Smells Good? Scientists Say Some May Disagree... With Good Reason
Lourdes Salvador
May 08, 2007
The researchers set out to determine whether subjects with MCS could have an increased odor-signal response in the odor-processing neuronal circuits. They used odor as the trigger and carried out positron emission tomography (PET) activation studies with various odors on 24 subjects consisting of 12 males and 12 females. The researchers were looking to see if there was a significant increase in regional cerebral blood flow (rCBF) during smelling of the respective odorant compared to smelling of odorless air. There was no change in the baseline rCBF.
It is interesting to note that the MCS subjects activated odor-processing brain regions less than controls while experiencing decreased respiratory frequency and amplitude and heart rate variations as recorded R wave intervals (RR) on a surface electrocardiogram.
MCS subjects did show an increase in activation of the anterior cingulate cortex (a part of the brain situated in the medial aspect of the cortex) and cuneus-precuneus (a structure in the brain located in the parietal lobe) when subjected to the odors, indicating that the subjects with MCS processed odors differently. There were no signs of neuronal sensitization. These patterns were only present in response to odor signals leading researchers to hypothesize that the observed pattern of activation in MCS is a top-down regulation of odor-response via the cingulate cortex.
MCS is also known as Environmental Illness (EI), Toxic Injury (TI), Toxicant Induced Loss of Tolerance (TILT), and several other names. Originally identified in a 1989 multidisciplinary survey of 89 clinicians and researchers, and modified in 1999, top consensus criteria (Nethercott et al, 1993) for MCS define the condition as:
1. A chronic condition.
2. Symptoms recur reproducibly.
3. Symptoms recur in response to low levels of chemical exposure.
4. Symptoms occur when exposed to multiple unrelated chemicals.
5. Symptoms improve or resolve when trigger chemicals are removed.
6. Multiple organ systems are affected.
Products that MCS patients react to include any quantity of exposures to pesticides, secondhand smoke, alcohol, fresh paint, scented products and perfumes, candles, fragrances, food preservatives, flavor enhancers, aerosols, tap water, cosmetics, personal care products, new carpets, petroleum products, formaldehyde, outdoor pollutants, newspaper ink, cleaning compounds, printing and office products, and other synthetically derived chemicals. Some also react to natural products that are highly concentrated such as natural orange cleaners due to high volatile organic compound and pesticide concentration. Symptoms can range from minor annoyances such as headache to life-threatening reactions including seizure and respiratory problems.
Dr. Martin L. Pall, PhD at Washington State University's Department of Molecular Biosciences has extensively studied multi-system illnesses. He has found that elevated levels of peroxynitrite cause the blood brain barrier to break down. Normally the blood brain barrier acts to protect the brain. Without this protective barrier, toxicants from everyday chemicals can easily enter the brain and cause disruption leading to many of the symptoms reported by MCS patients. Excess levels of peroxynitrite are also known to cause the chronic fatigue associated with many multi-system illnesses.
Pall has just released his book Explaining "Unexplained Illnesses": Disease Paradigm for Chronic Fatigue Syndrome, Multiple Chemical Sensitivity, Fibromyalgia, Post Traumatic Stress Disorder, Gulf War Syndrome, and Others, which is available via Amazon.com among other booksellers. ISBN-10: 078902389X
Reference
Hillert L, Musabasic V, Berglund H, Ciumas C, Savic I. Odor processing in multiple chemical sensitivity. Hum Brain Mapp. 2007 Mar;28(3):172-82.
Nethercott J.R., Davidoff L.L., Curbow B., et al. (1993) Multiple Chemical Sensitivities Syndrome: Toward a Working Case Definition. Arch Environ Health, 48:19-26
About the Author
Lourdes Salvador is a writer and social advocate based in Hawaii. She is the president of MCS America and a featured monthly writer for MCS America News at www.mcs-america.org. She is a passionate advocate for the homeless, having worked with her local governor to open new shelters and provide services to the homeless based on a presentation of her ideas. That passion soon turned to advocacy and activism for victims of multiple chemical sensitivity. For more information about Lourdes and her advocacy work, please visit: www.mcs-america.org, www.thetruthaboutmcs.blogspot.com, and www.cafepress.com/mcsamerica.
Copyrighted © 2007 Lourdes Salvador
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