and which processes are the most important in controlling how quickly they form.

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Is There Treatment Available

At present there is no cure for Alzheimers disease. However, one group of drugs called cholinergeric drugs appears to be providing some temporary improvement in cognitive functioning for some people with mild to moderate Alzheimers disease.

Drugs can also be prescribed for secondary symptoms such as restlessness or depression or to help the person with dementia sleep better.

Community support is available for the person with Alzheimers disease, their families and carers. This support can make a positive difference to managing dementia. Dementia Australia provides support, information and counselling for people affected by dementia. Dementia Australia also aims to provide up-to-date information about drug treatments.

Further help

For more information contact the National Dementia Helpline on 1800 100 500.

For a range of books and videos contact our Library.

For advice, common sense approaches and practical strategies on the issues most commonly raised about dementia, read our Help Sheets.

What Causes Dementia With Lewy Bodies

Your Amazing Brain – Dementia Explained – Alzheimer’s Research UK

Lewy bodies are named after the German doctor who first identified them. They are tiny deposits of a protein that appear in nerve cells in the brain. Researchers dont have a full understanding of why Lewy bodies appear, or exactly how they contribute to dementia. However, this is linked to two factors:

  • low levels of important chemicals that carry messages between nerve cells
  • a loss of connections between nerve cells, which then die.

Lewy bodies are the cause of DLB and Parkinsons disease. They are two of several diseases caused by Lewy bodies that affect the brain and nervous system and get worse over time. These are sometimes called Lewy body disorders.

The way someone is affected by DLB will depend partly on where the Lewy bodies are in the brain:

  • Lewy bodies at the base of the brain are closely linked to problems with movement . These are the main feature of Parkinsons disease.
  • Lewy bodies in the outer layers of the brain are linked to problems with mental abilities , which is a feature of DLB.

People with a Lewy body disorder can have problems with movement and changes in mental abilities at the same time.

A person with Parkinsons disease is at high risk of going on to develop dementia as their condition progresses. Dementia may be more likely in a person who has developed Parkinsons later in life or who has been living with it for several years.

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What Particular Part Of The Brain Does Alzheimers Effect

Alzheimers is first detected in the hippocampus, an area of the brain responsible for recent learning and more complex thoughts. From there the disease spreads out to the other sections of the brain as the disease continues to progress. Eventually, Alzheimers affects all aspects of everyday living and, in the end-stages, even the immune system is compromised. The person becomes susceptible to recurrent infections which quite often lead to the immediate cause of death.

Oxidative Stress And Damage

Oxidative damage occurs in AD. Studies have demonstrated that an increase in oxidative damage selectively occurs within the brain regions involved in regulating cognitive performance.

Oxidative damage potentially serves as an early event that then initiates the development of cognitive disturbances and pathological features observed in AD. A decline in protein synthesis capabilities occurs in the same brain regions that exhibit increased levels of oxidative damage in patients with mild cognitive impairment and AD. Protein synthesis may be one of the earliest cellular processes disrupted by oxidative damage in AD.

Oxidative stress is believed to be a critical factor in normal aging and in neurodegenerative diseases such as Parkinson disease, amyotrophic lateral sclerosis, and AD. Formation of free carbonyls and thiobarbituric acid-reactive products, an index of oxidative damage, are significantly increased in AD brain tissue compared with age-matched controls. Plaques and tangles display immunoreactivity to antioxidant enzymes.

Multiple mechanisms exist by which cellular alterations may be induced by oxidative stress, including production of reactive oxygen species in the cell membrane . This in turn impairs the various membrane proteins involved in ion homeostasis such as N -methyl-D-aspartate receptor channels or ion-motive adenosine triphosphatases.

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How Is Alzheimer’s Different From Other Forms Of Dementia

Alzheimer’s disease is distinguished from other forms of dementia by characteristic changes in the brain that are visible only upon microscopic examination during autopsy. Brains affected by Alzheimer’s disease often show presence of the following:

  • Fiber tangles within nerve cells

  • Clusters of degenerating nerve endings

Another characteristic of Alzheimer’s disease is the reduced production of certain brain chemicals necessary for communication between nerve cells, especially acetylcholine, as well as norepinephrine, serotonin, and somatostatin.

Who Has Alzheimers Disease

  • In 2020, as many as 5.8 million Americans were living with Alzheimers disease.1
  • Younger people may get Alzheimers disease, but it is less common.
  • The number of people living with the disease doubles every 5 years beyond age 65.
  • This number is projected to nearly triple to 14 million people by 2060.1
  • Symptoms of the disease can first appear after age 60, and the risk increases with age.

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Alzheimer’s And Dementia: Which Areas Of The Brain Are Affected

The human brain is made of billions of specialized cells designed to process and transmit information. When these cells lose their ability to function properly, vital communication between neurons is impaired or completely interrupted.

Dementia and Alzheimers disease disrupt neurons and cause damage to many areas of the brain, leading to a wide array of progressive symptoms. If you suspect dementia or Alzheimers in a loved one, it is important to find a neurologist to diagnose the cause of these cognitive and behavioral changes.

Before identifying the specific brain changes and the areas of the brain which are affected by Alzheimer’s, its important to define neurology terms to better understand this disease.

Signs And Symptoms Of Alzheimer’s Disease

Memory problems are typically one of the first signs of cognitive impairment related to Alzheimers. Some people with memory problems have a condition called mild cognitive impairment . With MCI, people have more memory problems than normal for their age, but their symptoms do not interfere with their everyday lives. Movement difficulties and problems with the sense of smell have also been linked to MCI. Older people with MCI are at greater risk for developing Alzheimers, but not all of them do so. Some may even revert to normal cognition.

The first symptoms of Alzheimers vary from person to person. For many, decline in nonmemory aspects of cognition, such as word-finding, vision/spatial issues, and impaired reasoning or judgment may signal the very early stages of the disease. Researchers are studying biomarkers to detect early changes in the brains of people with MCI and in cognitively normal people who may be at greater risk for Alzheimers. More research is needed before these techniques can be used broadly and routinely to diagnose Alzheimers in a health care providers office.

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In The Alzheimer’s Brain

Scientists have identified several hallmark brain abnormalities in people affected by Alzheimer’s:

  • Amyloid plaques, which are microscopic clumps of a protein called beta-amyloid peptide. These abnormal clusters of protein fragments build up between nerve cells which disrupts electrical signals. Diseased tissue has many fewer nerve cells and synapses compared to healthy brain tissue.
  • Dead and dying nerve cells contain neurofibrillary tangles, which are made up of twisted strands of another protein called tau .
  • These plaques and tangles tend to spread through the cortex in a predictable pattern as AD progresses.
  • There is a profound loss of connections among brain cells called synapses. These connections transmit information from cell to cell and are responsible for memory, learning and communication.
  • Inflammation results from the brain’s efforts to fend off the lethal effects of these and other neurological changes.
  • Brain cells eventually die, resulting in significant tissue shrinkage or atrophy.

Scientists are not absolutely sure what mechanism specifically causes cell death and tissue loss in a diseased brain, but plaques and tangles are the prime suspects.

There are several larger scale effects on the brain as well:

Safety And Supportive Measures

What Does Alzheimers Do to the Human Brain?

Creating a safe and supportive environment can be very helpful.

Generally, the environment should be bright, cheerful, safe, stable, and designed to help with orientation. Some stimulation, such as a radio or television, is helpful, but excessive stimulation should be avoided.

Structure and routine help people with Alzheimer disease stay oriented and give them a sense of security and stability. Any change in surroundings, routines, or caregivers should be explained to people clearly and simply.

Following a daily routine for tasks such as bathing, eating, and sleeping helps people with Alzheimer disease remember. Following a regular routine at bedtime may help them sleep better.

Activities scheduled on a regular basis can help people feel independent and needed by focusing their attention on pleasurable or useful tasks. Such activities should include physical and mental activities. Activities should be broken down in small parts or simplified as the dementia worsens.

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Medications To Treat The Underlying Alzheimer’s Disease Process

Aducanumab is the first disease-modifying therapy approved by the FDA to treat Alzheimers disease. The medication helps to reduce amyloid deposits in the brain and may help slow the progression of Alzheimers, although it has not yet been shown to affect clinical outcomes such as progression of cognitive decline or dementia. A doctor or specialist will likely perform tests, such as a PET scan or analysis of cerebrospinal fluid, to look for evidence of amyloid plaques and help decide if the treatment is right for the patient.

Aducanumab was approved through the FDAs Accelerated Approval Program. This process requires an additional study after approval to confirm the anticipated clinical benefit. If the follow-up trial fails to verify clinical benefit, the FDA may withdraw approval of the drug. Results of the phase 4 clinical trial for aducanumab are expected to be available by early 2030.

Several other disease-modifying medications are being tested in people with mild cognitive impairment or early Alzheimers as potential treatments.

How Is Alzheimers Disease Diagnosed

There is currently no single test to identify Alzheimers disease. The diagnosis is made only after careful clinical consultation.

The clinical diagnosis might include:

  • A detailed medical history
  • Lumbar puncture for cerebral spinal fluid tests
  • Medical imaging

These tests will help to eliminate other conditions with similar symptoms such as nutritional deficiencies or depression. After eliminating other causes, a clinical diagnosis of Alzheimers disease can be made with about 80% to 90% accuracy if the symptoms and signs are appropriate. The diagnosis can only be confirmed after death by examination of the brain tissue.

It is important to have an early and accurate diagnosis to determine whether a treatable condition other than Alzheimers disease, is causing the symptoms. If Alzheimers disease is diagnosed, medical treatment and other assistance can be discussed.

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