Anxiety, Fear and Human Defensive Reactions: Behavioural Differentiation of Generalised Anxiety Disorder and Panic Disorder
General, Cognitive and Mathematical Psychology
Final Report Abstract
Clinical disorders such as generalised anxiety disorder, panic disorder and depression tend to frequently co-occur, and their symptom profiles typically differ widely between different patients. For these reasons, it has proven very challenging to determine their causes. One argument has been that a magnified perception of threat may be a risk factor for different affective disorders in general. This would suggest that sensitivity to different types of threat may influence vulnerability to different categories of affective disorder. In this project, we aimed to explore this possibility. To do so, we compared the threat sensitivity of 99 affective disorders patients to that of 35 healthy controls. The affective disorders cohort comprised 32 patients with Generalized Anxiety Disorder (GAD), 34 patients with Panic Disorder (PD) and 33 patients with a Major Depressive Disorder (MDD). Threat sensitivity was measured both at the level of objectively quantifiable behaviour and at the subjective level using a self-report questionnaire. We used the Joystick Operated Runway Task (JORT) as the behavioural measure of threat-sensitivity and the Fear Survey Schedule (FSS) as the self-report measure of threat-sensitivity. All participants completed the study once, under the same conditions. The data from this study were analysed to probe for effects of clinical disorders, comparing all patients as a group to controls, and contrasting different patient groups more specifically. Additionally, given previous observations of sex effects in affective disorders, male and female participants were compared to each other and across groups. Statistical analysis revealed that there was a significant group by sex interaction effect on JORT Flight Intensity, a behavioural measure of the intensity with which a threatening situation is escaped from. This effect showed that female patients, irrespective of their specific diagnosis, scored significantly higher than male patients or healthy controls of either sex. There were no other significant group by sex interactions on other behavioural or self-report measures. However, when considering individual affective disorders, we found that PD and GAD but not MDD patients scored significantly higher than healthy controls on FSS Tissue Damage Fear, a self-report measure of the fear intensity evoked from threat to physical injury. All three patient groups scored significantly higher than healthy controls on FSS Social Fear, a self-report measure of fear arising in social settings. Overall, these intriguing results suggest that the vulnerability to affective disorders is influenced by female-specific threat-sensitivity, an effect that is observed across different clinical disorders and is captured by JORT Flight Intensity, as well as disorder-specific but not sex-specific threat-sensitivity which is captured by the FSS. These findings may shed light on shared and separate factors underlying the development of anxiety, fear and depression and emphasise the importance of including different levels of analysis in the study of affective disorders.
