Are There Any Genetic Tests For Alzheimers Disease
Researchers have identified certain genes that increase the risk of developing Alzheimers and other rare deterministic genes that directly cause Alzheimers. Although genetic tests are available for some of these genes, health professionals do not currently recommend routine genetic testing for Alzheimers disease.
Preparing For A Doctor’s Visit
Genetic Causes Of Dementia
One rare form of Alzheimers disease is passed from generation to generation. This is called Familial Alzheimers disease . If a parent has a mutated gene that causes FAD, each child has a 50% chance of inheriting it. The presence of the gene means that the person will eventually develop Alzheimers disease, usually in their 40s or 50s. This form of Alzheimers disease affects an extremely small number of people probably no more than 100 at any given time among the whole population of Australia.
Three genes have been identified which, if mutated in certain ways, will cause FAD. These are called presenilin 1 , presenilin 2 and the amyloid precursor protein gene on chromosome 21.
Read Also: Dementia Ribbon Color
Are There Physical Tests For Dementia
A complete physical examination will be performed by the doctor to look for conditions that may lead to dementia. In addition, he or she will assess the risk factors for dementia, such as alcohol use and heart disease, among others. In addition, the person will be examined for signs of a stroke, such as difficulty speaking, hearing, or moving, as well as a complete neurological examination.
What Kind Of Doctor Tests For Dementia
A primary care doctor can perform a physical exam and find out more about your symptoms to determine what may be the cause. They will likely refer you to one or several specialists that can perform specific tests to diagnose dementia. Specialists may include neurologists, who specialize in the brain and nervous system psychiatrists or psychologists, who specialize in mental health, mental functions, and memory or geriatricians, who specialize in healthcare for older adults.
You May Like: Dementia Neurotransmitter
Scientists Have Identified Genetic Mutations That Cause Early
While researchers have found genetic risk factors for late-onset Alzheimers, they have, on the other hand, identified rare genetic mutations that cause early-onset Alzheimers, which affects people younger than the age of 65.
Langbaum said people who carry hereditary genetic mutations in one of three genes PSEN1, PSEN2 and APP nearly always develop the disease. They account for less than 1 percent of all people with Alzheimers.
She noted that the decision to order genetic testing for a genetic mutation that causes early-onset Alzheimers is typically made between the patient, clinician and in many cases, family members.
Meanwhile, there seems to be certain genetic factors that may be protective against Alzheimers. Scientists from the Banner Alzheimers Institute and colleagues found that an extremely rare variant of ApoE, known as the Christchurch mutation, appeared to protect a Colombian woman from the ravages of the disease.
The woman, who carried the PSEN1 mutation and two copies of the Christchurch mutation, had normal cognitive abilities until her 70s when she began to develop memory decline. Even though she had high levels of beta-amyloid plaques in her brain, there were very limited atrophy and tau pathology.
For more guidance on this topic to be the first to know about upcoming live talks with experts on practical topics related to Alzheimers, dementia and caregiving.
Why I Want To Know My Genetic Risk For Alzheimers
Genes are one of many risk factors for Alzheimers and related dementias. Science is evolving on the influence of alleles such APOE e4, the most common variant associated with Alzheimers disease, across age, gender, race and ethnicity. To date, routine genetic testing in medical care is not widely recommended. It is estimated, however, that more than 100 million people have undergone direct-to-consumer genetic testing, and this market is expected to grow.
UsAgainstAlzheimers does not hold a position on consumer genetic testing and recommends consulting with a healthcare provider about brain heath and considering genetic counseling in concert with any DNA test. To learn more about the genetics of Alzheimer’s disease and the contribution of the APOE genes, check out the National Institute on Aging’s Alzheimer’s Disease Genetics Fact Sheet.
I used the direct-to-consumer DNA test 23andMe to learn I have one copy of the APOE e4 gene, the most common genetic variant associated with Alzheimers disease. This increases my lifetime risk of developing Alzheimer’s disease by a little more than two times, on average. About 10 percent to 15 percent of people carry one copy of APOE4 and 2 percent to 3 percent carry two copies.
But what happens when the impediment cannot be moved? Like many people, I thought that my genes were outsized determinates of my fate and I did not want to look into the genetic crystal ball at something I could not control.
