Christian Schuetz
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Graduate Student Supervision
Doctoral Student Supervision
Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
The Lancet published a large multicenter randomized controlled clinical trial of noradrenergic and specific serotonergic antidepressant (NSSA) and selective serotonin re-uptake inhibitors (SSRI) for depression in Alzheimer’s disease (AD) suggesting that these compounds have no clinical benefit [Banerjee et al 2011]. We felt that it might be premature to suggest that the use of all antidepressant treatments is ineffective [Sepehry et al 2012]. In response, we ran a meta-analysis examining the evidence for the use of SSRIs for treatment of depression co-occurring with AD [Sepehry et al 2012, see Appendix N]. This study suggested that treatment effects are potentially assessment dependent, and provided the motivation for the current examination of depression diagnostic criteria and assessment/screening scales for AD. A literature search showed that Provisional Diagnostic Criteria for depression of AD (PDC-dAD) was proposed to diagnose depression in AD. Their validity has not been established, yet they have been used in epidemiological studies and clinical trials. Likewise, no study examined short and easy to use screening measures with comparable collateral version’s validity and utility for use with the PDC-dAD. Hence, I set these as my goals : to examine the validity-evidence of the PDC-dAD followed by simultaneous examination of the reliability (internal consistency), utility, and validity (content, construct, and concurrent) of screening measures already validated for use with older adults, for use with the PDC-dAD. Thus, the literature around depression in older adults and in AD was reviewed to improve understanding of the importance of investigating depression and its diagnostic/assessment approaches. Briefly, the result of the validity studies showed that, first, the PDC-dAD are the best that exist to date for diagnosing depression in AD; however it needs optimization. Second, screening measures developed for depression in older adults, including the collateral version, are psychometrically acceptable (valid and reliable) allowing for adequate screening of mild to mildly-moderate AD for dAD; however, the collateral version was the most valid given its psychometric properties, particularly, positive predictive value, specificity, and clinical accuracy for use with the PDC. Hence, recommendations are made for the use of the screening scales with the PDC and for future research.
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Master's Student Supervision
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
Background: Bipolar disorder (BD) affects more than 1% of the population and causes deficits in response inhibition. Response inhibition involves three sub-components (interference inhibition, action withholding, and action cancellation), that can be assessed together in the Hybrid Response Inhibition (HRI) task. The right Inferior Frontal Gyrus (rIFG) is a potential target for augmentation of response inhibition. Current investigations of repetitive transcranial magnetic stimulation (rTMS) in BD remain limited. This proof-of-concept study will explore rTMS of the rIFG and its effect on response inhibition using the HRI task in BD and controls.Methods: Within individuals with BD (n = 12) and a sex / age-matched control group (n = 12), we investigated the HRI performance scores associated with the three sub-components of response inhibition immediately before and after intermittent TMS (iTMS) and continuous TMS (cTMS) to either increase or decrease cortical excitability of the rIFG, respectively.Results: The response inhibition sub-component ‘action withholding’ was significantly improved in the HRI task following iTMS for the BD group. While there were no other significant effects observed in the results, noticeable trends may imply that there may be other effects of TMS on response inhibition in BD that differs from controls.Conclusions: Overall, this exploratory study successfully provided an initial evaluation of the effects of TMS on response inhibition in BD, showing trends and patterns that demonstrate the potential effectiveness of this novel intervention. Our study provides insights for further development and research of TMS over the rIFG in BD.
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Background: Several studies have shown that substance use disorders are characterized by an enhanced attention processing of substance and substance-related cues, with lower attentional processing of non-substance-related affective cues. Additionally, previous research has shown that attentional processing, within addiction, is malleable and can reverse from enhanced processing of substance cues to pleasant cues following prolonged abstinence. This study examines the neural processing of stimulant, pleasant, and stimulant relative to pleasant cues in individuals with a concurrent diagnosis of mental health and substance use disorders (i.e., concurrent disorders) compared to controls using event-related potentials (ERPs). Methods: Within in-patient individuals with concurrent disorders (n = 33) and a control group (n = 32), we studied the P300 amplitude elicited by stimulant (stimulant – neutral), pleasant (pleasant – neutral), stimulant relative to pleasant (stimulant – pleasant) cues. Additionally, individuals completed surveys and tasks to examine the implications of diagnoses, self-reported craving, cognitive function, and affect. Results: The results indicate that in-patient participants with concurrent disorder display a larger P300 difference wave for stimulant and pleasant cues, which remained significant after controlling for age, ethnicity, and working memory, compared to controls. Conclusions: These findings suggest that larger P300 amplitudes for stimulant and pleasant cues may be explaining emotional dysregulation within concurrent disorders. Together these findings suggest that non-invasive electrophysiological measures, such as EEG, may be used within future research to investigate the differences in concurrent disorder, mental health, and substance use disorders alone, necessary for identifying shared processes among these disorders.
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