Browsing by Subject "Neuropsychiatry"

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    An Evaluation of the Psychometric Properties of the Montreal Cognitive Assessment Tool when Administered in a Memory Clinic At Groote Schuur Hospital, Cape Town, South Africa
    (2022) Thungana, Yanga; Joska, John; Thomas, Kevin
    Worldwide, the population is aging, and the prevalence of neurocognitive disorders is expected to rise exponentially. Therefore, early detection of dementia is favorable for the patient and may even be of greater significance if disease-modifying treatments are discovered. The Montreal Cognitive Assessment (MoCA) is a reliable and valid cognitive screening tool but is sensitive to several sociodemographic factors, including language, culture, and quality of education. This underscores the need for cognitive screening scales validated in the culturally diverse South African setting. Aim. The purpose of this study was to investigate the utility of the MoCA as a brief cognitive screening tool in a specialized clinical South African sample. Methods. A retrospective medical folder review of 162 patients seen at Groote Schuur Hospital Memory Clinic for the first time between January 2014 and August 2021. Results. The median age of participants was 67 years (IQR 58-73). Most were females (63%, n =102), and had dementia (58%, n = 94); more than half (51%, n = 78) had at least 12 years of formal education. Older age and lower levels of education were associated with lower MoCA scores (p < 0.001). Conclusion. In a specialized South African clinical setting, the MoCA demonstrated good psychometric properties as a screening tool for evaluating different levels of cognitive impairment. However, to our knowledge, this is the first South African study to assess the factor structure of the MoCA in a clinical setting. More comprehensive and larger studies should evaluate the validity of our findings.
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    The relationship between neurocognitive disorders, prospective memory impairment and white matter damage in clade C HIV-positive subjects
    (2010) Hoare, Jacqueline; Joska, John Anton; Stein, Dan J
    AIMS: To examine the relationship between prospective memory, cognitive function and Diffusion tensor imaging (DTI)/ White matter integrity of human immunodeficiency virus (HIV) positive individuals in the Western Cape. We hypothesize that: 1. Individuals infected with HIV will exhibit significantly poorer microstructural integrity of the white matter than HIV negative individuals, as determined by in vivo diffusion tensor imaging. We expect that values of fractional anisotropy (FA) - a measure of directional water diffusion- in the frontal white matter will be significantly lower among HIV patients compared to controls 2. Lower FA measured in the frontal white matter will correlate significantly with impaired performance on tests of prospective memory
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    Screening for HIV-associated neurocognitive disorders in perinatally infected youth: Validation of the CAT-rapid version 2 screening tool
    (2023) Mgweba-Bewana, Lihle; Phillips, Nicole; Joska John
    Objectives: There is a lack of locally validated cognitive screening tools for youth living with HIV. To test the validity of the Cognitive Assessment Tool Rapid v2 tool in screening for all forms of neurocognitive impairment in a sample of youth living with HIV in Cape Town, South Africa. Design: We analysed the existing dataset of the neuro sub-study which was nested within the larger CTAAC study (Cape Town Adolescent Antiretroviral Cohort). The main study examined the long-term effects and outcomes of ARV treatment in 500 HIV-infected children and adolescents. HIV negative, matched controls were also included in the study. Component scores of the CAT-rapid version 1, the psychomotor speed and Luria hand sequence of the youth International HIV Dementia Scale were combined to form the CAT-rapid v2. SPSS version 28.0 was used for statistical analysis. Methods: For the CAT-rapid v2 validation, the sample of YLWH was dichotomised according to the impaired and not impaired groups, based on their neuropsychological test scores. Impairment in this sample, relates to all levels of neurocognitive impairment. The combined tool has a total score of 20. Cross tabulations were then conducted in SPSS. The results were then entered into the medcalc.org online calculator to determine the sensitivity and specificity, positive and negative predictive values, positive and negative likelihood ratios, disease prevalence and the overall accuracy of the screening tool. A Receiver Operator Characteristic (ROC) curve was constructed to investigate the sensitivity, specificity, positive and negative Running head: YLWH HAND SCREENING: CAT-RAPIDV2 VALIDATION 5 predictive values of the CAT-rapid v2 in detecting all forms of neurocognitive disorder in YLWH. Results: Statistical analyses did not detect significant between-group differences with regard to age, sex, language, or years of education. Significantly more participants in the YLWH however, had repeated at least one grade at school. Analyses detected significant betweengroup differences for CAT-rapid v2 total score, as well as for score in every cognitive domain except for attention. In each case, the healthy control group performed better than the YLWH group. A CAT-rapid v2 cut-off score of ≤17 yielded the best balance between sensitivity and specificity. At this cut off, the sensitivity of the CAT-rapid v2 screening tool was 69.31%, specificity was 50.35%, PPV of 49.65% and NPV of 69.90%. Finally, we conducted a ROC analysis for the CAT-rapid v2 total score, plotted against the gold standard battery neuropsychological tests in the YLWH group only. The ROC analysis showed that at the cut off score of ≤ 17, the CAT-rapid v2 had a significantly better chance of screening for any cognitive impairment in YLWH from those with no impairment. The area under the curve was acceptable at 0.651. Conclusion: Our study showed that the CAT-rapid v2 - at a cut off score of 17 or less – had reasonable sensitivity, however, it did not meet the generally acceptable statistical threshold in use for clinical settings. This screening tool may be useful for consideration in research settings and requires further development and validation for use in clinical settings.
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    White matter correlates of neuropsychological function in young adult methamphetamine users
    (2016) Freeman, Carla Patricia; Joska, John A; Stein, Dan J
    Background: Methamphetamine (MA) abuse is a global health concern due to widespread use and harmful effects, which includes neurotoxicity. This study aimed to describe neurocognitive deficits associated with MA dependence in young adults and to explore whether these deficits correlate with white matter (WM) microstructural abnormalities using diffusion tensor imaging (DTI). Methods: Twenty-one MA dependent individuals recently enrolled in an outpatient rehabilitation program and nineteen healthy controls participated in the study. Each participant completed a neuropsychological evaluation and underwent diffusion tensor imaging within one week of testing. Average whole-brain fractional anisotropy (FA) and mean diffusion (MD) measures derived from DTI data were compared between groups. Group differences in performance within specific neurocognitive domains and in a composite global neurocognitive score (GNS) were tested using non-parametric univariate statistics and within a linear regression framework, adjusting for age and gender. Correlation analyses were conducted to test associations between the neuropsychological data and selected frontal white matter (WM) tracts, including the genu and body of the corpus callosum (CC); right and left cingulum bundle (CB); right and left uncinate fasciculus (UF); right and left anterior corona radiata (CR) and the right and left superior longitudinal fasciculus (SLF). Results: No significant between-group differences were detected for performance in any of the neuropsychological domains assessed. No relationship between FA or MD and the GNS was demonstrated in the tracts of interest. After adjusting for age and gender, significant group differences in FA and MD were detected across several regions of interest (ROI), however, these did not survive corrections for multiple comparisons. Conclusion: Cognitive performance and white matter integrity did not differ between young MA dependent subjects and healthy controls. Whatever differences that were found in white matter did not survive correction for multiple comparisons. These findings may reflect one or more of several possibilities: that brain function and structure is relatively preserved in younger individuals; or that differences were too small to be detected in this sample. Further studies should explore the effects of aging, poly-substance abuse and HIV coinfection on neurocognitive functioning and structural brain integrity in methamphetamine users.