The 2002 Supreme Court decision (Atkins vs. Virginia, 536 U. S. 304), prohibiting the execution of mentally retarded persons, may potentially increase malingering of mental retardation (MR). There is limited research addressing the detection of feigned MR. The present study compared results from tests of intelligence, adaptive functioning, legal/courtroom knowledge, and psychiatric and neurocognitive feigning to determine how effectively these instruments discriminate between MR participants and community volunteers asked to either approach the test honestly (CVH group) or feign, or malinger, MR (CVM group). CVMs suppressed their IQ scores sufficiently to appear MR. CVMs overestimated deficits on individuals with genuine MR on tests of adaptive functioning and courtroom knowledge. Psychiatric feigning instruments did not discriminate between MR and CVM groups. Neurocognitive feigning instruments discriminated between groups, however specificity and Positive Predictive Power were unacceptably low. Revising cutting scores to hold specificity at .95 improved PPP significantly, suggesting the potential utility of these instruments to detect feigned mental retardation. Results from this study suggest that applying published decision rules to MR populations on tests commonly used in forensic neuropsychological evaluations will likely result in a high rate of false positive errors. Given the high stakes associated with classification errors in capital cases involving MR defendants, alternative cutting scores appropriate for this population should be determined.

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.

Despite widespread availability of effective antiretroviral therapy (ART), people living with HIV (PWH) remain at risk of developing comorbidities including HIV-associated neurocognitive impairment (H-NCI). These individuals may then be at an increased risk for treatment non-adherence, which leads to poor quality of life and early mortality. Despite this risk, there is a paucity in trained professionals in low- and middle-income countries with appropriate knowledge and skills to identify H-NCI and make appropriate referrals for additional confirmatory testing or intervention, depending on the severity and context of the screening. General medical doctors, nurses and adherence counsellors provide most HIV related healthcare services at a primary healthcare level in South Africa. However, awareness of the clinical presentation of H-NCI, and their current screening practices among these cadres, is unclear. To address these knowledge gaps this thesis set out to explore the following aims (1) examine existing H-NCI knowledge and practices among healthcare workers delivering HIV services in South Africa, (2) develop an appropriate H-NCI training programme for primary healthcare workers, and (3) lastly, pilot the H-NCI training to determine whether H-NCI screening would be feasible at a primary healthcare level in South Africa. Methods To achieve these objectives, the study was divided into two phases. In phase one, a scoping review identified and summarised published studies addressing brain and/or behaviour training approaches, including H-NCI, targeting frontline HIV healthcare workers in Africa. An online survey was developed and administered to examine existing H-NCI knowledge and current practices among healthcare workers providing HIV services in South Africa. Focus group discussions and in-depth interviews were then conducted to explore knowledge gaps, previous H-NCI training and healthcare workers' perspectives of screening at a primary healthcare level. In phase two, an H-NCI training curriculum was developed and a work-integrated H-NCI training programme targeting primary healthcare workers was piloted. The pilot training assessed knowledge of H-NCI signs and symptoms, healthcare workers' attitude toward and comfort with H-NCI screening tools and healthcare workers ability to accurately administer an H-NCI screening tool. The assessments were repeated two months post-training to evaluate retention of knowledge and skills. Results The scoping review of the existing literature suggested that there were few brain and/ or behaviour training programs targeting healthcare workers providing HIV services in Africa. Of the ten studies identified in the scoping review, one study included H-NCI in the training curriculum. The online survey found that H-NCI knowledge was limited and screening practices virtually non-existent among healthcare workers providing HIV care in South Africa. Qualitative data gathered during the focus group discussions and the in-depth interviews provided greater insight on the existing knowledge and practices gaps as well as highlighting that healthcare workers had not received training on H-NCI. The results from the qualitative investigations showed that primary healthcare workers were in favour of receiving such training. Overall, knowledge of H-NCI improved among primary healthcare workers following the work-integrated H-NCI training programme. The training demonstrated that primary healthcare workers providing clinical services, such as medical doctors or professional nurses were able to administer an H-NCI screening tool. Although knowledge of the clinical presentation of H-NCI improved among adherence counsellors, these healthcare workers experienced challenges in administering the H-NCI screening tool. Conclusion As a body of work, the findings from this thesis suggest that healthcare professionals providing HIV services in South Africa have limited knowledge to identify H-NCI, and screening practices are uncommon. Although training revealed differences between cadres in administering screening tools, healthcare workers providing clinical care, including general medical doctors and professional nurses, may be able to provide H-NCI screening at routine annual visits. Although adherence counsellors are ideally situated in the clinic flow to provide targeted screening by flagging clinical presentation of H-NCI among PWH accessing care, this cadre will require additional training, mentorship and support to successfully administer H-NCI screening tools. However, the feasibility of H-NCI screening at a primary healthcare, timing and nature of any screening remains to be explored. This body of work is a step toward increasing the availability of skilled healthcare workers with appropriate knowledge and skills to screen and identify H-NCI in low- and middle-income countries. The work presented in this thesis provides a foundation for further development of the H-NCI training module and future investigations examining targeted screening strategies at a primary healthcare level, feasibility and access to existing interventions post-screening

