<p>The development of alcohol use disorder (AUD) is believed to involve functional adaptations in corticostriatal projections which regulate the reinforcing properties of ethanol (EtOH). To further our understanding of how repeated EtOH consumption impacts the corticostriatal circuit, extracellular electrophysiological recordings (local field potentials; LFPs) were gathered from the nucleus accumbens and prefrontal cortex of female and male C57BL/6J mice voluntarily consuming EtOH or water using ‘drinking-in-the-dark’ (DID) procedures. Mice were given 15 consecutive days of two-hours of access to EtOH (20% v/v), three hours into the dark cycle while LFPs were recorded. To determine the impact of repeated EtOH consumption on neural activity between these brain regions, theta phase-locking value (PLV, a measure of synchrony) was calculated. Specifically, theta PLV was calculated during active drinking periods (bouts) and average PLV during the first bout was compared to the last bout to determine within session changes in synchrony. Results indicated significantly lower PLV during the last bout than the first bout. Additionally, longer bouts predicted lower PLV during the last bout, but not the first bout when mice were consuming EtOH. These results may suggest that alcohol intoxication decreases corticostriatal synchrony over a drinking period. Results considering changes in theta power spectral density (PSD) indicated an increase in PSD when mice were given access to water during the typical EtOH access time following the 15-day EtOH drinking history. This effect was not seen when mice were drinking water prior to EtOH access and may be indicative of a successive negative contrast effect. This work identifies unique functional characteristics of corticostriatal communication associated with binge-like EtOH intake and sets the stage for identifying the biological mechanisms subserving them.</p>

To investigate the possibility that chronic diabetes mellitus was related to specific neuropsychological deficits, cognitive functioning was measured in subjects with diabetic retinopathy (without secondary disabilities), and in subjects classified as normal blind adults (also without secondary disabilities). The scores for the two groups were then compared.

The blind have generally been considered to be a homogeneous population whose deficits arise from an interaction of loss of vision, age of onset and socialization. Sequelae are posited to exist merely due to the limiting effects of blindness on experience. This is believed to affect all blind persons equally regardless of cause of blindness provided that independent secondary disabilities do not exist. This study investigated the possibility that different causes of blindness are related to specific neuropsychological deficits which cannot be explained by the mere presence of blindness. It was found that neuropsychological differences existed among specific sub-populations of blind persons. These results suggested that the cause of blindness may be a marker for specific Central Nervous System involvement.

It has been hypothesized that a disproportionate percentage of the blind population are learning disabled. In the past, norms and technology were not available to assess in a cost effective manner the blind client's neuropsychological functioning. Norms for the Wide Range Achievement Test - Revised (WRAT-R2) are now available for a blind population without any neuropsychological dysfunctioning. This study utilized the adapted WRAT-R2 and the Comprehensive Vocational Evaluation System (CVES), a neuropsychological test battery adapted for the blind, to investigate the possibility that learning disabilities are present in the adult blind population. Suspected learning disabled, blind subjects were compared with normal blind subjects. There were significant neuropsychological differences between the two groups.

Psychological trauma may affect higher-order executive functions, which include selective attention, inhibition, and task-switching processes. Difficulty in these executive processes can in turn influence individuals' daily functioning and may also negatively affect the psychological treatment of post-trauma symptoms. Women may be most at risk for developing problems with executive functioning following trauma, consistent with their overall greater risk of developing post-trauma symptoms. Yet, little is understood about the influence of psychological variables, premorbid functioning, and specific trauma factors in determining post-trauma cognitive functioning in women. Additionally, individual variability in susceptibility to psychological distress and neuropsychological deficits following trauma remains an open area of study. The present study investigated the relationship between psychological and trauma factors with neuropsychological outcomes in women with trauma histories as well as individual variability in risk for poor neuropsychological outcomes. In total, 60 participants' data (age M = 29.73, SD = 10.91) were included in analyses. The final sample consisted of 33 community members recruited from the UNT Psychology Clinic and the UNT student body and 27 veterans recruited from the Veterans Affairs North Texas Healthcare System (VANTHCS). Regression and path analysis identified premorbid intellectual functioning as a predictor of better neuropsychological outcomes and anxiety and depression symptoms as risk factors for worse neuropsychological functioning. Person-centered cluster analyses focused on individual differences in outcomes identified three groups differing in psychological distress and neuropsychological functioning. Additional analyses identified differences in trauma exposure, psychological functioning, and neuropsychological performance between subgroups of civilians and veterans and those with and without a history of PTSD.

Given that neurocognitive impairment is a frequent complication of HIV-1 infection in Spanish-speaking adults, the limited number of studies assessing HIV-associated neurocognitive disorders (HAND) in this population raises serious clinical concern. In addition to being appropriately translated, instruments need to be modified, normed, and validated accordingly. The purpose of the current study was to examine the diagnostic utility of the HIV Dementia Scale (HDS) and International HIV Dementia Scale (IHDS) to screen for HAND in Spanish-speaking adults living with HIV infection. Participants were classified as either HAND (N = 47) or No-HAND (N = 53) after completing a comprehensive neuropsychological evaluation. Receiver operating characteristic analyses found the HDS (AUC =.706) was more sensitive to detecting HAND than the IHDS (AUC =.600). Optimal cutoff scores were 9.5 for the HDS (PPV = 65.2%, NPV = 71.4%) and 9.0 for the IHDS (PPV = 59.4%, NPV = 59.1%). Canonical Correlation Analysis found the HDS converged with attention and executive functioning. Findings suggest that while the IHDS may not be an appropriate screening instrument with this population, the HDS retains sufficient statistical validity and clinical utility to screen for HAND in Spanish-speaking adults as a time-efficient and cost-effective measure in clinical settings with limited resources.

