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This thesis describes five studies that systematically examined the effects of anxiety on cognitive performance, based on high trait versus low trait anxious university students. It directly tests the main assumptions of attentional control theory (ACT, Eysenck et al., 2007). The first two studies investigated the effects of anxiety on two central executive functions (inhibition and shifting) both jointly and separately. Task switching and an auditory distractor were used to investigate respectively the shifting and inhibition functions. Different switching tasks were used in both studies. The increased response time and switch cost in both studies suggested that anxiety impaired the shifting function. In addition, anxiety impaired response time but not accuracy (efficiency over effectiveness). These findings are as predicted by ACT. The next study investigated separately the effects of anxiety on three central executive functions (inhibition, shifting and updating). A switching task and a computerised version of the Hayling sentence completion test were used to test respectively the shifting and the inhibition functions. A letter memory task was used to study the updating function. In accordance with ACT, the results revealed that anxiety negatively affected the shifting function. However the inhibition and updating functions were not significantly affected. The fourth study investigated whether anxiety impairs the ability to co-ordinate the performance of two concurrent tasks. A memory and a reasoning task were used singly and concurrently. Results revealed that anxiety negatively affected the reasoning task response time when it was performed concurrently with the memory task, as predicted by ACT. The last study investigated effects of motivation on performance of high-anxious versus low-anxious individuals. A modified version of the digit symbol test (WAIS-III) was used. Results revealed that the high-anxious felt more motivated when the goal difficulty was high than the low-anxious. These five studies contribute to further understanding of the effects of anxiety on cognitive performance. Finally, the thesis outlines directions for future research.

Background and rationale unlike many other anxiety disorders, health anxiety has received relatively little attention in research until recently. Further research is required to better understand this difficulty, and thereby improve clinical interventions designed to address it. Substantial over-lap has been proposed between health anxiety and obsessive-compulsive disorder, and this link was utilised to identify a number of factors' worthy of exploration with respect to health anxiety. Method This study investigated how worry, intolerance of uncertainty, self-ambivalence and attachment insecurity were related to health anxiety. It also explored mediating relationships between these factors, based on a theoretically informed understanding of how they may be related. The study employed a correlational, cross-sectional design and had a non-clinical sample. A web- based survey was completed by 249 participants. The sample was predominantly female (81.5%) and had a mean age of 23.1 (SD=6.4). Results Intolerance of uncertainty was found to be a predictor of health anxiety after mood was controlled for. In addition, the relationship between these variables was found to be mediated by worry. A relationship between self-ambivalence and health anxiety was found, and this was shown to be mediated by intolerance of uncertainty. A relationship between attachment insecurity and health anxiety was not found at the .05 significance level. Attachment insecurity was found to be related to intolerance of uncertainty, and this relationship was shown to be mediated by self-ambivalence. Discussion The results are discussed in the context of previous findings. The role of intolerance of uncertainty in particular is considered, as analyses suggest it is both correlated with and a predictor of health anxiety. The relevance of the study findings to a transdiagnostic approach to treating anxiety is discussed. Methodological limitations of the study, areas for future research and clinical implications of the results are also considered.

