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Mittels einer klinischen Studie wurden die Furchtgeneralisierung und Aufmerksamkeitslenkung von 44 gesunden Kindern und Jugendlichen im Alter von 9-17 Jahren untersucht. Eine Übergeneralisierung konditionierter Furcht sowie veränderte Aufmerksamkeitsprozesse werden in zahlreichen Arbeiten mit der Entstehung und Aufrechterhaltung von Angsterkrankungen in Verbindung gebracht. Der Hauptteil der Forschung beschränkte sich bislang auf die Untersuchung von erwachsenen Probanden. Da Angsterkrankungen jedoch häufig bereits im Kindes- und Jugendalter entstehen und sich in der Erforschung psychiatrischer Erkrankungen zunehmend eine dimensionale Betrachtungsweise durchsetzt, bestand das Ziel der Studie darin, etwaige Alterseffekte und den Einfluss der Ängstlichkeit auf die genannten Phänomene bei gesunden Probanden zu untersuchen. Darüber hinaus wurde ein potentiell präventiver Ansatz erforscht. Im Ergebnis zeigten sich in den Gruppenvergleichen keine relevanten Differenzen. Interessanterweise deutete sich in der Gruppe der älteren Probanden entgegen der Erwartung eine verstärkte Furchtgeneralisierung an, die womöglich mit einer veränderten Beziehung zu Furcht und Risiko in der Adoleszenz zusammenhängt. Aus den Befunden ergibt sich die Notwendigkeit weiterer, prospektiver Arbeiten, um unser Verständnis der Ätiologie von Angsterkrankungen zu verbessern. Weiterhin ist noch offen, inwiefern es sich bei der Übergeneralisierung und einer veränderten Aufmerksamkeitslenkung um Risikofaktoren für die Entwicklung von Angsterkrankungen oder vielmehr um Epiphänomene handelt, die erst mit Ausbruch der Erkrankung auftreten. Der Einsatz von Methoden der virtuellen Realität erscheint besonders geeignet, diese Prozesse zukünftig noch besser zu erforschen.
Pavlovian fear conditioning describes a form of associative learning in which a previously neutral stimulus elicits a conditioned fear response after it has been temporally paired with an aversive consequence. Once acquired, the fear response can be extinguished by repeatedly presenting the former neutral stimulus in the absence of the aversive consequence. Although most patients suffering from anxiety disorders cannot recall a specific conditioned association between a formerly neutral stimulus and the feeling of anxiety, the produced behavioral symptoms, such as avoidance or safety behavior to prevent the anticipated aversive consequence are commonly exhibited in all anxiety disorders. Moreover, there is considerable similarity between the neural structures involved in fear and extinction in the rodent and in the human. Translational research thus contributes to the understanding of neural circuitries involved in the development and maintenance of anxiety disorders, and further provides hypotheses for improvements in treatment strategies aiming at inhibiting the fear response.
Since the failure to appropriately inhibit or extinguish a fear response is a key feature of pathological anxiety, the present preclinical research focuses on the interplay between the amygdala and the medial prefrontal cortex (mPFC) during fear learning with particular regard to the prefrontal recruitment during fear extinction and its recall. By firstly demonstrating an increased mPFC activity over the time course of extinction learning with functional near-infrared spectroscopy, the main study of this dissertation focused on repetitive transcranial magnetic stimulation (rTMS) as brain stimulation technique suitable to enhance extinction learning. Since hypofrontality is assumed to underlie the maintenance of pathological anxiety, rTMS application revealed an increased mPFC activity, which resulted in a decreased fear response on the behavioral level both during extinction learning as well as during the recall of extinction 24 hours later and in the absence of another stimulation. The following attempt to improve the generalization of extinction with rTMS from an extinguished stimulus to a second stimulus which was reinforced but not extinguished was at least partially evidenced. By revealing an increased prefrontal activity to the non-extinguished stimulus, the active and the placebo rTMS condition, however, did not differ on behavioral parameters. These preclinical findings were discussed in the light of genetic and environmental risk factors with special regard to the combination of a risk variant of the neuropeptide S receptor 1 gene polymorphism (NPSR1 rs324981) and anxiety sensitivity. While the protective homozygous AA genotype group showed no correlation with anxiety sensitivity, the NPSR1 T genotype group exhibited an inverse correlation with anxiety sensitivity in the presence of emotionally negative stimuli. In light of other findings assuming a role of the NPSR1 T allele in panic disorder, the revealed hypofrontality was discussed to define a risk group of patients who might particularly benefit from an augmentation of exposure therapy with rTMS.
