Association between motor timing and treatment outcomes in patients with alcohol and/or cocaine addiction in a rehabilitation programme

[摘要] ENGLISH SUMMARY : Introduction: Motor timing deficits have been found in DA system related disorders and, morerecently, 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 motortiming 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 betweenthe 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 studyinvestigated 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 oftreatment 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 thatmotor 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.

[发布机构] Stellenbosch University