@phdthesis{Gruendahl2023,
  author    = {Gr{\"u}ndahl, Marthe Erda},
  title     = {From Lab to Life: Investigating the Role of Social Contact for Anxiety and Related Autonomic Responses},
  doi       = {10.25972/OPUS-31685},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-316859},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Social contact is an integral part of daily life. Its health-enhancing effects include reduced negative affective experiences of fear and anxiety, a phenomenon called social buffering. This dissertation studied different forms of social contact and their anxiety-buffering effects with diverse methodologies. The laboratory-based first study investigated minimal social contact in the context of pain relief learning. Results showed that the observed decreased autonomic and increased subjective fear responses following pain relief learning were independent of social influence. The minimalistic and controlled social setting may have prevented social buffering. Study 2 targeted social buffering in daily life using Ecological Momentary Assessment. We repeatedly assessed individuals' state anxiety, related cardiovascular responses, and aspects of social interactions with smartphones and portable sensors on five days. Analyses of over 1,500 social contacts revealed gender-specific effects, e.g., heart rate-reducing effects of familiarity in women, but not men. Study 3 examined anxiety, loneliness, and related social factors in the absence of social contact due to social distancing. We constructed and validated a scale measuring state and trait loneliness and isolation, and analysed its link to mental health. Results include a social buffering-like relation of lower anxiety with more trait sociability and sense of belonging. In sum, the studies showed no fear reduction by minimal social contact, but buffering effects relating to social and personal factors in more complex social situations. Anxiety responses during daily social contacts were lower with more familiar or opposite-gender interaction partners. During limited social contact, lower anxiety related to inter-individual differences in sociability, social belonging, and loneliness. By taking research from lab to life, this dissertation underlined the diverse nature of social contact and its relevance to mental health.},
  subject      = {Angst},
  language  = {en}
}
@phdthesis{Kneer2022,
  author    = {Kneer, Katharina Johanna},
  title     = {The association of three anxiety dimensions in children and adolescents: their influence on the brain and malleability by a prevention program},
  doi       = {10.25972/OPUS-25746},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257468},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Anxiety disorders are the most prevalent group of neuropsychiatric disorders and go along with high personal suffering. They often arise during childhood and show a progression across the life span, thus making this age a specific vulnerable period during development. Still most research about these disorders is done in adults. In light of this, it seems of utmost importance to identify predictive factors of anxiety disorders in children and adolescents. Temperament or personality traits have been proclaimed as risk markers for the development of subsequent anxiety disorders, but their exact interplay is not clear. In this dissertation an effort is made to contribute to the understanding of how risk markers of early temperamental traits, in this case Trait Anxiety, Anxiety Sensitivity and Separation Anxiety are interplaying. While Trait Anxiety is regarded as a more general tendency to react anxiously to threatening situations or stimuli (Unnewehr, Joormann, Schneider, \& Margraf, 1992), Anxiety Sensitivity is the tendency to react with fear to one's own anxious sensations (Allan et al., 2014; S. Reiss, Peterson, Gursky, \& McNally, 1986), and Separation Anxiety is referring to the extent to which the child is avoiding certain situations because of the fear of being separated from primary care givers (In-Albon \& Schneider, 2011). In addition, it will be addressed how these measurements are associated with negative life events, as well as brain functioning and if they are malleable by a prevention program in children and adolescents. In study 1 the aim was to extend the knowledge about the interrelations of this anxiety dimensions and negative life events. Results indicated positive correlations of all three anxiety traits as well as with negative life events. Thus, a close connection of all three anxiety measures as well as with negative life events could be indicated. The closest association was found between Anxiety Sensitivity and Trait Anxiety and between Separation Anxiety and Anxiety Sensitivity. Furthermore, negative life events functioned as mediator between Anxiety Sensitivity and Trait Anxiety, indicating that a part of the association was explained by negative life events. In study 2 we extended the findings