Impulsivity traits in patients with multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease with a lifetime prevalence of 4.41/100000 in Bogota, Colombia. It is known that it can be related with neuropsychiatric disorders, increasing by a factor of three the prevalence of depression in MS patients compared to general population. However, less attention has been given to the association between MS and impulsive behavior.

This cross-sectional study compared the levels of impulsivity controlling for the presence of MS. 60 patients with MS and 60 sex- and age-matched subjects without MS were included. In order to assess depression and impulsivity, participants completed the 13-item short form of the Beck Depression Inventory (BDI-SF), the self-report Barratt Impulsiveness Scale version 11 (BIS-11) and the Immediate and Delayed Memory Tasks (IMT-DMT) as an objective measure of impulsive behavior.

Total scores, motor and cognitive subscales on the BIS-11 were significantly higher in the MS group. However, median BDI-SF score was also higher in MS patients than in subjects without MS (p < 0.001). To rule out depression as a confounding factor, stratification was performed using the BDI-SF score. In the subgroup of individuals with a BDI-SF< 8, the BIS-11 cognitive subscale scores were significantly higher in patients with MS than in subjects without MS (p = 0.041). In the IMT/DMT test, subjects with MS had a fewer number of correct detections than did subjects without MS, after controlling for BDI-SF score (p = 0.0001/p = 0.003). The ratio of commission errors to correct detections in the IMT was significantly higher in the MS group (p = 0.011).

Patients with MS showed higher levels of cognitive impulsivity than subjects without MS. Objective measures for impulsiveness further support this finding. Impulsiveness scales scores might be biased by depression, which should be considered when assessing impulsivity in MS.