Masters Degrees (Psychiatry)

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Browsing Masters Degrees (Psychiatry) by Author "Martin, Lindi Imelda"

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    Relationship between childhood trauma, neuropsychological deficits, neural circuitry, and anxiety proneness in high-anxiety prone and low-anxiety prone adolescents
    (Stellenbosch : Stellenbosch University, 2017-12) Martin, Lindi Imelda; Seedat, Soraya; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Psychiatry.
    ENGLISH SUMMARY : Anxiety disorders, which commonly have their onset during critical developmental periods of childhood, adolescence and early adulthood, are associated with high rates of comorbidity, chronicity, and impairment. A number of risk factors, notably anxiety-related temperamental traits, and environmental and genetic influences, have been implicated in the aetiology and maintenance of anxiety disorders. Research to date, predominantly conducted in developed countries among Caucasian samples, has repeatedly shown that anxiety prone youth, characterized by elevated levels of self-reported anxiety-related temperamental traits [e.g., anxiety sensitivity and trait anxiety, together referred to as anxiety proneness (AP)] and/or youth with childhood maltreatment (CM) histories, manifest with deficits in a number of key neuropsychological domains, and in the processing of emotionally salient material. The present study investigated the effects of low and high levels of AP and CM on neuropsychological performance and emotion processing in a representative sample of predominantly non-Caucasian adolescents recruited from secondary schools in Cape Town, South Africa. In addition, the interactive effect of the BDNF Val66Met polymorphism and CM on susceptibility to AP in a subsample of mixed race adolescents was assessed. The present study comprised a two-tier study in a non-clinical sample of adolescents. The 1st tier constituted a cross-sectional survey and utilized a stratified, two-stage cluster sampling design. The 2nd tier comprised a cross-sectional study in which participants were closely matched on age, ethnicity, gender and educational status. In the 2nd tier, participants underwent neuropsychiatric and neuropsychological assessments, and functional neuroimaging. Adolescents were categorized into four groups, based on self-reported levels of AP and CM, namely low AP and low CM, low AP and high CM, high AP and low CM, and high AP and high CM. Evidence for the unique effects of AP and CM on verbal working memory were found. The interaction of AP with CM was associated with deficits in cognitive flexibility, processing speed, verbal fluency and IQ. In terms of emotion processing, neither AP nor CM had any significant main or combined effects on neural responses to negative or positive images, relative to neutral images, in the amygdala, hippocampus, or insula. There were no significant group differences in neural responses in the aforementioned regions. A trend for greater activation in response to negative and positive images in the right amygdala was evident in anxiety prone adolescents, relative to those adolescents with low levels of AP. Lastly, a trend toward statistical significance in terms of an interaction effect of the BDNF Met66 allele (relative to Val66 homozygotes) and CM on AP was observed. Our findings of the impact of AP and CM on various functional parameters, underscores the importance of screening adolescents for AP and CM and suggests the need for early intervention in youth focused on reducing levels of AP, reducing and preventing CM, and improving neuropsychological skills.