Neurological findings and HHV-6

Not all CFS patients show evidence of neurological abnormalities, but many do; he is specifying episodes of encephalitis (inflammation of the brain) at onset of illness. Other neurological findings include the previously mentioned white matter and EEG abnormalities."

Human Herpes Virus-6 (HHV-6)

In discussing the neurological aspects of CFS, Dr. Komaroff expanded on the effects that one particular virus, Human Herpes Virus-6 (HHV-6), can have on the brain. In vitro testing (in the test tube) has demonstrated that HHV-6, a virus that is reactivated in some patients with CFS, can infect multiple types of brain cells, including neuroblastoma and glioma cells, glial cells and neurons. 

Moreover, this infection can persist in the brain long after the initial exposure.

Studies also show that HHV-6 can cause seizures in children and encephalitis in the young and old alike—and in both immunosuppressed and immunocompetent individuals. 

In addition to encephalitis, HHV-6 can cause demyelination in the brain through infection of the glial cells.  Glial cells form myelin sheaths around neuronal axons, providing an insulating layer that helps increase the speed of electrical impulses moving along the axon (these myelinated axons are also known as the white matter area of the brain).

Interestingly, HHV-6 is also associated with both multiple sclerosis and temporal lobe seizures, both of which share other physiological irregularities with CFS, such as the aforementioned white matter abnormalities and brain wave aberrations, respectively. 

Dr. Komaroff was quick to point out, however, that just because CFS shares these types of abnormalities with MS and temporal lobe seizures does not mean that the abnormalities are identical, nor that CFS is in any way connected to these two other illnesses. Nevertheless, there could potentially be a link, and if so, that link could be ascribed to HHV-6.

The studies of active infection with this virus in CFS—that show a positive association between CFS and the virus—are much more numerous than the studies that do not show an association. Also, the number of patients in the studies that show the association between the virus and the illness are nearly ten-fold higher than the number of patients in the studies where no association was found. (These comparisons are shown on the following slide, Active HHV-6 Infection in CFS – Results of Studies.) The number of positive vs. negative studies are 9 to 2. The number of patients in positive studies vs. the number of patients in negative studies are 1061 vs. 122.

So there is a link between HHV-6 and some cases of CFS  according to Dr. Komaroff, but whether HHV-6 can cause CFS remains to be shown.