Immune System And Neuroinflammation
Signs of chronic inflammatory reaction are seen in areas affected by AD, and upregulation of the components of the complement system are observed in neurofibrillary tangles and neuritic plaques. While these phenomena may represent a local response to neuronal damage and aggregated proteins, evidence suggests that they are not merely a byproduct of a pathological cascade. Inflammatory processes potentially could turn a relatively slowly progressive condition into rapid neurodegeneration., Several of the late onset AD genes are involved directly or indirectly in the regulation of inflammatory mechanisms. This further supports a prominent role for the immune system and neuroinflammation in AD pathogenesis.
Genetic variants in CR1 have been implicated in autoimmune and inflammatory diseases. Depending upon the number of homologous repeats, CR1 contains multiple extracellular binding sites for C3b and C4b. A- oligomers bound to C3b adhere to the erythrocyte and are subsequently cleared from the circulation. Transgenic mouse models overexpressing APP have increased A accumulation and inhibition of C3b, suggesting a protective role of CR1 in AD. Genetic variation in CR1 might affect AD pathogenesis through neuroinflammation related to local complement inhibition.
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.
Whos A Good Candidate
ApoE4 genotyping is not regularly used by most neurologists,Dr. Sabbagh says, and advisory groups recommend that people who do not havesymptoms not get tested.
But he does believe that the test can be used safely and without causing harm or distress in some people.
To me, people who are appropriate candidates are people with mild cognitive impairment, Dr. Sabbagh says. These are likely adults between the ages of about 50 and 75 who demonstrate early symptoms of Alzheimers disease and have already gone through a family history and neuropsychological testing with a neurologist.
I do order it to answer the question why not just what, he explains. Some people want to know why they got Alzheimers disease, so this can help explain that they inherited it and were born with the risk.
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Most Cases Of Alzheimers Are Not Caused By A Single Gene
The good news is that most cases of Alzheimers disease are not passed along by a single gene. Among the millions of people in the world affected by AD, those known to have developed the disease due to the inheritance of a single gene account for a very small percentage.
The bad news is that even without inheriting one of the genes that are known to transmit AD, the disease is still a significant health risk for any older adult.
Do Genes Cause Diseases
Genetic mutations can cause diseases. If a person inherits a genetic mutation that causes a certain disease, then he or she will usually get the disease. Sickle cell anemia, cystic fibrosis, and some cases of early-onset Alzheimer’s disease are examples of inherited genetic disorders.
Other changes or differences in genes, called genetic variants, may increase or decrease a person’s risk of developing a particular disease. When a genetic variant increases disease risk but does not directly cause a disease, it is called a genetic risk factor.
Identifying genetic variants may help researchers find the most effective ways to treat or prevent diseases such as Alzheimer’s in an individual. This approach, called precision medicine, takes into account individual variability in genes, environment, and lifestyle for each person.
The expression of geneswhen they are switched on or offcan be affected, positively and negatively, by environmental and lifestyle factors, such as exercise, diet, chemicals, or smoking. The field of epigenetics is studying how such factors can alter a cell’s DNA in ways that affect gene activity.
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Genes And Vascular Dementia
Vascular dementia is caused when blood flow to the brain is reduced, damaging nerve cells. This can happen as a result of a stroke or damage to blood vessels deep in the brain. The majority of cases of vascular dementia are not caused by faulty genes.
We may carry genes that affect our risk of stroke, heart disease or other diseases that may contribute to vascular dementia. However, lifestyle factors such as smoking, lack of exercise, obesity, drinking alcohol over the recommended limits, and an unbalanced diet can also affect our risk.
There are rare genetic disorders that can cause vascular dementia by damaging blood vessels in the brain. One is called CADASIL and can be passed down through families. CADASIL only affects around 1,000 people in the UK.
Genes And Dementia With Lewy Bodies
Dementia with Lewy bodies is caused by a build-up of abnormal proteins in the brain and may have symptoms similar to those seen in Parkinsons disease. Age is currently the biggest known risk factor for dementia with Lewy bodies, although research is underway to find out whether genes may also play a role.
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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 .
Is There Anything You Can Do
Unlike glaucoma, diabetes, or some cancers, there is no early detection screening for Alzheimerâs disease. Thereâs no definitive way to prevent it either.