from study 1 with neurobiological parameters and examined the influence of anxiety traits on emotional brain activation by administering the "emotional face matching task". This task activated bilateral prefrontal regions as well as both hippocampi and the right amygdala. Further analyses indicated dimension-specific brain activations: Trait Anxiety was associated with a hyperactivation of the left inferior frontal gyrus (IFG) and Separation Anxiety with a lower activation bilaterally in the IFG and the right middle frontal gyrus (MFG). Furthermore, the association between Separation Anxiety and Anxiety Sensitivity was moderated by bi-hemispheric Separation-Anxiety-related IFG activation. Thus, we could identify distinct brain activation patterns for the anxiety dimensions (Trait Anxiety and Separation Anxiety) and their associations (Separation Anxiety and Anxiety Sensitivity). The aim of study 3 was to probe the selective malleability of the anxiety dimensions via a prevention program in an at-risk population. We could identify a reduction of all three anxiety traits from pre- to post-prevention-assessment and that this effect was significant in Anxiety Sensitivity and Trait Anxiety scores. Furthermore, we found that pre-intervention Separation Anxiety and Anxiety Sensitivity post-intervention were associated. In addition, pre-interventive scores were correlated with the intervention-induced change within the measure (i.e., the higher the score before the intervention the higher the prevention-induced change) and pre-intervention Anxiety Sensitivity correlated with the change in Separation Anxiety scores. All relations, seemed to be direct, as mediation/moderation analyses with negative life events did not reveal any significant effect. These results are very promising, because research about anxiety prevention in children and adolescents is still rare and our results are indicating that cognitive-behavioural-therapy based prevention is gilding significant results in an indicated sample even when samples sizes are small like in our study. In sum the present findings hint towards distinct mechanisms underlying the three different anxiety dimensions on a phenomenological and neurobiological level, though they are highly overlapping (Higa-McMillan, Francis, Rith-Najarian, \& Chorpita, 2016; Taylor, 1998). Furthermore, the closest associations were found between Anxiety Sensitivity and Trait Anxiety, as well as between Separation Anxiety and Anxiety Sensitivity. Specifically, we were able to find a neuronal manifestation of the association between Separation Anxiety and Anxiety Sensitivity (Separation Anxiety-specific IFG activation) and a predictive potential on prevention influence. The results of these studies lead to a better understanding of the etiology of anxiety disorders and the interplay between different anxiety-related temperamental traits and could lead to further valuable knowledge about the intervention as well as further prevention strategies.},
  subject      = {Pr{\"a}vention},
  language  = {en}
}
@phdthesis{Vietz2022,
  author    = {Vietz, Melanie Sabrina},
  title     = {Pr{\"a}vention von Angsterkrankungen: Etablierung und Validierung des Kognitiven Angstsensitivit{\"a}tstrainings (KAST) - Deutsche Version},
  doi       = {10.25972/OPUS-22312},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-223122},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Angsterkrankungen stellen mit einer 12-Monats-Pr{\"a}valenz von 14\% die h{\"a}ufigsten psychischen Erkrankungen in der westlichen Gesellschaft dar. Angesichts der hohen querschnittlichen wie sequentiellen Komorbidit{\"a}t von Angsterkrankungen, der ausgepr{\"a}gten individuellen Einschr{\"a}nkungen sowie der hohen {\"o}konomischen Belastung f{\"u}r das Gesundheitssystem ist neben therapeutischen Behandlungsans{\"a}tzen die Entwicklung von kurzzeitigen, kosteng{\"u}nstigen und leicht zug{\"a}nglichen Pr{\"a}ventionsmaßnahmen von großer Bedeutung und steht zunehmend im Fokus des gesundheitspolitischen Interesses, um die Inzidenz von Angsterkrankungen zu reduzieren. Voraussetzung f{\"u}r die Entwicklung von gezielten und damit den effektivsten Pr{\"a}ventionsmaßnahmen sind valide Risikofaktoren, die die Entstehung von Angsterkrankungen beg{\"u}nstigen. Ein Konstrukt, das in der Literatur als subklinisches Symptom in Form einer kognitiven Vulnerabilit{\"a}t f{\"u}r Angsterkrankungen und damit als Risikofaktor angesehen wird, ist die sogenannte Angstsensitivit{\"a}t (AS). AS umfasst die individuelle Tendenz, angstbezogene k{\"o}rperliche Symptome generell als bedrohlich einzustufen und mit aversiven Konsequenzen zu assoziieren. Das Ziel der vorliegenden Arbeit war daher die Etablierung und Validierung eines Pr{\"a}ventionsprogramms zur Reduktion der AS an einer nicht-klinischen Stichprobe von 100 Probanden (18-30 Jahre) mit einer erh{\"o}hten AS (Anxiety Sensitivity Index [ASI-3] ≥17) sowie die Rekrutierung von 100 alters- und geschlechtsangeglichenen Probanden