Your Brain on Viruses: Study Finds Even Common Viruses Cause Cognitive Declines
The 'Manhattan Project'
The Northern Manhattan Study is an immense project that's taking a deep look at health in Northern Manhattan, New York . The project consists of analyzing basic health characteristics of several thousand people over time and it's spinning out studies at a dizzying rate. The project is not on chronic fatigue syndrome, but because it's looking at factors that have shown up in ME/CFS it may shed some light on what's happening there. In fact it may shed a lot of light.
For instance, each of the studies below looked at a factor that's been found (in at least some studies) in ME/CFS and each of the findings seemed to make sense what we know of ME/CFS.Increased IL-6 levels were associated with cognitive declines in one study, and increased soluble tumour necrosis factor receptor 1 (sTNFR1) levels were associated with increased mortality in another. Increased levels of daytime sleepiness in the elderly were associated with increased risk of stroke, heart attack and vascular events in another. Metabolic syndrome was associated with cognitive declines in another. Eating a Mediterranean diet was associated with reduced 'white matter hyperintensity volume' a marker of small blood vessel breakage in the brain and reduced vascular events such as stroke.
- Dig Deeper: The Best Diet for ME/CFS?
Infectious Burden
The most applicable study to ME/CFS, however, is clearly the latest one which determined if infectious disease burden was associated with cognitive declines. In this study the researchers tested blood from a broad swath of the population in New York for antibodies to common bacteria and viruses (three of them herpes viruses) and gave the participants cognitive tests. Then they created an index of infectious burden (IB) and determined if more infections meant more problems with cognition...and found they did; the more active infections present, the worse the cognitive impairment.
No ME/CFS studies have attempted to associate pathogen load with cognitive declines but given the increased rate of infections Dr. Peterson and other immunologically oriented ME/CFS doctors have found and the documented cognitive impairment in ME/CFS, the finding made sense. Cognitive impairment is associated with brain issues but the researchers didn't zero in on the brain; instead they focused on cardiovascular problems which interfered with blood flows to the brain.It turns out that studies have linked common infectious agents to inflammation, coronary artery disease and stroke and a past 'Manhattan project' study found that high infectious burdens were associated with an increased risk of stroke and increased carotid plaque buildup.
Many viral pathogens in the herpesviridae family, characterized by latent or persistent infection, were implicated in increased stroke risk.
It appears that chronic infections often play havoc with cardiovascular functioning. Infectious organisms can impact cardiovascular functioning in various ways. They can directly invade the vascular walls. C. pneumoniae and H. pylori DNA was found in aetherosclerotic lesions in 26% and 37% of cardiac bypass patients in one study. With regards to pathogens commonly found in ME/CFS, high rates of active HHV6 infection found in Italian cardiac patients who did not have aetherosclerosis suggested the virus may play a role in heart patients who have idiopathic heart disease.
Cardiovascular Issues
At the 2008 HHV6 Symposium in Baltimore, a German researcher, Dr. Lassner reported that heart biopsies he'd done in German heart patients commonly revealed parvovirus B-19, HHV-6, enterovirus and/or Epstein-Barr Virus infections. He noted that HHV-6 infection of the blood vessel walls results in the production pro-inflammatory cytokines which can constrict the blood vessels, impair capillary production and reduce heart blood flows. HHV6's ability to trigger blood vessel wall constriction is intriguing given studies suggesting it may play a key role in ME/CFS.
Lassner, interestingly, found antivirals (IVIG-parvovirus, interferon-enterovirus) to be effective in virus infected heart patients, but reported much the same treatment response pattern found in many ME/CFS patients; improvement while on antivirals followed by relapse when off them.Infections can also turn on the macrophages which help create the dangerous plaques, they can confuse the immune system into attacking parts of the body and they can help an inflammatory state that is damaging, etc.These observations, along with the results of this current study lend support to the notion that past or chronic exposure to common infections, perhaps by exacerbating inflammation, may be an important etiologic factor of atherosclerosis.Simply the presence of active herpesvirus or other infections can contribute to an inflammatory mileu that can be detrimental. Katan reported that an inflammatory state could lead to aetherosclerosis, 'subclinical stroke' and dementia. Subclinical strokes (ie transient ischemic attacks from which patients recover) primarily effect executive functioning, one of the cognitive processes known to be impaired in ME/CFS. Changes in mood and the ability to organize and take on multiple tasks could be a sign of a 'subclinical stroke'. Other symptoms can include feelings of numbness or weakness, double vision, dizziness/vertigo, confusion, inability to speak, loss of balance or coordination.Cardiovascular issues have been found in ME/CFS and more and more attention is being given to this area. Cardiovascular control is impaired, reduced cardiac vagal tone is associated with cognitive declines, impaired blood pressure variability, reduced cerebral blood flows, reductions in stroke volume and cardiac output (all this in the past year and a half) provide ample evidence of impaired cardiovascular functioning in this disorder. Interestingly autonomic nervous system issues similar to those found in ME/CFS were correlated with cognitive declines in fibromyalgia.All in all the finding of decreased cognitive functioning with increased infectious burden in the Northern Manhattan Study findings may not be surprising for many people with ME/CFS. At the most recent HHV6 Conference in Paris Dr. Peterson reported on several ME/CFS patients who's cognitive abilities rebounded remarkably following Vistide infusions for herpesvirus infections and Dr. Lerner has reported similar results in his herpesvirus infected patients.
- Dig Deeper: Report From Paris: Dr. Peterson Reports Antiviral (Vistide) Effective in Treating Herpesvirus Infected Chronic Fatigue Syndrome (ME/CFS) Patients
- Dig Deeper: Vistide for Chronic Fatigue Syndrome (ME/CFS)
Conclusions
The latest Manhattan project study should be helpful in highlighting not only the cognitive declines but the cardiovascular risks that are associated with common or chronic latent or active infections. Since active infections are part and parcel of ME/CFS, this study's important association of decreased cognitive function with increased infectious burden suggests that measuring both those factors in ME/CFS should be routine, and may offer objective measurements of treatment efficacy.