Taken together, the presented studies support the central role of the prefrontal cortex in fear extinction and suggest the usefulness of rTMS as an augmentation strategy to exposure therapy in order to decrease therapy relapse rates. The combination of rTMS and extinction has been herein evidenced to modulate fear processes in a preclinical approach thereby establishing important implications for the design of future clinical studies.
Defensive behaviors in response to threats are key factors in maintaining mental and physical health, but their phenomenology remains poorly understood. Prior work reported an inhibition of oculomotor activity in response to avoidable threat in humans that reminded of freezing behaviors in rodents. This notion of a homology between defensive responding in rodents and humans was seconded by concomitant heart rate decrease and skin conductance increase. However, several aspects of this presumed defense state remained ambiguous. For example, it was unclear whether the observed oculomotor inhibition would 1) robustly occur during preparation for threat-avoidance irrespective of task demands, 2) reflect a threat-specific defensive state, 3) be related to an inhibition of somatomotor activity as both motion metrics have been discussed as indicators for freezing behaviors in humans, and 4) manifest in unconstrained settings.
We thus embarked on a series of experiments to unravel the robustness, threat-specificity, and validity of previously observed (oculo)motor and autonomic dynamics upon avoidable threat in humans. We provided robust evidence for reduced gaze dispersion, significantly predicting the speed of subsequent motor reactions across a wide range of stimulus contexts. Along this gaze pattern, we found reductions in body movement and showed that the temporal profiles between gaze and body activity were positively related within individuals, suggesting that both metrics reflect the same construct. A simultaneous activation of the parasympathetic (i.e., heart rate deceleration) and sympathetic (i.e., increased skin conductance and pupil dilation) nervous system was present in both defensive and appetitive contexts, suggesting that these autonomic dynamics are not only sensitive to threat but reflecting a more general action-preparatory mechanism. We further gathered evidence for two previously proposed defensive states involving a decrease of (oculo)motor activity in a naturalistic, unconstrained virtual reality environment. Specifically, we observed a state consisting of a cessation of ongoing behaviors and orienting upon relatively distal, ambiguous threat (Attentive Immobility) while an entire immobilization and presumed allocation of attention to the threat stimulus became apparent upon approaching potential threat (Immobility under Attack).
Taken together, we provided evidence for specific oculomotor and autonomic dynamics upon increasing levels of threat that may inspire future translational work in rodents and humans on shared mechanisms of threat processing, ultimately supporting the development of novel therapeutic approaches.
Objectives
Virtual reality exposure therapy (VRET) is a promising treatment for patients with fear of driving. The present pilot study is the first one focusing on behavioral effects of VRET on patients with fear of driving as measured by a post-treatment driving test in real traffic.
Methods
The therapy followed a standardized manual including psychotherapeutic and medical examination, two preparative psychotherapy sessions, five virtual reality exposure sessions, a final behavioral avoidance test (BAT) in real traffic, a closing session, and two follow-up phone assessments after six and twelve weeks. VRE was conducted in a driving simulator with a fully equipped mockup. The exposure scenarios were individually tailored to the patients’ anxiety hierarchy. A total of 14 patients were treated. Parameters on the verbal, behavioral and physiological level were assessed.
Results
The treatment was helpful to overcome driving fear and avoidance. In the final BAT, all patients mastered driving tasks they had avoided before, 71% showed an adequate driving behavior as assessed by the driving instructor, and 93% could maintain their treatment success until the second follow-up phone call. Further analyses suggest that treatment reduces avoidance behavior as well as symptoms of posttraumatic stress disorder as measured by standardized questionnaires (Avoidance and Fusion Questionnaire: p < .10, PTSD Symptom Scale–Self Report: p < .05).
Conclusions
VRET in driving simulation is very promising to treat driving fear. Further research with randomized controlled trials is needed to verify efficacy. Moreover, simulators with lower configuration stages should be tested for a broad availability in psychotherapy.