A more severe disease course has been reported in African-American (AA) in comparison with Caucasian (CA) MS patients. Sociodemographic differences and limited access to treatment have been often used to explain the different disability profile in the two groups. To date, an objective assessment of disability in AA and potential differences with CA patients is still lacking.
Here, we characterized sociodemographic, motor and neuropsychological features of AA and CA patients with multiple sclerosis.
Fifty-seven AA patients (43F, mean age 37.84 ± 10.54 yrs, mean disease duration 5.64 ± 5.74 yrs, median EDSS 2, EDSS range 0-6.5), 37 AA healthy controls (HC) (25F, mean age 35.97 ± 12.44 yrs), 50 CA patients (36F, mean age 39.02 ± 10.83 yrs, mean disease duration 5.90 ± 5.94 yrs, median EDSS 1.5, EDSS range 0-6) and 28 CA HC (17F, mean age 35.57 ± 11.77 yrs) were prospectively enrolled. In all subjects, an extensive neuropsychological and sensory-motor evaluation was performed. The sensory-motor evaluation included 9-hole peg test (9-HPT), grooved pegboard test (GPT), finger tapping test (FTT), 25-foot walk test (25-FWT), 2-minutes walk test (2-MWT), evaluation of segmental strength, grip strength, vibration sensitivity (VS) and standing balance (theta score from NIH toolbox). The neuropsychological evaluation included Symbol Digit Modalities Test (SDMT), California Verbal Learning Test-II (CVLT), Brief Visuospatial Memory Test–Revised (BVMT), Stroop Color and Word Test (SCVT), Controlled Oral Word Association Test (COWAT) and a multitasking attention-memory test (MAMT). Each patient’s group was compared with a race-matched HC group via ANCOVA analysis, accounting for age, gender, years of education and socioeconomic status expressed as yearly income (9 categories with 1 = less than $5,000 and 9 = $100,000+). In the comparison of cognitive performance, years of education, premorbid intelligence estimated with the Wechsler Test of Adult Reading (WTAR) and depressive symptoms evaluated via Beck Inventory were also included as covariates of no interest.
AA and CA patients did not differ in age, gender, disease duration, while they did differ in total years of education (p<0.001) and yearly income (p=0.001). When compared to their matched HC group, AA and CA patients showed similar deficits in information processing speed, ambulation, manual dexterity, sensitivity and balance (p ranging from 0.029 to <0.001). While CA showed an additional impairment of verbal memory (p=0.009), AA patients showed additional involvement of verbal fluency (p=0.005), multitasking capability (p=0.024), motor speed and coordination (p=0.048) and grip strenght (p=0.041).
Even when accounting for sociodemographic features, AA patients show more severe and widespread disability than CA patients with MS.