Researchers Find Alarming Link Between Viruses and Neurodegenerative Diseases in Review of Medical Records of 450,000 People
A new study published in the scientific journal _Neuron_ by American researchers has identified clear evidence that even a simple influenza virus can significantly increase the risk of developing neurodegenerative diseases.
The study suggests that severe viral infections, such as encephalitis and pneumonia, can increase the risk of neurodegenerative diseases including Parkinson's and Alzheimer's. Scientists from the National Institute on Aging in the United States concluded this after combing through approximately half a million medical records.
Initially, the medical records of 35,000 Finnish people suffering from six different neurodegenerative diseases were analyzed and compared to a control group of 310,000 individuals without such brain disorders. The analysis showed correlations in 45 different points between virus exposure and neurodegenerative diseases, which were further confirmed through examining an additional 100,000 medical records from the UK Biobank. Ultimately, the researchers identified 22 connections between viral infections and neurodegenerative conditions across nearly 500,000 medical records for approximately 450,000 people, as reported by Science Alert.
For instance, individuals treated for viral encephalitis had a 31 times higher risk of developing Alzheimer's compared to those without such health issues. Out of every 406 people, 24 developed the disease, which represents a 6 percent ratio.
Perhaps even more startling, those hospitalized for pneumonia caused by the influenza virus showed a greater propensity for developing Alzheimer's, dementia, Parkinson's disease, as well as amyotrophic lateral sclerosis (ALS).
Additionally, gastrointestinal infections and the herpes zoster virus (varicella-zoster virus), which causes shingles, played a role in the development of several neurodegenerative diseases. The impact of viral infections on the brain could last up to 15 years and there was no case where virus exposure provided later protection.
About 80 percent of the viruses implicated in brain diseases were considered "neurotropic," meaning that the pathogens are capable of crossing the blood-brain barrier.
According to Michael Nalls, one of the authors of the study, the existence of vaccines against these diseases is a significant triumph. While vaccines do not make anyone completely immune, they greatly reduce the likelihood of requiring hospital treatment during an infection. Thus, vaccinations can be said to decrease the risk of developing neurodegenerative diseases.
The researchers emphasize that the study does not establish a cause-and-effect relationship between viral infections and the onset of Alzheimer's or Parkinson's, but it does highlight the need for further investigation on the topic.
Initially, the medical records of 35,000 Finnish people suffering from six different neurodegenerative diseases were analyzed and compared to a control group of 310,000 individuals without such brain disorders. The analysis showed correlations in 45 different points between virus exposure and neurodegenerative diseases, which were further confirmed through examining an additional 100,000 medical records from the UK Biobank. Ultimately, the researchers identified 22 connections between viral infections and neurodegenerative conditions across nearly 500,000 medical records for approximately 450,000 people, as reported by Science Alert.
For instance, individuals treated for viral encephalitis had a 31 times higher risk of developing Alzheimer's compared to those without such health issues. Out of every 406 people, 24 developed the disease, which represents a 6 percent ratio.
Perhaps even more startling, those hospitalized for pneumonia caused by the influenza virus showed a greater propensity for developing Alzheimer's, dementia, Parkinson's disease, as well as amyotrophic lateral sclerosis (ALS).
Additionally, gastrointestinal infections and the herpes zoster virus (varicella-zoster virus), which causes shingles, played a role in the development of several neurodegenerative diseases. The impact of viral infections on the brain could last up to 15 years and there was no case where virus exposure provided later protection.
About 80 percent of the viruses implicated in brain diseases were considered "neurotropic," meaning that the pathogens are capable of crossing the blood-brain barrier.
According to Michael Nalls, one of the authors of the study, the existence of vaccines against these diseases is a significant triumph. While vaccines do not make anyone completely immune, they greatly reduce the likelihood of requiring hospital treatment during an infection. Thus, vaccinations can be said to decrease the risk of developing neurodegenerative diseases.
The researchers emphasize that the study does not establish a cause-and-effect relationship between viral infections and the onset of Alzheimer's or Parkinson's, but it does highlight the need for further investigation on the topic.
