Cold sore virus likely to cause brain abnormalities

WASHINGTON - Exposure to the common virus that causes cold sores may be partly responsible for a shrinking brain and loss of concentration skills and memory –symptomatic of schizophrenic patients.

“We’re finding that some portion of cognitive impairment usually blamed solely on the disease of schizophrenia might actually be a combination of schizophrenia and prior exposure to herpes simplex virus 1 infection, which reproduces in the brain,” says David J. Schretlen, who led the study.

Schretlen is an associate professor of psychiatry at Johns Hopkins University School of Medicine.

The research could lead to new ways to treat or prevent the cognitive impairment (or brain fog, defined as unusually poor mental function) that typically accompanies this mental illness, including with antiviral drugs, the scientists say.

Doctors have long known that cognitive impairment are prevalent features of schizophrenia, which affects an estimated one percent of US population.

Cognitive deficits often surface months to years before symptoms that are traditionally used to diagnose this disease, such as delusions or hallucinations.

Some previous studies have shown that schizophrenic patients with antibodies to herpes simplex virus 1 (HSV-1), the virus that causes cold sores, often have more severe cognitive deficits than patients without these antibodies.

Schretlen and colleagues recruited 40 schizophrenic patients from outpatient clinics at the Johns Hopkins and Sheppard Enoch Pratt hospitals in Baltimore.

Blood tests showed that 25 of the patients had antibodies for HSV-1 and 15 didn’t. The researchers gave all of the patients tests to measure speed of coordination, organisational skills and verbal memory.

The patients then underwent MRI brain scans to measure the volume of particular regions of their brains.

As in previous studies, results showed that patients with antibodies to HSV-1 performed significantly worse on the cognitive tests than patients without the antibodies.

But expanding on those earlier studies, analysis of the brain scans showed that the same patients who performed poorly on the tests also had reduced brain volume in the anterior cingulate, which controls processing speed and the ability to switch tasks.

There was also shrinkage in the cerebellum, which controls motor function, said a Johns Hopkins release.

These results suggest that HSV-1 might be directly causing the cognitive deficits by attacking these brain regions, Schretlen says.

These findings were described in the May issue of Schizophrenia Research.