PET in patients with clear-cut multiple chemical sensitivity (MCS)

Aim: Multiple chemical sensitivity (MCS) is a controversially discussed symptom complex. Patients afflicted by MCS react to very low and generally nontoxic concentrations of environmental chemicals. It has been suggested that MCS leads to neurotoxic damage or neuroimmunological alteration in the brain detectable by positron emission tomography (PET) and single photon emission computer tomography (SPECT). These methods are often applied to MCS patients for diagnosis, although they never proved appropriate. Method: We scanned 12 MCS patients with PET, hypothesizing that it would reveal abnormal findings. Results: Mild glucose hypometabolism was present in one patient. In comparison with normal controls, the patient group showed no significant functional brain changes. Conclusion: This first systematic PET study in MCS patients revealed no hint of neurotoxic or neuroimmuno-logical brain changes of functional significance.

[The influence of diet on mental health]

The influence of nutritional factors on brain metabolism and the course of mental illness are increasingly being addressed in international research. It is a matter of discussion whether dietary habits, e.g., the amount of fish or vegetables, have an effect on the incidence of certain illnesses. Furthermore an optimized or supplemented diet could offer therapeutic possibilities; one example is the role of polyunsaturated fatty acids as an add-on therapy in affective disorders. The limitations of psychopharmacotherapy (drug interactions, side effects, noncompliance) underline the theoretical and practical relevance of nutrition in mental illness, the more so as mentally ill patients (especially when demented, anorectic, depressed, or schizophrenic) are at higher risk of malnutrition anyway. Even if the therapeutic evidence is still limited and the effects may be relatively weak, nutritional assessment and an optimized diet can be recommended for every patient.

Dysfunctional cognitions in idiopathic environmental intolerances (IEI)—An integrative psychiatric perspective

Idiopathic environmental intolerances (IEI) - formerly multiple chemical sensitivities (MCS) - are characterized by diffuse symptoms reported after exposure to low doses of everyday chemicals. Previous theories about the origin of IEI have emphasized either biological or psychological factors, neglecting a probable interplay. Many have suggested classifying IEI as a somatoform or an anxiety disorder, irrespective of some incongruities. By focusing on dysfunctional cognitions we discuss obvious parallels of IEI with somatoform disorders, and also indicate overlaps with anxiety and delusional disorders. To propose a hypothetical psycho-neurobiological basis of IEI, recent evidence about cortically represented symptoms in the absence of peripheral stimuli is briefly summarized. We conclude that IEI can serve as an illustrative example for the impact of cognitive, representational processes in symptom generation.

[Multiple chemical sensitivity. Is the patient suffering as a result of environmental pollutants or psychological problems?]

Multiple chemical sensitivity (MCS) poses a medical challenge. Proposed etiologies are as numerous as they are contradictory, direct and indirect costs are high, and patient suffering considerable. In the absence of objective diagnostic criteria, estimation of its prevalence is difficult. Nevertheless, establishment of the diagnosis is frequently strikingly uncritical. We support an holistic approach that gives consideration both to psychological and physical aspects, as well as taking account of the high level of comorbidity, and we warn against "over-diagnosis". Therapeutical approaches should consider carefully the risk of avoidance and social withdrawal.

[Psychiatric aspects of multiple chemical sensitivity (MCS)]

Patients with multiple chemical sensitivity (MCS) react to low levels of common environmental chemicals with various health complaints. The etiology and pathogenesis of MCS is not clear. Objective criteria for diagnosis are lacking. Usually there are no pathological somatic findings, while psychiatric morbidity is considerably high. Somatoform, mood and anxiety disorders are diagnosed most frequently. A subgroup of MCS patients may suffer from a special form of somatoform disorders related to the environment. Critics of a psychogenic model of MCS argue that psychiatric diagnoses are descriptive, and causality can not be derived from them. However, clinicians are expected to evaluate the most probable cause of the complaints and give therapeutic recommendations. There are promising therapeutic concepts for somatoform and other psychiatric disorders, but not for MCS. Double-blind challenge tests, but also therapy evaluation studies could contribute to a better understanding of the pathogenesis of MCS in the future.

