Slow EEG amplitude oscillations during NREM sleep and reading disabilities in children with dyslexia.
OBJECTIVE
To analyze non-rapid eye movement (NREM) sleep microstructure of children with dyslexia, by means of cyclic alternating pattern (CAP) analysis and to correlate CAP parameters with neuropsychological measures.


METHODS
Cross-sectional study using polysomnographic recordings and neuropsychological assessments.


METHODS
Sleep laboratory in academic center.


METHODS
Sixteen subjects with developmental dyslexia (mean age 10.8 years) and 11 normally reading children (mean age 10.1 years) underwent overnight polysomnographic recording.


METHODS
N/A.


RESULTS
Sleep architecture parameters only showed some statistically significant differences: number of sleep stage shifts per hour of sleep, percentage of N3, and number of R periods were significantly lower in dyslexic children versus controls. CAP analysis revealed a higher total CAP rate and A1 index in stage N3. A2% and A2 index in stage N2 and N3 were lower in dyslexic children while no differences were found for A3 CAP subtypes. The correlation analysis between CAP parameters and cognitive-behavioral measures showed a significant positive correlation between A1 index in N3 with Verbal IQ, full-scale IQ, and Memory and Learning Transfer reading test; while CAP rate in N3 was positively correlated with verbal IQ.


CONCLUSIONS
To overcome reading difficulties, dyslexic subjects overactivate thalamocortical and hippocampal circuitry to transfer information between cortical posterior and anterior areas. The overactivation of the ancillary frontal areas could account for the CAP rate modifications and mainly for the increase of CAP rate and of A1 index in N3 that seem to be correlated with IQ and reading abilities.
Bruni
Oliviero
O
Department of Developmental Neurology and Psychiatry, Sapienza University, Rome, Italy.
Ferri
Raffaele
R
Novelli
Luana
L
Finotti
Elena
E
Terribili
Monica
M
Troianiello
Miriam
M
Valente
Donatella
D
Sabatello
Ugo
U
Curatolo
Paolo
P
D002648:Child; D003430:Cross-Sectional Studies; D004410:Dyslexia / Q000503:physiopathology* / Q000523:psychology*; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D017286:Polysomnography / Q000379:methods; D011932:Reading; D012894:Sleep Stages