Background Cognitive models propose that perceptions of diminished control are associated with the experience of anxiety (e.g., Chorpita & Barlow, 1998). Furthennore, parental over-control has been linked to anxiety in children and adolescents (e.g., Rapee, 1997). Emerging evidence suggests it is control over personal issues, rather than other areas, that is associated with intemalising symptoms in adolescents (Hasebe, Nucci, & Nucci, 2004). Design Using a non-experimental cross-sectional design, the present study examined the extent to which adolescent anxiety was associated with perceptions of control across three domains. The personal domain comprised private matters deemed outside legitimate parental control, the prudential/conventional domain included issues of health, safety and social regulation, while the overlapping domain covered issues that extend across the two. Method A community sample of 125 parent and adolescent dyads each completed questionnaires assessing anxiety symptoms and perceptions of parental control. Adolescents were aged 11-16 years (M 13.4 years). The parent respondents were 110 mothers and 15 fathers. Adolescent and parent self-reported anxiety symptoms were measured using the State-Trait Anxiety Inventory (Spielberger, 1983). Perceptions of control were assessed using the Parental Authority Index (Hasebe et al.,2004). Results Contrary to predictions, adolescent perceptions of parental control over personal issues were not associated with adolescent anxiety symptoms. However, adolescent perceptions oflow parental control over prudential/conventional matters were significantly associated with higher levels of adolescent anxiety. Adolescent age influenced the relationships between perceptions of control and adolescent anxiety. Adolescent and parent anxiety were significantly related, but adolescent perceptions of parental control did not mediate or moderate the relationship between parent and adolescent anxiety. Conclusions This study found adolescent perceptions of low parental control over matters of health, safety, and social convention were significantly associated with higher levels of adolescent anxiety. The direction of effect is in contrast to research using unitary measures of control, suggesting global measures may mask the complexity of the relationship between parental control and adolescent anxiety. These findings have important clinical and theoretical implications and support the utility of taking a multidimensional and developmental approach to the role of parental control in adolescent anxiety.

Anxiety is a clinically significant feature of bipolar spectrum disorders [BP]. The. rate of anxiety symptoms and/or comorbid anxiety diagnoses is high, and it contributes to worse outcomes in a range of domains. There is an accumulation of evidence that psychological therapy is effective for anxiety, which is not so for BP. Mental imagery is implicated in the maintenance of anxiety and is a promising avenue of research in BP. A cognitive model of bipolar disorder posits that imagery is an emotional amplifier in mania and anxiety. Paper A presents a systematic review of the literature of psychological therapies for anxiety in BP. Twenty-two studies were identified, though no formal synthesis was possible. Preliminary data for CBT for obsessive compulsive disorder, generalised anxiety disorder, and post-traumatic stress disorder in a BP population are promising, and further research is warranted. Furthermore, the addition of an anxiety module to CBT for BP effectively reduces anxiety, and may have additional benefits in other domains. Pilot research applying other evidence-based CBT treatments for comorbid anxiety is indicated, as are RCTs for CBT for cyclothymia and rapid cycling BP. The addition of an anxiety module may Improve the effectiveness of psychological therapy for BP, further review and research is necessary to explore this. Paper B presents an empirical study, com paring imagery processes in adults with BP (currently euthymic), mixed anxiety disorders, and non-clinical controls. Genera imagery use, intrusive and deliberate prospective imagery, and characteristics of image ' during different mood states are explored. People with anxiety have high levels 0 general imagery use and intrusive prospective imagery. Unlike the clinical groups, the control group appears to have a bias against negative imagery in a deliberate prospective imagery task. Retrospective report of mental imagery during past low, anxious and high mood states gives partial support to the imagery as an emotional amplifier theory, and similarities between the clinical groups may illuminate the high rates of comorbidity. Future research is discussed.

Adult Separation Anxiety (ASA) is an under-researched phenomenon and is currently not included in the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) despite a growing body of research literature showing its presentation in adults. There are a significant number of studies of adults using illicit substances and studies linking the use of substances and anxiety, yet none found so far to link substance use with Adult Separation Anxiety. The first aim of the current study was to investigate if Adult Separation Anxiety was present in a group of substance using clients in a drug treatment service. The second aim was to then explore the meaning and construction of the anxiety in those substance users presenting with this anxiety. Thirty-two substance using clients within a drug treatment service were given the Adult Separation Anxiety Self-Report Questionnaire (ASA-27), see Appendix 11. From this, 12 were interviewed using the Adult Separation Anxiety Semi-Structured Interview (SASI-II). The questionnaire data was analysed using the cut-off rates given by the questionnaire creators as indicators for the presence of Adult Separation Anxiety Disorder. The interview data was analysed using a Grounded Theory methodology to generate a theory. From the questionnaire scores 16 of the 32 participants who completed the ASA-27 questionnaire scored above 22, the cut-off for Adult Separation Anxiety Disorder, and 21 of the 32 participants scored above 16, the cut-off rate indicating the presence of Adult Separation Anxiety. Analysis of the interviews generated a theory of the importance of others to the participants and how this impacted their anxiety, substance use, self-perception and their fear of loss. 20

