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What Causes Alzheimer’s Disease In The Brain

We May Finally Know What Causes Alzheimers And How To Stop It

What causes Alzheimer’s Disease?

Alzheimers disease has destroyed neurons in the right-hand brain above

Jessica Wilson/Science Photo Library

AFTER decades of disappointment, we may have a new lead on fighting Alzheimers disease. Compelling evidence that the condition is caused by a bacterium involved in gum disease could prove a game-changer in tackling one of medicines biggest mysteries, and lead to effective treatments or even a vaccine.

As populations have aged, dementia has skyrocketed to become the fifth biggest cause of death worldwide. Alzheimers constitutes some 70 per cent of these cases , yet we dont know what causes it. The condition, which results in progressive loss of memory and cognitive function, usually over a decade or so, is devastating both to those who have it and to their loved ones.

The condition often involves the accumulation of two types of proteins called amyloid and tau in the brain. As these are among the earliest physical signs of the disease, the leading hypothesis since 1984 has been that the condition is caused by the defective control of these proteins, especially amyloid, which accumulates to form large, sticky plaques in the brain.

The bulk of research into understanding and treating Alzheimers has centred on this amyloid hypothesis. Huge sums of money have been invested in experiments involving mice genetically modified to produce amyloid, and in developing drugs that block or destroy amyloid proteins, or sometimes degraded tangles of tau.

What To Do If You Suspect Alzheimers Disease

Getting checked by your healthcare provider can help determine if the symptoms you are experiencing are related to Alzheimers disease, or a more treatable conditions such as a vitamin deficiency or a side effect from medication. Early and accurate diagnosis also provides opportunities for you and your family to consider financial planning, develop advance directives, enroll in clinical trials, and anticipate care needs.

Planning For The Future

If possible, make decisions while your loved one is able to take part in the decision making. These are difficult but important conversations. Questions include:

  • What kind of care does he or she need right now?
  • Who will take care of him or her in the future?
  • What can the family expect as the disease progresses?
  • What kind of financial and legal planning needs to be done?

Education of the family and other caregivers is critical to successfully caring for someone who has dementia. If you are or will be a caregiver, start learning what you can expect and what you can do to manage problems as they arise. For more information, see Home Treatment.

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What Causes Alzheimer Disease

Lots of research is being done to find out more about the causes of Alzheimer disease. There is no one reason why people get it. Older people are more likely to get it, and the risk increases the older the person gets. In other words, an 85-year-old is more likely to get it than a;65-year-old. And women are more likely to get it than men.

Researchers also think genes handed down from family members can make a person more likely to get Alzheimer disease. But that doesn’t mean everyone related to someone who has it will get the disease. Other things may make it more likely that someone will get the disease, such as high blood pressure, high cholesterol, Down syndrome, or having a head injury.

On the positive side, researchers believe exercise, a healthy diet, and taking steps to keep your mind active may help delay the start of Alzheimer disease.

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Research suggests that a host of factors beyond genetics may play a role in the development and course of Alzheimer’s disease. There is a great deal of interest, for example, in the relationship between cognitive decline and vascular conditions such as heart disease, stroke, and high blood pressure, as well as metabolic conditions such as diabetes and obesity. Ongoing research will help us understand whether and how reducing risk factors for these conditions may also reduce the risk of Alzheimer’s.

A nutritious diet, physical activity, social engagement, sleep, and mentally stimulating pursuits have all been associated with helping people stay healthy as they age. These factors might also help reduce the risk of cognitive decline and Alzheimer’s disease. Clinical trials are testing some of these possibilities.

Early-life factors may also play a role. For example, studies have linked higher levels of education with a decreased risk of dementia. There are also differences in dementia risk among racial groups and sexesall of which are being studied to better understand the causes of Alzheimers disease and to develop effective treatments and preventions for all people.

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Signs Of Mild Alzheimers Disease

In mild Alzheimers disease, a person may seem to be healthy but has more and more trouble making sense of the world around him or her. The realization that something is wrong often comes gradually to the person and his or her family. Problems can include:

  • Memory loss
  • Poor judgment leading to bad decisions
  • Loss of spontaneity and sense of initiative
  • Taking longer to complete normal daily tasks
  • Repeating questions
  • Increased sleeping
  • Loss of bowel and bladder control

A common cause of death for people with Alzheimers disease is aspiration pneumonia. This type of pneumonia develops when a person cannot swallow properly and takes food or liquids into the lungs instead of air.

There is currently no cure for Alzheimers, though there are medicines that can treat the symptoms of the disease.

Causes Of Alzheimer’s Disease

The brain is made up of billions of nerve cells that connect to each other. In Alzheimers disease, connections between these cells are lost. This is because proteins build up and form abnormal structures called plaques and tangles. Eventually nerve cells die and brain tissue is lost.

The brain also contains important chemicals that help to send signals between cells. People with Alzheimers have less of some of these chemical messengers in their brain, so the signals are not passed on as well. There are some drug treatments for Alzheimers disease that can help boost the levels of some chemical messengers in the brain. This can help with some of the symptoms.

