Alzheimer’s disease: what is the pathology to which Chris Hemsworth is predisposed?
Australian actor Chris Hemsworth discovers he has a genetic predisposition to Alzheimer’s. Let’s find out what the genetic test that the actor carried out means.
Actor Chris Hemsworth discovers he has a genetic predisposition to Alzheimer’s and decides to ease the work pressure regarding the films to “shoot”. In particular, genetic tests have shown that the actor has two copies of the APOE4 gene. What is the role of this gene?
Chris Hemsworth , the famous Australian actor who played Thor, has taken a break from work after discovering that he has a significantly higher risk of developing Alzheimer’s disease. The actor performed genetic tests for the docuseries Limitless, released by Disney +, in which he tried to explore his physical and mental limits in different situations. The results of these tests showed that Hemsworth inherited two copies of the ApoE4 gene from both parents , which predisposes him to an increased risk of developing Alzheimer ‘ s disease . But what real risks are there as a result of these tests? Is it an analysis that is better to recommend to everyone? Let’s find out a few more details about this story.
Let’s start by saying that 2-3% of the world’s population share the same risk as Hemsworth
Hemsworth is in fact one of the 2-3% of the population who are up to ten times more likely to develop Alzheimer ‘s than those who have none of the copies of the ApoE4 gene . The APOE gene, located on chromosome 19, encodes the major carrier of cholesterol from astrocytes to neurons and is associated with accelerated formation of beta-amyloid deposits , making it one of the major susceptibility factors for early-onset Alzheimer’s disease late, by definition a multifactorial condition .
Chris Hemsworth says , “ Working on the show, where she tests her body and explores ways to live longer and healthier lives , really triggered something in me that made me want to take some time off. When you look at Alzheimer’s prevention , the benefit of preventative measures is that they affect the rest of your life. These are sleep management, stress management , nutrition, movement, fitness. They are all the same tools that need to be applied consistently.
Clearly the results of genetic tests are not a definitive diagnosis. It’s not a predeterministic gene , but it’s a strong indication. In fact, Professor Giuseppe Novelli , geneticist of the Tor Vergata University of Rome, wanted to remind the medical portal sanitaeducazione.it that not all carriers of the ε4 allele will develop the pathology and not all patients are carriers of the specific allele. The test must therefore be performed following genetic counseling which can contextualize and possibly ascertain the usefulness of the analysis. The risk is that of incurring psychological reactions following the communication of the result in the absence of adequate preparation contextualization of the molecular notions available to date regarding the forms of cognitive impairment, which have a known etiopathogenesis basis.
But what is the genetic predisposition for Alzheimer’s?
Among the various causes we have mentioned the genetic factor and Chris Hemsworth is seen to have a genetic predisposition to Alzheimer’s disease. But what is this double copy of the APOE4 gene?
APOE is the apolipoprotein most present in the brain and has the function of transporting cholesterol and other fats in the blood
Its synthesis is the responsibility of astrocytes in the blood-brain barrier, but neurons and microglia also participate in its production. The APOE gene is located on chromosome 19 and has 3 alleles:
- APOE3: most common allele
- APOE4: allele conferring susceptibility to dementia
- APOE2: protective allele against dementia, therefore having the opposite function to APOE4
As can be seen from this classification of the different alleles, APOE4 is the main genetic risk factor for Alzheimer’s disease. In particular, following various studies it was seen that what was altered was the transport of lipids; in the brains of people with one or two copies of the APOE4 gene, enormous amounts of cholesterol were observed accumulating in the cell body, rather than around axons. The axons, therefore, which should be surrounded by a consistent layer of lipids constituting the myelin sheath , in people having the APOE4 gene are protected by a thin myelin sheath. The cause responsible for the onset of Alzheimer’s disease, among others, is an abnormal accumulation of cholesterol in the cell body of neurons.
Put in this way, one would think that intervening with specific treatments, to reduce cholesterol, could also have benefits in the onset of the disease. Unfortunately it is not that simple. In fact, despite the beneficial effects of cyclodextrins, talking about an effective treatment for affected patients is still early as it is a recent discovery. Therefore, we can say that to date Alzheimer’s cannot be cured, but through certain pharmacological therapies it is possible to reduce some cognitive , behavioral symptoms, etc.
Examples of the most commonly used drugs are: acetylcholinesterase inhibitors and memantine.
But Chris Hemsworth received this information only after doing very specific analyzes due to his commitment on the set of Limitless , a very particular TV series that stresses the body and mind beyond what is necessary. With regard to this event, is it indicative to do this test in general? In reality, since it is a gene that affects risk , but does not directly determine the disease, not all people who possess this genetic variant eventually develop Alzheimer’s and at the same time the disease can also arise in those who do not have the alleles ApoE-e4. So the genetic test is not a diagnosis (like all tests for that matter). Singular is the statement of Gary Small, psychiatrist at Hackensack University Medical Center .
Typically, in my clinical practice, I dissuade people from getting tested. If you have a family history of dementia, you should assume you are at increased risk; therefore, doing the genetic test will not tell much more
It all depends on the psychological approach of the patient and the person himself. In many cases it is believed that a certain test result can lead to a positive attitude , in which the person will adopt the behaviors deemed most effective to mitigate the onset of the disease, as in the case of Chris Hemsworth himself who also wants all the teachings received from the same TV series Limitless has decided to review his work plans to devote himself much more to himself and his family.
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