Kombucha como alimento potencialmente psicobiótico / Kombucha as a potential psychobiotic food

Os casos de transtorno de ansiedade têm apresentado crescimento considerável desde o início do século XX, onde a terapia medicamentosa oferecida, geralmente apresenta efeito sedativo, portanto, a busca por tratamentos adjuvantes para tratar quadros de ansiedade se fazem necessários. Estudos indicam que a modulação da microbiota intestinal pode estar relacionada à regulação neural dos indivíduos através de diversas vias, incluindo a aplicação de cepas probióticas e consumo de alimentos fermentados tradicionais como iogurte e kombucha, colaborando para a melhoria da qualidade de vida destes pacientes. Este projeto teve como objetivo buscar os metabólitos e neurotransmissores presentes no kombucha a fim de verificar seu potencial psicobióticos e comparar as aplicações e metabólitos produzidos por cepas probióticas existentes no mercado e em alimentos fermentados tradicionais que atuem no eixo intestino-cérebro. Foram realizadas pesquisas em bases de dados online, como Pubmed, Web of Science, Scielo, Scopus e Google Scholar no período entre 2002 e 2022 relacionados aos possíveis efeitos dos probióticos em condições de ansiedade, bem como como os mecanismos que envolvem o eixo cérebro-intestino, seja por meio de testes em humanos e em modelos animais. As espécies mais testadas quanto ao seu potencial probiótico e ação nos transtornos de ansiedade encontradas foram Lactobacillus paracasei, L. casei, L. rhamnosus, Bifidobacterium infanti e B. longum. Cada gênero demonstra um grau diferente na redução da ansiedade dos indivíduos. Os alimentos potencialmente probióticos, incluindo alimentos fermentados tradicionais, além de atuar como complemento à terapia em quadros de ansiedade, tem relevância no setor socioeconômico

Anxiety disorder cases have shown considerable growth since the beginning of the 20th century, where the drug therapy offered usually has a sedative effect. Therefore, the search for adjuvant treatments to treat anxiety disorders is necessary. Studies indicate that the modulation of the intestinal microbiota may be related to the neural regulation of individuals in several ways, including the application of probiotic strains and consumption of traditional fermented foods such as yogurt and kombucha, contributing to the improvement of the quality of life of these patients. This project aimed to identify and compare the psychobiotic effect in the gut-brain axis of the metabolites and neurotransmitters produced by kombucha and commercial probiotic strains. The research was carried out in online databases, such as Pubmed, Web of Science, Scielo, Scopus, and Google Scholar in the period between 2002 and 2022 related to the possible effects of probiotics in anxiety conditions as the mechanisms that involve the brain-gut axis either through tests in humans or animal models. The species most tested for their probiotic potential and action on anxiety disorders were Lactobacillus paracasei, L. casei, L. rhamnosus, Bifidobacterium infanti, and B. longum. Each genus demonstrates a different degree of reducing individuals' anxiety. Potentially probiotic foods, including traditional fermented foods, acting as a complement to therapy in cases of anxiety, have relevance in the socioeconomic sector

Nomophobia in Lebanon: Scale validation and association with psychological aspects.