mit niedriger Angstsensitivit{\"a}t (ASI-3 <17). In einem randomisiert-kontrollierten Studiendesign durchliefen die Probanden mit hoher AS entweder das {\"u}ber f{\"u}nf Wochen angelegte „Kognitive Angstsensitivit{\"a}tstraining" (KAST) als erste deutschsprachige {\"U}bersetzung des Computer-basierten „Cognitive Anxiety Sensitivity Treatment" (CAST) von Schmidt et al. (2014) oder wurden der Wartelisten-Kontrollgruppe zugeteilt. Das KAST Training bestand aus einer einmaligen Vermittlung kognitiv-behavioraler Psychoedukation zum Thema Stress und Anspannung sowie deren Auswirkungen auf den K{\"o}rper und der Anleitung von zwei interozeptiven Expositions{\"u}bungen (‚Strohhalm-Atmung' und ‚Hyperventilation'), die {\"u}ber den anschließenden Zeitraum von f{\"u}nf Wochen in Form von Hausaufgaben wiederholt wurden. Es konnte gezeigt werden, dass die Teilnehmer des KAST-Programms nach Beendigung des Trainings (T1) eine signifikant niedrigere AS-Auspr{\"a}gung im Vergleich zur Wartelisten-Kontrollgruppe aufwiesen und diese Reduktion auch {\"u}ber den Katamnese-Zeitraum von sechs Monaten (T2) stabil blieb. Erg{\"a}nzend wurde auch die Targetierbarkeit weiterer intermedi{\"a}rer Risikomarker wie der Trennungsangst (TA), des Index der kardialen Sensitivit{\"a}t sowie der Herzratenvariabilit{\"a}t (HRV) untersucht, die jedoch nicht durch das KAST-Training direkt ver{\"a}ndert werden konnten. Im Vergleich der Subgruppen von Probanden mit hoher AS und gleichzeitig hoher TA (Adult Separation Anxiety Questionnaire [ASA-27] ≥22) und Probanden mit hoher AS, aber niedriger TA (ASA-27 <22) zeigte sich, dass die AS-TA-Hochrisikogruppe ebenfalls gut von der KAST-Intervention profitieren und eine signifikante Reduktion der AS erzielen konnte, indem sie sich bei T1 dem Niveau der Gruppe mit niedriger TA anglich. Zudem korrelierte die prozentuale Ver{\"a}nderung der Einstiegswerte der inneren Anspannung w{\"a}hrend der Strohhalm-Atmungs{\"u}bung positiv mit der prozentualen Ver{\"a}nderung der dimensionalen TA bei T1. Zusammenfassend weisen die Ergebnisse der vorliegenden Arbeit erstmalig auf die Wirksamkeit der deutschsprachigen {\"U}bersetzung des CAST-Programms (Schmidt et al., 2014), eines Computer-basierten, und damit leicht zu implementierenden sowie kosteng{\"u}nstigen Programms, in Bezug auf die Reduktion der AS sowie indirekt der TA hin und k{\"o}nnen damit zur indizierten und demnach besonders effektiven Pr{\"a}vention von Angsterkrankungen in Hochrisikogruppen beitragen.},
  subject      = {Angstst{\"o}rung},
  language  = {de}
}
@phdthesis{Auth2021,
  author    = {Auth, Charlotte Sophie},
  title     = {Die Auswirkungen von Tph2-Defizienz und negativen fr{\"u}hen Umwelterfahrungen auf Angstverhalten in weiblichen M{\"a}usen},
  doi       = {10.25972/OPUS-23948},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239488},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Angsterkrankungen geh{\"o}ren zu den am weitesten verbreiteten psychischen Erkrankungen und stellen eine betr{\"a}chtliche soziale und wirtschaftliche Herausforderung f{\"u}r unsere Gesellschaft dar. Aversive fr{\"u}he Erfahrungen sind ein bekannter Risikofaktor f{\"u}r die Entwicklung verschiedener psychischer Erkrankungen, insbesondere Angstst{\"o}rungen. W{\"a}hrend der fr{\"u}hen Entwicklung findet die Programmierung der Hypothalamus-Hypophysen-Nebennierenrinden- (HHN)-Achse, die die Aussch{\"u}ttung des Stresshormons Cortisol in Menschen bzw. Corticosteron in M{\"a}usen steuert, statt. Wenn Individuen in dieser kritischen Phase Stress ausgesetzt sind, wird die regelrechte Ausbildung der HHN-Achse gest{\"o}rt, was zu dysregulierten Verhaltensantworten auf Stressreize im sp{\"a}teren Leben f{\"u}hren kann. Das Serotonin (5-HT)-System als eines der ausgedehntesten Neurotransmittersysteme ist an der Vermittlung der Effekte von fr{\"u}her Stressexposition auf angst{\"a}hnliche Verhaltensweisen beteiligt. Das Ziel dieser Studie ist es, die Interaktion zwischen genetischer Pr{\"a}disposition und negativen Einfl{\"u}ssen in fr{\"u}hen Entwicklungsstadien auf die Ausbildung von Angstverhalten im Erwachsenenalter n{\"a}her zu beleuchten. In dieser Studie wurden Tryptophanhydroxylase 2 (Tph2)-defiziente weibliche M{\"a}use als Modell f{\"u}r ein lebenslanges konstitutives 5-HT Synthesedefizit im zentralen Nervensystem verwendet. Nachkommen dieser Mauslinie wurden im fr{\"u}hen Lebensalter Maternaler Separation (MS), d.h. einem m{\"u}tterlichen Trennungsparadigma, unterzogen und im Erwachsenenalter im „Open field" (OF) oder in der „Dark-light box" (DLB) getestet. Im Anschluss an die Verhaltensexperimente wurde die neuronale Aktivierung immunhistochemisch durch Darstellung des fr{\"u}hzeitig auftretenden Genprodukts c-Fos bestimmt. In der DLB zeigten homozygot Tph2-defiziente M{\"a}use eine verringerte motorische Aktivit{\"a}t im hellen Kompartiment, und dieser Effekt konnte durch MS normalisiert werden. Zus{\"a}tzlich verst{\"a}rkte MS bei diesem Genotyp das Auftreten von