From BDNF to Reading: The Mediation Role of Patterns of Neural Activation and Phonology

From BDNF to Reading: The Mediation Role of Patterns of Neural Activation and Phonology

First Author: Sara Mascheretti -- Scientific Institute, IRCCS Eugenio Medea
Additional authors/chairs: 
Meaghan Perdue; Bei Feng; Chiara Andreola; Ginette Dionne; Kaja K. Jasińska; Kenneth R. Pugh; Nicole Landi
Keywords: Reading, Genetics, functional MRI, Phonological processing, mediation model
Abstract / Summary: 

Purpose: The BDNF-Val66Met polymorphism associated with reading-related traits and brain activation patterns during a reading task (Jasińska et al., 2016, doi:10.1371/journal.pone.0157449). However, the mechanism by which this gene impacts reading is unknown. We apply a mediation model to data presented in Jasińska and colleagues (2016) to simultaneously test the direct and indirect effects from the Val66Met polymorphism to reading via brain activation and phonological processing.
Method: Ninety-four children (age 5-13) who were 1) Val/Val homozygotes (n=65), or 2) Met (risk) allele carriers (n=29), were included. Children completed a battery of cognitive assessments and an fMRI reading task. We included six clusters that differentiated the genotype groups (Jasińska et al., 2016) and two factors from principal components analysis on cognitive assessments: ‘Reading’ and ‘Phonology’. Indirect effects among genotype, brain activation, and behavior, were tested by a serial multiple mediation model using Structured Equation Modelling as implemented in the MPLUS 8.1 software.
Results: We found significant indirect effects from the BDNF-Val66Met polymorphism to Reading via Phonology and activation in the: bilateral precuneus/left inferior parietal lobule (β=-0.118; SE=0.046; 95% CI=-0.227/-0.034), bilateral medial temporal lobe/cerebellum (β=-0.113; SE=0.045; 95% CI=-0.227/-0.035), left frontal lobe/thalamus (β=-0.147; SE=0.052; 95% CI=-0.279/-0.057), and right cingulate/frontal lobe(β=-0.104; SE=0.042; 95% CI=-0.206/-0.028). Met allele carriers had greater activation in these clusters; brain activation, Phonology, and Reading, were positively related.
Conclusions: These findings suggest that BDNF-Val66Met polymorphism affects reading via phonological processing and functional activation in regions that are ancillary to the primary reading network. Reading proficiency in genetically at-risk individuals may be facilitated by compensatory neural resources.