Preterm birth (defined as birth before 37 weeks) is a leading cause of neurocognitive impairment in childhood, including difficulties in social cognition and executive function. Microstructural divergence from typical brain development in the preterm brain can be quantified using diffusion magnetic resonance imaging (dMRI) tractography during the neonatal period. The relationship between dMRI tractography metrics and later cognitive difficulties remains inconclusive. A general measure of white matter microstructure (gWM) offers a neural basis for cognitive processes in adults, however it remains unclear when gWM is first detectable in the developmental trajectory. Eye-tracking is a technique which assesses eye-gaze behaviour in response to visual stimuli, which permits inference about underlying cognitive processes, such as social cognition and executive function in infancy. The primary aims of this thesis were to test the hypotheses: dMRI tractography reveals significant differences in tract-average fractional anisotropy (FA) and mean diffusivity (MD) between preterm and term infants, and variance in tract-average FA and MD is shared across major tracts. Secondly, infants born preterm have altered social cognition and executive function compared to term born peers, assessed by eye-tracking and finally, neonatal MRI gWM is associated with cognitive function in infancy. Preterm (birth weight ≤ 1500g) and term infants (born ≥ 37 weeks’ post-menstrual age [PMA]) were recruited and underwent a MRI scan at term equivalent age (between 38 - 42 weeks’ PMA) and an eye-tracking assessment six to nine months later. Preterm infants were assessed at two years using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III). dMRI tractography metrics were generated using probabilistic neighbourhood tractography (PNT) in eight pre-defined tracts-of-interest. Principal component analyses (PCA) were used to determine the correlations between the eight tracts-of-interest for four tract-averaged water diffusion parameters. dMRI metrics were compared to the eye-tracking performance and two year outcome data. Quantitative microstructural changes were identifiable within the preterm brain when compared to infants born at term. PCA revealed a single variable that accounts for nearly 50% of shared variance between tracts-of-interest, and all tracts showed positive loadings. Eye-tracking revealed group-wise differences in infant social cognition, attributable to preterm birth, but executive functions inferred from eye-tracking did not differ between groups. dMRI tractography metrics within the neonatal period did not relate to later outcome measures. This thesis shows that variance in dMRI parameters is substantially shared across white matter tracts of the developing brain and suggests that anatomical foundations of later intelligence are present by term equivalent age. Social cognition is altered by preterm birth, however social cognitive ability in infancy is independent of gWM.

Magister Public Health - MPH / Despite the effectiveness and scale-up of antiretroviral treatment (ART), HIV-Associated neurocognitive disorders (HAND) still persist. Currently no gold standard tool exists to detect all forms of HAND, including major and minor cognitive impairments. In light of this, a newly developed screening tool was conceptualised, namely the Quick Paediatric Neurocognitive Screening tool (QPNST). The QPNST has been developed to detect HAND in perinatally HIV-infected children aged 5-10 years.

Memory deficits and executive dysfunction are highly prevalent among HIV-infected adults. These conditions can affect their quality of life, antiretroviral adherence, and HIV risk behaviors. Several factors have been suggested including the role of genetics in relation to HIV disease progression. This dissertation aimed to determine whether genetic differences in HIV-infected individuals were correlated with impaired memory, cognitive flexibility and executive function and whether cognitive decline moderated alcohol use and sexual transmission risk behaviors among HIV-infected alcohol abusers participating in an NIH-funded clinical trial comparing the efficacy of the adapted Holistic Health Recovery Program (HHRP-A) intervention to a Health Promotion Control (HPC) condition in reducing risk behaviors. A total of 267 individuals were genotyped for polymorphisms in the dopamine and serotonin gene systems. Results yielded significant associations for TPH2, GALM, DRD2 and DRD4 genetic variants with impaired executive function, cognitive flexibility and memory. SNPs TPH2 rs4570625 and DRD2 rs6277 showed a risk association with executive function (odds ratio = 2.5, p = .02; 3.6, p = .001). GALM rs6741892 was associated with impaired memory (odds ratio = 1.9, p = .006). At the six-month follow-up, HHRP-A participants were less likely to report trading sex for food, drugs and money (20.0%) and unprotected insertive or receptive oral (11.6%) or vaginal and/or anal sex (3.2%) than HPC participants (49.4%, p

This chapter will address the issue of risk for HIV-associated neurocognitive disorder (HAND), focusing on HIV-associated dementia (HAD), among persons living with HIV in relationship to the risk for other dementias. Advances in effective antiretroviral therapy (ART) have led to an increase in the prevalence of older persons surviving with HIV – in addition to older persons who become infected by HIV later in life. Hence, HIV is no longer a disease of younger persons, and additional attention has been brought to bear against the plight of older persons living with HIV – not only as it pertains to treatment but also to prevention. The additional risk caused by aging among older persons living with HIV is complex to asses, and HIV infection is a research area that requires a robust approach to multiple other factors causing neurocognitive impairment with older age. The long-term and potentially neurotoxic exposure to ART and the deleterious consequences of chronic infection with HIV and its associated neuro-inflammation have been described for health. This aids in the understanding of dementia risk factors in this patient population, but the comorbidities (HIV- and non-HIV-associated) occurring among older persons living with HIV must also be addressed to properly assess the overall impact on dementia risk in this group. This need also warrants our examination of the risk factors for other dementias (and comorbid dementias) in persons living with HIV versus the general population through the assessment and quantification of modifiable and non-modifiable risk factors identified as major contributors toward dementia.