Study finds hidden virus in brains of Parkinson’s patients

A virus long thought to be harmless may play a role in Parkinson’s disease, new research suggests.

Scientists at Northwestern Medicine detected Human Pegivirus (HPgV) in the brains and spinal fluid of people with Parkinson’s, but not in those without the condition.

The virus appeared in half of the Parkinson’s brain samples examined but was absent from healthy controls.

The findings challenge decades of assumptions about HPgV – a common infection not previously linked to the brain.

Dr Igor Koralnik is chief of neuroinfectious diseases at Northwestern.

He said: “HPgV is a common, symptomless infection previously not known to frequently infect the brain.

“We were surprised to find it in the brains of Parkinson’s patients at such high frequency and not in the controls.”

Researchers analysed post-mortem brain tissue from 10 Parkinson’s patients and 14 people who died of other causes.

The virus was found in five of the 10 Parkinson’s brains but in none of the 14 controls.

It was also present in spinal fluid samples, suggesting it may be active in the nervous system.

Patients carrying HPgV showed more advanced changes associated with Parkinson’s, including protein build-up and altered brain chemistry.

Using blood samples from more than 1,000 participants in a project run by The Michael J. Fox Foundation, the team observed similar immune system changes linked to the virus.

Patients with a Parkinson’s-related mutation in the LRRK2 gene responded differently to HPgV than those without the mutation.

Koralnik said: “This suggests it could be an environmental factor that interacts with the body in ways we didn’t realise before.

“It may influence how Parkinson’s develops, especially in people with certain genetic backgrounds.”

Parkinson’s disease is the second most common brain disorder after Alzheimer’s.

While a minority of cases are inherited, most patients have no family history and the cause remains unclear.

If HPgV plays a role, it could help explain why some people develop Parkinson’s while others do not.

It could also open the door to new treatments aimed at viruses or the immune system.

Dr Joel Salinas, a behavioural neurologist and associate professor at NYU Grossman School of Medicine who was not involved in the research, urged caution.

Salinas told Fox News Digital: “The study detected traces of HPgV more often in brains of people with Parkinson’s disease than in controls.

“This raises the possibility of a link between viral exposure and Parkinson’s, but it’s far too early to say the virus causes the disease.

He said much larger and longer-term studies will be needed to see whether this association has real clinical significance.

“For now, people should know this is early research and not a reason to worry—there’s no overwhelming evidence yet that this virus causes Parkinson’s, similar to how work on herpesviruses in Alzheimer’s has suggested a possible link but remains to be fully established.”