fluchtartigen Spr{\"u}ngen. Im OF hat MS fluchtartige Verhaltensweisen in homo- und heterozygoten Tph2-defizienten M{\"a}usen bef{\"o}rdert. Beide Verhaltenstests f{\"u}hrten zu spezifischen neuronalen Aktivierungsmustern, die mithilfe von c-Fos- Immunhistochemie ausgewertet wurden. Die Durchf{\"u}hrung des DLB-Tests f{\"u}hrte in Abh{\"a}ngigkeit vom Vorhandensein von Tph2 zur Aktivierung des paraventrikul{\"a}ren Kerns des Hypothalamus (PVN) und der basolateralen Amygdala (BL), wohingegen die Exposition gegen{\"u}ber dem OF-Test zu einer Aktivierung der lateralen Amygdala (La) in Tieren, die einem m{\"u}tterlichen Trennungsparadigma unterzogen wurden, sowie einer Aktivierung des ventrolateralen (VLPAG) und dorsolateralen (DLPAG) periaqu{\"a}duktalen H{\"o}hlengraus in Abh{\"a}ngigkeit von Tph2 und MS f{\"u}hrte. Zusammenfassend weisen die Ergebnisse dieser Studie darauf hin, dass MS aktive Verhaltensantworten auf aversive Reize in Abh{\"a}ngigkeit vom Vorhandensein von 5-HT im Gehirn f{\"o}rdert. Diese Effekte k{\"o}nnten durch die spezifische Aktivierung von mit Angstverhalten in Zusammenhang stehenden Gehirnregionen w{\"a}hrend der Verhaltensexperimente vermittelt werden.},
  subject      = {Angst},
  language  = {de}
}
@phdthesis{Stegmann2021,
  author    = {Stegmann, Yannik},
  title     = {Electrocortical mechanisms of sustained attention during the acquisition and interaction of conditioned fear and anxiety},
  doi       = {10.25972/OPUS-23770},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-237700},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Adapting defensive behavior to the characteristics of a threatening situation is a fundamental function of the brain. Particularly, threat imminence plays a major role for the organization of defensive responses. Acute threat prompts phasic physiological responses, which are usually associated with an intense feeling of fear. In contrast, diffuse and potentially threatening situations elicit a sustained state of anxious apprehension. Detection of the threatening stimulus defines the key event in this framework, initiating the transition from potential to acute threat. Consequently, attention to threat is crucial for supporting defensive behavior. The functions of attention are finely tuned to the characteristics of a threatening situation. Potential threat is associated with hypervigilance, in order to facilitate threat detection. Once a threatening stimulus has been identified, attention is selectively focused on the source of danger. Even though the concepts of selective attention and hypervigilance to threat are well established, evidence for their neural correlates remain scarce. Therefore, a major goal of this thesis is to elucidate the neural correlates of selective attention to acute threat and hypervigilance during potential threat. A second aim of this thesis is to provide a mechanistic account for the interaction of fear and anxiety. While contemporary models view fear and anxiety as mutually exclusive, recent findings for the neural networks of fear and anxiety suggest potential interactions. In four studies, aversive cue conditioning was used to induce acute threat, while context conditioning served as a laboratory model of potential threat. To quantify neural correlates of selective attention and hypervigilance, steady-state visual evoked potentials (ssVEPs) were measured as an index of visuocortical responding. Study 1 compared visuocortical responses to acute and potential threat for high versus low trait-anxious individuals. All individuals demonstrated enhanced electrocortical responses to the central cue in the acute threat condition, suggesting evidence for the neural correlate of selective attention. However, only low anxious individuals revealed facilitated processing of the contexts in the potential threat condition, reflecting a neural correlate of hypervigilance. High anxious individuals did not discriminate among contexts. These findings contribute to the notion of aberrational processing of potential threat for high anxious individuals. Study 2 and 3 realized orthogonal combinations of cue and context conditioning to investigate potential interactions of fear and anxiety. In contrast to Study 1 and 2, Study 3 used verbal instructions to induce potentially threatening contexts. Besides ssVEPs, threat ratings and skin conductance responses (SCRs) were recorded as efferent indices of defensive responding. None of these studies found further evidence for the neural correlates of hypervigilance and selective attention. However, results for ratings and SCRs revealed additive effects of fear and anxiety, suggesting that fear and anxiety are not mutually exclusive, but interact linearly to organize and facilitate defensive behavior. Study 4 tested ssVEPs to more ecologically valid forms of context conditioning, using flickering video stimuli of virtual offices to establish context representations. Contrary to expectations, results revealed decreased visuocortical responses during sustained presentations of anxiety compared to neutral contexts. A disruption of ssVEP signals eventually suggests interferences by continuously changing video streams which are enhanced as a function of motivational relevance. In summary, this thesis provided evidence for the neural correlates of attention only for isolated forms of fear and anxiety, but not for their interaction. In contrast, an additive interaction model of fear and anxiety for measures of defensive responding offers a new perspective on the topography of defensive behavior.},
  subject      = {Furcht},
  language  = {en}
}
@phdthesis{Genheimer2020,
  author    = {Genheimer, Hannah},
  title     = {The acquisition of anxiety and the impact of transcutaneous vagus nerve stimulation on extinction learning in virtual contexts},
  doi       = {10.25972/OPUS-20639},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206390},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {This thesis aims for a better understanding of the mechanisms underlying anxiety as well as trauma- and stressor-related disorders and the development of new therapeutic approaches. I was first interested in the associative learning mechanisms involved in the etiology of anxiety disorders. Second, I explored the therapeutic effects of transcutaneous vagus nerve stimulation (tVNS) as a promising new method to accelerate and stabilize extinction learning in humans. For these purposes, I applied differential anxiety conditioning protocols realized by the implementation of virtual reality (VR). Here, a formerly neutral virtual context (anxiety context, CTX+) is presented whereby the participants unpredictably receive mildly aversive electric stimuli (unconditioned stimulus, US). Another virtual context (safety context, CTX-) is never associated with the US. Moreover, extinction of conditioned anxiety can be modeled by presenting the same contexts without US delivery. When unannounced USs were administered after extinction, i.e. reinstatement, the strength of the "returned" conditioned anxiety can provide information on the stability of the extinction memory. In Study 1, I disentangled the role of elemental and conjunctive context representations in the acquisition of conditioned anxiety. Sequential screenshots of two virtual offices were presented like a flip-book so that I elicited the impression of walking through the contexts. Some pictures of CTX+ were paired with an US (threat elements), but not some other screenshots of the same context (non-threat elements), nor the screenshots depicting CTX- (safety elements). Higher contingency ratings for threat compared to non-threat elements revealed elemental representation. Electro-cortical responses showed larger P100 and early posterior negativity amplitudes elicited by screenshots depicting CTX+ compared to CTX- and suggested conjunctive representation. These results support the dual context representation in anxiety acquisition in healthy individuals. Study 2 addressed the effects of tVNS on the stabilization of extinction learning by using a context conditioning paradigm. Potentiated startle responses as well as higher aversive ratings in CTX+ compared to CTX- indicate successful anxiety conditioning. Complete extinction was found in startle responses and valence ratings as no differentiation between CTX+ and CTX- suggested. TVNS did not affect extinction or reinstatement of anxiety which may be related to the inappropriate transferability of successful stimulation parameters from epilepsy patients to healthy participants during anxiety extinction. Therefore, in Study 3 I wanted to replicate the modulatory effects of tVNS on heart rate and pain perception by the previously used parameters. However, no effects of tVNS were observed on subjective pain ratings, on pain tolerance, or on heart rate. This led to the conclusion that the modification of stimulation parameters is necessary for a successful acceleration of anxiety extinction in humans. In Study 4, I prolonged the tVNS and, considering previous tVNS studies, I applied a cue conditioning paradigm in VR. Therefore, during acquisition a cue (CS+) presented in CTX+ predicted the US, but not another cue (CS-). Both cues were presented in a second context (CTX-) and never paired with the US. Afterward, participants received either tVNS or sham stimulation and underwent extinction learning. I found context-dependent cue conditioning only in valence ratings, which was indicated by lower valence for CS+ compared to CS- in CTX+, but no differential ratings in CTX-. Successful extinction was indicated by equal responses to CS+ and CS-. Interestingly, I found reinstatement of conditioned fear in a context-dependent manner, meaning startle response was potentiated for CS+ compared to CS- only in the anxiety context. Importantly, even the prolonged tVNS had no effect, neither on extinction nor on reinstatement of context-dependent cue conditioning. However, I found first evidence for accelerated physiological contextual extinction due to less differentiation between startles in CTX+ compared to CTX- in the tVNS than in the sham stimulated group. In sum, this thesis first confirms the dual representation of a context in an elemental and a conjunctive manner. Second, though anxiety conditioning and context-dependent cue conditioning paradigms worked well, the translation of tVNS accelerated extinction from rats to humans needs to be further developed, especially the stimulation parameters. Nevertheless, tVNS remains a very promising approach of memory enhancement, which can be particularly auspicious in clinical settings.},
