Objective Multiple Sclerosis (MS) is the most prevalent neurological progression that often affects young adults. Cognitive impairment is a frequent symptom of the disease. One cognitive domain is an executive function. Executive function is important in individuals’ cognitive skills, adaptive behaviors,  and life satisfaction. Thus, accurately recognizing and investigating the factors affecting it greatly helps with improving MS. The current study investigated the relationship between individual and clinical characteristics and executive dysfunction in patients with MS. 
Materials & Methods This was a cross-sectional, descriptive and analytical study conducted on MS patients referring to Rofeydeh Rehabilitation Hospital in 2017. In total, 71 patients were selected through unpredictable sampling method. MS patients and their families provided written consent forms for participation in the study, and the subjects' data were kept confidential. Moreover, the patients were allowed to discontinue study participation as desired. The inclusion criteria were a diagnosis of MS disease based on McDonald's criteria  by a neurologist, the lack of memory impairments, including Alzheimer's disease, non-congenital syndromes like Down syndrome, no thyroid dysfunction, the lack of consuming drugs that affect memory and cognitive function like benzodiazepines, and the lack of severe vision and motor impairments. Exclusion criteria included the lack of patient’s cooperation with completing the questionnaire and performing the test, dissatisfaction with continuing the collaboration, and the emergence of an acute problem in the patient that enables him/her to continue cooperation. In this research, instruments such as Pittsburgh Sleep Quality Index (PSQI), Fatigue Assessment Scale (FAS), Beck's Depression Inventory (BDI), Expanded Disability Status Scale (EDSS), and Delis–Kaplan Executive Function System (D-KEFS) test were used. The collected data were analyzed in SPSS. For data analysis, general linear regression was used.
Results The obtained results suggested that age, disease duration, and fatigue had a significant reverse relationship with executive functions (descriptive and categorical) (P>0.05). Executive function (classification) had a significant relationship with the first symptom of the onset of disease (P>0.05).  
Conclusion We investigated the relationship between individual and clinical characteristics and the executive function in MS patients. A significant relationship was observed between the first sign of the disease onset and the level of performance. People who initially demonstrated vision problems had a weaker performance than others. This can be considered as an important finding in the early stages of diagnosis and the development of therapeutic programs to postpone cognitive complications.