Influence of cognition on the correlation between objective and subjective upper limb measures in people with multiple sclerosis

Background: A comprehensive assessment of upper limb (UL) function is mandatory in people with multiple sclerosis (PwMS), and the use of multiple objective and subjective measures is advisable. Findings on the role of cognitive impairment on the assessment of UL function are scant and inconclusive. The present study investigated the influence of cognitive function on the distribution of objective and subjective UL measures and on their association. Methods: In the cross-sectional study, subjects with a diagnosis of MS, age ≥ 18 years, right-hand dominance, no presence of orthopedic UL impairment, or other neurological diseases were recruited. The assessment protocol included the Nine-Hole Peg Test (9-HPT), Box and Block Test (BBT), and hand grip strength (HGS), a validated PROM (MAM-36), and the Symbol Digit Modalities Test (SDMT). Results: Two hundred forty-six PwMS were recruited (158 females, mean age = 51.65 ± 13.45 years; mean EDSS = 5.10 ± 1.88) Subject with mild-to-moderate cognitive impairment (SDMT ≤ − 2 SD of normative values) scored lower on the 9-HPT and higher on the BBT and MAM-36 when compared with subject with no cognitive impairment. Cognitive impairment showed a small but significant effect on the association between 9-HPT scores and the MAM-36. Discussion: Findings suggest that cognitive impairment is associated with subjects’ performance on 9-HPT, BBT, and MAM-36 (but not HGS), resulting in scores indicating a poorer UL function. Interestingly, cognitive impairment slightly affected the congruence between subjective and objective UL measures, although only minor differences in the correlation pattern across groups reporting different cognitive performances emerged.