Browsing by Author "Young, Susanne Yvette"

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    Association between motor timing and treatment outcomes in patients with alcohol and/or cocaine addiction in a rehabilitation programme
    (Stellenbosch : Stellenbosch University, 2017-12) Young, Susanne Yvette; Seedat, Soraya; Hoof, J. J. M. van; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Psychiatry.
    ENGLISH SUMMARY : Introduction: Motor timing deficits have been found in DA system related disorders and, more recently, also in individuals with Substance Use Disorders (SUD). Motor timing is fundamental to our ability to coordinate movements and is defined as a component of temporal brain processing. Modifications to neural systems associated to these domains contribute to motor timing deficits and pathology; however, the underlying mechanisms that lead to these deficits are still poorly understood. A bimodal distribution and evolutionary neurobiological model may provide a useful pathogenic framework for the classification of major psychiatric disorders, including SUD. In this model, major psychiatric disorders (including SUD) may be understood as progressive manifestations of imbalances between dual neural circuitries in the brain. These include an automatic mechanism (referred to as the Drive Mechanism, DM) and a more cognitive-predictive mechanism (referred to as the Guidance Mechanism, GM). To our knowledge, motor timing has not been investigated in populations with SUDs with regard to treatment outcome and relapse. The main question of this study was: Do imbalances between the DM and GM, as expressed in motor timing deficits, differentiate individuals with SUD from normal controls and predict poorer treatment response and relapse? Methods: This study investigated motor timing and its relation to treatment response and relapse in individuals with Alcohol and/or Cocaine Use Disorder (AUD and/or CUD) compared to a Healthy Control (HC) group. Owing to the novelty of the motor task battery, the tested sensitivity values of motor timing parameters were assessed on test retest variability. The possible confounding effects of attention and working memory on motor timing paradigms, and the high impulsivity levels found in individuals with SUD were addressed by comparing the motor task paradigms with a battery of neuropsychological tests. Results: Motor timing was found to be predictive of treatment outcomes at 8 weeks. Synchronisation abilities were predictive, but decision making and motor planning abilities were not predictive. Owing to the small size of the follow up sample, a prediction of motor timing with regards to relapse at 12 months was not possible. Motor timing improved with prolonged abstinence. Specifically, synchronisation abilities improved. Decision making and motor planning abilities did not improve over time. Motor timing performance found in our AUD and/or CUD population only partially supported van Hoof’s proposed model. However, no deficits were found in internal clock rates or the capacity to plan and coordinate actions. Deficits were found in decision making (DM) and synchronisation abilities (GM) in patients versus HC. Decision making abilities were poorer in CUD compared to AUD. No correlation was found between motor timing and impulsivity. Working memory and attention were found to bepredictive of motor timing. Robust test-retest reliability of the test battery was found. Discussion: These findings provide partial support for the deficits in neurocircuitry, as proposed by van Hoof. Additionally, the findings show that motor timing holds prognostic for recovers with prolonged abstinence. These findings may have significant implications for future studies and warrant further investigation in SUD populations going forward.
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    Prognostic value of motor timing in treatment outcome in patients with alcohol- and/or cocaine use disorder in a rehabilitation program
    (Frontiers Media, 2018) Young, Susanne Yvette; Kidd, Martin; Van Hoof, Jacques J. M.; Seedat, Soraya
    Introduction: Individuals with Substance Use Disorder (SUD) often have cognitive deficits in multiple domains, including motor timing deficits, with recovery times of up to 1 year. Cognitive deficits influence treatment outcomes and abstinence. To our knowledge, timing deficits have not been investigated with regard to treatment outcome and relapse. Methods: This prospective study tested the prognostic value of motor timing in SUD with regard to treatment outcome. The study sample consisted of 74 abstinent in-patients at a private treatment programme for drug/alcohol dependence at the Momentum Mental Healthcare clinic in Somerset West, South Africa, diagnosed with alcohol and/or cocaine dependence. Participants were tested at three points: (i) Within 72 hours of the start of the treatment programme (ii) after completion of the treatment programme at 8 weeks (measure of treatment response) through filling out self-report questionnaires and experimental motor task testing, and (iii) a third visit followed through a telephonic interview at 12-months (measure of relapse). Results: Motor timing alone predicted 27 percent of the variance in alcohol self-efficacy score change, and 25 percent variance in cocaine self-efficacy change scores at treatment completion. Specifically, spatial errors, synchronization errors and inter- response interval errors of a spatial tapping task at baseline predicted self-efficacy in alcohol self-efficacy. Cocaine self-efficacy was predicted by spatial errors and contact times of a spatial tapping task at very high tempi (300 ms) only. The high rate of dropout at 12 months post-treatment did not allow for further analysis of the prognostic value of motor timing on relapse. Conclusions: The results of this investigation show us that motor timing holds prognostic value with regard to treatment outcomes. Motor timing predictors for relapse require further investigation going forward.