Amyloid: Still An Important Piece Of The Alzheimer’s Puzzle
The initial 1907 report of Dr. Aloysius Alzheimer described senile plaques, later recognized as containing beta amyloid. These plaques, along with neurofibrillary tangles, are hallmarks of AD.
The Amyloid Cascade Hypothesis proposes that deposition of beta amyloid in the brain triggers the formation of amyloid plaques and neurofibrillary tangles . This theory fits with evidence from mice studies.
It also fits with genetic findings that I’ll discuss later in this article. However, brain injury can trigger the formation of senile plaques, raising the possibility that these plaques are an effect rather than a cause of some more basic disease process in AD. Furthermore, the connection between plaques and the development of NFTs is not yet fully understood. There is an additional concern about the ACH: The theory’s prediction that reducing brain amyloid might improve cognitive performance or diminish the risk of AD has been tested with trials of medications that do indeed reduce amyloid in the blood and brain. So far, clinical trial results have been negative for many of these medications and the small number of positive findings have been of limited magnitude.
Is There Treatment Available
At present there is no cure for Alzheimer’s 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 Alzheimer’s 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 Alzheimer’s 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.
Improve Your Lifestyle For Alzheimers Prevention
Healthy habits may help ward off Alzheimer’s. Consider the following steps to help prevent Alzheimers.
Exercise. “The most convincing evidence is that physical exercise helps prevent the development of Alzheimer’s or slow the progression in people who have symptoms,” says Dr. Marshall. “The recommendation is 30 minutes of moderately vigorous aerobic exercise, three to four days per week.”
Eat a Mediterranean diet. “This has been shown to help thwart Alzheimer’s or slow its progression. A recent study showed that even partial adherence to such a diet is better than nothing, which is relevant to people who may find it difficult to fully adhere to a new diet,” says Dr. Marshall. The diet includes fresh vegetables and fruits whole grains olive oil nuts legumes fish moderate amounts of poultry, eggs, and dairy moderate amounts of red wine and red meat only sparingly.
Get enough sleep. “Growing evidence suggests that improved sleep can help prevent Alzheimer’s and is linked to greater amyloid clearance from the brain,” says Dr. Marshall. Aim for seven to eight hours per night.
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Genetic Testing For Alzheimers Disease
A blood test can tell which APOE gene you have, but the results canât predict whether youâll get Alzheimerâs. Doctors use these tests mostly for research purposes. The test can tell them who has certain risk factors so they can watch for brain changes in case the disease develops.
Doctors donât typically recommend genetic testing for late-onset Alzheimerâs because the results can be confusing and cause emotional distress. If youâre showing symptoms or have a family history, your doctor may recommend testing to help diagnose early-onset Alzheimerâs. Doctors can usually diagnose Alzheimerâs without a genetic test.
What Is The Difference Between Alzheimer’s And Dementia
First, some explanation of dementia vs. Alzheimer’s. According to the Alzheimer’s Association, dementia is a general term for a decline in mental ability that interferes with daily life. Not a normal part of aging, most dementias are typically caused by damaged brain cells.
Of all the dementias, Alzheimer’s disease is the most common, accounting for 60-80% of the cases. In other words, it is a specific disease while “dementia” is a general term for a life-altering decline in brain function .
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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.
Social And Economic Impact
Dementia has significant social and economic implications in terms of direct medical and social care costs, and the costs of informal care. In 2015, the total global societal cost of dementia was estimated to be US$ 818 billion, equivalent to 1.1% of global gross domestic product . The total cost as a proportion of GDP varied from 0.2% in low- and middle-income countries to 1.4% in high-income countries.
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What Are The Early Signs And Symptoms Of Alzheimers
Alzheimers is characterized by the progressive loss of memory, cognition, judgment, reasoning, spatial awareness, communication, motor skills, and, eventually, the ability to live independently. Symptoms are easy to miss in the early stages but often include:
- Difficulty completing routine tasks
- Getting loss or losing things
- Missing appointments
- Forgetting recent events or conversations
- Poor judgment, especially with finances
- Difficulty finding words or writing
- Personality changes
The Role Of Genetics: Will I Get Alzheimers Disease
Scientists are still trying to determine the underlying causes of Alzheimers disease. The hope is that one day we will be able to stop the disease from progressing or perhaps even prevent it altogether. To date, researchers have identified a few genes that play an important role in Alzheimers. Some of these genes are simply risk factors for Alzheimers disease. Other genes are hereditary and will cause Alzheimers disease to develop.
There are two types of Alzheimers disease: early-onset Alzheimers disease and late-onset Alzheimers disease. Early-onset Alzheimers disease is rare, occurring in people age 60 and younger. This represents less than 5% of all people with Alzheimers. One type of early-onset Alzheimers disease is known as autosomal dominant Alzheimers disease or early-onset familial Alzheimers disease . This is even more uncommon, affecting less than 1% of all people with Alzheimers. What makes this type of early-onset Alzheimers disease so unusual is that it is caused by a hereditary genetic mutation to one of three genes PSEN1, PSEN2, or APP.