Caffeine is anxiogenic and theanine is claimed to induce relaxation. One functional magnetic resonance imaging (fMRI) study and two behavioural studies were designed to better understand the effects of these two components of tea, the world's second most popular drink, on anxiety. Single doses (250 mg) of caffeine and/or theanine were administered to healthy adults. Given previous findings, the measures also included self-ratings of other mental/physical states, blood pressure, heart rate and cortisol. Initially, an anxiety-induction manipulation, comprising an acute stressor task, was refined in three pilot studies. This was applied in the first behavioural study (n = 151) that examined the reputed anxiolytic effect oftheanine alone and in combination with caffeine. As expected, caffeine (vs. placebo) increased anxiety and blood pressure. Theanine did not reduce caffeine- or task-induced anxiety, whereas it did reduce the caffeine-induced rise in blood pressure. Another noteworthy result is that caffeine failed to enhance mental alertness in non/infrequent caffeine consumers. Using an emotional face processing task, fMRI and a region of interest approach to examine the neural correlates of caffeine-induced anxiety, Study 2 found that caffeine (vs. placebo) selectively induced threat-related (angry/fearful faces> happy faces) midbrain- periaqueductal gray activation and abolished threat-related medial prefrontal cortex wall activation. Furthermore, effects of caffeine on extent of threat-related amygdala activation correlated negatively with level of dietary caffeine intake. Returning to theanine, Study 3 examined the potential oftheanine to reduce anxiety using a stronger anxiety-induction manipulation, provided by the 7.5% carbon dioxide (C02) inhalation model of anxiety. Theanine (vs. placebo) did not reduce anxiety increased in this context, whereas there was some indication that it reduced the CO2-induced rise in blood pressure. Together, the findings of these studies enhance understanding of caffeine-induced anxiety, and challenge the claim that theanine is anxiolytic. Instead, they suggest theanine may be useful for reducing raised blood pressure. More broadly, this research provides insight into the role of caffeine and theanine in health and wellbeing, and informs claims for products containing these compounds.

Generalised anxiety disorder (GAD) is a common mental illness characterised by excessive worry and anticipatory anxiety. The present study aims to elucidate the neuropsychology, neurochemistry, structural and functional neuroanatomy of female patients with GAD using dietary manipulation of 5-HT and magnetic resonance imaging (MRI).

Background & Aims: Perseverative worry constitutes a cardinal feature of Generalized Anxiety Disorder (GAD) and has been thought to be crucial in the maintenance of the disorder. According to the Processing Efficiency Theory (Eysenck & Calvo, 1992), worry consumes working memory capacities, leading therefore to worry perseveration. This thesis sought to examine such capacities in healthy participants and determine whether and how these may be compromised in individuals diagnosed with GAD. Methods: To examine residual working memory capacities, participants performed a randomization task while thinking about a worry or positive topic. To explore whether limitations in randomization might reflect more general attentional deficits, participants also performed a single working memory task without concurrent task demands. Results GAD participants were less random than healthy participants, irrespective of task condition. Although GAD individuals were less random while worrying compared to the positive condition, healthy participants did not show such differences. Moreover, GAD participants required longer reaction times to perform the higher load conditions of the single working memory task relative to healthy participants. Conclusions: Results provide further empirical support that GAD individuals have less residual working memory capacity when worrying and, thus, fewer attentional resources available to redirect their thoughts away from worry (and onto other tasks). GAD participants exhibited attentional deficits during the higher load conditions of the single task, suggesting they were less able to sustain focus on tasks requiring a high degree of attentional control, even without concurrent task demands. Findings implicate depletion of working memory capacities in-the pathophysiology of GAD and suggest that exploring further the impact of the worrying process on such capacities may be of great clinical significance. Findings may be valuable in delineating possible vulnerability and protective factors to the development of GAD and help inform early and effective interventions for this debilitating disorder.