Effects of Home-Based Working Memory Training on Visuo-Spatial Working Memory in Parkinson’s Disease: A Randomized Controlled Trial

Abstract

Background: Cognitive impairment is a very frequent and severe nonmotor symptom of Parkinson’s disease (PD). Early intervention in this at-risk group for cognitive decline may be crucial for long-term preservation of cognitive functions. Computerized working memory training (WMT) has been proven beneficial in non-PD patient populations, but such evidence is still needed for patients with PD. Objective: This study aimed to evaluate the effect of WMT on visuo-spatial working memory (WM) in cognitively unimpaired patients with PD. Methods: A single-blind randomized controlled trial encompassing 76 patients with PD but no cognitive impairment according to level II diagnostic criteria was conducted. Thirty-seven patients engaged in home-based adaptive WMT 5 times per week for a period of 5 weeks, whereas the remaining patients were in the waiting list arm of the study (control group [CG]). Working memory performance was evaluated using a computerized task before and after intervention and at 14-week follow-up, allowing to quantify the precision of WM on a continuous scale, ie, to test not only if an item was remembered but also how well the location of this item was retained. Results: Coincidently, the WMT group showed slightly worse WM performance compared with the CG at baseline, which was ameliorated after WMT. This training-induced effect remained stable until follow-up. Conclusion: Patients showing relatively low WM performance, despite not formally diagnosable as Parkinson’s disease with mild cognitive impairment (PD-MCI), seem to benefit from home-based WMT. Thus, WMT could potentially be implemented in future trials as a time- and cost-efficient route to counteract subtle cognitive changes in early disease stages. Trial registration: German Clinical Trial Register (drks.de, DRKS00009379)

Working memory training increases neural efficiency in Parkinson’s disease: a randomized controlled trial

“…When investigating the relationship between WMT-induced activation change in the AS and the observed significant post-testing–baseline testing-change in cognition as operationalized via a neuropsychological composite score of verbal WM ( Ophey et al , 2020 ) and a measure of visuospatial WM ( Giehl et al , 2020 ), a moderate positive correlation between both WM measures and blood oxygen level dependent signal change could be observed for the maintain versus rest contrast [ r (17) = 0.48, P = 0.039 for verbal WM, and r (17) = 0.50, P = 0.029 for visuospatial WM, respectively]. For the manipulate versus rest contrast, there was a moderate positive correlation for verbal WM only [ r (17) = 0.56, P = 0.013].…”

“…Clinical and neuropsychological examinations were repeated after WMT completion and again after 3 months with no training in-between. Details of the randomization, the WMT intervention, feasibility and immediate as well as long-term clinical and neuropsychological effects of the intervention can be found elsewhere ( Giehl et al , 2020 ; Ophey et al , 2020 ).…”

“…Since the fMRI paradigm used here was not designed to pick up small variations in behaviour, we used results from more sensitive measures of WM from the neuropsychological test battery to calculate correlations between behaviour and WMT-induced neural change. Thus, change scores for significantly improving neuropsychological measures including a verbal WM composite score ( Ophey et al , 2020 ) and an experimental measure of visuospatial WM function ( Giehl et al , 2020 ) were calculated. These were then correlated with the mean blood oxygen level dependent signal change associated with each task condition showing a significant WMT effect (maintain versus rest; manipulate versus rest; manipulate versus maintain), extracted from an 8-mm sphere around the overall WMT-induced peak corresponding to the left AS (−4/4/−4).…”

“…This is in accordance with the neural efficiency idea, stating that highly trained processes require less neural energy ( Haier et al , 1988 ; Neubauer and Fink, 2009 ). Although first results of WMT in Parkinson’s disease show promising behavioural WM improvements ( Giehl et al , 2020 ; Ophey et al , 2020 ), the neural effects of WMT underlying these effects are currently unknown.…”

“…We therefore conducted a single-blind randomized controlled trial (RCT) to investigate the effects of a 5-week home-based WMT in patients with Parkinson’s disease without cognitive impairment compared to a no-intervention Parkinson’s disease control group (CG) ( Ophey et al , 2020 ). While the clinical and neuropsychological outcomes are reported elsewhere ( Giehl et al , 2020 ; Ophey et al , 2020 ), this report focuses on the neural effects of the conducted WMT on different aspects of WM using a newly developed WM paradigm and functional magnetic resonance imaging (fMRI). Specifically, activation and functional connectivity (FC) changes with regards to pure maintenance as opposed to manipulation of WM content were examined.…”