A recent study examined data from 4 large, observational studies of adults ages 60 and older. The study reported the association between various APOE genotypes and the risk of developing mild cognitive impairment or dementia due to Alzheimers by age 85 as follows:
- No family history of dementia
- Being male
Factors that may increase a persons risk of developing Alzheimers include:
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Alzheimers / Dementia Testing Alternatives
Despite the lack of an FDA-approved blood test, families who suspect their loved one may have Alzheimers have a well-trod, if meandering, path to a diagnosis. To begin the process, there are online tests for Alzheimers that can be downloaded, printed, completed and taken to your doctor, and even some interactive tests that might provide immediate results. However, these online tests do not actually test for Alzheimers or dementia. Instead, they offer families answers to these questions: Are my concerns about my loved one justified?Is this just normal aging or is there something more going on? Officially, the tests are looking for Mild Cognitive Impairment . These tests are not definitive, but they can help a family figure out what their next step should be.
If a doctor suspects a patient may have Alzheimers, there are more definitive approaches. Brain scans and tests on extracted spinal fluid when coupled with multiple physicians consultations can make a diagnosis of Alzheimers with upwards of 90 percent accuracy. Families should expect their loved one to be evaluated by a neurologist, a psychiatrist, and very likely a psychologist as well. Since Alzheimers is so common among the elderly, a diagnosis is less about finding a condition which fits and more about eliminating other possibilities.
Racial And Ethnic Discrimination
Although discrimination by providers against racial and ethnic minorities in the United States is commonly asserted as the cause of racial and ethnic disparities, we were unable to find any empirical studies on this topic that focused on people with Alzheimer’s disease. Indeed, there appear to be few empirical studies on this topic in health care.
A rare study of discrimination in health care used the implicit association test to assess the degree to which implicit racial bias affected physicians’ decisions on thrombosis . A total of 287 internal and emergency medicine residents from four hospitals in Boston and Atlanta participated in an online study. Half of the physicians received information about a White patient, and the other half received the same information but were told that the patient was African American. Although physicians self-reported that they did not prefer treating one group or the other and did not see either group as more cooperative, the test found a preference for treating Whites and the perception that African Americans were less cooperative. Similarly, Blanchard and Lurie found that minorities were more likely to report being looked down upon or treated with disrespect than Whites. Specifically, adjusting for sex, language, income, insurance coverage, and education, 20% of Asians, 19% of Hispanics, and 14% of Blacks reporting being treated disrespectfully or looked down upon by their provider compared to 9% of Whites.
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Stage 3 Early Confusional/mild Cognitive Impairment
While subtle difficulties begin to impact function, the person may try to cover up their problems. They may have difficulty with retrieving words, planning, organization, misplacing objects, and forgetting recent learning, which can affect life at home and work. Depression and other changes in mood can also occur.
Duration: 2 to 7 years.
What Causes Alzheimers Disease
Scientists dont fully know what causes Alzheimers disease but recognize that certain changes in the brain cause the progressive loss of neurons and their connections. This is due in large part to the formation of lesions, called plaques, and twisted protein fibers, called tangles, in the brain. These changes may be due to aging-related changes in the brain combined with genetic, environmental, and lifestyle factors the contribute to the onset of the disease.
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Will I Get Alzheimer’s
After hearing all this information, the question we’ve probably all asked ourselves remains: will I get Alzheimer’s?
The simple answer is that, unfortunately, there’s no real way to tell. There are a number of risk factors that can increase your chances of developing the condition, but it is very rare that these factors will guarantee that you will get Alzheimer’s at some point.
Much more research is needed into the causes and risk factors associated with Alzheimer’s disease, but the good news is that this research is going on right now. The Jackson Laboratory is one such institution leading the charge with cutting edge discoveries, a strong focus on personalized medicine, and our renowned JAX Center for Dementia and Alzheimer’s Research.
Another institution internationally known for its research and charity is the Alzheimer’s Association. If you are concerned about signs or symptoms of dementia in yourself or a loved one, we recommend turning first to the Alzheimers Association Help & Support page. This page includes a many helpful articles, ways to connect with local support groups, and a 24/7 hotline for any Alzheimers and dementia related questions.
Topics
What Is Alzheimers And How Does It Work
Alzheimers disease is a progressive neurologic disorder that causes the brain to shrink and brain cells to die. Alzheimers disease is the most common cause of dementia a continuous decline in thinking, behavioral and social skills that affects a persons ability to function independently.
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What Is Alzheimer Disease
Alzheimer disease, which affects some older people, is different from everyday forgetting. It is a condition that permanently affects the brain. Over time, the disease makes it harder to remember even basic stuff, like how to tie a shoe.
Eventually, the person may have trouble remembering the names and faces of family members or even who he or she is. This can be very sad for the person and his or her family.
It’s important to know that Alzheimer disease does not affect kids. It usually affects people over 65 years of age. Researchers have found medicines that seem to slow the disease down. And there’s hope that someday there will be a cure.
