Dyslexic children have abnormal brain lactate response to reading-related language tasks

BACKGROUND AND PURPOSE: Children with dyslexia have difficulty learning to recognize written words owing to subtle deficits in oral language related t o processing sounds and accessing words automatically. The purpose of this study was to compare regional changes in brain lactate between dyslexic chi ldren and control subjects during oral language activation. METHODS: Brain lactate metabolism was measured during four different cognit ive tasks (three language tasks and one nonlanguage task) in six dyslexic b oys and in seven control subjects (age- and IQ-matched right-handed boys wh o are good readers) using a fast MR spectroscopic imaging technique called proton echo-planar spectroscopic imaging (1-cm(3) voxel resolution). The ar ea under the N-acetylaspartate (NAA) and lactate peaks was measured to calc ulate the lactate/NAA ratio in each voxel. RESULTS: Dyslexic boys showed a greater area of brain lactate elevation (2. 33 +/- SE 0.843 voxels) as compared with the control group (0.57 +/- SE 0.3 0 voxels) during a phonological task in the left anterior quadrant. No sign ificant differences were observed in the nonlanguage tasks. CONCLUSION: Dyslexic and control children differ in brain lactate metabolis m when performing language tasks, but do not differ in nonlanguage auditory tasks.