PET in patients with clear-cut multiple chemical sensitivity (MCS)

AIM

Multiple chemical sensitivity (MCS) is a controversially discussed symptom complex. Patients afflicted by MCS react to very low and generally non-toxic concentrations of environmental chemicals. It has been suggested that MCS leads to neurotoxic damage or neuroimmunological alteration in the brain detectable by position emission tomography (PET) and single photon emission computer tomography (SPECT). These methods are often applied to MCS patients for diagnosis, although they never proved appropriate.

METHOD

We scanned 12 MCS patients with PET, hypothesizing that it would reveal abnormal findings.

RESULTS

Mild glucose hypometabolism was present in one patient. In comparison with normal controls, the patient group showed no significant functional brain changes.

CONCLUSION

This first systematic PET study in MCS patients revealed no hint of neurotoxic or neuroimmunological brain changes of functional significance.

Psychiatric and somatic disorders and multiple chemical sensitivity (MCS) in 264 'environmental patients'

BACKGROUND

An increasing number of individuals with diverse health complaints are currently seeking help in the field of environmental medicine. Multiple chemical sensitivity (MCS) or idiopathic environmental intolerances (IEI) is defined as an acquired disorder with multiple recurrent symptoms associated with environmental chemicals in low concentrations that are well tolerated by the majority of people. Their symptoms are not explained by any known psychiatric or somatic disorder.

METHOD

Within a 2-year period we examined 264 of 267 consecutive patients prospectively presenting to a university based out-patient department for environmental medicine. Patients underwent routine medical examination, toxicological analysis and the structured clinical interview for DSM-IV psychiatric disorders (SCID).

RESULTS

Seventy-five per cent of the patients met DSM-IV criteria for at least one psychiatric disorder and 35% of all patients suffered from somatoform disorders. Other frequent diagnoses were affective and anxiety disorders, and dependence or substance abuse. In 39% a psychiatric disorder, in 23% a somatic condition and in 19% a combination of the two were considered to provide sufficient explanation of the symptoms. Toxic chemicals were regarded as the most probable cause in only five cases. The suspected diagnosis of MCS/IEI could not be sustained in the vast majority of cases.

CONCLUSION

This investigation confirms previous findings that psychiatric morbidity is high in patients presenting to specialized centres for environmental medicine. Somatoform disorders are the leading diagnostic category, and there is reason to believe that certain 'environmental' or MCS patients form a special subgroup of somatoform disorders. In most cases, symptoms can be explained by well-defined psychiatric and medical conditions other than MCS, which need specific treatment. Further studies should focus on provocation testing in order to find positive criteria for MCS and on therapeutic approaches that consider psychiatric aspects.

[Psychiatric and somatic morbidity of patients with suspected multiple chemical sensitivity syndrome (MCS)]

Multiple chemical sensitivity (MCS) or idiopathic environmental intolerance (IEI) is understood as an acquired disorder with multiple recurrent symptoms that cannot be traced to any well-known medical or psychiatric condition and is associated with diverse environmental influences that are well tolerated by the majority of people. In a prospective study, we investigated 120 consecutive patients admitted a university-based outpatient department for environmental medicine during 1 year. Apart from routine medical examination and special toxicological diagnostic procedures, a structured clinical interview for DSM-IV psychiatric disorders was performed with every patient. At least one psychiatric diagnosis was found in 100 patients. The diagnostic criteria for somatoform disorders were filled by 53 patients. We found lifetime or current affective disorders in 39 patients, anxiety disorders in 29, and substance dependency or abuse in 25. In 16 patients, personality disorders were diagnosed. Nine suffered from psychotic disorders. This is the largest prospective study with standardized psychiatric diagnostic methods concerning psychiatric morbidity and MCS. The data show that many patients with environmental health problems obviously suffer from somatoform disorders but also from other, well-known psychiatric conditions.