Browsing by Author "Njomboro, Progress"

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    An investigation of functional correlates and predictors of apathy in a Memory Clinic sample
    (2025) Sebolai, Katlego; Njomboro, Progress
    Apathy is a common neuropsychiatric symptom in neurological and psychiatric illnesses and is associated with adverse outcomes, significant caregiver burden, cognitive and functional impairment, and poor quality of life. Marin's (1991) definition of apathy as an amotivational disorder has gained widespread acceptance, despite recent contentions about this conceptualization. Marin's Apathy Evaluation Scale reflects his view on apathy as constituted by motivation related deficits. In this study I used Marin's Apathy Evaluation scale to assess apathy in a sample of patients (n = 200) presenting at the University of Cape Town/Groote Schuur Hospital's memory clinic with a query of subjective cognitive impairment. I then investigated the cognitive and functional correlates of apathy in this sample. Due to recent debates on the dimensions of apathy symptoms and the disorder's diagnostic features, I initially performed an exploratory factor analysis of the Apathy Evaluation Scale to determine its factors. I then examined associations between the resulting factors or dimensions of the AES and disease-related characteristics such as depressive symptoms (measured on the Cornell Scale for Depression), year-on cognitive impairment (measured on the Deterioration Cognitive Observee), and functional impairment (measured on the Bristol Activities Daily Living Scale). I found that depression and functional impairment were significant predictors of apathy. Behavioral, cognitive, and emotional subdomains of apathy predicted decline in basic and instrumental activities of daily living differently. Lastly, year-on cognitive impairment was not a predictor of apathy. Results from the exploratory factor analysis supported a three-factor model of the Apathy Evaluation Scale but it yielded a sub-domain of social apathy instead of emotional apathy. Previous factor analysis studies reported emotional apathy, together with behavioral and cognitive apathy as sub-domains of apathy. Results from this study have important implications for understanding factors that influence patients' capacities for performing activities of daily living and meeting their functional needs.
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    Effect of high-beta versus gamma binaural beat exposure on immediate and delayed recall
    (2025) Grobler, Etienne; Njomboro, Progress
    In this study, I investigate the effect of binaural beats on immediate and delayed recall. Binaural beat exposure within the Gamma frequency band has been linked to alterations in neural connectivity and increased attention during working memory tasks, while stimulation in the Beta frequency band has been associated with increased memory performance. However, there is a lack of direct comparison between the effects of exposure to High-Beta versus Gamma binaural beats on immediate and delayed recall performance. This study employs a Bayesian approach and a between-groups 3 (exposure condition) x 2 (task presentation format) x 2 (timing of exposure) experimental design to examine the effects of both High-Beta and Gamma binaural beats on immediate and delayed recall performance in 75 participants. The results show that exposure to binaural beats resulted in mixed effects, with exposure to Gamma binaural beats only having a significant impact on immediate recall when combined with visual presentation, and exposure to High-Beta binaural beats during encoding and recall potentially interfering with recalling semantic information such as story themes after a delay. Comparatively, High-Beta binaural beat exposure did not significantly improve memory performance, while exposure to Gamma binaural beats only showed a significant improvement in memory performance when participants recalled information from the auditory memory tasks. These results have important implications for research and clinical work focused on cognitive improvement.
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    Exploring social cognition in patients with apathy following acquired brain damage
    (2014-01-23) Njomboro, Progress; Humphreys, Glyn W; Deb, Shoumitro
    Abstract Background Research on cognition in apathy has largely focused on executive functions. To the best of our knowledge, no studies have investigated the relationship between apathy symptoms and processes involved in social cognition. Apathy symptoms include attenuated emotional behaviour, low social engagement and social withdrawal, all of which may be linked to underlying socio-cognitive deficits. Methods We compared patients with brain damage who also had apathy symptoms against similar patients with brain damage but without apathy symptoms. Both patient groups were also compared against normal controls on key socio-cognitive measures involving moral reasoning, social awareness related to making judgements between normative and non-normative behaviour, Theory of Mind processing, and the perception of facial expressions of emotion. We also controlled for the likely effects of executive deficits and depressive symptoms on these comparisons. Results Our results indicated that patients with apathy were distinctively impaired in making moral reasoning decisions and in judging the social appropriateness of behaviour. Deficits in Theory of Mind and perception of facial expressions of emotion did not distinguish patients with apathy from those without apathy. Conclusion Our findings point to a possible socio-cognitive profile for apathy symptoms and provide initial insights into how socio-cognitive deficits in patients with apathy may affect social functioning.