OBJECTIVES: Nomophobia, an abbreviation of "No mobile phone phobia", is characterized by the illogical fear of being detached from the mobile phone or unable to use it. Research have provided evidence of an association between increased cellular phone use and multiple health issues, such as anxiety, depression, insomnia, and others. To our knowledge, there are no Lebanese studies about nomophobia, despite the high incorporation rate of mobile phones in Lebanon and the likelihood of suffering from anxiety, depression, and other conditions due to nomophobic attitudes. The study objectives were to validate and confirm psychometric properties of the Nomophobia Questionnaire (NMP-Q) and examine the associations between particular psychological conditions (anxiety, depression, stress, insomnia and impulsivity) and nomophobia among a representative sample of Lebanese people. METHODS: This cross-sectional study was carried out between January and July 2019. It enrolled 2260 residents of the community randomly selected from Lebanon's Mohafazat. Two villages per sub-district and households from each village were chosen using a random sampling technique. A questionnaire was distributed randomly to the households. SPSS version 25 was used to perform the statistical analysis. A multinomial regression was computed taking the nomophobia categories as the dependent variable (and taking the absence of nomophobia as the reference category) and all variables that showed a significant association in the bivariate analysis as independent variables. RESULTS: A total of 2260 (80.71%) out of 2800 questionnaires distributed was collected back. The mean age of the participants was 27.98 ± 9.66 years (58.8% females). Moreover, the mean nomophobia score was 71.56 ± 26.92 (median = 71; minimum = 14; maximum = 140). The results showed that 46 (2.0%) had no nomophobia, 769 (34.1%) mild nomophobia [95% CI 0.322-0.361], 1089 (48.3%) moderate nomophobia [95% CI 0.463-0.504] and 349 (15.5%) severe nomophobia [95% CI 0.140-0.170]. Items of the nomophobia scale converged over a solution of three factors that had an Eigenvalue over 1 (Factor 1 = emotions associated to losing connectedness, Factor 2 = not being able to communicate, Factor 3 = not being able to access information; total variance explained = 66.65%, and Cronbach's alpha = 0.948). The results of a multinomial regression, taking the nomophobia score as the dependent variable, showed that higher age was significantly associated with lower odds of having mild (aOR = 0.97), moderate (aOR = 0.93) and severe (aOR = 0.97) nomophobia respectively. Higher anxiety (aOR = 1.09) and higher insomnia (aOR = 1.04) were significantly associated with higher odds of having severe nomophobia. CONCLUSION: The results suggest a positive correlation between nomophobia and psychological conditions. There is a need for longitudinal and prospective studies that furnish information with regards of the impact of time on the variables measured, in order to better understand the nature, causes, and attributes of nomophobia.

Neuronal correlates of spider phobia in a combined fNIRS-EEG study.

Specific phobia is associated with aberrant brain activation in confrontation paradigms with phobic stimuli. In previous EEG research enhanced event-related potentials (ERPs) in the late-positive potential (LPP) window have been observed. Further, studies with functional near-infrared spectroscopy (fNIRS) and fMRI suggest that spider phobia is associated with enhanced activation within cortical and subcortical areas. In the current study we investigated the neuronal correlates of spider phobia in a combined fNIRS-EEG study. To this end, 37 spider phobic patients (PP) and 32 healthy controls (HC) underwent a symptom provocation paradigm during which subjects watched video clips of spiders and domestic animals (confrontation phase) after being primed on the content of the video (anticipation phase). Simultaneously, fNIRS, EEG, electromyography (EMG), electrocardiography and behavioral measures were assessed. Results showed increased LPP amplitudes, increased hemodynamic responses in the cognitive control network, and increased EMG activity and heart rate during spider conditions in PP in comparison to HC. Furthermore, in behavioral ratings PP showed higher emotional distress and avoidance. Behavioral ratings, fNIRS and EEG data showed positive correlations on a between-subject as well as on a within-subject level. Our results merge the existing data on neurophysiological correlates of phobic stimulus processing in hemodynamic and electrophysiological research and extend those of static visual material (pictures) to dynamic visual material (videos).

On-line anxiety level detection from biosignals: Machine learning based on a randomized controlled trial with spider-fearful individuals.

We present performance results concerning the validation for anxiety level detection based on trained mathematical models using supervised machine learning techniques. The model training is based on biosignals acquired in a randomized controlled trial. Wearable sensors were used to collect electrocardiogram, electrodermal activity, and respiration from spider-fearful individuals. We designed and applied ten approaches for data labeling considering individual biosignals as well as subjective ratings. Performance results revealed a selection of trained models adapted for two-level (low and high) and three-level (low, medium and high) classification of anxiety using a minimal set of six features. We obtained a remarkable accuracy of 89.8% for the two-level classification and of 74.4% for the three-level classification using a short time window length of ten seconds when applying the approach that uses subjective ratings for data labeling. Bagged Trees proved to be the most suitable classifier type among the classification models studied. The trained models will have a practical impact on the feasibility study of an augmented reality exposure therapy based on a therapeutic game for the treatment of arachnophobia.

