Toxicant Induced Loss of Tolerance (TILT)

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Toxicant Induced Loss of Tolerance (TILT)

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_http://www.ei-resource.org/toxicant-induced-loss-of-tolerance-(tilt)/_

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What is TILT?

Originally described in 1996 by Dr. Claudia Miller, Toxicant Induced Loss

of Tolerance, or TILT, is a theory of illness that has the _symptom_

(http://www.ei-resource.org/#) of chemical sensitivity, most commonly referred

to as _multiple chemical sensitivity (MCS)_

(http://www.ei-resource.org/illness-information/environmental-illnesses/multiple\

-chemical-sensitivity-(mcs)/)

, at its heart. Miller suggests that the theory not only explains the

mechanisms behind multiple chemical sensitivity but can also be used to explain

those behind other unexplained illnesses such as _chronic fatigue syndrome

(CFS)_

(http://www.ei-resource.org/illness-information/environmental-illnesses/chronic-\

fatigue-syndrome-cfs-myalgic-encephalopathy-me/) and _Gulf War

syndrome (GWS)_

(http://www.ei-resource.org/illness-information/environmental-illnesses/gulf-war\

-syndrome/) . Claudia Miller is Assistant Professor of

Environmental and Occupational Medicine at the University of Texas Health

Science Center, a leading MCS researcher, and co-author of the book

_Chemical_ (http://www.ei-resource.org/#) Exposures: Low Levels and High

Stakes.

Statistical data shows that chemical sensitivity is much more common in

people suffering from chronic fatigue syndrome, Gulf War syndrome, and

_fibromyalgia_

(http://www.ei-resource.org/illness-information/environmental-illnesses/fibromya\

lgia-(fms)/) , than in the population as a whole. A large

proportion of these people do not report being sensitive to chemicals however,

so many in the medical profession dismiss an important connection between

these illnesses, chemical sensitivity, and chemicals as a causative factor.

Miller explains that the TILT theory not only explains an underlying

mechanism behind all of these unexplained illnesses, but also accounts for why

people with CFS, GWS, and _fibromyalgia_ (http://www.ei-resource.org/#) ,

don't always report being chemically sensitive. Essentially, according to

TILT, these people may very well be chemically sensitive but because they are

routinely exposed to a bewildering array of chemicals every day and their

symptoms are chronic, they don't associate exposure to specific chemicals

with their symptoms. It's only when the person has been in a chemical free

environment for an extended period and then is re-exposed to certain chemicals

that the association with symptoms becomes apparent. More on this later.

In the simplest terms, the TILT theory is described accurately by its

name, Toxicant Induced Loss of Tolerance. TILT explains multiple chemical

sensitivity in terms of a condition caused by a loss of tolerance for chemicals

that the person previously tolerated. This mechanism is likely to be

neurological, perhaps limbic sensitization (kindling), but could also involve

immunological mechanisms. The TILT theory does not require the eaxt

biochemical mechanisms to be known however. Those who are skeptical that MCS

even

exists point to the fact that the majority of people tolerate chemicals just

fine, so people claiming to be made ill by them most likely have a

psychiatric condition. TILT explains why some people become ill while others do

not.

The TILT theory makes a connection between drug addiction and chemical

sensitivity, essentially saying they are two sides of the same coin, or

different manifestations of the same underlying neurological dysfunction. In

both

cases the person affected tries to avoid _withdrawal_

(http://www.ei-resource.org/#) symptoms that are associated either with a lack

OR presence of

a substance. In drug addiction the person must get regular doses of the

substance to which they are addicted to avoid unpleasant symptoms. In

chemical sensitivity the person must avoid a substance (or substances) to avoid

unpleasant symptoms. This avoidance is known as abdiction. The basic idea is

that the normal response to a stimulant (eg. caffeine) involves stimulation

followed by recovery. The loss of tolerance described by TILT leads to an

increased response that leads to alternative strategies, either abdication

(avoidance) in the case of MCS or addiction (persistent reinforcing doses)

in the case of drug addiction.

Miller points out that people suffering from multiple chemical sensitivity

are almost always sensitive not just to environmental chemicals in the

form of volatile organic compounds (VOC's) in the air, but also to such things

as caffeine, alcoholic beverages, various drugs, and foods. As such, TILT

should not just been seen as an explanation for chemical sensitivity, but a

theory describing a whole class of unexplained conditions (CFS, Gulf War

syndrome etc) in which chemical sensitivity is often a defining feature.

Miller suggests that chemical sensitivity is a misnomer for the process

under discussion and that the term toxicant-induced loss of tolerance (TILT)

is a more useful one to both patients and doctors/researchers for the

following reasons:

* It describes the process as it has been observed by clinicians and

patients.

* It allows for the possibility that various toxicants may initiate

the process.

* It does not limit the resulting intolerance to chemicals.

This brings us back to a questioned raised earlier. If TILT is behind

conditions such as chronic fatigue syndrome and chemical sensitivity is a

central feature, why don't all CFS patients complain of chemical sensitivities?

