Multiple chemical sensitivities (MCS) is an acquired condition in which the sufferer becomes sensitised or abnormally reactive to volatile chemicals following prolonged, recurrent or high dose exposure to volatile chemicals. The most distinctive symptom is "pathosmia", or a heightened sensitivity and lowered threshold to odours that most of the population find inoffensive or would not notice.
Multiple chemical sensitivities is a condition that primarily
affects the nervous system, particularly the brain, and most often
has characteristic symptoms, including
Recent published studies demonstrate alterations of SPECT brain scans, central evoked responses (especially visual and auditory), and altered autonomic nervous system function. The mechanisms of such damage remain unclear at present, but direct neurotoxicity is regarded as the most likely cause. There is no current evidence that the condition is reversible, and MCS appears to represent a form of subtle toxic brain damage with the potential for lifelong disability.
The sufferer's history and clinical state should meet the criteria laid down by Cullen, that multiple chemical sensitivities is
This and subsequent publications suggest that the critical defining features of multiple chemical sensitivities are that
Specific tests such as Auditory Evoked Response Potential (AERP) testing and SPECT brain have shown significant changes in people suffering multiple chemical sensitivities, and these changes are consistent with neurotoxic brain damage. Minimising of exposure is the only proven way of reducing the disability experienced, as there is no form of treatment proven to be effective.
The degree of disability suffered by those suffering is very high, and there is currently no clear evidence as to whether the damage to the nervous system is permanent. Based on my clinical experience with over 500 sufferers in the past nine years, is that complete recovery is rare, and that the condition is associated with permanent neurotoxicity, or brain damage, in adults. Most people are able to adapt to the condition, varying their lifestyles to reduce the impact of their chemical sensitivity on their health.
It is more difficult to make an informed judgement regarding recovery in children. Full recovery would be more likely in pre-pubertal children, assuming that they have minimal ongoing exposure, because of the ability of neurons (brain cells) to regenerate and form new links during those years. Whether this does happen is an entirely different, and at present unanswered, question.
Although described and defined by Cullen in 1987, acceptance of multiple chemical sensitivities as a distinct clinical entity (disease) has been slow in occurring. The fact that the dosage for such damage is so low, and apparently 'neurotic' symptoms are maintained many years after exposure, has led many people to dismiss it as a psychological complaint, or a psychiatric disease. As increasing evidence of neuro-biochemical and neuropathological changes accrue, this view is currently changing among serious researchers.
Of the 84 articles and letters in the peer reviewed literature from 1993 to 1996, the majority now support the view of multiple chemical sensitivities as a distinct clinical entity deserving of further research. Of the original articles (as opposed to letters, opinions and editorials), 51 identify non psychiatric causes and contributions as being of major importance in the development of multiple chemical sensitivities, while 14 attribute the disorder to psychiatric or psychological causes. All note the neuropsychological abnormalities in sufferers. This is a significant reversal of the weight of medical opinion presented in the peer reviewed medical literature in the five years prior to 1993.
In my opinion, it would now be correct to say that the majority of the medical literature on the subject supports the existence of the disease, both specific and non-specific organ pathology, and the low level exposure as a significant factor in causation and symptom generation. In Australia in 1997, the majority of physicians appear to be relatively unaware of the change in scientific perspective on this condition. Others, who have previously made public their incredulity about the existence of the syndrome, appear to have understandable difficulties in changing their viewpoint based on the recent available data.
While the disease is now generally well accepted as a clinical entity, however, the mechanisms of damage and therapeutic approaches which may be of benefit to sufferers are far from elucidated. This is true for many diseases, however, including Multiple Sclerosis, most cancers, and sudden infant death, to name only a few.
The current evidence is that multiple chemical sensitivities is associated with significant alteration of brain function, especially short term memory, concentration, emotional lability and decision making capacity. Because of this, the sufferer may have unreliable recollection of facts and events, and be quite unable to reliably recall what they or others have said previously, even a few minutes beforehand.
This occurs especially following accidental exposure to agents which induce symptoms, and is commonly seen even in the undemanding settings of a medical consultation. Sufferers often must write information down if they are to recall it later. Confusion with complex issues is common for those affected.
In addition, there is frequently increased symptomatology under conditions of physical or emotional distress. This is most often manifest as emotional lability and severe mental confusion, rapidly leading to severe fatigue and exhaustion.
For the majority of people in the community, a court of law is unfamiliar territory, and probably most would find it stressful to be involved in legal action of any type. The severity of this stress is most likely well known to those within the legal profession. For people suffering from multiple chemical sensitivities, however, the symptoms generated by the emotional and physical stress of the court appearance may severely incapacitate them, exacerbating the condition in question.
Sufferers should be considered as a person with an acquired mental disability, and questioning in the setting of a court may need to be moderated to ensure questions are short, simple and simply answerable, and that the person affected is able to take a break when needed. They are often not aware of their own deterioration of mental function when affected, and may need a 'chaperon' to advise them independently.
Any attempt to confuse the sufferer with complex or rapid questioning will most likely succeed, and under these circumstances, the sufferer will frequently answer inaccurately, often even apparently contradicting clear facts and even their own previous answers.
This is not uncommon in many types of brain injury, and is seen in similar brain damage caused by alcohol abuse. It needs to be recognised as part of the clinical condition in question. Appropriate considerations and arrangements need to be made to accommodate this disability in many settings, including the court.
Dr Mark Donohoe
mark@geko.net.au
Last updated 21/9/98