Acceptance and commitment therapy for breast cancer survivors with fear of cancer recurrence: A 3-arm pilot randomized controlled trial.

BACKGROUND: Fear of cancer recurrence (FCR) has a profound negative impact on quality of life (QOL) for many cancer survivors. Breast cancer survivors (BCS) are particularly vulnerable, with up to 70% reporting clinically significant FCR. To the authors' knowledge, evidence-based interventions for managing FCR are limited. Acceptance and commitment therapy (ACT) promotes psychological flexibility in managing life's stressors. The current study examined the feasibility and preliminary efficacy of group-based ACT for FCR in BCS. METHODS: Post-treatment BCS (91 patients with stage I-III disease) with clinical FCR randomly were assigned to ACT (6 weekly 2-hour group sessions), survivorship education (SE; 6 weekly 2-hour group sessions), or enhanced usual care (EUC; one 30-minute group coaching session with survivorship readings). FCR severity (primary outcome) and avoidant coping, anxiety, post-traumatic stress, depression, QOL, and other FCR-related variables (secondary outcomes) were assessed at baseline (T1), after the intervention (T2), 1 month after the intervention (T3), and 6 months after the intervention (T4) using intent-to-treat analysis. RESULTS: Satisfactory recruitment (43.8%) and retention (94.5%) rates demonstrated feasibility. Although each arm demonstrated within-group reductions in FCR severity over time, only ACT produced significant reductions at each time point compared with baseline, with between-group differences at T4 substantially favoring ACT over SE (Cohen d for effect sizes, 0.80; P < .001) and EUC (Cohen d, 0.61; P < .01). For 10 of 12 secondary outcomes, only ACT produced significant within-group reductions across all time points. By T4, significant moderate to large between-group comparisons favored ACT over SE and EUC with regard to avoidant coping, anxiety, depression, QOL, and FCR-related psychological distress. CONCLUSIONS: Group-based ACT is a feasible and promising treatment for FCR and associated outcomes in BCS that warrants testing in larger, fully powered trials.

Sub-types of safety behaviours and their effects on social anxiety disorder.

Cognitive models suggest that social anxiety disorder (SAD) is maintained through the use of safety behaviours. Previous reports propose that these safety behaviours can be subdivided into two main categories: avoidance and impression management. Study 1 investigates whether certain safety behaviours are specific to SAD. The social behaviour questionnaire was administered to individuals with SAD (N = 106), post-traumatic stress disorder (N = 28) and non-patient controls (N = 59). A factor analysis (N = 164) replicated the previously reported avoidance and impression management subtypes. Scores for both subtypes were significantly higher in individuals with SAD than in individuals with post-traumatic stress disorder or non-patient controls. Study 2 investigated the causal role of such safety behaviours using an experimental design in a non-clinical population (N = 96). Pairs of participants each engaged in two conversations. In one of the conversations, a randomly selected participant performed either avoidance or impression management safety behaviours. In the other conversation, neither participant was instructed to use safety behaviours. Each participant rated their own anxiety and performance as well as rating the other person. Videos of the conversations were also rated. Both types of safety behaviour increased anxiety in the person performing the safety behaviour. The avoidance subtype also had broader effects on the other person that were largely absent from the impression management subtype. Taken together the studies provide support for the distinction between safety behaviour subtypes and have implications for the treatment of SAD.

Biobehavioral threat sensitivity and amygdala volume: A twin neuroimaging study.

