en Neurology Neurology Review Article Review Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background:</span></i></b> One of the complications of multiple sclerosis (MS) is cognitive impairment (CI). The prevalence of CI is reported variously in previous studies. The goal of this systematic review and meta-analysis to estimate pooled prevalence of CI in patients with MS and also the prevalence of CI based on the type of applied test. </span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods</span></i></b><i><span style="color:blue">:</span></i> Two independent researchers systematically searched PubMed, Scopus, EMBASE, Web of Science, and google scholar as well as gray literature (conference abstracts, references of the references) which were published before up January 2022.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results</span></i></b><i><span style="color:blue">:</span></i> We found 4089 articles by literature search, after deleting duplicates 3174 remained.&nbsp; Ninety articles remained for meta-analysis. The pooled prevalence of CI using all types of tests was 41% (95% CI: 38-44%) (I2=91.7%, p<0.001). The pooled prevalence of CI using BRB test was 39% (95%CI: 36-42%) (I2=89%, p<0.001). The pooled prevalence of CI using BICAMS was 44% (95%CI: 37-51%, I2=95.4%, p<0.001). The pooled prevalence of CI using MACFIMS was 44% (95% CI: 36-53%)(I2=89.3%, p<0.001).</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusions:</span></i></b> The pooled prevalence of cognitive impairment in patients with MS is estimated as 41%, so CI it should be considered by clinicians.<b><i><span style="color:#0033cc"></span></i></b></span></span></span><br> &nbsp; Multiple sclerosis, cognitive impairment, systematic review 392 413 http://caspjim.com/browse.php?a_code=A-10-2449-9&slc_lang=en&sid=1 Mozhde Askari mozhas@gmail.com 100319475328460048902 100319475328460048902 Yes Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran Omid Mirmosayyeb omidmir@gmail.com 100319475328460048903 100319475328460048903 No Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Fatemeh Fattahi fattahf@gmail.com 100319475328460048904 100319475328460048904 No Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Hamed Ghoshouni hghosh@yahoo.com 100319475328460048905 100319475328460048905 No Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Elham Moases Ghaffary mo0assess@gmail.com 100319475328460048906 100319475328460048906 No Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Vahid Shaygannejad V.SHAYGAN@GMAIL.COM 100319475328460048907 100319475328460048907 No Isfahan Neurosciences Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. Mahsa Ghajarzadeh m.ghajarzadeh@gmail.com 100319475328460048908 100319475328460048908 No Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran