Environmental intolerance (EI) is a condition characterized by low tolerance to environmental stimuli at levels that would not affect most people. EI is an ill-defined condition from which sufferers experience highly individual multisystem symptoms following exposure from specific environmental sources. Subgroups of EI are typically distinguished by the source that cause negative effects. In this study, intolerance attributed to noise and odors was investigated. Most research on EI is conducted using cross sectional approaches and among the instruments used to quantify EI is the Noise Sensitivity Scale (NSS-11) and the Chemical Sensitivity Scale for Sensory Hyperreactivity (CSS-SHR). To fully understand EI, more longitudinal research is needed. The aim of this study was to establish how a recently developed smartphone app, intended for longitudinal research, compares to the NSS-11 and CSS-SHR with regards to its ability to detect EI. 12 participants (mean age 29 years, SD=10.7 years) filled out the NSS-11/CSS-SHR following a period of two weeks using the app. It was hypothesized that individuals scoring high/low on the NSS-11/CSS-SHR would also express high/low levels of EI as measured by reports in the app on the variables discomfort rating, number of unique symptoms reported and number of reports. Although analyses revealed effects in the direction of the hypothesis for all variables, Independent samples t-test analyses yielded no significant associations. Either there are in fact no differences, but speculatively, the lack of significant associations can also be attributed any the following: (1) the groups were to similar (2) the sample was too small (3) the participants used avoidance as coping strategies.

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Chemical intolerance (CI) is a term that refers to the surprisingly common phenomenon of persons getting ill from everyday chemicals. Although seemingly similar to asthma and allergies, CI sufferers do not react to exposures with increased histamine release. CI neither conforms to toxicological dose-response relationships as sufferers react to very low concentrations of chemicals assumed to be harmless. In addition, no particular chemical can be tied to any particular set of symptoms as in the case of other kinds of toxic injuries. The two overreaching goals of this thesis were to empirically investigate important hypotheses regarding CI, and to develop a theoretical framework that integrates previous theories of CI into a coherent whole.There are four empirical studies in this thesis. Utilizing event-related potentials (ERPs), magnitude estimations of perceived intensity, detection tests and functional magnetic resonance imaging (fMRI), the studies provided support for the following hypotheses: (1) persons with self-reported CI sensitize to olfactory and chemosomatosensory stimuli, whereas non-intolerant individuals habituate; (2) sensitization in CI is similar in terms of brain activation patterns to both non-clinical sensitization and other unexplained illnesses such as fibromyalgia; (3) persons with CI have an attention bias to chemical exposures, reflected by problems with withdrawing attention from such stimuli; (4) measures of peripheral hyperreactivity are correlated with chemosensory ERP measures; but failed to corroborate (5) the reactions of women resemble those found in persons with CI to a greater degree than the case in men.Three major theories of CI are also discussed. The neural sensitization theory describes CI as pathological and non-immunological increases in neural responsiveness. The conditioning theory describes CI as the result of basic associative learning mechanisms. The neurogenic inflammation theory describes CI as proliferation of sensory c-fibers and inflammatory responses carried to several parts of the body through axon reflexes and release of inflammatory mediators. The main point of the theoretical synthesis is that the theories offer different and complementary perspectives on CI, rather than presenting conflicting ontologies. With an integrated perspective, infected debates whether CI is a psychological or organic illness can hopefully be avoided.Finally, the unexplained characteristics of CI, the empirical findings and the theoretical accounts are described within the theoretical framework of signal detection theory. Several features of CI, e.g. sensitization and peripheral hyperreactivity, are described in terms of applying a low criterion (ß). / Kemisk intolerans, det vill säga att få symtom av vardagliga lukter, är ett förvånansvärt vanligt problem. Trots att åkomman i många avseenden liknar astma och allergi, reagerar de drabbade inte med exempelvis ökad histaminfrisättning. Kemisk intolerans överensstämmer inte heller med toxikologiska dos-responsförhållanden, eftersom de drabbade blir sjuka av väldigt låga koncentrationer av luktämnen. Enskilda kemikalier kan inte kopplas till en karaktäristisk symtombild, vilket är vanligt vid andra typer av toxikologiska skador. I denna avhandling har jag två mål. För det första undersöker jag viktiga hypoteser om kemisk