Current literature on the relationship between dispositional fear (or threat sensitivity) and amygdala gray matter volume (GMV) is heterogeneous, with findings including positive, negative, and null correlations. A clearer understanding of this relationship would help to determine the potential utility of amygdala volume as a biomarker of anxious/depressive (internalizing) disorders and contribute to understanding of neural mechanisms for variations in fearfulness. The study reported here used voxel-based morphometry to quantify amygdala GMV scores from structural neuroimaging data in a sample of 44 monozygotic twins (i.e., 22 pairs). Dispositional threat sensitivity (THT) was quantified using a biobehavioral cross-domain score that combined neurophysiological indicators with a psychological scale measure. Analyses revealed expected high concordance for amygdala GMV between co-twins. With respect to the major question of the study, a negative correlation was found between biobehavioral THT scores and amygdala volume - with individuals higher in THT showing smaller amygdala GMV scores. More modest associations of amygdala GMV with symptoms of social phobia, and fear disorder symptomology more broadly, were mediated by THT. These results provide insight into prior mixed findings and support the combined use of biological and behavioral measures to quantify characteristics relevant to mental health problems.

Neurobiology of fear and specific phobias.

Fear, which can be expressed innately or after conditioning, is triggered when a danger or a stimulus predicting immediate danger is perceived. Its role is to prepare the body to face this danger. However, dysfunction in fear processing can lead to psychiatric disorders in which fear outweighs the danger or possibility of harm. Although recognized as highly debilitating, pathological fear remains insufficiently treated, indicating the importance of research on fear processing. The neurobiological basis of normal and pathological fear reactions is reviewed in this article. Innate and learned fear mechanisms, particularly those involving the amygdala, are considered. These fear mechanisms are also distinguished in specific phobias, which can indeed be nonexperiential (implicating innate, learning-independent mechanisms) or experiential (implicating learning-dependent mechanisms). Poor habituation and poor extinction are presented as dysfunctional mechanisms contributing to persistence of nonexperiential and experiential phobias, respectively.

Commonalities and differences in the neural substrates of threat predictability in panic disorder and specific phobia.

Different degrees of threat predictability are thought to induce either phasic fear or sustained anxiety. Maladaptive, sustained anxious apprehension is thought to result in overgeneralization of anxiety and thereby to contribute to the development of anxiety disorders. Therefore, differences in threat predictability have been associated with pathological states of anxiety with specific phobia (SP) representing phasic fear as heightened response to predictable threat, while panic disorder (PD) is characterized by sustained anxiety (unpredictable threat) and, as a consequence, overgeneralization of fear. The present study aimed to delineate commonalities and differences in the neural substrates of the impact of threat predictability on affective processing in these two anxiety disorders. Twenty PD patients, 20 SP patients and 20 non-anxious control subjects were investigated with an adapted NPU-design (no, predictable, unpredictable threat) using whole-head magnetoencephalography (MEG). Group independent neural activity in the right dlPFC increased with decreasing threat predictability. PD patients showed a sustained hyperactivation of the vmPFC under threat and safety conditions. The magnitude of hyperactivation was inversely correlated with PDs subjective arousal and anxiety sensitivity. Both PD and SP patients revealed decreased parietal processing of affective stimuli. Findings indicate overgeneralization between threat and safety conditions and increased need for emotion regulation via the vmPFC in PD, but not SP patients. Both anxiety disorders showed decreased activation in parietal networks possibly indicating attentional avoidance of affective stimuli. Present results complement findings from fear conditioning studies and underline overgeneralization of fear, particularly in PD.

Quantitative representations of an exaggerated anxiety response in the brain of female spider phobics-a parametric fMRI study.

We employed a novel parametric spider picture set in the context of a parametric fMRI anxiety provocation study, designed to tease apart brain regions involved in threat monitoring from regions representing an exaggerated anxiety response in spider phobics. For the stimulus set, we systematically manipulated perceived proximity of threat by varying a depicted spider's context, size, and posture. All stimuli were validated in a behavioral rating study (phobics n = 20; controls n = 20; all female). An independent group participated in a subsequent fMRI anxiety provocation study (phobics n = 7; controls n = 7; all female), in which we compared a whole-brain categorical to a whole-brain parametric analysis. Results demonstrated that the parametric analysis provided a richer characterization of the functional role of the involved brain networks. In three brain regions-the mid insula, the dorsal anterior cingulate, and the ventrolateral prefrontal cortex-activation was linearly modulated by perceived proximity specifically in the spider phobia group, indicating a quantitative representation of an exaggerated anxiety response. In other regions (e.g., the amygdala), activation was linearly modulated in both groups, suggesting a functional role in threat monitoring. Prefrontal regions, such as dorsolateral prefrontal cortex, were activated during anxiety provocation but did not show a stimulus-dependent linear modulation in either group. The results confirm that brain regions involved in anxiety processing hold a quantitative representation of a pathological anxiety response and more generally suggest that parametric fMRI designs may be a very powerful tool for clinical research in the future, particularly when developing novel brain-based interventions (e.g., neurofeedback training). Hum Brain Mapp 38:3025-3038, 2017. © 2017 Wiley Periodicals, Inc.