âThereâs just nothing practical or actionable to do with this information,â Weissman says. âItâs not going to change anyoneâs medical management.â
The lifestyle recommendations that might help lower risk for Alzheimerâs, Weissman explains, are the things that doctors encourage their patients to do anyway. Research shows that a healthy diet, plenty of exercise, enough sleep, fewer calories per day or periodic fasting, and brain stimulation can all improve your odds of living out your life dementia-free.
But, 23andMeâs Wu argues, âWe know these are standard recommendations for staying healthy, but we also know that most people donât follow them. Genetic information can be the triggering event that gets people motivated.â
It certainly motivated Julie Gregory of Long Beach, IN, to overhaul her lifestyle. Like Tyrone, she took a genetic test for reasons unrelated to her Alzheimerâs risk. When her 23andMe results revealed that she had two copies of APOEe4, she thought of those âsenior momentsâ sheâd had since she was 49. Sheâd forget the names of people sheâd known for 20 years when she ran into them at the grocery store. Her test results filled her with dread. Were the wheels already in motion on the road to Alzheimerâs disease?
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What Does Pgd Involve
PGD involves the following steps:
When Is Genetic Testing For Dementia Appropriate
In some cases, it may seem likely that a persons dementia is caused by a single-gene change for example, if the person has a very strong family history of dementia. In these cases, it may be appropriate to offer genetic testing to the person and to their family.
However in most families dementia will not be caused by a single-gene change. In these cases, genetic testing will not be appropriate. This is because testing for risk variants does not provide any certainty about the persons chances of developing dementia.
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Apoe 4 Does Not Guarantee That Someone Will Develop Alzheimer’s Steps Can Be Taken To Reduce Alzheimer’s Risk
Research has shown us that individuals with the ApoE 4 gene are able to reduce their risk for developing Alzheimers. Individuals with the ApoE 4 gene can reduce their risk by proactively managing other risk factors and by pursuing activities and lifestyles which have been shown to reduce the risk of Alzheimers.
Individuals with the ApoE 4 gene are more vulnerable to certain factors which increase the risk of Alzheimers, risk factors like diabetes or high blood pressure. This makes it even more important than normal for individuals with the ApoE 4 gene to manage their blood pressure and diabetic status.
The chance of developing Alzheimers is influenced by behaviors that occur decades before and leading up to when the symptoms first become noticeable. Individuals with the ApoE 4 gene should begin addressing risk factors sooner, rather than later.
Individuals who have a family history of Alzheimers and individuals who believe they are experiencing memory loss should be tested for the ApoE 4 gene. Other individuals can be tested, but individuals in these two groups are most likely to possess the ApoE 4 gene.
Before being tested it is important to consider the emotional consequences of learning your result and how the result may affect you and your loved ones.
We believe that emotionally-stable individuals willing to take a proactive approach to managing their Alzheimers risk will benefit from genetic testing.
As Part Of Our Livetalk Series Being Patient Spoke With Jessica Langbaum Co
Certain genes like ApoE that play an important role in the disease. ApoEs genetic variant, known as ApoE4, is the strongest genetic risk factor for developing Alzheimers in later life. Genetic tests by mail, like 23andMe and AncestryDNA, make it easy to learn about ones ApoE status and to learn that one may have a much higher likelihood of developing Alzheimers in their lifetime. But just because a person carries the ApoE4 variant doesnt mean that their fate is sealed: Alzheimers is a complicated disease, and genetics is one among many factors, from lifestyle and environmental factors to preexisting health conditions, that influence peoples risk.
Being Patient sat down with Jessica Langbaum, co-director of the Alzheimers Prevention Initiative at the Banner Alzheimers Institute, to discuss the complex role of genetics in Alzheimers, asking: Should people seek genetic testing for Alzheimers? And if they do, how can they ensure they are prepared for what they find?
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Blood Tests Available Now
A blood test is available now, through your doctor, that delivers a result in about 10 days and accurately determines whether someone has Alzheimers disease. The Preclivity AD Test from C2N Diagnostics measures proteins in blood plasma that indicate a buildup of plaques known to cause dementia in peoples brains.
Cost
The cost of this Alzheimers blood test is $1,250, less expensive than a PET scan that looks for the same protein buildups. Unfortunately, the price tag cannot be covered by Medicare or Medicaid, but C2N says people who cant afford the test can qualify for a discount based on their income.
Does it Work?
C2N Diagnostics says they tested Preclivity AD in 686 people and compared it to the results of PET scans. When PET scans showed a high amount of amyloid-beta, a protein that turns to plaques and tangles in the brains of people with Alzheimers, the blood test agreed 92 percent of the time. When the PET scan showed no amyloid, the blood test showed the same about 77 percent of the time.