Not Powerless
Recommended Reading: Alzheimer Ribbon Color
Is In Favour Of Testing If Early Detection Might Allow For Treatment That Could Slow The Course Of The Disease
We have, its something that my daughter and I have talked about because, you know she, she said to me quite recently ‘Well, Mum, has got dementia, my grandmother had dementia, we think almost certainly her mother also probably had it in the last stages of her life, maybe I shall get it.’ so, certainly we, we’ve kind of thought whether this might be a, this might be something that, would be helpful to the female side of the family.I think the research suggests that you know over the next twenty or thirty years we are, we are going to, we probably are going to come up with.Something which will if not cure dementia at least will, can alleviate it dramatically. And therefore anything which can make the younger generation more alert to the possibilities of developing it and, and therefore can take any actions, which might alleviate the early stages seems to me a good thing. So on the whole I think I’m probably rather in favour of, genetic testing. Yes, I think on the whole I’m in favour of it and I think my daughter is also probably too.
Weve Done The Research For You
Genetic testing is available on the NHS if:
Genetic testing is NOT available if you have:
You May Like: Does Ben Carson Have Dementia
Has Changed His Views About Tests Since Looking After His Wife Is Now Planning A Test For Prostate Cancer To Reassure Himself And His New Partner
I wouldn’t mind it, yeah. Yeah I wouldn’t mind it because I, I have changed my views, I must admit previous, previously to, looking after I would have said ‘I don’t want to know anything.’ But I think I’ve only changed my views now because I’ve met somebody else who as I said before, her husband died of prostate cancer, so I’ve, I felt prepared to go and have that test just for their peace of mind. I mean it would give me peace of mind obviously, but I was thinking more in that direction. So yeah I, I think I would now, if somebody said, ‘Well you know there’s a test going for so and so’, I would probably go for it.Would you want your children to be tested?Are we talking about grandchildren or tiny children? Well even if I’d like my family tested, they’re at an age where they make their own decisions but, usually you know they’re, I would say ‘Yes,’ but then they would have to make their own decision. If it was a, a small child then I’d have it done, now. Because there’s so many things that can be done in the early stages, so instead of you being seriously ill or dying you can be made better. So yeah I think it’s a good idea now to have these different tests, and that’s why I’m having the one as I’ve already said.
Genetic Testing And Counseling For Early Onset Familial Alzheimer Disease
“I am finding out this month. If I have it, I will never have kids. It’s got to stop somewhere in our family.” Tom Drury , 36.
“If I knew I carried the mutation, I would not be able to get up in the morning.” Jane Smith , 26, at risk for eFAD.
Interview with a Genetic Counselor: Jennifer Williamson is a genetic counselor at the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain and the Gertrude H. Sergievsky Center at Columbia University, New York
Genetic Status Protocol: Get a sense of the careful process you may want to ask for should you decide to find out about your genetic status.
Introduction Early onset familial Alzheimer disease is an autosomal-dominant genetic disease. This means that in each family it is caused by a mutation in a single gene, and that a single copy of the mutant gene, inherited from one parent, will cause the disease. The discovery in the mid 1990s of eFAD genes aroused the specter of knowing one’s genetic future, not only for patients but also for their children and entire families. Indeed, the age of genetic testing is here. DNA testing has been used since the mid-1990s for Huntington disease and certain types of cancer. The experience with these families provides helpful guidance for families with eFAD, who have turned to genetic testing more recently. Indeed, there is a large literature on genetic testing for HD and a small but growing literature for AD.
Also Check: Did Reagan Have Alzheimers
I Think I Am At Risk Of Fad What Next
This page is here to guide you on what to do if you think you or your family may be at risk of familial Alzheimers disease .
When living at risk of FAD, people naturally ask what will happen next. Will I inherit this condition from my parents, and can I pass it on to my children? Should I get tested? What support is available to me?
If you think you are at risk of FAD, we have provided some information that you may find helpful.
Genes And Frontotemporal Dementia
Frontotemporal dementia , originally called Picks disease, is a rarer type of dementia mostly affecting people under the age of 65 years. The symptoms of FTD can be quite varied but include changes that mostly affect behaviour or language. There are different types of FTD, and these are likely to have different causes.
Some people with FTD have a family history of dementia and the condition may be inherited in some of these families. For behavioural variant FTD, a third to half of people could have a family history. This figure is thought to be much lower for other types of FTD.
Overall, around one in ten cases of FTD are thought to be caused by a faulty gene passed down in families. Several genes have been found that can cause these inherited types of FTD, including:
- tau
- progranulin
Mutations in the MAPT gene can cause the tau protein to behave abnormally, forming toxic clumps that can damage brain cells. We still need to understand more about how mutations in progranulin and C9ORF72 cause the disease.
The C9ORF72 gene can cause people to develop motor neurone disease, FTD or both conditions, and may affect members of the same family differently.