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    Negative Mood Reduces Self-Referential Memory Effects in an Online Object Ownership Simulation
    (2023) Mciver, Nicole; Njomboro, Progress
    The Self-Reference Effect (SRE) is a cognitive bias in which self-relevant stimuli are prioritised for processing. This bias allocates more attentional and encoding resources to selfrelevant objects making their memory traces more robust and easily retrievable. Research has repeatedly shown that self-owned and self-proximal objects benefit from this bias. However, little is known about the factors that impact the SRE. Emerging research suggests that emotion may attenuate the SRE. For instance, studies show that the salience of a self-related stimulus reduces when the stimulus is associated with negative self-referential information. However, there is limited research on how the SRE may be modulated by transient mood states. The major aim of the present study is to determine whether the SRE may be modulated by transient mood states. We investigated whether an induced negative mood state alters memory for self-related objects using an online emotion induction and shopping task. This task was selected because although SRE effects are robust in laboratory conditions, most studies rely on tasks with low external validity. All participants completed an online mood induction protocol (either negative or neutral mood induction). Thereafter, participants completed an online self-referencing object ownership task involving encoding (and subsequent recall) of self-owned, familiar other-owned, or unfamiliar other-owned everyday household shopping items. The group induced into a negative mood showed reduced memory recognition accuracy compared to the neutral mood group, with reduced memory for selfowned items. Further analyses revealed that negative mood interacted with both depression scores and object ownership to influence self-referential processing. Our results add to current SRE evidence and offer insights into how this bias can be influenced by both transient mood states and affective symptoms. Keywords: Self-reference, Object Ownership, Mood, Negative Emotion, Online.
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    Neurocognitive screening following acquired brain injury: an adaptation of the Birmingham Cognitive Screen for Zimbabwe (Zim-BCoS)
    (2020) Machando, Debra; Njomboro, Progress
    Neuropsychology as a discipline has not taken root in low- and middle-income countries. Most neurocognitive tests used in these countries were developed and normed in high-income, mostly western countries. The psychometric robustness of these tests is often weak when they are used on low to middle-income clinical populations. The objectives of this study were to select, adapt and generate normative data for a suitable neurocognitive screen for use in Zimbabwe. To achieve these objectives, we divided the study into 4 phases. In Phase 1 of the study, we did a systematic review that identified 83 neurocognitive assessment instruments commonly used in low- and middle-income countries on patients who have suffered a stroke. From these instruments, we selected, adapted and normed the Birmingham Cognitive Screen (BCoS; Humphreys al., 2012) through phases 2 to 4 of this study. The screen offers a robust and sufficiently broad but shallow assessment tool for cognitive deficits across key cognitive domains commonly impaired following a stroke. In particular, in Phase 2 of the study, we evaluated the cross-cultural sensitivity of BCoS on healthy participants (N=105). We then performed surveys using the Delphi method on a panel of experts to culturally adapt BCoS for use in Zimbabwe (Zim-BCoS). We evaluated the inter-rater and test-retest reliability of the translated and validated Zim-BCoS and also compared its agreement with the original BCoS version to determine its robustness. In Phase 3, we evaluated the effects of demographic variables on performance on the cognitive domains assessed by Zim-BCoS. To do this, we performed multiple linear regression analyses to calculate regression-based norms using scores from a sample of healthy participants (N=412). From these analyses, participants' age, level of education and sex had significant effects, mainly on subtests in the language cognitive domain (Picture Naming, Sentence/Word Reading/Writing and Instruction Comprehension). In Phase 4 of the study, we performed neurocognitive assessments using Zim-BCoS (and other tests) to assess and determine the frequency of specific neurocognitive deficits in patients who had suffered a stroke and were attending two major hospitals in Harare, Zimbabwe's capital city (N=103). We also compared the performance of these patients to a matched control sample (N=103). To determine the psychometric stability of Zim-BCoS we determined its validity and reliability by comparing scores on its subtests to parallel neurocognitive tests that assess similar cognitive domains. We also assessed the predictive value of Zim-BCoS on patients' neuropsychiatric and functional outcomes. We evaluated the convergence and predictive validity as well as the inclusivity of Zim-BCoS to assess patients with aphasia. We used the Zim-BCoS test scores to establish prevalence rates of cognitive deficits and other post-stroke sequelae in the sample of patients with stroke. We also assessed the predictive value of ZimBCoS subtests on patients' neuropsychiatric and functional outcomes. All comparisons of ZimBCoS against standard cognitive tests and post-stroke sequelae measures had statistically significant convergence, predictive validity and inclusivity. In this study, we demonstrated the utility of Zim-BCoS for assessing cognitive impairment in patients who have suffered a stroke, particularly in resource poor contexts typical of low-income countries. We concluded that ZimBCoS is a robust neuropsychological screen suitable for research and clinical use in Zimbabwe. The screen has the potential to offer a cost effective and easy to use neurocognitive screen for patients with acquired neurological changes in low-income countries in Southern Africa.
