Brain responses to olfactory and trigeminal exposure in idiopathic environmental illness (IEI) attributed to smells — An fMRI study

Andersson, Linus; Claeson, Anna-Sara; Nyberg, Lars; Stenberg, Berndt; Nordin, Steven

doi:10.1016/j.jpsychores.2014.09.014

Cited by 28 publications

(22 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results also may support the theory of response regulation by memory in the PFC. Andersson et al furthermore suggested the involvement of a limbic hyperreactivity and speculatively described the sensitivity with MCS as an inability to inhibit salient external stimuli in MCS [46]. …”

Section: Discussionmentioning

confidence: 99%

Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity

Azuma¹,

Uchiyama²,

Tanigawa³

et al. 2016

PLoS ONE

View full text Add to dashboard Cite

Multiple chemical sensitivity (MCS) is a disorder characterized by nonspecific and recurrent symptoms from various organ systems associated with exposure to low levels of chemicals. Patients with MCS process odors differently than controls do. Previously, we suggested that this odor processing was associated with increased regional cerebral blood flow (rCBF) in the prefrontal area during olfactory stimulation using near-infrared spectroscopic (NIRS) imaging. The aim of this study was to investigate the association of odor thresholds and changes in rCBF during olfactory stimulation at odor threshold levels in patients with MCS. We investigated changes in the prefrontal area using NIRS imaging and a T&T olfactometer during olfactory stimulation with two different odorants (sweet and fecal) at three concentrations (zero, odor recognition threshold, and normal perceived odor level) in 10 patients with MCS and six controls. The T&T olfactometer threshold test and subjective assessment of irritating and hedonic odors were also performed. The results indicated that the scores for both unpleasant and pungent odors were significantly higher for those for sweet odors at the normal perceived level in patients with MCS than in controls. The brain responses at the recognition threshold (fecal odor) and normal perceived levels (sweet and fecal odors) were stronger in patients with MCS than in controls. However, significant differences in the odor detection and recognition thresholds and odor intensity score between the two groups were not observed. These brain responses may involve cognitive and memory processing systems during past exposure to chemicals. Further research regarding the cognitive features of sensory perception and memory due to past exposure to chemicals and their associations with MCS symptoms is needed.

show abstract

Section: Discussionmentioning

confidence: 99%

Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity

Azuma¹,

Uchiyama²,

Tanigawa³

et al. 2016

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…For instance, many studies have tried to find an unifying pathophysiology for all IEIs, focusing on CNS reactions to environmental stimuli, with activation changes of the brain areas related to sensory processing and emotional responses [1,[5][6][7][8][9][10][11][12][13][14][15]41,42]. Since environmental noise has been recognised as an important health quality stressor [43], relevant literature up to now has focused mainly on auditory symptoms [21,22] without highlighting possible vestibular and postural consequences.…”

Section: Discussionmentioning

confidence: 99%

“…Possible explanations for the rearranged model along vestibular processing and symptoms cohort referred to by MCS patients could be considered to reside within pathophysiological cascades, such as those involving limbic structures in the natural history of MCS [1,[4][5][6][7][8][9][10][11][12][13][14][15]. According to these notions, repeated exposure to MCS inducing agents were found to provide in MCS subjects both time-dependent sensitization and kindling, especially within hippocampal and limbic areas [65].…”

Section: Discussionmentioning

confidence: 99%

“…According to these theories, several studies in the last few years have shown cerebral blood flow distribution abnormalities in patients with MCS, especially while processing odorous substances [10][11][12]. In particular, MCS sufferers have been seen to react peculiarly to sensory stimuli, with activation of brain areas connected with motivational, emotional and non-conscious processing of information, such as the amygdala and the hippocampus, encompassed in the limbic system [10][11][12][13][14], whose pathways are known to mediate CNS sensitization and their dysregulation contributes to abnormalities of behaviour and mood, endocrine, autonomic and immune function [15].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deranged Dimensionality of Vestibular Re-Weighting in Multiple Chemical Sensitivity