Less is more: Neural activity during very brief and clearly visible exposure to phobic stimuli.

Research on automatic processes in fear has emphasized the provocation of fear responses rather than their attenuation. We have previously shown that the repeated presentation of feared images without conscious awareness via backward masking reduces avoidance of a live tarantula in spider-phobic participants. Herein we investigated the neural basis for these adaptive effects of masked exposure. 21 spider-phobic and 21 control participants, identified by a psychiatric interview, fear questionnaire, and approaching a live tarantula, viewed stimuli in each of three conditions: (1) very brief exposure (VBE) to masked images of spiders, severely limited awareness; (2) clearly visible exposure (CVE) to spiders, full awareness; and (3) masked images of flowers (control), severely limited awareness. Only VBE to masked spiders generated neural activity more strongly in phobic than in control participants, within subcortical fear, attention, higher-order language, and vision systems. Moreover, VBE activated regions that support fear processing in phobic participants without causing them to experience fear consciously. Counter-intuitively, CVE to the same spiders generated stronger neural activity in control rather than phobic participants within these and other systems. CVE deactivated regions supporting fear regulation and caused phobic participants to experience fear. CVE-induced activations also correlated with measures of explicit fear ratings, whereas VBE-induced activations correlated with measures of implicit fear (color-naming interference of spider words). These multiple dissociations between the effects of VBE and CVE to spiders suggest that limiting awareness of exposure to phobic stimuli through visual masking paradoxically facilitates their processing, while simultaneously minimizing the experience of fear. Hum Brain Mapp 38:2466-2481, 2017. © 2017 Wiley Periodicals, Inc.

Obsessive-compulsive skin disorders: a novel classification based on degree of insight.

Individuals with obsessive-compulsive features frequently visit dermatologists for complaints of the skin, hair or nails, and often progress towards a chronic relapsing course due to the challenge associated with accurate diagnosis and management of their psychiatric symptoms. The current DSM-5 formally recognizes body dysmorphic disorder, trichotillomania, neurotic excoriation and body focused repetitive behavior disorder as psychodermatological disorders belonging to the category of Obsessive-Compulsive and Related Disorders. However there is evidence that other relevant skin diseases such as delusions of parasitosis, dermatitis artefacta, contamination dermatitis, AIDS phobia, trichotemnomania and even lichen simplex chronicus possess prominent obsessive-compulsive characteristics that do not necessarily fit the full diagnostic criteria of the DSM-5. Therefore, to increase dermatologists' awareness of this unique group of skin disorders with OCD features, we propose a novel classification system called Obsessive-Compulsive Insight Continuum. Under this new classification system, obsessive-compulsive skin manifestations are categorized along a continuum based on degree of insight, from minimal insight with delusional obsessions to good insight with minimal obsessions. Understanding the level of insight is thus an important first step for clinicians who routinely interact with these patients.

[Real Time Fuctional Magnetic Resonance Imaging Biofeedback: a New Generation of Neurotherapy].

The review summarizes the data related to the potential of the real time fMRI biofeedback (the rt-fMRI), a novel technology implementing instructing patients to modify the neural activity in the certain brain regions related to the disordered function. The recent positive results were gained for a treatment of the post-stroke impairments, the Parkinson disease, the pain syndrome, the tinnitus, the alcohol and nicotine abuse, the major depression, and phobias of contamination and spiders. The intervention Was found to be less promising for schizophrenia and nearly ineffective for the criminal antisocial personality disorder. The reliability of the results is mostly poor due to suboptimal study designs, lack of the control groups, and insufficient sample sizes. The article deals with biological basis of the technology, its current applications and perspectives; and also its method- ologicdl and methodical problems.

