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Background: Freezing of gait (FOG), is associated with impairment of different cognitive functions. Previous studies hypothesized that FOG may be due to a loss of automaticity. Research question: To explore whether FOG is associated with impairment in cognitive functions, focusing on retrograde procedural memory, the memory responsible for the automatic, implicit stored procedures that have been acquired in earlier life stages. Methods: In this cross-sectional, case--control study, 288 people with typical Parkinson's disease (PD) from the Luxembourg Parkinson's Study were assigned to Freezers (FOG+) and non-Freezers (FOG-) based on the MDS-UPDRS 2.13 (self- reported FOG episodes) and 3.11 (FOG evaluated by clinicians during gait assessment). Both groups were matched on age, sex and disease duration. Global cognition (MoCA), retrograde procedural memory and visuo-constructive abilities (CUPRO), psychomotor speed and mental flexibility (TMT) were assessed. Furthermore, we repeated our analyses by additionally controlling for depression (BDI-I). Results: Besides lower global cognition (MoCA; p = 0.007) and mental flexibility (TMT-B and Delta-TMT; p < 0.001), FOG+ showed a lower performance in retrograde procedural memory (CUPRO-IS1; p < 0.001) compared to FOG-. After controlling additionally for depression, our main outcome variable CUPRO-IS1 remained significantly lower in FOG+ (p = 0.010). Conclusion: Our findings demonstrated that besides lower global cognition and mental flexibility scores, FOG+ showed lower performance in retrograde procedural memory compared to matched FOG-control patients, even when accounting for factors such as age, sex, disease duration or depression. Significance: In the context of limited treatment options, especially for non-invasive therapeutic approaches, these insights on procedural memory and FOG may lead to new hypotheses on FOG etiology and consequently the development of new treatment options. [ABSTRACT FROM AUTHOR]

Background: The analysis of the procedural memory is particularly relevant in neurodegenerative disorders like Parkinson's disease, due to the central role of the basal ganglia in procedural memory. It has been shown that anterograde procedural memory, the ability to learn a new skill, is impaired in Parkinson's disease. However, retrograde procedural memory, the long-term retention and execution of skills learned in earlier life stages, has not yet been systematically investigated in Parkinson's disease. Objective: This study aims to investigate retrograde procedural memory in people with Parkinson's disease. We hypothesized that retrograde procedural memory is impaired in people with Parkinson's disease compared to an age- and gender-matched control group. Methods: First, we developed the CUPRO evaluation system, an extended evaluation system based on the Cube Copying Test, to distinguish the cube copying procedure, representing functioning of retrograde procedural memory, and the final result, representing the visuo-constructive abilities. Development of the evaluation system included tests of discriminant validity. Results: Comparing people with typical Parkinson's disease (n = 201) with age- and gender-matched control subjects (n = 201), we identified cube copying performance to be significantly impaired in people with Parkinson's disease (p = 0.008). No significant correlation was observed between retrograde procedural memory and disease duration. Conclusion: We demonstrated lower cube copying performance in people with Parkinson's disease compared to control subjects, which suggests an impaired functioning of retrograde procedural memory in Parkinson's disease. [ABSTRACT FROM AUTHOR]