Alzheimers is a progressive disease. This means that gradually, over time, more parts of the brain are damaged. As this happens, more symptoms develop, and they also get worse.More than 520,000 people in the UK have dementia caused by Alzheimers disease and this figure is set to rise.

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Talk To Your Doctor About Dementia Expert Advice

Significant changes in memory are not normal at any age and should be investigated by a doctor as soon as possible.

Its important not to assume a person has dementia. Many other conditions can cause the symptoms of dementia, so the first step is to talk to your doctor.

A medical diagnosis is important because there could be other reasons for these changes, such as:

  • medicines or alcohol
  • mild cognitive impairment

Watch the video below and learn how you can start a conversation with someone who may be showing signs of dementia about the need to see a doctor.

Read the related video transcript

Research Into The Cause Of Dementia With Lewy Bodies

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Dementia with Lewy bodies is characterised by the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells in the brain. Lewy bodies are accumulations of a protein called alpha-synuclein. It is thought that these contribute to the degeneration and death of nerve cells.

Dementia with Lewy bodies sometimes co-occurs with Alzheimers disease and/or vascular dementia. It may also be hard to distinguish dementia with Lewy bodies from Parkinsons disease, which is also associated with Lewy bodies, and some people who have Parkinsons disease develop a similar dementia.

At present there is no known cause of dementia with Lewy bodies and no risk factors have been identified. In very rare cases, the disease appears to be inherited, but a genetic cause has not yet been found. In short, we do not know why Lewy bodies form in the brain and research continues in the attempt to find an answer. Much of this research is focussed on searching for the genetic roots of dementia with Lewy bodies, exploring the mechanisms of alpha-synuclein accumulation, and discovering how Lewy bodies cause the particular symptoms of dementia with Lewy bodies.;

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What Happens In Alzheimer Disease

You probably know that your brain works by sending signals. Chemical messengers, called neurotransmitters , allow brain cells to talk to each other. But a person with Alzheimer disease has lower amounts of neurotransmitters.

People with Alzheimer disease also develop deposits of stuff that prevent the cells from working properly. When this happens, the cells can’t send the right signals to other parts of the brain. Over time, brain cells affected by Alzheimer disease also begin to shrink and die.

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A small, light-activated molecule recently tested in mice represents a new approach to eliminating clumps of amyloid protein found in the brains of Alzheimers disease patients. If perfected in humans, the technique could be used as an alternative approach to immunotherapy and used to treat other diseases caused by similar amyloids.

Researchers injected the molecule directly into the brains of live mice with Alzheimers disease and then used a specialized probe to shine light into their brains for 30 minutes each day for one week. Chemical analysis of the mouse brain tissue showed that the treatment significantly reduced amyloid protein. Results from additional experiments using human brain samples donated by Alzheimers disease patients supported the possibility of future use in humans.

The importance of our study is developing this technique to target the amyloid protein to enhance clearance of it by the immune system, said Yukiko Hori, a lecturer at the University of Tokyo and co-first author of the research recently published in Brain.

The small molecule that the research team developed is known as a photo-oxygenation catalyst. It appears to treat Alzheimers disease via a two-step process.

First, the catalyst destabilizes the amyloid plaques. Oxygenation, or adding oxygen atoms, can make a molecule unstable by changing the chemical bonds holding it together. Laundry detergents or other cleaners known as oxygen bleach use a similar chemical principle.

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Key Biological Processes In The Brain

Most neurons have three basic parts: a cell body, multiple dendrites, and an axon.

  • The cell body contains the nucleus, which houses the genetic blueprint that directs and regulates the cells activities.
  • Dendrites are branch-like structures that extend from the cell body and collect information from other neurons.
  • The axon is a cable-like structure at the end of the cell body opposite the dendrites and transmits messages to other neurons.

The function and survival of neurons depend on several key biological processes:

Neurons are a major player in the central nervous system, but other cell types are also key to healthy brain function. In fact, glial cells are by far the most numerous cells in the brain, outnumbering neurons by about 10 to 1. These cells, which come in various formssuch as microglia, astrocytes, and oligodendrocytessurround and support the function and healthy of neurons. For example, microglia protect neurons from physical and chemical damage and are responsible for clearing foreign substances and cellular debris from the brain. To carry out these functions, glial cells often collaborate with blood vessels in the brain. Together, glial and blood vessel cells regulate the delicate balance within the brain to ensure that it functions at its best.

A Word About Clinical Trials

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Although not right for everyone, clinical trials may be an option. Begin your research at a credible place, such as the Alzheimers Disease Clinical Trials Database. This is a joint project of the National Institute on Aging and the U.S. Food and Drug Administration. Its maintained by the NIAs Alzheimers Disease Education and Referral Center.

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Symptoms Of Alzheimers Disease

Alzheimers disease typically starts slowly and the symptoms can be very subtle in the early stages. As the disease progresses, symptoms become more noticeable and interfere with daily life. The disease affects each person differently and the symptoms vary.Common symptoms include:

  • persistent and frequent memory loss, especially of recent events
  • vagueness in everyday conversation
  • being less able to plan, problem-solve, organise and think logically
  • language difficulties such as finding the right word and understanding conversations
  • apparent loss of enthusiasm for previously enjoyed activities
  • taking longer to do routine tasks
  • becoming disoriented, even in well-known places
  • inability to process questions and instructions
  • deterioration of social skills
  • emotional unpredictability
  • changes in behaviour, personality and mood.

Symptoms vary as the disease progresses and different areas of the brain are affected. A persons abilities may fluctuate from day to day, or even within the one day, and can become worse in times of stress, fatigue or ill health.The stages of Alzheimers disease progress from mild Alzheimers disease to moderate Alzheimers disease and then severe Alzheimers disease. During severe Alzheimers disease, people need continuous care. The rate of progression between these stages differs between people.

Home Remedies For Short

You might have heard that certain vitamin supplements can help improve your short-term memory. However, even though these supplements are safe, theres conflicting research on whether they help memory loss.

In some cases, they can be helpful. For example, a B-12 supplement may help if your short-term memory loss is caused by a B-12 deficiency.

Otherwise, theres mixed evidence for how well other supplements work for memory loss. For example, ginkgo biloba is a popular supplement for memory and concentration issues. But a review of 36 studies found that while the supplement is safe, its effects on dementia or other cognitive impairments is inconsistent and unreliable.

Fish oil is another supplement you may have heard helps memory. A Cochrane review found that fish oil doesnt have any significant cognitive benefits for healthy older adults. However, they suggested that more research should be done on this topic.

Curcumin, which is extracted from turmeric, has been said to help improve cognitive function, including memory.

A review of curcumins effect on people with Alzheimers disease found that theres some evidence that curcumin positively affects some of the pathways affected by Alzheimers disease. However, the researchers found that more research is needed to say definitively if curcumin can help memory problems.

Even if supplements arent effective in treating short-term memory loss, there are some lifestyle modifications you can try, including:

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What Is The Outlook For People With Alzheimers Disease

Alzheimers disease gets worse over time and is ultimately fatal. Persons with Alzheimers disease live, on average, four to eight years after diagnosis. Some patients can live as long as 20 years after diagnosis. The course of the disease varies from person to person.

Last reviewed by a Cleveland Clinic medical professional on 03/18/2019.

References

How Does Alzheimers Disease Affect The Brain

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The brain typically shrinks to some degree in healthy aging but, surprisingly, does not lose neurons in large numbers. In Alzheimers disease, however, damage is widespread, as many neurons stop functioning, lose connections with other neurons, and die. Alzheimers disrupts processes vital to neurons and their networks, including communication, metabolism, and repair.

At first, Alzheimers disease typically destroys neurons and their connections in parts of the brain involved in memory, including the entorhinal cortex and hippocampus. It later affects areas in the cerebral cortex responsible for language, reasoning, and social behavior. Eventually, many other areas of the brain are damaged. Over time, a person with Alzheimers gradually loses his or her ability to live and function independently. Ultimately, the disease is fatal.

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What Are The Signs Of Alzheimer’s Disease

Scientists continue to unravel the complex brain changes involved in the onset and progression of Alzheimers disease. It seems likely that damage to the brain starts a decade or more before memory and other cognitive problems appear. During this preclinical stage of Alzheimers disease, people seem to be symptom-free, but toxic changes are taking place in the brain.

Damage occurring in the brain of someone with Alzheimers disease begins to show itself in very early clinical signs and symptoms. For most people with Alzheimersthose who have the late-onset varietysymptoms first appear in their mid-60s. Signs of early-onset Alzheimers begin between a persons 30s and mid-60s.

The first symptoms of Alzheimers vary from person to person. Memory problems are typically one of the first signs of cognitive impairment related to Alzheimers disease. Decline in non-memory aspects of cognition, such as word-finding, vision/spatial issues, and impaired reasoning or judgment, may also signal the very early stages of Alzheimers disease. And some people may be diagnosed with mild cognitive impairment. As the disease progresses, people experience greater memory loss and other cognitive difficulties.

Alzheimers disease progresses in several stages: preclinical, mild , moderate, and severe .

Research Into The Genetics Of Dementia

Genes carry patterns for the many proteins that form our bodies. Proteins are the essential building blocks of life – forming cells, organs, and enzymes which help the body to function. Once they are made, proteins can be folded into different structures and shapes to fulfil their many functions. Genes are found in every cell in the body in packages of twisted DNA called chromosomes. Half of these chromosomes are inherited from each parent – providing the basis for genetic inheritance. Genes explain why family resemblances occur and why some diseases can run in families.

There is still much we don’t know about the role of genes in Alzheimer’s disease and other dementias, but researchers continue to study this area. In most cases, dementia occurs sporadically, is not directly caused by a single gene and has no clear pattern of family inheritance. However, in a minority of cases, Alzheimer’s disease and some other types of dementia can be directly caused by an inherited gene mutation. The table below summarises some of the genes that have been found to cause or be involved in dementia. Each type is discussed in more detail under the relevant section below.

Disorder

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