Presence and significant determinants of cognitive impairment in a large sample of patients with multiple sclerosis.

Objectives: To investigate the presence and the nature of cognitive impairment in a large sample of patients with Multiple Sclerosis (MS), and to identify clinical and demographic determinants of cognitive impairment in MS.

Methods: 303 patients with MS and 279 healthy controls were administered the Brief Repeatable Battery of Neuropsychological tests (BRB-N); measures of pre-morbid verbal competence and neuropsychiatric measures were also administered.

Results: Patients and healthy controls were matched for age, gender, education and pre-morbid verbal Intelligence Quotient. Patients presenting with cognitive impairment were 108/303 (35.6%). In the overall group of participants, the significant predictors of the most sensitive BRB-N scores were: presence of MS, age, education, and Vocabulary. The significant predictors when considering MS patients only were: course of MS, age, education, vocabulary, and depression. Using logistic regression analyses, significant determinants of the presence of cognitive impairment in relapsing-remitting MS patients were: duration of illness (OR = 1.053, 95% CI = 1.010-1.097, p = 0.015), Expanded Disability Status Scale score (OR = 1.247, 95% CI = 1.024-1.517, p = 0.028), and vocabulary (OR = 0.960, 95% CI = 0.936-0.984, p = 0.001), while in the smaller group of progressive MS patients these predictors did not play a significant role in determining the cognitive outcome.

Conclusions: Our results corroborate the evidence about the presence and the nature of cognitive impairment in a large sample of patients with MS. Furthermore, our findings identify significant clinical and demographic determinants of cognitive impairment in a large sample of MS patients for the first time. Implications for further research and clinical practice were discussed.