Conservative behavior in multiple sclerosis, a reflection of prefrontal cortex dysfunction

• Published in: Multiple sclerosis Vol. 14; p. S256
• Main Authors: Ekhtiari, H, Jannati, A, Sikaroodi, H, Zarei, S, Behzadi, A, Ganjgahi, H, Jangouk, P, Sahraian, MA, Mokri, A, Lotfi, J
• Format: Journal Article
• Language: English
• Published: 01-09-2008
• ISSN: 1352-4585

Background: Different studies have shown the relationship between cognitive impairment in multiple sclerosis patients and prefrontal cortex function based on neuro-imaging and neuropsychological assessment. Thus few investigations have been done to complete the image of prefrontal cortex dysfunction in these patients. Objective: To illustrate a complete image of cognitive impairment in MS patients considering the assessment of Dorso-Lateral and Ventro-Medial prefrontal cortex function. Methods: 43 relapsing-remitting MS patients (27 females)(Expanded Disability Status Scale (EDSS) mean=3.46 plus or minus 1.79) and 40 healthy age-gender-education-matched controls included the study. We used neuropsychological assessment tasks specific for Dorso-Lateral prefrontal cortex: WCST (Wisconsin Card Sorting Task) and TPT (Time Perception Task) and for Ventro-Medial prefrontal cortex: Iowa Gambling Test (IGT), Delayed Discounting Task (DDT), Balloon Analogue Risk Task (BART). Results: MS patients performed poor results in WCST which assesses cognitive flexibility and executive functions (preservative-error: M plus or minus SD=15.49 plus or minus 9.94 vs. 8.778.6 plus or minus 2, P-value=0.007). They also showed over-estimation and over-reproduction of time intervals doing TPT which evaluates working memory and chronological speed of cognition. IGT results showed that MS patients have more delay in making more risky choices (required time for choosing from risky cards mean=4292 plus or minus 2552 millisecond vs. 2814 plus or minus 1465, p-value=0.015). DDT, which assesses the process of reward values over delays, showed that MS patients have lower discounting amounts over delays. MS patients also had lower levels of risky behavior tendency according to BART results (saved balloons=20.75 plus or minus 4.17 vs. 18.5S plus or minus 4.39, p-value= 0.034). Conclusions: The result of this study strengthened the hypothesis of a conservative behavior in decision making both logically and emotionally in MS patients. Some possible explanations for such result could be "Multiple Disconnection Syndrome" particularly seen in frontal lobe lesions in MS patients, lower processing speed and the social effect of disease stigma on patients' behavior. Thus more investigation must be done to clarify the nature of such behavior in MS patients.