Demographic features, behavioral measures, and clinical factors as predictors of cognitive function in patients with multiple sclerosis.

BACKGROUND

One of the most concerning features that involves 40-70% of patients with multiple sclerosis (MS) is cognitive impairment. Moreover, it affects various aspects of patients' life. In this regard, this study was conducted to find independent predictors of cognitive function.

METHOD

We performed a cross-sectional analysis on 92 patients chosen from MS clinic of Sina hospital, Iran. After completing a general questionnaire of demographic and various clinical features, the included participants (patients with RRMS) underwent neuropsychological assessment using Minimal Assessment of Cognitive function in Multiple Sclerosis (MACFIMS), Expanded disability Status Scale (EDSS), Beck Depression Inventory II (BDI-II), and National American Adult Reading Test (NAART). An un-weighted average of MACFIMS subscales z-scores was reported as cognitive index. In order to find the association between CI and different factors, each variable was entered in a simple regression model first. Then, a univariate multiple regression model was invoked to evaluate the predictors of cognitive index in patients.

RESULTS

Simple regression for cognitive index of 92 patients (86% female) with a mean age of 33.4±7.6 years old suffering of RRMS for 6.8±4.8 years revealed patients with history of former smoking (p=0.001), sole visual symptoms as the presentation sign of the study (β=-0.341, p=0.001), lower EDSS score (β=-0.299, p=0.005), higher NAART score (β=0.416, p≤0.0001), and college education (p=0.001), had better cognitive function in our study population. Such factors including age, educational status, BDI-II score, EDSS score, and disease duration were fixed and the other significant factors entered once separately and then simultaneously in the univariate multiple linear regression model. It was revealed that former smoking (β=-0.372, p≤0.0001), NAART (β=0.304, p=0.002), and EDSS (β= -0.185, P=0.045) are associated significantly with the cognitive function of patients with multiple sclerosis.

CONCLUSION

This study demonstrated NAART, as a proxy of premorbid intelligence, history of former smoking, and EDSS score may have effects on cognitive function in MS. Future studies need to be invoked for the evaluation of the causality relation of these factors.