Dear Editor,,
We have read the study which was conducted by Topçular et al. with patients with relapsing remitting multiple sclerosis (RRMS) with interest (1). They applied the Brief Repeatable Battery (BRB), Multiple Sclerosis Neuropsychological Questonnaire (MSNQ), Beck Depression Inventory (BDI) and Functional Assessment of MS (FAMS) quality of life scales to patients with RRMS. In this study, cognitive disorder was found in 41.17% (n=21) of the RRMS patients. The study exclusion criteria included non-RRMS cognitive dysfunction, addiction, psychosis, severe personality disorder, use of medication with cognitive side effects and attack or use of steroid in the last 30 days. When the methodology of this study was examined, it was found that vitamin B12 deficiency and hypothyroidism were not considered exclusion criteria.
Low serum vitamin B12 levels were found to be associated with cognitive disorders (2). Many studies related with multiple sclerosis (MS) and vitamin B12 deficiency have been conducted for long years and it has been found that serum vitamin B12 deficiency is common in patients with MS (3,4,5,6). In the study conducted by Koçer et al., vitamin B12 deficiency was found with a rate of 20% in MS patients and with a rate of 3.3% in the contol group (7). Hypothyroidism also causes to cognitive disorder (8).
The term “non-MS cognitive disorder” in the exclusion criteria of the study could not be understood clearly. Since vitamin B12 deficiency is observed commonly in MS patients and causes to cognitive disorder, we think that readers should keep in mind that cognitive disorder in the study of Topçu et al. might not be related only with MS, but also with vitamin B12 deficiency and hypothyroidism.
References
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