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    NREM sleep spindles and slow wave sleep in younger and elderly women: an investigation of their influence on declarative memory consolidation
    (2017) McCreesh, Siobhan; Njomboro, Progress
    Previous research shows that slow wave sleep (SWS) and sleep spindles play an essential role in declarative memory consolidation. However, this role is not well understood in the ageing women. With advancing age, SWS and sleep spindles undergo significant decreases in duration and density, while there is a simultaneous decline in declarative memory. The primary aim of this research was to investigate the relationship between sleep architecture, sleep spindle activity, and declarative memory retention in two groups of women: 14 younger (M = 20.5±1.28 years) and 14 older females (M = 63.14±2.03 years). Participants underwent polysomnography on a baseline and experimental night and encoded a list of word-pairs of graded difficulty on the experimental night. Word-pair type included integrative, concrete and low concrete measures. Memory retention was then assessed pre- and post-sleep. Our results confirm the characteristic age-related decrease in SWS and sleep spindle activity in older adults. In the older group, SWS positively correlated with concrete word-pair retention, while spindle density and the number of spindles positively correlated with overall retention. In addition, the percentage change in spindle density, slow and fast density, and fast intensity from baseline to experimental night positively correlated with low concrete word-pairs. Finally, in the younger group, the number of spindles positively correlated with low concrete word-pairs and the percentage change in fast and slow spindle intensity correlated with concrete word-pair retention. Although younger women recalled more word-pairs than older women in both conditions, memory retention was largely preserved in both groups after sleep.
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    The effects of apathy and depression on cognitive and functional outcomes in Alzheimer's disease
    (2021) Lekhutlile, Tlholego; Njomboro, Progress
    Alzheimer's disease (AD) is the most common cause of dementia initially characterised by short-term memory deficits followed by a progressive cross domain cognitive and functional decline over time and loss of independence in carrying out activities of daily living (ADL). Apathy and depression are also the two most frequent neuropsychiatric sequalae associated with AD and have an impact on patients' ability to execute ADLs. Little is still known if apathy subdomains differently predict ADL performance in these patients. In this study, we aimed to quantitatively investigate if global apathy and depression predict ADL performance. We also wanted to establish if the apathy evaluation scale (AES) items resolve into three factors as proposed by Marin and if those factors differently predict performance of ADLs. We recruited a sample of 115 patients diagnosed with probable or possible AD. Basing on current literature, we hypothesised that apathy and depression predict ADL performance. We also hypothesised that AES items will load into three factors relating to cognitive, behavioural and affective apathy subdomains and that these subdomains will differentially predict ADL performance in our patient sample. Our results indicated that high apathy and depression symptoms were associated with problems to carryout ADLs. They also indicated that AES items resolved into a three factor solution in analogy with Marin's conceptualisation but they did not cluster in the manner that he proposed. Finally, when these factors are regressed simultaneously, (derived from factor analysis) only behavioural apathy significantly predicted ADLs.