Study: Link Between Viral Illness and Brain Disease

Facts

In a study published in Neuron last week, researchers that analyzed 450k health records found at least 22 links between patients who suffered from a viral infection like influenza and the onset of neurodegenerative diseases like Parkinson's or Alzheimer's later in life.
The study examined around 35k records — sourced from a Finnish database — belonging to patients with brain diseases and approximately 310k without.^[1]
The team initially found 45 links between viral infection and brain disease, which were later compared to 100k records from a UK database, narrowing the pairings down to 22.
This comes one year after a study published in the journal Science that analyzed blood samples from 10M US military men and women found that it's very unlikely for an individual to develop Multiple Sclerosis without having been infected with the Epstein-Barr virus.
Many other researchers have also investigated similar links. According to Oxford University's Institute of Population Ageing's Professor Ruth Itzhaki, over 500 studies have been conducted demonstrating that there is a link between viruses and Alzheimer's, but she says it remains unclear "what the role of viruses is."
With continued studies into the links discovered between viruses and neurodegenerative diseases, some health professionals are optimistic they could help develop methods to slow or delay the onset of neurodegenerative disease.

Narrative A, as provided by Ox. Researchers are beginning to better understand the damage that a lifetime of viral infections can do to the brain, calling attention to the importance of vaccines, which could play a significant role in minimizing the number of viral infections occurring. If viral infections increase individuals' risk of developing neurological diseases, then vaccines and antivirals should be explored as a means of reducing this risk.
Narrative B, as provided by Alzheimers Research. While these types of studies are undoubtedly significant, we need to be cautious not to confuse correlation with causation. This analysis merely shows a relationship between viral infections and brain disease, but falls short of proving that a virus leads to neurodegenerative disease. More robust studies are needed to add weight to such a claim and offer tangible ways to delay or prevent neurological disorders.