Cold Sores May Be No Friend to a Vulnerable Brain
Date: February 1, 2010
The herpes virus holds a smoking gun in this new study.
A new Hopkins study holds the tantalizing possibility that a common virus, rather than schizophrenia by itself, accounts for troubling cognitive symptoms that people with the disease face.
In work led by neuropsychologist David Schretlen, patients with schizophrenia who’d been infected earlier with the common cold sore virus, herpes simplex type 1 (HSV-1), were slower and less able to respond to change than schizophrenic patients who tested negative for antibodies to the virus.
Further, virus-exposed patients had less gray matter in the brain regions that are home to that particular ability, the study showed, compared with patients without a trace of HSV-1. “This is the first study I know of,” says Schretlen, “that simultaneously ties having the virus to changes in specific thinking abilities and to changes in brain anatomy—all the sides of the triangle.”
A team including psychiatrist Nicola Cascella, who designed the study, and neurovirologist Robert Yolken reports the work in a coming issue of Schizophrenia Research.
Literally hundreds of studies agree that people with schizophrenia perform more poorly on neuropsychological tests. The new work suggests the virus has a hand in it.
It isn’t such a leap to believe that those with schizophrenia, or even a genetic leanings toward it, might respond differently to HSV-1 infection, Schretlen says. And that, in turn could explain some of the cognitive difficulties. “The study design, however, won’t let us go that far,” he adds. “It just shows that in virus-exposed patients, those difficulties both exist and also track to abnormal brain areas.” Wagging a causal finger, he says, will take further research.
In the study, 40 schizophrenia patients had MRI brain scans. Blood tests picked up those with antibodies to HSV-1. The team then compared antibody positive and negative patients on neuropsychological tests, including the well known “Trails B,” which tests cognitive speed and flexibility.
In the end, positive patients’ psychomotor speed and executive ability were clearly below par. And brain volume had decreased in the anterior cingulate and parts of the cerebellum.
Does this imply that HSV-1 ups the risk of having schizophrenia? “No”, says Schretlen. “But exposure to the virus might in some way amplify cognitive problems that schizophrenia patients suffer.” Perhaps, he explains, it’s just one more insult to their vulnerable brains.
For information: 410-955-3268