How to Get the Blood Test
The Preclivity AD Test has not been approved by the Food and Drug Administration. It is currently available only through a doctor, and can be sold by the company under rules for commercial laboratories. The test, in other words, is available despite lacking FDA approval, though C2N has said the FDA is planning on reviewing the test in 2021. The Alzheimers Association says it wont endorse the test until there is FDA approval.
Genetic Testing For Alzheimer’s Disease
A blood test can identify which APOE alleles a person has, but results cannot predict who will or will not develop Alzheimer’s disease. Currently, APOE testing is used primarily in research settings to identify study participants who may have an increased risk of developing Alzheimer’s. This knowledge helps scientists look for early brain changes in participants and compare the effectiveness of possible treatments for people with different APOE profiles.
Genetic testing is also used by physicians to help diagnose early-onset Alzheimers disease and to test people with a strong family history of Alzheimers or a related brain disease.
Genetic testing for APOE or other genetic variants cannot determine an individuals likelihood of developing Alzheimers diseasejust which risk factor genes a person has. It is unlikely that genetic testing will ever be able to predict the disease with 100 percent accuracy, researchers believe, because too many other factors may influence its development and progression.
Some people learn their APOE status through consumer genetic testing or think about getting this kind of test. They may wish to consult a doctor or genetic counselor to better understand this type of test and their test results. General information about genetic testing can be found at:
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How Can I Reduce My Risk Of Dementia
For the vast majority of people, our genes are only one factor affecting our risk of dementia. There are many other factors involved, such as age and lifestyle. While we cannot change our age or genes, research has found that up to a third of all cases of dementia could be avoided through lifestyle changes.
There are simple things we can do that may help lower our risk:
- Do not smoke.
- Drink fewer than 14 units of alcohol per week.
- Control high blood pressure.
- Keep cholesterol at a healthy level.
- Keep active and exercise regularly.
- Maintain a healthy weight.
- Eat a healthy balanced diet.
You can find more detailed information about how you can reduce your risk of dementia here.
What About Other Genes That Increase The Risk Of Developing Alzheimers Disease
The diagram below shows a number of genes associated with Alzheimers disease according to how common they are. Mutations in the APP, PSEN-1 and PSEN-2 genes are rare, but having a mutation gives a very high risk of developing Alzheimers disease, so these genes are shown in the top left of the diagram.
Most people who develop Alzheimers dont have familial Alzheimers disease, the particular reason that they develop the disease isnt clear. Its most likely to be due to a combination of factors such as age, environment, lifestyle and genetic risk factors. In these cases, the disease is known as sporadic there isnt one clear cause. Some of the risk factor genes are shown in the diagram above. Having one of these genes means youre more likely to develop Alzheimers disease than someone who doesnt have the gene, but it doesnt mean youll definitely develop Alzheimers. These genes increase your risk slightly, but some people with the genes dont get the disease, and vice versa. There are a number of genes that are very common lots of people have the form of the gene that increases the risk of developing Alzheimers disease, but they dont have a strong effect. These are shown in the bottom right of the diagram . TREM2 on the other hand is fairly rare, but has a greater effect than those more common genes2.
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Am I At Risk For Alzheimer’s
Whether we have seen early signs in ourselves or not, many of us want to know what our chances of getting this disease may be. Research has shown a number of possible factors that can impact your chances of getting Alzheimer’s disease, although none of these are a cause in and of themselves.
Some ages are more at risk
Old age is one of the most obvious risk factors. The vast majority of people develop the disease after the age of 65, and once you reach 65, your risk of getting Alzheimer’s doubles every five years. But Alzheimer’s doesn’t only affect people over 65 it has been known to affect people half that age, although this is much rarer.
Alzheimer’s is hereditary
A family history will also increase your risk of getting the disease. The risk increases even more if you have multiple family members who have suffered from the disease.
Whilst this may be due to the hereditary genetic factors we will look at in more depth later, there may be other factors at play. These could include environmental factors that impact both yourself and your family.
Gender predisposition
Gender is another significant risk factor. The first discovery of the disease back in 1906 was in a woman, and about twice as many women as men over 65 have Alzheimer’s. This may be in part to the fact that women have a longer lifespan or may even possibly be linked to menopause.
Genetic factors of Alzheimer’s
Other risk factors