In cases of FTD that are not caused by faulty genes, the risk factors are not yet fully understood, and research is ongoing.
Is genetic testing available for frontotemporal dementia?
Recommended Reading: Is Bobby Knight Still Alive
Says She Would Not Have Wanted Testing When Younger But Might Be Interested Now She Has Retired
If preventative treatment becomes available most people would favour testing. Several carers could not see the point of testing when it wasn’t clear what could be done with the information. Some thought that knowing that one would develop Alzheimer’s at some point in the future could be a Sword of Damocles, causing people to feel hopeless, although another woman pointed out that one could be knocked over by a car in middle age and never develop the predicted condition.
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.
Don’t Miss: What’s The Difference Between Parkinson’s And Alzheimer’s
Susceptibility Genes In Late Onset Ad
Many reports, mostly employing a candidate gene approach, have claimed or refuted hundreds of potential risk genes in AD. The nonreplication of many of these studies reflects the fact that most were insufficiently powered to detect small genetic effects. Recently, genome-wide association studies , which establish linkage to disease based on SNPs closely spaced across the full genome, have offered a more powerful approach to identify susceptibility genes for complex disorders.
In four recent major GWAS studies of AD, as well as in many earlier association studies, APOE was identified as a powerful genetic risk factor . The recent GWAS studies also identified 9 novel loci for which the evidence is compelling: CLU, PICALM, CR1, BIN1, ABCA7, MS4A cluster, CD2AP, CD33 and EPHA1. In comparison to APOE, these identified factors confer a relatively small risk for disease: an increased disease odds ratio of only 1.11.15. In contrast, the odds ratio for the APOE E4 allele is 3.0 to 4.0.
The newly identified genetic risk factors are:
How Does A Doctor Test For Dementia
There is no single diagnostic test for Alzheimers disease and other causes of dementia. Dementias are diagnosed by evaluating and understanding a persons memory and thinking patterns. Doctors will consider a persons memory, grasp of language, mood states, problem-solving skills, ability to maintain focus and perform complex tasks. Evaluation may include in-office cognitive screening , physical examination, and review of labs. Labwork helps to determine whether there are vitamin deficiencies or hormonal changes at play. In some cases, evaluation may require neuropsychological testing, brain imaging , and genetic testing.
Recommended Reading: Farts And Dementia
Apoe: A Marker For Alzheimers Risk
Experts believe there is a strong genetic component to Alzheimers disease. But for late-onset Alzheimers disease, the most common form of dementia that appears after age 65, it doesnt boil down to just genetics. Rather, there could be multiple genes as well as other lifestyle and environmental factors that play into whether a person develops the disease.
As of now, the gene that seems to be the strongest predictorof Alzheimers risk is called ApoE. There are three varieties of this gene:
- ApoE2
- ApoE3
- ApoE4
Each person has two copies of ApoE genes. Studies have shown that a person who carries the ApoE4 variety is at an increased risk for developing Alzheimers. Having one copy of ApoE4 can triple a persons risk, Dr. Sabbagh says, and having two copies raises the risk even further.
But ApoE4 is not a deciding factor for Alzheimers. Its a statistical risk, but its not an absolute risk, Dr. Sabbagh reiterates.
That means that having ApoE4 doesnt mean youre guaranteed to develop Alzheimers, and not having it doesnt necessarily put you in the clear.
That uncertainty is part of why its important to carefullyconsider whether knowing your ApoE4 status would benefit you.
Synaptic Dysfunction And Endocytosis
In AD the disease process itself probably reflects, in part, an aberration of normal physiological processes at or near the synapse. Amyloid precursor protein is normally proteolytically processed during synaptic activity. Its amino-terminal, soluble APP fragment has neurotrophic properties, and the intracellular domain released by gamma-secretase is thought to enter the nucleus and regulate gene expression events. While A- was thought by many simply to be a waste byproduct of these sequential proteolytic events, recent studies suggest that A- is normally produced during synaptic activity and may function to provide a negative feedback signal on excess synaptic activity. In other words, A- production may normally help to maintain synaptic homeostasis. As such, the inevitable day-to-day production of A- at highly active synapses can lead to its accumulation and eventual oligomerization. Maybe this is why the basal brain activity pattern known as the default pathway aligns closely with the initial sites of amyloid deposition in AD. While the critical toxic species formed by A- remains uncertain, recent studies suggest that dimers or slightly larger oligomers are the key toxic species., Since oligomerization is a concentration-dependent process, excess A- at or just outside the neuronal membrane will favor oligomerization and eventual plaque formation.
Recommended Reading: What Causes Low Blood Pressure In Dementia Patients