How Is Alzheimers Disease Treated
Medical management can improve quality of life for individuals living with Alzheimers disease and for their caregivers. There is currently no known cure for Alzheimers disease. Treatment addresses several areas:
- Helping people maintain brain health.
- Managing behavioral symptoms.
- Slowing or delaying symptoms of the disease.
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What Will The Doctor Do
It can be hard for a doctor to diagnose Alzheimer disease because many of its symptoms can be like those of other conditions affecting the brain. The doctor will talk to the patient, find out about any medical problems the person has, and will examine him or her.
The doctor can ask the person questions or have the person take a written test to see how well his or her memory is working. Doctors also can use medical tests to take a detailed picture of the brain. They can study these images and look for signs of Alzheimer disease.
When a person is diagnosed with Alzheimer disease, the doctor may prescribe medicine to help with memory and thinking. The doctor also might give the person medicine for other problems, such as depression . Unfortunately, the medicines that the doctors have can’t cure Alzheimer disease they just help slow it down.
Is Ad Just An Exaggeration Of Normal Aging
Normal aging is associated with brain changes such as tissue loss and degeneration of the synapse, which is the part of the nerve cell that is involved in passing an electrical or chemical signal to another nerve cell. Plaques and sometimes tangles are known to develop in cognitively normal older adults. These changes occur more frequently and severely in people with advanced vascular disease, suggesting that reduced blood flow to brain cells may be important in the development of AD. Many cognitively normal older adults show no NFTs, suggesting that AD is more than just normal aging of the brain.
The loss of brain cells that produce acetylcholine, a neurotransmitter that is active in the transmission of nerve impulses was an early finding in AD research. It led to the development of the cholinesterase-inhibiting drugs such as donepezil . Unfortunately, these medications are symptomatic treatments at best and often achieve only a limited benefit. The loss of these particular brain cells, therefore, is thought by many to be an effect rather than a cause of AD. In support of that idea is the finding that cell loss includes not only cholinergic cells but other cell types as well. Other neurotransmitters such as serotonin are also reduced in AD.
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Can You Prevent Alzheimers Disease
There is no sure way to prevent Alzheimers disease. However, you can reduce the risk of Alzheimers disease by caring for your health:
- your heart whats good for your heart is good for your brain so stick to a healthy diet and dont smoke
- your body regular physical activity increases blood flow to the brain so maintain an active lifestyle
- your mind an active mind helps build brain cells and strengthens their connections so socialise, do things such as puzzles and crosswords, and learn new things, such as a language
Learn more about the risk factors associated with Alzheimers and other types of dementia, and what you can do to reduce your risk:
Read the related video transcript.
Possible Reasons For Racial And Ethnic Disparities
Possible reasons for racial and ethnic disparities include factors related to measurement of Alzheimer’s disease, genetics, cardiovascular and cerebrovascular disease, socioeconomic factors, cultural differences, and racial and ethnic discrimination. A range of pathways have been suggested that link race and ethnicity with cognitive impairment, some of which have implications for disparities . In this section, we describe the evidence underlying selected factors, mediators, and pathways associated with disparities in this population.
FIGURE 3. Pathways Linking Race/Ethnicity and Cognitive Impairment
: Adapted from Glymour and Manly, 2008.
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Stage : Very Mild Changes
You still might not notice anything amiss in your loved one’s behavior, but they may be picking up on small differences, things that even a doctor doesn’t catch. This could include forgetting words or misplacing objects.
At this stage, subtle symptoms of Alzheimer’s don’t interfere with their ability to work or live independently.
Keep in mind that these symptoms might not be Alzheimer’s at all, but simply normal changes from aging.
A Whole New Hypothesis
When science converges from multiple independent laboratories like this, it is very compelling, says Casey Lynch of Cortexyme, a pharmaceutical firm in San Francisco.
Now researchers from Cortexyme and several universities have reported finding the two toxic enzymes that P. gingivalis uses to feed on human tissue in 99 and 96 per cent of 54 human Alzheimers brain samples taken from the hippocampus a brain area important for memory . These protein-degrading enzymes are called gingipains, and they were found in higher levels in brain tissue that also had more tau fragments and thus more cognitive decline.
The team also found genetic material from P. gingivalis in the cerebral cortex a region involved in conceptual thinking in all three Alzheimers brains they looked for it in.
This is the first report showing P. gingivalis DNA in human brains, and the associated gingipains co-localising with plaques, says Sim Singhrao at the University of Central Lancashire, UK, who wasnt involved in the study. Her team has previously found that P. gingivalisactively invades the brains of mice with gum infections.
The Porphyromonas gingivalis bacteria that can cause gum disease
A. Dowsett, Public Health England/Science Photo Library
When the team gave P. gingivalis gum disease to mice, it led to brain infection, amyloid production, tangles of tau protein and neural damage in the regions and nerves normally affected by Alzheimers. This suggests causation, says Lynch.
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