Objective: Analyze differences in cognitive profiles among freezing of gait (FOG) subtypes in Parkinson’s disease (PD).

Background: FOG in PD has been shown to be associated with cognitive impairment. However, there are little data on cognitive deficits within FOG subtypes.

Method: 39 individuals with PD (19 with FOG) completed the Freezing of Gait Score (FOGscore) in the OFF and ON PD medication state and were dichotomized on the following non-mutually exclusive subtypes: Levodopa-responsive FOG (n=11), dual task (DT)-triggered FOG (n=10), turn-triggered FOG (n=13), initiation-triggered FOG (n=6). Demographic information and PD symptoms (MDS-UPDRS III, Hoehn and Yahr stage (HY)) were also collected. DT cost (DTC) was determined using the Timed UP and Go (TUG). Cognitive testing included the following: global cognition (MMSE); processing speed (symbol digit modalities test (SDMT) and trails A); inhibition (DKEFS color word inhibition); and, multi-tasking (DKEFS category switching, DKEFS color word switching, and trails B).

Results: There were no group differences on demographic factors among FOG subtypes (ps>.122). Individuals with FOG, demonstrated poorer performance on DTC (ps<.008) and multi-tasking (ps<.010), had more advanced motor disease (ps<.005), and poorer global cognition (p=.028). The levodopa-responsive group had lower MDS-UPDRS III scores (p=.034) and FOGscore (ps<.027); they had higher inhibition (ps<.043) and more DTC (ps<.033). DT-triggered and turn-triggered FOG groups exhibited similar results to each other showing poorer performance on trails B (ps< .041). The initiation-triggered FOG group demonstrated poorer performance on the MMSE (p=.037), FOGscore (p<.004), trails A (ps<.047), and SDMT (ps<.043). They also had a higher stage of severity on the HY (p=.013).

Conclusion: Our results suggest that FOG is complex and that subtypes may be differentially associated with disease severity and cognitive impairment. Specifically, individuals with levodopa-responsive FOG had less severe motor impairment and FOG compared to non-levodopa-responsive freezers; however, they had more trouble under DT conditions and poorer ability to tune out irrelevant stimuli. While previous research has shown an association between processing speed and global cognitive deficits and FOG, our findings suggest that these may be more associated with initiation-triggered FOG compared to the other subtypes.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-cognitive-profiles-differ-among-freezing-of-gait-subtypes-in-parkinsons-disease/