Objective: To determine whether ε4 status relates to impaired somatosensory integration deficits in males more than females in people with Parkinson’s disease (PwPD).

Background: Previous work observed that male ε4+ exhibited an accelerated decline in gait performance compared to female ε4+. Additionally, PwPD exhibit worse somatosensory integration than controls, which related to worse gait performance, particularly with dual task gait. It remains unknown if ε4+ status in PwPD exacerbates somatosensory integration and gait performance, or if sex affects this relationship. We hypothesize that male ε4+ PwPD will have worse sensorimotor integration and this relates to worse gait performance than ε4 PwPD and female PwPD.

Method: 11 male ε4+ (UPDRS III: 27), 6 female ε4+ (UPDRS III: 16), 36 male ε4- (UPDRS III: 28), and 13 female ε4- (UPDRS III: 13) PwPD completed a two-minute walk with (dual task) and without (single task) a continuous attention task, allowing for dual task cost (DTC) comparison. Gait characteristics include DTC gait velocity, stride length, stride time, and foot strike angle. Short-latency afferent inhibition (SAI) characterized somatosensory integration. SAI is computed as the grand mean of the percent of the conditioned trials compared to the unconditioned trials. PwPD were tested “ON” medication.

Results: Female ε4+ PwPD had significantly worse DTC foot strike angle (female ε4+: -7.7±2.5; female ε4-: -0.3±7.2; p = 0.03) and DTC stride length (female ε4+: -2.9±1.7; female ε4-: -0.1±1.8; p = 0.01) than female ε4- PwPD. No other DTC differences were observed. Female ε4+ PwPD had significantly worse somatosensory integration (i.e. less inhibition of motor evoked response from somatosensory stimulation) compared to the other groups (female ε4+: 93±12; male ε4+:78±10; female ε4-: 75±17; male ε4-:76±19; p ≤ 0.02). SAI was not different between any other groups. SAI was significantly correlated to DTC foot strike angle (r = 0.82; p = 0.47) in female ε4+ PwPD.

Conclusion: These data suggest that sex may be a factor in the relationship between somatosensory integration and gait performance deficits in ε4+ PwPD. While contrary to findings of ε4+ status and sex in healthy controls, our results mimic the effects of ε4+ status and sex in people with Alzheimer’s. Female ε4+ PwPD may be at a higher risk for falls than male ε4+ or ε4- PwPD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/role-of-apoe-%ce%b54-status-and-sex-on-somatosensory-integration-and-dual-task-cost-in-parkinsons-disease/