intolerans. För det andra erbjuder jag ett teoretiskt ramverk där jag integrerar tidigare teorier om kemisk intolerans till en sammanhängande helhet.Den empiriska delen av avhandlingen består av fyra forskningsstudier. Baserat på händelserelaterade hjärnpotentialer (ERPs), magnitudestimationer av upplevd styrka, detektionstest samt funktionell magnetresonansavbildning (fMRI) stöder studierna följande hypoteser: (1) personer med självrapporterad kemisk intolerans sensitiserar till olfaktoriska och kemosomatosensoriska stimuli, medan icke-intoleranta individer habituerar; (2) med avseende på hjärnaktiveringsmönster liknar sensitisering hos kemiskt intoleranta det mönster man finner både i icke-klinisk sensitisering och i exempelvis fibromyalgi; (3) personer med kemisk intolerans har en benägenhet att uppmärksamma kemisk exponering, vilket reflekteras i en oförmåga att ignorera sådana stimuli; (4) mått på perifer hyperreaktivitet korrelerar med kemosensoriska ERP-mått. Hypotesen att (5) kvinnors reaktioner på kemosensoriska stimuli liknar de man kan finna hos de kemiskt intoleranta i större utsträckning än vad fallet är för män, stöds däremot inte.Tre teorier om kemisk intolerans diskuteras. Den neurala sensitiseringsteorin beskriver intoleransen som en patologisk ökning av neural aktivitet. Betingningsteorin beskriver kemisk intolerans som ett resultat av grundläggande associativa inlägningsmekanismer. Slutligen beskriver teorin om neurogen inflammation intoleransen som en förhöjd aktivering av c-fiberaktivitet och ökade inflammatoriska processer. Huvudargumentet i den teoretiska sammanfattningen är att dessa teorier erbjuder komplementära perspektiv på kemisk intolerans. Med ett integrerat perspektiv kan förhoppningsvis infekterade debatter om huruvida kemisk intolerans är en psykologisk eller organisk åkomma undvikas.De oförklarade egenskaperna av kemisk intolerans, de empiriska fynden, samt de teoretiska förklaringarna beskrivs slutligen inom ett teoretiskt ramverk som utgår från signaldetektionsteorin. Flera egenskaper hos kemisk intolerans beskrivs i termer av ett förändrat eller lågt satt kriterium (ß).

Asthma and allergies are some of the most common illnesses worldwide that almost everybody will come in contact with. This thesis studied persons with allergic asthma, non-allergic asthma, allergic rhinitis and atopic dermatitis in a population-based sample. At an early stage, these illnesses were regarded as psychosomatic. Over time, as knowledge about asthma/allergy has increased more of a biomedical perspective was taken by the research field. In considering early documentations well as contemporary research, a psychobiosocial perspective was taken in this thesis when conducting the three studies. Thus, as psychological factors may affect the illness and be a result of the illness, it is important to incorporate these factors to better understand asthma and allergy. Study I examined the co- and multimorbidity in asthma/allergy with the environmental intolerances in the form of chemical and building-related intolerance. Study II investigated psychological distress in the four forms of asthma and allergy. Psychological distress was in this study defined as stress, burnout, anxiety, depression and environmental health worries. Study III examined usage of problem and emotion focused coping strategies and perceived social support from the surrounding in high and low asthma/allergy severity. All studies were performed using data from the Västerbotten Environmental Health Study, a questionnaire-based survey with focus on various environmental hypersensitivities and asthma and allergy. The result showed that the co- and multimorbidity with the environmental intolerances in asthma/allergy was larger than what was statistically excepted. Those with allergic asthma and atopic dermatitis experienced more stress, burnout and anxiety than those with non-allergic asthma, allergic rhinitis and non-asthma/allergy. Moreover, the most common way of coping with asthma and allergy was found to be strategies such as avoiding environments that are believed to affect health, and trying to accept the situation, independent of asthma/allergy severity. Finally, in general, those with asthma and allergy reported receiving most support from their partner, other family members and health care, and least support was perceived by those with low asthma/allergy severity.The findings suggest that co- and multimorbidity with environmental intolerances is relatively common in asthma and allergy, and should therefore be included in the clinical anamnesis for this patient group. The elevated level of distress in allergic asthma and atopic dermatitis evokes the question of use of therapies such as mindfulness maybe beneficial in certain afflicted persons. The results on coping and social support provide a foundation for further research regarding informing the asthma/allergy patient and family members about effective coping strategies and the importance of adequate social support. A metaperspective is taken in which interrelations between important variables in the thesis are discussed.