Another important question is why challenge studies looking at people

claiming to be chemically sensitive have failed to prove its existence. In

these

kinds of studies, chemically sensitive individuals have been alternately

exposed to triggering chemicals and placebo substances in a controlled

environment and have often failed to identify the chemical trigger by

monitoring

their symptoms. The TILT theory offers an explanation for all of this.

Masking

Central to this explanation is the phenomenon known as masking. Masking

describes the situation in which patients suffering chronic symptoms don't

realize that the symptoms are the result of repeated exposure to substances

to which they have lost tolerance. When routinely exposed to triggering

substances on a regular basis the symptoms these substances trigger appear to

be constant, and therefore unrelated.

Miller notes that many chemically sensitive patients report that it was

not until they accidentally or intentionally avoided a sufficient number of

their problem substances that they noticed feeling better. The same goes for

patients who go on a food elimination _diet_ (http://www.ei-resource.org/#)

and then reintroduce foods one at a time. When they reencounter one of

the offending substances, a distinct set of symptoms emerges. As patients

repeat this investigative process of avoidance and reexposure, they notice

that particular symptoms occur with particular exposures. Most indicate that

had they not avoided many chemicals and foods simultaneously, or " unmasked

themselves " , they might not have determined what was making them sick.

To clarify further, when chemically sensitive individuals live in a

relatively chemical-free home in a hilly/mountainous region, away from the

pollution of urban and agricultural areas, and follow a diet free from their

problem foods, they are said to be in an unmasked state. Whilst in this

unmasked state, if they were to be exposed to a specific trigger such as diesel

exhaust from a passing truck, or someone spraying insect repellent on

themselves nearby, they would experience a distinct cluster of symptoms and be

able to identify the triggering substance.

In the opposite circumstances, when patients travel to a large city like

Los Angeles or London and engage with society as normal, staying in a hotel,

and eating in restaurants, their symptoms become masked. In this situation

the chemically sensitive person is exposed to many triggering substances

simultaneously (vehicle exhaust, fragrances, volatiles offgassing from

building interiors, various foods) and will usually complain of being

chronically ill with symptoms akin to those of the flu such as weakness, muscle

aches, headache, nausea etc. If the person were to be exposed to a specific

known trigger such as the exhaust from a passing diesel truck under these

conditions, most report they would not be able to attribute any particular

symptoms to the exhaust because of background noise from overlapping symptoms

occurring as a consequence of overlapping or successive exposures.

According to the TILT theory it is this background noise from concurrent

exposures and resulting symptoms, masking, that accounts for people

suffering from TILT related illnesses such as CFS who don't relate their

symptoms

to specific triggers. Masking also explains why researchers have such a hard

time designing studies to adequately assess people claiming to be

chemically sensitive and tie symptoms down to particular triggering chemicals.

Miller explains that past research into chemical sensitivity utilizing

challenge testing has failed because it hasn't taken into account the

phenomenon of

masking. Chemically sensitive subjects have been exposed to too many

triggering substances in too short a period of time so that symptoms overlap

and

masking occurs, confusing their ability to correctly identify the trigger

for their symptoms when challenged. Dr. Miller suggests that future

research studies must be carefully designed, taking masking into account. This

she

says, must involve carefully designed 'Environmental Medical Units'

(EMU's) which are essentially living quarters for chemically sensitive subjects

which are entirely free from triggering substances. Materials that do not

offgas must be used and other sources of triggers such as electronic devices

like tv's must be considered. Only when investigators are certain that a

subjects environment is totally free from triggers can accurate challenge

testing be undertaken. Sufficient time between challenges with different

substances must also be allowed for the patients symptoms to abate, once again

avoiding symptom overlap.

In Conclusion

Since Miller first introduced the TILT theory in 1996 it has attracted a

lot of interest and many amongst those investigating chemical sensitivity

and unexplained illness feel it is an accurate explanation for what is seen

in these conditions. Rather than provide detailed biochemical explanations

for the various tissues, cells or molecules, behind the symptoms experienced

by the chemically sensitive, TILT provides an overarching theory for a new

class of illnesses that involve environmental triggers and individual

tolerance, or more importantly intolerance, for these triggers. Indeed TILT and

the conditions it explains have brought comparisons with the early days of

the germ theory of disease. Additionally the masking phenomenon that TILT

introduces, from a chemically sensitive individual's point of view,

accurately describes how exposures to triggering substances and resulting

symptoms can overlap and appear continuous when exposures are concurrent.

Finally,

TILT provides vital information that can be used to radically improve the

design of research studies into chemical sensitivity which will hopefully

lead to recognition of the validity of the condition as a physical illness.

 

Related Articles:

_Toxicant-induced Loss of Tolerance--An Emerging Theory of Disease?_

(http://www.ei-resource.org/articles/multiple-chemical-sensitivity-articles/toxi\

ca

nt-induced-loss-of-tolerance:-an-emerging-theory-of-disease?/) - Claudia

Miller, M.D.

_Engaging with Multiple Chemical Sensitivity (MCS)_

(http://www.ei-resource.org/engaging-with-mcs.pdf)

 

_http://www.satori-5.co.uk/word_articles/mcs/engaging_with_mcs.html_

(http://www.satori-5.co.uk/word_articles/mcs/engaging_with_mcs.html) -

Professor Malcolm Hooper