  subject      = {Angst},
  language  = {en}
}
@phdthesis{Schiele2019,
  author    = {Schiele, Miriam},
  title     = {Interaction of 5-HTT/NPSR1 variants with distal and acute stress on dimensional and neuroendocrine anxiety endophenotypes - A multi-dimensional model of anxiety risk},
  doi       = {10.25972/OPUS-14860},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148600},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {The etiology of anxiety disorders is multifactorial with contributions from both genetic and environmental factors. Several susceptibility genes of anxiety disorders or anxiety-related intermediate phenotypes have been identified, including the serotonin transporter gene (5-HTT) and the neuropeptide S receptor gene (NPSR1), which have been shown to modulate responses to distal and acute stress experiences. For instance, gene-environment interaction (GxE) studies have provided evidence that both 5-HTT and NPSR1 interact with environmental stress, particularly traumatic experiences during childhood, in the moderation of anxiety traits, and both 5-HTT and NPSR1 have been implicated in hypothalamic-pituitary-adrenal (HPA) axis reactivity - an intermediate phenotype of mental disorders - in response to acute stress exposure. The first part of this thesis aimed to address the interplay of variations in both 5-HTT and NPSR1 genes and distal stress experiences, i.e. childhood trauma, in the moderation of anxiety-related traits, extended by investigation of the potentially protective effect of positive influences, i.e. elements of successful coping such as general self-efficacy (GSE), on a GxE risk constellation by introducing GSE as an indicator of coping ability ("C") as an additional dimension in a GxExC approach conferring - or buffering - vulnerability to anxiety. Increased anxiety was observed in 5-HTTLPR/rs25531 LALA genotype and NSPR1 rs324981 AA genotype carriers, respectively, with a history of childhood maltreatment but only in the absence of a person's ability to cope with adversity, whereas a dose-dependent effect on anxiety traits as a function of maltreatment experiences irrespective of coping characteristics was observed in the presence of at least one 5-HTT S/LG or NSPR1 T allele, respectively. The second part of this thesis addressed the respective impact of 5-HTT and NPSR1 variants on the neuroendocrine, i.e. salivary cortisol response to acute psychosocial stress by applying the Maastricht Acute Stress Test (MAST). A direct effect of NPSR1 - but not 5-HTT - on the modulation of acute stress reactivity could be discerned, with carriers of the more active NPSR1 T allele Summary III displaying significantly higher overall salivary cortisol levels in response to the MAST compared to AA genotype carriers. In summary, study 1 observed a moderating effect of GSE in interaction with childhood maltreatment and 5-HTT and NPSR1, respectively, in an extended GxExC model of anxiety risk, which may serve to inform targeted preventive interventions mitigating GxE risk constellations and to improve therapeutic interventions by strengthening coping ability as a protective mechanism to promote resilient functioning. In study 2, a modulation of HPA axis function, considered to be an endophenotype of stress-related mental disorders, by NPSR1 gene variation could be discerned, suggesting neuroendocrine stress reactivity as an important potential intermediate phenotype of anxiety given findings linking NPSR1 to dimensional and categorical anxiety. Results from both studies may converge within the framework of a multi-level model of anxiety risk, integrating neurobiological, neuroendocrine, environmental, and psychological factors that act together in a highly complex manner towards increasing or decreasing anxiety risk.},
  subject      = {Angst},
  language  = {en}
}
@phdthesis{Aboagye2019,
  author    = {Aboagye, Benjamin},
  title     = {Behavioral and physiologic consequences of inducible inactivation of the \(Tryptophan\) \(hydroxylase\) 2 gene in interaction with early-life adversity},
