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Anxiety is a common disorder which affects about 25% of the population and whose pathophysiology is still poorly understood. Animal models of disease have been widely used to investigate the molecular basis of human disorders, including psychiatric illnesses. This thesis is about the study of the genetic basis of a mouse model of anxiety. I have carried out a QTL mapping study of behavioural measures thought to model anxiety. I report results from 1,636 mice, assessed for a large number of phenotypes in five ethological tests. Mice belonged to two F2 intercrosses originated by four lines generated in a replicate selection experiment. By comparing mapping results between the two crosses, I have demonstrated that selection operated on the same relatively small number of loci in the four selected lines. Analysis of genetic effect of QTL across phenotypes has allowed me to identify loci with specific roles on different dimensions of anxious behaviour, therefore enhancing our understanding of the anxiety phenotype in mice. For some of these QTL I have also accomplished fine mapping experiments: a locus on chromosome 15 is now contained in an interval of only 3 centimorgans. This work is the basis for further molecular dissection of the genetic loci that underlie anxiety and provides a starting point for the discovery of genes involved in a common psychiatric condition.

Literature reports that test anxiety may have an influence on aptitude test performance for some racial groups and therefore serves as a source of bias (Zeidner, 1998). Testing organisations have also found that individuals from African groups perform poorly on measures of fluid intelligence, putting them at a disadvantage when these scores are used for selection and training purposes. The current study examines a model defining the relationship between test anxiety, attentional resources and fluid intelligence in the following manner: an increase in test anxiety will result in a decrease of attentional resources as well as a decrease in fluid intelligence. With a decrease in attentional resources we will see a negative influence on fluid intelligence and test performance for different racial groups. Twenty-five African individuals and twenty-five individuals from Caucasian racial groups have set the stage to answer the question if certain groups experience higher test anxiety and thus perform poorly on fluid intelligence measures. Significant relationships were found, within and between groups, for attentional resources and fluid intelligence. Meanwhile, other factors, such as test anxiety, were not strongly associated with fluid intelligence performance. Future research into reasons why certain racial groups display lower overall attention in testing situations is suggested in order to ensure that tests for selection and training and aptitude tests are fair to all racial groups. / Psychology / M.A. Soc. Sc.(Psychology)

Literature reports that test anxiety may have an influence on aptitude test performance for some racial groups and therefore serves as a source of bias (Zeidner, 1998). Testing organisations have also found that individuals from African groups perform poorly on measures of fluid intelligence, putting them at a disadvantage when these scores are used for selection and training purposes. The current study examines a model defining the relationship between test anxiety, attentional resources and fluid intelligence in the following manner: an increase in test anxiety will result in a decrease of attentional resources as well as a decrease in fluid intelligence. With a decrease in attentional resources we will see a negative influence on fluid intelligence and test performance for different racial groups. Twenty-five African individuals and twenty-five individuals from Caucasian racial groups have set the stage to answer the question if certain groups experience higher test anxiety and thus perform poorly on fluid intelligence measures. Significant relationships were found, within and between groups, for attentional resources and fluid intelligence. Meanwhile, other factors, such as test anxiety, were not strongly associated with fluid intelligence performance. Future research into reasons why certain racial groups display lower overall attention in testing situations is suggested in order to ensure that tests for selection and training and aptitude tests are fair to all racial groups. / Psychology / M.A. Soc. Sc.(Psychology)

The objective of this study is to see if nonclinical panickers with unexpected panic attacks (NCPs-U) may be a more useful panic disorder (PD) analogue than nonclinical panickers with expected panic attacks (NCPs-E).

Indiana University-Purdue University Indianapolis (IUPUI) / Stress has been shown to contribute to alcohol drinking; however, inconsistencies in both the clinical and pre-clinical literature speak to the need for better paradigms to study this interaction. The present experiments compared animal models of the propensity to consume ethanol, the selectively bred alcohol-preferring (P) and high-alcohol-drinking (HAD) rat lines, in their response to yohimbine on ethanol seeking and self-administration and anxiety-like behavior. The P and HAD lines consume similar amounts of ethanol, yet differ in apparent motivation to drink ethanol, in anxiety-like behavior, and response to stress in alcohol drinking. Therefore, it was of interest to determine whether stress may differentially affect ethanol-motivated behaviors between the P and HAD lines. Acute administration of yohimbine, an α-2 adrenoreceptor antagonist that increases anxiety and activate stress systems, increased operant ethanol self-administration and reinstatement of ethanol seeking in P rats, and free-choice ethanol drinking in both P and HAD rats. However, acute yohimbine administration decreased ethanol drinking when given limited access in the home cage, an effect that was diminished by extending the pre-treatment interval or increasing the number of ethanol exposure sessions. Yohimbine did not alter appetitive responding during a non-reinforced trial, nor did yohimbine alter the acquisition of free-choice ethanol drinking. Exposure to alcohol deprivation resulted in modest increases in ethanol intake, but yohimbine did not potentiate this effect. While acute yohimbine administration increased anxiety-like behavior, prior experience with repeated yohimbine exposures or with repeated deprivation periods did not. P rats were shown to be more active and less anxious and to display greater responding during a non-reinforced trial than HAD rats. Taken together, the results of these experiments demonstrate that the timing of yohimbine exposure relative to ethanol access is a critical component to determining its effects on ethanol seeking and self-administration and anxiety-like behavior. Further investigation into the parameters under which stress alters the motivation to seek and consume ethanol between these selectively bred lines is warranted, and future work that incorporates therapeutic agents aimed at reducing stress reactivity and alcohol drinking could elucidate effective strategies in the treatment of alcoholism.

M.A. / The goal of the present study was to investigate the relationship between trait anxiety, years of service and posttraumatic stress disorder in the South African Police Service. This study was regarded as important because posttraumatic stress can have a significant influence on the personal life and work-related performance of police officers. One hundred and twenty white, male police officers volunteered to participate in the study. A structural model of the relationships between trait anxiety, years of service and posttraumatic stress was postulated. The model specified that trait anxiety and years of service influence posttraumatic stress both individually and jointly. Trait anxiety is operationalised by means of the IPAT Anxiety Scale and posttraumatic stress disorder by means of the Posttraumatic Stress Disorder Interview Schedule. The fit of the postulated model with the observed data was investigated by means of structural equation modelling. The results indicated that the postulated model showed an acceptable fit with the observed data. The estimated parameters of the model indicated that the subscales of the IPAT Anxiety Scale and the Posttraumatic Stress Disorder Interview Schedule are good indicators of their respective constructs. It was further shown that trait anxiety and years of service have a significant influence on posttraumatic stress disorder. The results support those of previous studies where it was shown that these variables can influence posttraumatic stress disorder. The present study emphasizes that trait anxiety may predispose police officers to the development of trait anxiety. The study also shows that if police officers are exposed to extended periods of traumatic experiences, they run the risk of developing posttraumatic stress disorder.