RESUMO
BACKGROUND: In today's globalised world, the heterogeneity of diseases such as multiple sclerosis has been studied since it has been suggested that ethnic differences, in conjunction with geographical and environmental factors, influence its incidence and prevalence. AIM: Based on this, an attempt has been made to identify the genetic factors that may confer risk or protection, not only for developing multiple sclerosis but also for determining the course of its evolution. RESULTS: In Latin America we have some data about this, which have been replicated in different populations in the entire region, with very different results compared with other regions, which could explain not only the different frequencies in some populations, such as Caucasians, but also the course of the disease and the response to actual treatments. However, in addition to these findings, other associated epigenetic mechanisms have also been found in our populations, such as levels of vitamin D, parasitic diseases, and indigenous populations. Therefore, the study of epigenetics plays a crucial role in understanding the physiopathology of multiple sclerosis. It must be studied in each population, especially in Latin America, due to its broad heterogeneity. CONCLUSION: It is very important to understand not only the genetic and external factors with these very specific effects in multiple sclerosis patients, but also the way they interact and are able to explain the frequency and some specific phenotypes of the disease in our populations besides the posibility to be a very specific treatment target.
RESUMO
Although previous studies have shown that patients with multiple sclerosis (MS) may exhibit impaired decision making (DM), the specific neuro-cognitive processes that underlie this deficiency remain unknown. Inefficient DM may occur due to poor option assessment or a deficit in the evaluation of choice outcomes. This study uses, for the first time, the event-related potential (ERP) technique to analyze these DM subprocesses in patients with MS. Sixteen MS patients and nineteen control subjects performed a DM task based on the Iowa Gambling Task while a digital EEG was recorded. The P3b was analyzed as an index of option assessment, and both the feedback-related negativity (FRN) and P3b were considered markers for choice outcome evaluation. We found that MS patients made a larger number of unfavorable choices during the DM task (P = 0.02), with no differences between groups for reaction times. There were no significant differences in P3b for option assessment between the groups. In the control group, the type of feedback (gain, loss, or nothing) modified the FRN (F = 3.72, P = 0.033) and the P3b (F = 3.15, P = 0.059). This effect was not observed in the MS group. Also, FRN latencies were shorter in the MS group compared to controls (P = 0.047). Finally, lesions in temporal regions revealed by MRI were associated with DM both in behavioral and electrophysiological terms. We conclude that the DM impairment of patients with MS may be due to a deficit in their evaluation of choice outcomes or a general alteration in emotional reactivity.