  doi       = {10.25972/OPUS-17358},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173581},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Disruptions in brain serotonin (5-hydroxytryptamine, 5-HT) signaling pathways have been associated with etiology and pathogenesis of various neuropsychiatric disorders, but specific neural mechanisms of 5-HT function are yet to be fully elucidated. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme for brain 5-HT synthesis. Therefore, in this study a tamoxifen (Tam)-inducible cre-mediated conditional gene (Tph2) knockout in adult mouse brain (Tph2icKO) has been established to decipher the specific role of brain 5-HT in the regulation of behavior in adulthood. Immunohistochemistry and high-performance liquid chromatography (HPLC) were used first to test the efficacy of Tam-inducible inactivation of Tph2 and consequential reduction of 5-HT in adult mouse brain. Tam treatment resulted in ≥90\% reduction in the number of 5-HT immuno-reactive cells in the anterior raphe nuclei. HPLC revealed a significant reduction in concentration of 5-HT and its metabolite 5-hydroxyindole acetic acid (5-HIAA) in selected brain regions of Tph2icKO, indicating the effectiveness of the protocol used. Second, standard behavioral tests were used to assess whether reduced brain 5-HT concentrations could alter anxiety-, fear- and depressive-like behavior in mice. No altered anxiety- and depressive-like behaviors were observed in Tph2icKO compared to control mice (Tph2CON) in all indices measured, but Tph2icKO mice exhibited intense and sustained freezing during context-dependent fear memory retrieval. Tph2icKO mice also exhibited locomotor hyperactivity in the aversive environments, such as the open field, and consumed more food and fluid than Tph2CON mice. Lastly, the combined effect of maternal separation (MS) stress and adult brain 5-HT depletion on behavior was assessed in male and female mice. Here, MS stress, 5-HT depletion and their interaction elicited anxiety-like behavior in a sex-dependent manner. MS reduced exploratory behavior in both male and female mice. Reduced 5-HT enhanced anxiety in female, but not in male mice. Furthermore, expression of genes related to the 5-HT system and emotionality (Tph2, Htr1a, Htr2a, Maoa and Avpr1a) was assessed by performing a quantitative real-time PCR. In Tph2icKO mice there was a reduction in expression of Tph2 in the raphe nuclei of both male and female mice. Interaction between MS stress and 5-HT deficiency was detected showing increased Htr2a and Maoa expression in raphe and hippocampus respectively of female mice. In male mice, MS stress and 5-HT depletion interaction effects reduced Avpr1a expression in raphe, while the expression of Htr1a, Htr2a and Maoa was differentially altered by 5-HT depletion and MS in various brain regions.},
  subject      = {Anxiety},
  language  = {en}
}
@phdthesis{Baumann2018,
  author    = {Baumann, Christian},
  title     = {Psychologische und genetische Einflussfaktoren auf die Furchtkonditionierung und die Generalisierung konditionierter Furcht},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153656},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Bei der Entstehung und Aufrechterhaltung von Furcht und Angsterkrankungen stellt, neben der Furchtkonditionierung, die Generalisierung der konditionierten Furcht einen wesentlichen Mechanismus dar. Die der Generalisierung zugrunde liegenden psychologischen und biologischen Prozesse sind jedoch beim Menschen bisher nur wenig untersucht. Ziel dieser Arbeit war, anhand eines neu entwickelten experimentellen Paradigmas den Einfluss eines psychometrisch bestimmbaren angstspezifischen Faktors sowie der mit Furcht und Angst assoziierten Genotypen Stathmin1, COMT Val158Met und BDNF Val66Met auf die Furchtkonditionierung und Generalisierung konditionierter Furcht zu untersuchen und somit m{\"o}gliche Risikofaktoren f{\"u}r die Entstehung von Angsterkrankungen zu bestimmen. Hierf{\"u}r wurden N = 126 gesunde Versuchspersonen (n = 69 weiblich; mittleres Alter M = 23.05, SD = 3.82) f{\"u}r die genannten Polymorphismen genotypisiert und zu {\"a}ngstlichen und affektiven Symptomen befragt. In einer Akquisitionsphase wurden den Probanden zwei neutrale weibliche Gesichter pr{\"a}sentiert (CS), von denen eines mit einem Schrei sowie einem {\"a}ngstlichen Gesichtsausdruck (UCS) gepaart wurde. Der sich anschließende Generalisierungstest erfolgte anhand von vier Gesichtern, die in der {\"A}hnlichkeit zwischen den beiden CS schrittweise {\"u}bergingen. Die Furchtreaktion wurde {\"u}ber die Bewertung von Valenz, Arousal und Kontingenzerwartung sowie {\"u}ber die Hautleitf{\"a}higkeitsreaktion (SCR) erfasst. Die Analyse der Frageb{\"o}gen anhand einer Hauptachsenanalyse und anhand von Strukturgleichungsmodellen erbrachte eine zweifaktorielle L{\"o}sung, die die Konstrukte Depression und Angst abbildete. Nur der Faktor Angst war mit einer ver{\"a}nderten Furchtkonditionierung und Furchtgeneralisierung assoziiert: Hoch {\"A}ngstliche zeigten eine st{\"a}rkere konditionierte Furchtreaktion (Arousal) und wiesen eine st{\"a}rkere Generalisierung der Valenzeinsch{\"a}tzung und Kontingenzerwartung auf. F{\"u}r den Stathmin1 Genotyp ergaben sich geschlechtsspezifische