Multipl Sklerozda Fonksiyonel Bağlantısallık Değişimleri ve Bilişsel Bozukluk

Öz

Genç yetişkinlerde engelliliğin en yaygın nörolojik nedenlerinden biri olan multipl skleroz (MS), denge ile ilgili semptomlar, yorgunluk ve görsel semptomlara ek olarak bilişsel eksikliklerle karakterizedir. Hastalar başta bilgi işleme hızı olmak üzere hafıza, öğrenme, yürütücü işlevler ve dikkat gibi farklı bilişsel alanlarda zorluklar yaşamaktadır. Mevcut geleneksel görüntüleme yöntemleri bilişsel bozuklukları aydınlatmak için yetersizdir. Manyetik rezonans görüntüleme (MRG) ile elde edilen beyindeki yapısal değişiklikler, tüm bilişsel eksiklikleri açıklamada yüksek bir korelasyona sahip değildir. Bu nedenle, beyin işlevlerini daha bütüncül bir bakış açısıyla ele alan bağlantısallık temelli yaklaşımlar bilişsel işlevlerin açıklanmasında ön plana çıkmaktadır. Dinlenim durumu fonksiyonel manyetik rezonans görüntüleme aracılığıyla fonksiyonel bağlantısallık temelli yaklaşımlarla bilişsel eksikliklerin büyük ölçekli fonksiyonel ağlarla ilişkisi araştırılmaya başlanmıştır. Fonksiyonel bağlantısallık çalışmaları bilişsel işlevleri açıklamada başarılı olsa da bulgular homojen değildir. Bu derlemenin amacı, klinik-görüntüleme uyumsuzluğunu anlamada işlevsel bağlantı temelli yaklaşımların katkısını analiz etmek ve MS hastalarında sıklıkla görülen bilişsel işlev bozukluklarının geleneksel yapısal görüntüleme teknikleriyle yalnızca kısmen açıklanabildiğini göstermektir. Bu bakımdan, çalışma son on beş yılda yayınlanan literatürün gözden geçirilmesine dayalı bir naratif derlemedir. Bilişsel işlevlerin açıklanmasında fonksiyonel bağlantısallığın önemine değinilirken, bu çalışmanın bulgularının bilişsel rezerv gibi bireysel faktörlerden etkilenebileceği de vurgulanmaktadır.

Anahtar Kelimeler

• Multipl skleroz
• bilişsel bozukluk
• fonksiyonel bağlantısallık
• bilişsel rezerv

Functional Connectivity Alterations and Cognitive Impairment in Multiple Sclerosis

Abstract

Multiple sclerosis (MS), one of the most common neurological causes of disability in young adults, is characterized by cognitive deficits in addition to balance-related symptoms, fatigue, and visual symptoms. Patients have difficulties in different cognitive domains such as memory, learning, executive functions, and attention, especially information processing speed. Current conventional imaging methods are insufficient to elucidate cognitive impairments. Structural alterations in the brain obtained by magnetic resonance imaging (MRI) do not have a high correlation in explaining all cognitive deficits. Therefore, connectivity-based approaches that address brain functions in a more holistic perspective come to the forefront in explaining cognitive functions. The relationship of cognitive deficits with large-scale functional networks through functional connectivity-based approaches via resting-state functional magnetic resonance imaging has begun to be investigated. Although functional connectivity (FC) studies are successful in explaining cognitive functions, the findings are not homogenous. The aim of this review is to analyse the contribution of functional connectivity-based approaches in understanding the clinical-imaging mismatch and to show that cognitive dysfunctions frequently seen in MS patients can only be partially explained by conventional structural imaging techniques. In this respect, this study is a narrative review based on a review of the literature published in the last fifteen years. While the importance of FC in explaining cognitive functions is mentioned, it is also emphasized that the findings of this study may be affected by individual factors such as cognitive reserve.

Keywords

• Multiple sclerosis
• cognitive impairment
• functional connectivity
• cognitive reserve

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