Objective: To investigate the associations between executive function and information processing speed and gait, turning and falls in fragile X premutation carriers (PMC) with and without fragile X-associated tremor/ataxia syndrome (FXTAS).

Background: Executive function and information processing speed deficits occur in some fragile X PMC with and without FXTAS. Gait and functional mobility are negatively impacted by cognitive deficits in many neurological disorders resulting in increased morbidity and falls; however, these relationships have not been studied in FXTAS.

Methods: Global cognition and the cognitive domains of information processing speed, attention, response inhibition, working memory and verbal fluency were tested with a neuropsychological test battery in 18 PMC with FXTAS (9 men, 9 women; age 69.06 + 6.59 years), 15 PMC without FXTAS (4 men, 11 women; 62.73 + 7.12 years), and 27 controls (14 men, 13 women; age 63.5 + 7.7 years). A reliable, well validated inertial sensor based instrumented Timed Up and Go (i-TUG; APDMTM) was employed to test gait, turns and functional mobility. Participants self-reported the number of falls occurring in the past year. Multivariable linear regression analyses adjusted for age and sex was used to determine the association between cognitive variables and i-TUG parameters.

Results: Lower information processing speed was significantly associated with shorter stride length, reflecting slower gait speed, in PMC with FXTAS (b + SE = 0.70 + 0.191; p = 0.0006) but not PMC without FXTAS or controls. Lower response inhibition was also significantly associated with slower turn-to-sit times in PMC with FXTAS (b + SE = -0.465 + 0.212; p = 0.034) but not in those without FXTAS or controls. Lower information processing speed (p = 0.012), working memory (p = 0.004), verbal fluency (p = 0.003), global cognition (p = 0.048) and stride length (p = 0.04) were significantly correlated with a greater number of self-reported falls in the past year in FXTAS participants.

Conclusions: This is the first study demonstrating that worse executive function and slower information processing speed is associated with reduced gait speed and functional mobility, as well as with a higher retrospective fall history in participants with FXTAS. This information may be important in the design of cognitive and motor interventions for this neurodegenerative disorder.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-function-impacts-gait-functional-mobility-and-falls-in-fragile-x-associated-tremor-ataxia-syndrome/