et al. 2016

View full text Add to dashboard Cite

Abstract:Background: Multiple chemical sensitivity (MCS) is a chronic multisystem condition characterized by low levels of multiple chemical susceptibility inducing a spectrum of central nervous system symptoms, including dizziness. Thus, considering (i) the overlapping psychogenic and organic burdens shared in MCS development and in vestibular disorders; (ii) the number of previous studies describing central processing impairment related to inner ear inflow in this syndrome; and (iii) the lack of literature with respect to clinical evidence of the presentation of MCS dizziness, the purpose of the present study was to highlight the possible hidden aspects of vestibular impairment by applying the recent contribution of implemented otoneurological testing, inferential statistic and principal component (PC) analysis in 18 MCS and 20 healthy subjects (HC); Methods: Both groups filled in a dizziness and environment exposure inventory and underwent the Rod and Disc and Rod and Frame Test, video Head Impulse Test (vHIT) and Static Posturography Test (SPT) with fast Fourier Transform (FFT). Between-group analysis of variance and PC analysis implemented on otoneurological variables were performed; Results: Defective vestibular processing was identified in 18 MCS patients (11 female and 7 male; mean age 49.5 ± 9.3 years) by finding a significant increase in SPT and FFT parameters and in Visual Dependency (VD) behaviour and a decrease in vHIT scores. Component correlation analysis in MCS showed a positive correlation of FFT parameters in PC1 and SPT parameters in PC2 with a negative correlation of vHIT and VD values in PC2. HC subjects demonstrated a positive correlation of VD and SPT parameters in PC1 and FFT parameters in PC2. Conclusion: Inferential and PC analysis provided the opportunity to disclose such possible hidden phenomena to (i) support that MCS physiopathological cascades could lead to a vestibular decay; and (ii) suggest rearrangement of the dimension of the variables as an aspect of near-optimal re-weighting, possibly underpinning the dizzy symptoms complained of by MCS patients.

show abstract

“…A recent investigation reporting 18 F-2-fluoro-2-deoxy-Dglucose (FDG)-positron emission tomography (PET)/computer tomography (CT) cortical changes after a pure olfactory stimulation in MCS patients (Chiaravalloti et al 2015) demonstrated to overcome that possible unintended sensory stimulation (Alessandrini et al 2014a;Benjamin et al 2010;Hillert et al 2007;Orriols et al 2009, Azuma et al 2013Andersson et al 2014) related to such neuroimaging techniques coupling the olfactory task with the acquisition phase. These aspects could have constituted a possible common bias to the interpretation of the majority of existing data.…”

Section: Introductionmentioning

confidence: 99%

Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity

et al. 2015

View full text Add to dashboard Cite

Multiple chemical sensitivity (MCS) patients usually react to odour compounds and the majority of neuroimaging studies assessed, especially at the cortical level, many olfactory-related correlates. The purpose of the present study was to depict sub-cortical metabolic changes during a neutral (NC) and pure (OC) olfactory stimulation by using a recently validated (18)F-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computer tomography procedure in 26 MCS and 11 healthy (HC) resting subjects undergoing a battery of clinical tests. Twelve subcortical volumes of interest were identified by the automated anatomical labeling library and normalized to thalamus FDG uptake. In both groups, when comparing OC to NC, the within-subjects ANOVA demonstrated a relative decreased metabolism in bilateral putamen and hippocampus and a relative increased metabolism in bilateral amygdala, olfactory cortex (OLF), caudate and pallidum. The between-groups ANOVA demonstrated in MCS a significant higher metabolism in bilateral OLF during NC. As in HC subjects negative correlations were found in OC between FDG uptake in bilateral amygdala and hippocampus and odor pleasantness scale, the latter positively correlated with MCS subjects' bilateral putamen FDG uptake in OC. Besides FDG uptake resemblances in both groups were found, for the first time a relative higher metabolism increase in OLF in MCS subjects at rest with respect to HC was found. When merging this aspect to the different subcortical FDG uptake correlations patterns in the two groups, the present study demonstrated to describe a peculiar metabolic index of behavioral and neurological aspects of MCS complaints.

show abstract

Brain responses to olfactory and trigeminal exposure in idiopathic environmental illness (IEI) attributed to smells — An fMRI study

Cited by 28 publications

References 49 publications

Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity

Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity

Deranged Dimensionality of Vestibular Re-Weighting in Multiple Chemical Sensitivity

Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity

Contact Info

Product

Resources

About