Gray matter abnormalities in patients with social anxiety disorder: A voxel-based morphometry study.

The main objective of this study was to investigate the gray matter volume (GMV) differences between the patients with social anxiety disorder (SAD) and healthy controls, using VBM analysis. A total of 27 consecutive patients (15 women and 12 men) with SAD and 27 age and sex-matched healthy control subjects were included in this study. With magnetic resonance imaging, we examined GMV differences between SAD and healthy control groups. We found that GMV in the right middle and inferior temporal, left superior parietal, left precuneus and right fusiform areas were significantly greater in patients with SAD than in healthy controls. In addition, GMV in the right inferior and middle temporal regions were positively correlated with the social avoidance and total social anxiety scores of the participants in the SAD group. Lastly, greater GMV in the left superior parietal and precuneal regions were correlated with the higher disability in the social life of the patients with SAD. Our results suggest that the regions that showed significant GMV differences between the two groups play an important role in the pathophysiology of SAD and increased GMV in these regions might reflect a pathological process of neural abnormalities in this disorder.

[An update on the conceptual and classification issues of anxiety, its neuroanatomy and problems of anxiolytic drug discovery]. / A szorongás konceptuális aspektusai, klasszifikációja, neuroanatómiája és az anxiolítikum-fejlesztés problémái.

Anxiety disorders are highly prevalent psychiatric diseases. In this short review we provide an overview of concepts of fear, anxiety and anxiety disorders. In addition, based on the recent literature, neuroanatomical structures involved in anxiety and functional/structural changes of these structures in anxiety disorders are also discussed. Furthemore, the pitfalls of anxiolytic drug discovery is also concerned in the paper.

The Significance of Experiences of Nature for People with Parkinson's Disease, with Special Focus on Freezing of Gait--The Necessity for a Biophilic Environment. A Multi-Method Single Subject Study.

Freezing of Gait (FOG) is a common condition in people with Parkinson's disease (PD). FOG entails suddenly experiencing difficulties moving or feeling that one's feet are as glued to the ground. It is triggered, e.g., when passing through doorways. Earlier studies suggest that being in natural environments affects FOG in a positive way. Five subjects were recruited to serve as five single subject cases. We used interviews, observations, questionnaires and collected gait pattern data with aid of an accelerometer. A special designed outdoor setting was used, where we investigated whether passing through hedge openings with or without built elements triggered FOG. We found that no one experienced a FOG reaction when they passed through hedge openings without built elements. However, FOG was triggered when a doorframe was inserted into a hedge opening, and/or when peripheral vision was blocked. We interpret the results such that the doorframe triggered a phobic reflex, causing a freezing reaction. Passing through hedge openings does not trigger FOG, which we interpret as a biophilic reaction. Our results, if repeated in future studies, may have significance to everyday lives of PD patients, who could get a simpler life by consciously prioritizing stays in natural surroundings.

Neurostructural abnormalities in pediatric anxiety disorders.

Functional neuroimaging studies have consistently demonstrated abnormalities in fear and threat processing systems in youth with anxiety disorders; however, the structural neuroanatomy of these systems in children and adolescents remains largely unknown. Using voxel-based morphometry (VBM), gray matter volumes were compared between 38 medication-free patients with anxiety disorders (generalized anxiety disorder; social phobia; separation anxiety disorder, mean age: 14.4±3 years) and 27 comparison subjects (mean age: 14.8±4 years). Compared to healthy subjects, youth with anxiety disorders had larger gray matter volumes in the dorsal anterior cingulate and had decreased gray matter volumes in the inferior frontal gyrus (ventrolateral prefrontal cortex), postcentral gyrus, and cuneus/precuneus. These data suggest the presence of structural differences in regions previously implicated in the processing and regulation of fear in pediatric patients with anxiety disorders.

