MRT-basierte Bestimmung des Risikos für die Lese-Rechtschreib-Störung im Vorschulalter

Zusammenfassung

Die Lese-Rechtschreib-Störung (LRS) gilt als die häufigste aller Lernentwicklungsstörungen überhaupt. Etwa 5% der deutschen Bevölkerung leidet unter den psychischen und sozialen Folgen schwerwiegender umschriebener Probleme beim Erlernen des Lesens und Schreibens. LRS entsteht aus dem komplexen Zusammenspiel von genetischen Faktoren und Umweltfaktoren (z. B. sprachliche Lernvoraussetzungen im Elternhaus). In zahlreichen vorangegangenen Magnetresonanztomografie (MRT) Studien wurde zudem gezeigt, dass der linke gyrus fusiformis (FFG, sogenanntes „visuelles Wortformareal“) des Gehirns eine entscheidende Rolle für den Schriftspracherwerb spielt. Die hier vorgestellte Arbeit legt nahe, dass die kortikale Plastizität des FFG bei LRS durch das Tragen einer Risikovariante des Gens NRSN1 eingeschränkt sein könnte, dessen Proteine u. a. das Wachstum von Dendriten steuern. NRSN1 erwies sich als signifikant mit dem Volumen des linken FFG assoziiert, welches mithilfe von voxelbasierter Morphometrie (VBM) auf Grundlage von MRT Aufnahmen gemessen wurde. Anhand der durch genetische Assoziation bestimmten volumetrischen Profile von Kindern, die sich etwa 10 Monate vor Schuleintritt befanden, konnte die spätere Ausprägung einer LRS mit einer Klassifikationsgenauigkeit von 75% vorhergesagt werden. Diese Daten lassen hoffen LRS in Zukunft so früh feststellen zu können, dass betroffene Kinder in der Lage sind ihre Defizite vor der Einschulung mithilfe von Frühförderungsmaßnahmen zu kompensieren.

Abstract

Developmental dyslexia (DD) is considered to be the most common among all learning disorders. About 5% of the population in Germany and 7% in the USA suffer from the psychological and social consequences of severe deficits in learning how to read and spell. DD arises from the complex interplay of genetic and environmental factors (e. g. home literacy environment). Moreover, numerous previous magnetic resonance imaging (MRI) studies have shown that the left fusiform gyrus (FFG, “visual word form area”) of the brain plays a crucial role in literacy acquisition. The present work suggests that the cortical plasticity of the FFG might be limited in individuals with DD because they carry a risk variant of the gene NRSN1 that codes proteins regulating neurite growth. NRSN1 turned out to be significantly associated with the volume of the left FFG that was estimated by conducting a voxel-based morphometry (VBM) analysis of MR images. Using volumetric profiles determined by genetic association in children, DD could be predicted 10 months before school entry with a classification accuracy of 75%. These data might make it possible in the future to diagnose DD so early that affected children might be able to compensate their deficits before school enrollment by making use of early intervention programs.

Schlüsselwörter

Lese-Rechtschreib-Störung (LRS) - Magnetresonanztomografie (MRT) - Gyrus fusiformis - NRSN1

Key words

developmental dyslexia - magnetic resonance imaging (MRI) - fusiform gyrus - NRSN1

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