What is known about the connection between COVID-19 and Alzheimer’s dementia

  • A Danish study establishes a link between coronavirus infections and the risk of later developing diseases such as dementia or Parkinson’s disease.
  • It has long been known that serious infections can lead to certain secondary diseases.
  • However, it is unclear whether the risk of COVID-19 is particularly high, what protection vaccination offers, and which variants of the virus play a role in those processes.

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Does anyone who has contracted COVID-19 have a higher risk of developing dementia or Parkinson’s later? A Danish study came to this conclusion.

Federal Health Minister Karl Lauterbach (SPD) picked up a corresponding report from the Bild newspaper on Twitter and wrote that the Alzheimer’s link “sadly was not alarming”: “It is good to point out this danger.”

What is the study about?

The researchers analyzed the medical records of around half of the Danish population, which corresponds to around one million people. About 43,000 of them tested positive for coronavirus during the study period.

It was recorded how many of those suffering from COVID-19 were subsequently diagnosed with Alzheimer’s, Parkinson’s, or an autoimmune disease such as multiple sclerosis and how many of these people suffered a stroke or a brain hemorrhage. This data was also collected for people who had had the flu and who had had bacterial pneumonia.

What were the results of the study?

Scientists found that people who previously tested positive for the coronavirus had a higher risk of developing Alzheimer’s and Parkinson’s six to 12 months later. They were also more likely to have strokes and brain hemorrhages.

However, the researchers also found that the risk of these diseases is similar after the flu and after bacterial pneumonia. Only the risk of stroke is slightly increased after COVID-19 compared to other diseases.

How should the study be evaluated?

According to Malik Böttcher, a general practitioner in Berlin and head of the vaccination center at the Havelhöhe hospital in Spandau, the significance of the study “is not that great”. The study provides some indications of connections, but no evidence. “Anyone under the age of 60 doesn’t have to worry that he could develop dementia after COVID-19 as a result of the study,” he says.

The authors of the study also limit the informative value: it is also conceivable, for example, that some of the people examined already had symptoms of dementia, but this was only diagnosed upon admission to hospital.

But: On the contrary, it has also been known for some time that severe infections can lead to secondary diseases. “We experience this in practice, for example, again and again after severe influenza outbreaks,” says Böttcher. It is therefore conceivable that this could also happen after a coronavirus infection, although perhaps not more frequently than with other diseases.

What explanation is there for the fact that infections can have such effects?

An explanatory model is the so-called neuroinflammation. This is an inflammation of the central nervous system (neuro = related to the nervous system), i.e. in the brain. Researchers have long suspected a connection between neuroinflammation and diseases such as Alzheimer’s and Parkinson’s.

How does neuroinflammation occur?

The brain receives oxygen and nutrients from the blood. But there are special filters that ensure that pathogens and immune cells from the rest of the body do not enter the brain. “This protection is also known as the blood brain barrier,” says Böttcher.

However, this barrier can become permeable and no longer reliably protect the brain. “We see it, for example, with viral pathogens or bacterial inflammations, which are particularly serious,” says the doctor. This puts some brain cells, which actually have a protective function, in a state of alarm. Then they attack certain structures in the brain. This is assumed to lead to the development of Alzheimer’s dementia, for example. However, this does not happen suddenly, but over the course of many years.

Can vaccinations be assumed to protect against neuroinflammation and thus Alzheimer’s disease after COVID?

“Vaccination naturally protects against such processes to the extent that it protects against infections,” says Böttcher. “However, at the moment we can only be moderately satisfied with the effect of vaccination.” An infection is just as common about two months after a booster as in unvaccinated people.

However, courses are almost always much easier in vaccinated people. “We therefore assume that a vaccination also protects against neuroinflammation to some extent because some immune processes are not heated further,” says the doctor. However, vaccines are desirable that are so closely adapted to current pathogens that an infection does not occur in the first place.

What role do the different variants of the virus play?

It is not yet known which variants of the corona virus can trigger these processes. “But we can see that the Long COVID phenomenon has decreased significantly under the omicron variant,” says Böttcher. Compared to the Delta variant, it’s about 1:20. “We therefore assume that there is less neuroinflammation with Omikron,” says the doctor. However, reliable data is still lacking on this.

What are the early warning signs of dementia?

According to Susanne Saxl-Reisen, a spokesperson for the German Alzheimer’s Society, one of the first warning signs is when people withdraw from social activities, are no longer able to orient themselves in space or time or suffer from memory impairment. Also, if someone suddenly finds themselves unable to find words during a conversation, has difficulty with daily activities or experiences mood swings and behaves differently than usual, these can also be warning signs.

“It’s important to talk to a doctor about symptoms that last a long time,” says Saxl-Reisen. These signs do not always mean that someone is suffering from dementia: “There can be very different causes, such as depression, a malfunction of the thyroid gland or drug interactions.”

Read also: “There is a lot of despair” – dementia in young people

How can you protect yourself?

There is no real protection against dementia. “But there are a number of risk factors that can be affected,” says the spokesperson. Everyone can do something to reduce the risk of dementia:

  • Be active physically and mentally
  • Maintain social contacts and avoid loneliness
  • Control high blood pressure and diabetes well
  • Correct hearing loss early with a hearing aid
  • Not smoking
  • Drink alcohol in moderation
  • Avoid being overweight
  • Protect your head from injuries

However, the greatest risk of dementia cannot be avoided: old age. “While less than two percent of people aged 65 to 69 are affected, this is more than a third of those over 90,” says the expert. Furthermore, women are more likely to be affected by dementia than men. This is largely due to the increased life expectancy of women.

How can therapy be?

There is currently no cure for dementia. “Depending on the cause, drug treatment options are limited,” says Saxl-Reisen: If dementia is related to circulatory disorders, drugs that increase blood circulation are prescribed. Drugs that increase certain neurotransmitters in the brain can also help with some forms of dementia.

Non-pharmacological therapeutic approaches are also important in dementia. “This includes, for example, occupational therapy, which helps to maintain independence for as long as possible,” says the expert. Memory therapy, physiotherapy, behavioral therapy, and other forms of therapy may also be helpful.

Furthermore, according to the German Alzheimer’s Society, treating people with respect is key – the goal is to accept that people with dementia live in their world. Even seemingly insane behavior should be taken seriously and you should try to understand it.

About experts:

Malik Boettcher he is a general practitioner and head of the vaccination center of the Havelhöhe hospital in Spandau. The doctor works for vaccinations both in the vaccination center and in his office at the Kleistpark in Berlin-Schoeneberg.

Susanne Saxl Travels is deputy general director of the German Alzheimer Society patient organization and head of public relations. The organization is committed to improving the lives of people with dementia and supports those affected and their families. It also strives for better diagnosis and more competent advice on site.

Sources used:

  • Pardis Zarifkar et. al .: Frequency of Neurological Diseases After COVID-19, Influenza A / B and Bacterial Pneumonia, in: Frontiers in Neurology, 23. June 2022
  • Malik Böttcher, general practitioner and head of the vaccination center at the Havelhöhe hospital in Spandau
  • Susanne Saxl-Reisen, Deputy Director General and Spokesperson for the German Alzheimer’s Society
  • German Alzheimer’s Society: the non-drug treatment of dementia (fact sheet 6)

According to “Ärzteblatt.de”, around 1.6 million people in Germany suffer from dementia. Now scientists want to have discovered that walking speed may be an early warning sign of the disease. (Image credit: Picture Alliance / ZB / Britta Pedersen) © ProSiebenSat.1

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