The neuroanatomical basis of panic disorder and social phobia in schizophrenia: a voxel based morphometric study.

OBJECTIVE: It is known that there is a high prevalence of certain anxiety disorders among schizophrenic patients, especially panic disorder and social phobia. However, the neural underpinnings of the comorbidity of such anxiety disorders and schizophrenia remain unclear. Our study aims to determine the neuroanatomical basis of the co-occurrence of schizophrenia with panic disorder and social phobia. METHODS: Voxel-based morphometry was used in order to examine brain structure and to measure between-group differences, comparing magnetic resonance images of 20 anxious patients, 20 schizophrenic patients, 20 schizophrenic patients with comorbid anxiety, and 20 healthy control subjects. RESULTS: Compared to the schizophrenic patients, we observed smaller grey-matter volume (GMV) decreases in the dorsolateral prefrontal cortex and precentral gyrus in the schizophrenic-anxiety group. Additionally, the schizophrenic group showed significantly reduced GMV in the dorsolateral prefrontal cortex, precentral gyrus, orbitofrontal cortex, temporal gyrus and angular/inferior parietal gyrus when compared to the control group. CONCLUSIONS: Our findings suggest that the comorbidity of schizophrenia with panic disorder and social phobia might be characterized by specific neuroanatomical and clinical alterations that may be related to maladaptive emotion regulation related to anxiety. Even thought our findings need to be replicated, our study suggests that the identification of neural abnormalities involved in anxiety, schizophrenia and schizophrenia-anxiety may lead to an improved diagnosis and management of these conditions.

Brain systems underlying encounter expectancy bias in spider phobia.

Spider-phobic individuals are characterized by exaggerated expectancies to be faced with spiders (so-called encounter expectancy bias). Whereas phobic responses have been linked to brain systems mediating fear, little is known about how the recruitment of these systems relates to exaggerated expectancies of threat. We used fMRI to examine spider-phobic and control participants while they imagined visiting different locations in a forest after having received background information about the likelihood of encountering different animals (spiders, snakes, and birds) at these locations. Critically, imagined encounter expectancies modulated brain responses differently in phobics as compared with controls. Phobics displayed stronger negative modulation of activity in the lateral prefrontal cortex, precuneus, and visual cortex by encounter expectancies for spiders, relative to snakes or birds (within-participants analysis); these effects were not seen in controls. Between-participants correlation analyses within the phobic group further corroborated the hypothesis that these phobia-specific modulations may underlie irrationality in encounter expectancies (deviations of encounter expectancies from objective background information) in spider phobia; the greater the negative modulation a phobic participant displayed in the lateral prefrontal cortex, precuneus, and visual cortex, the stronger was her bias in encounter expectancies for spiders. Interestingly, irrationality in expectancies reflected in frontal areas relied on right rather than left hemispheric deactivations. Our data accord with the idea that expectancy biases in spider phobia may reflect deficiencies in cognitive control and contextual integration that are mediated by right frontal and parietal areas.

Neurostructural correlates of two subtypes of specific phobia: a voxel-based morphometry study.

The animal and blood-injection-injury (BII) subtypes of specific phobia are both characterized by subjective fear but distinct autonomic reactions to threat. Previous functional neuroimaging studies have related these characteristic responses to shared and non-shared neural underpinnings. However, no comparative structural data are available. This study aims to fill this gap by comparing the two subtypes and also comparing them with a non-phobic control group. Gray and white matter data of 33 snake phobia subjects (SP), 26 dental phobia subjects (DP), and 37 healthy control (HC) subjects were analyzed with voxel-based morphometry. Especially DP differed from HC and SP by showing significantly increased grey matter volumes in widespread areas including the right subgenual anterior cingulate gyrus, left insula, left orbitofrontal and left prefrontal (PFC) cortices. In addition, white matter volume was significantly increased in the left PFC in DP compared with SP. These results are in line with functional changes observed in dental phobia and point toward those brain circuits associated with emotional processing and regulation. Future studies should aim to further delineate functional and structural connectivity alterations in specific phobia.