Effekte. Bei den m{\"a}nnlichen Versuchspersonen zeigte sich in Folge der Akquisition ein st{\"a}rkerer Abfall der Valenz f{\"u}r den CS+ in der Gruppe der Stathmin1 T Alleltr{\"a}ger, die ebenfalls eine st{\"a}rkere Generalisierung der Furchtreaktion, abgebildet in allen verbalen Maßen, aufwiesen. Ein gegenteiliger Befund ergab sich f{\"u}r die Gruppe der Frauen, insofern eine mit dem Stathmin1 C Allel assoziierte h{\"o}here Generalisierung der Valenz, des Arousals und der Kontingenzerwartung festgestellt werden konnte. F{\"u}r den COMT Val158Met Genotyp ergaben sich keine Einfl{\"u}sse auf die Akquisition der konditionierten Furcht. F{\"u}r Tr{\"a}ger des COMT 158Val Allels zeigte sich jedoch eine st{\"a}rkere Generalisierung der Valenz und der Kontingenzerwartung. Auch f{\"u}r den BDNF Val66Met Genotyp konnte keine Ver{\"a}nderung der Furchtakquisition beobachtet werden. Es ergaben sich jedoch Hinweise auf eine erh{\"o}hte Generalisierung der Kontingenzerwartung in der Gruppe der BDNF 66Val Homozygoten. F{\"u}r keinen der beschriebenen Faktoren konnte ein Einfluss auf die Furchtkonditionierung oder deren Generalisierung anhand der SCR abgebildet werden. Unsere Ergebnisse weisen auf einen psychometrisch erfassbaren Faktor und genetische Einfl{\"u}sse hin, die {\"u}ber den Prozess einer st{\"a}rkeren Generalisierung der konditionierten Furcht das Risiko f{\"u}r die Entstehung von Angsterkrankungen erh{\"o}hen k{\"o}nnen. Jedoch sollten die Befunde in gr{\"o}ßeren Stichproben repliziert werden. Neben der fr{\"u}hzeitigen Identifikation von Risikofaktoren sollten in zuk{\"u}nftigen Studien dar{\"u}ber hinaus wirksame Maßnahmen zur Pr{\"a}vention und Intervention entwickelt werden, um diesem Risiko entgegen zu wirken.},
  subject      = {Konditionierung},
  language  = {de}
}
@phdthesis{Raab2018,
  author    = {Raab, Annette},
  title     = {The role of Rgs2 in animal models of affective disorders},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-152550},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Anxiety and depressive disorders result from a complex interplay of genetic and environmental factors and are common mutual comorbidities. On the level of cellular signaling, regulator of G protein signaling 2 (Rgs2) has been implicated in human and rodent anxiety as well as rodent depression. Rgs2 negatively regulates G protein-coupled receptor (GPCR) signaling by acting as a GTPase accelerating protein towards the Gα subunit. The present study investigates, whether mice with a homozygous Rgs2 deletion (Rgs2-/-) show behavioral alterations as well as an increased susceptibility to stressful life events related to human anxiety and depressive disorders and tries to elucidate molecular underlying's of these changes. To this end, Rgs2-/- mice were characterized in an aversive-associative learning paradigm to evaluate learned fear as a model for the etiology of human anxiety disorders. Spatial learning and reward motivated spatial learning were evaluated to control for learning in non-aversive paradigms. Rgs2 deletion enhanced learning in all three paradigms, rendering increased learning upon deletion of Rgs2 not specific for aversive learning. These data support reports indicating increased long-term potentiation in Rgs2-/- mice and may predict treatment response to conditioning based behavior therapy in patients with polymorphisms associated with reduced RGS2 expression. Previous reports of increased innate anxiety were corroborated in three tests based on the approach-avoidance conflict. Interestingly, Rgs2-/- mice showed novelty-induced hypo-locomotion suggesting neophobia, which may translate to the clinical picture of agoraphobia in humans and reduced RGS2 expression in humans was associated with a higher incidence of panic disorder with agoraphobia. Depression-like behavior was more distinctive in female Rgs2-/- mice. Stress resilience, tested in an acute and a chronic stress paradigm, was also more distinctive in female Rgs2-/- mice, suggesting Rgs2 to contribute to sex specific effects of anxiety disorders and depression. Rgs2 deletion was associated with GPCR expression changes of the adrenergic, serotonergic, dopaminergic and neuropeptide Y systems in the brain and heart as well as reduced monoaminergic neurotransmitter levels. Furthermore, the expression of two stress-related microRNAs was increased upon Rgs2 deletion. The aversive-associative learning paradigm induced a dynamic Rgs2 expression change. The observed molecular changes may contribute to the anxious and depressed phenotype as well as promote altered stress reactivity, while reflecting an alter basal stress level and a disrupted sympathetic tone. Dynamic Rgs2 expression may mediate changes in GPCR signaling duration during memory formation. Taken together, Rgs2 deletion promotes increased anxiety-like and depression-like behavior, altered stress reactivity as well as increased cognitive function.},
  subject      = {Angst},
  language  = {en}
}