All posts tagged cognition

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.

Manhattan

The ‘Manhattan Project’ is examining health issues in a wide swath of the population. Several findings may have relevance to ME/CFS/FM

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.

Infectious Burden

Neurology. 2013 Mar 26;80(13):1209-15. doi: 10.1212/WNL.0b013e3182896e79.Infectious burden and cognitive function: The Northern Manhattan Study. Katan MMoon YPPaik MCSacco RLWright CBElkind MS.

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.

Infections

This study suggested that having more infections, active or latent, are associated with reduced cognition.

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.

Blood vessels

Pathogens can affect the cardiovascular system and cardiovascular problems appear to be rife 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.

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.