Neuropsychological assessment in linguistically heterogeneous populations is fraught with numerous challenges, such as lacking or inappropriate normative data or the unavailability of appropriate tests. Accommodating multilingual individuals exacerbates the issue by adding the question of which language(s) to use when assessing multilingual individuals. Different testrelated concepts may be accessible to them via different languages, as their lexicon is spread out over two or more languages. Hence, any monolingual instrument is likely to disadvantage them. The present set of three studies circumvents this question and presents evidence for an inherently multilingual English/Afrikaans/isiXhosa screening tool for intelligence, the Multilingual Vocabulary Test (MVT). I describe the instrument’s development from the pilot study to a psychometric analysis of the final, digitally administered version. For an abbreviated 13-item version, Study 3 (N = 494) shows an internal consistency of  = .59 and Study 2 (N = 101) produced significant criterion-related validity values of r = .46 and r = .52 with the KBIT-2 and Shipley-2 VIQ scores respectively. Linear regression analyses show that, while all criterion measures are biased toward E1-speakers, the MVT is largely immune to test-takers’ linguistic background. Thus, the MVT paves the way toward more fairness in cognitive assessments, in general, and provides a promising first step toward addressing one of South African neuropsychologists’ greatest needs—that of a quick and easy-to-administer, yet linguistically fair screening tool for cognitive impairment.

Researchers have found executive functioning (EF) to be important for reading and math performance but have paid less attention to their role in writing. Van Dijk and Kintsch (1983) identified three levels of writing: microstructure, macrostructure, and superstructure. The existing work on EF and writing has several limitations: researchers have primarily focused on microstructural writing in children, studied a limited range of EF, not included measures of self-reported EF to compare to laboratory-/lab-based-based measures of EF and not examined the differential contributions of multiple EF to the different levels of writing. Hence, the purpose of this study was to better understand the differential involvement of various laboratory and self-reported EF across various levels of micro- and macrostructural writing measures in emerging adult writing. Results indicated that inhibition was a significant predictor of microstructural writing, such that working carefully increases the accuracy of spelling and mechanics skills. Working memory was related to microstructural grammar and mechanics sentence formulation, potentially through processing the sentences, mentally manipulating the sentence structure, and recording the response while maintaining the sentence information in mind. Verbal fluency was related to microstructural spelling and grammar and mechanics accuracy, as well as macrostructural essay organization, possibly through the ability to efficiently retrieve knowledge critical to perform these tasks. The main analyses did not yield significant results for macrostructural theme development, likely due to methodological issues, but an exploratory analysis demonstrated that organization and problem solving skills predicted theme development, potentially through the ability to think critically about, and organize, the arguments made. Finally, lab-based EF measures were better predictors of the writing measures than the self-reported EF measure, suggesting that these two methods captured different aspects of EF, and that the lab-based predictors were more appropriate to use with lab-based outcome variables, likely due to their narrower and less environmentally-influenced constructs. The results of this study help inform the factors that contribute to writing skills, and this knowledge can be used to improve the detection of writing difficulties and to target writing interventions.

This thesis presents research aimed at elucidating neurophysiological and neuropsychological correlates of two psychiatric disorders, schizophrenia and PTSD. Although psychiatric disorders are not traditionally known for featuring cognitive deficits, research over the past three decades has revealed that deficits in many aspects of cognitive functioning are present across a wide range of disorders. Here, we aim to further our understanding of these deficits and provide evidence of the clinical utility of neurophysiological correlates of cognitive dysfunction. The cause and course of cognitive deficits in PTSD is poorly understood, and an investigation of one potential explanatory mechanism, dissociative symptomatology, is presented in the first part of this thesis. Our results suggest that dissociative symptomatology plays a role in cognitive dysfunction in PTSD, as among the clinical variables tested (including PTSD symptomatology, dissociative symptoms, depressive symptoms, and anxiety symptoms) dissociative symptoms were the only significantly correlated variables to cognitive dysfunction in a sample of combat-trauma exposed veterans with and without PTSD. In the second part of this thesis, we investigate the potential clinical utility of a neurophysiological biomarker for semantic processing deficits, the N400, in schizophrenia. Our results indicate that N400 measures are stable over a one week period and therefore may be clinically useful as a neurophysiological biomarker for semantic processing abnormalities in schizophrenia. Overall, these two studies contribute to our knowledge of cognitive deficits in psychiatric disorders and demonstrate their complexity as well as their potential to provide clinically useful tools to aid in the identification of novel treatments targeted at ameliorating cognitive deficits in schizophrenia and PTSD. / Thesis / Master of Science (MSc)

Compromised validity of test data due to exaggeration or fabrication of cognitive deficits inhibits the capacity to establish appropriate conclusions and recommendations in neuropsychological examinations. Detection of feigned neurocognitive impairment presents a formidable challenge, particularly for evaluations involving possibilities of significant secondary gain. Among specific populations examined in this domain, litigating mild traumatic brain injury (mTBI) samples are among the most researched. One subpopulation with potential to contribute significantly to this body of literature is that of retired athletes undergoing fixed-battery neuropsychological evaluations within an assessment program. Given the considerable prevalence of concussions sustained by athletes in this sport and the substantial monetary incentives within this program, a unique opportunity exists to establish rates of feigning within this population to be compared to similar forensic mTBI samples. Further, a fixed battery with multiple validity tests (VT) offers a chance to evaluate the classification accuracy of an aggregated VT failure paradigm, as uncertainty abounds regarding the optimal approach to the recommended use of multiple VTs for effort assessment. The current study seeks to examine rates of feigned neurocognitive impairment in this population, demonstrate prediction accuracy equivalence between models based on aggregated VT failures and logistic regression, and compare classification performance of various individual VTs.