Researchers at Yale University have identified two reading disabilities that account for why some children compensate for impaired ability but others struggle to read throughout their lives.
It's a finding that demonstrates the need for early intervention reading programs for children, says one of the study's authors, G. Reid Lyon, PhD, a psychologist and chief of the Child Development and Behavior Branch of the National Institute of Child Health and Human Development at the National Institutes of Health.
The study, published in the July issue of Biological Psychiatry (Vol. 54, No. 12), indicates the two reading disabilities are:
A primarily inherent disability in which poor readers form alternate neural pathways to decode words leading to accurate word recognition. While these compensated dyslexics continue to read slowly, their cognitive capabilities allow them to comprehend text.
A more environmentally influenced disability in which poor readers rely on memory for whole words rather than decoding strategies, leading to persistent difficulties in reading accuracy, reading fluency and comprehension. This type of reading difficulty is more common in disadvantaged schools and communities, says Lyon.
"Some kids, as they enter elementary school, have a tough time learning to read, even though they've had a lot of early language and literacy experiences--these are mostly dyslexics who can learn to overcome the problem," Lyon says. "But the majority, these persistently poor readers, are from disadvantaged homes where early reading doesn't happen frequently."
The study participants consisted of three groups of young adults: those who had tested poorly in reading in second or fourth grade and again in high school, those who tested poorly in elementary school but then showed improvement, and those with no impairment. The participants' reading was assessed yearly in primary and secondary schooling, and again in this study at ages 18 to 22.
Led by pediatricians Sally Shaywitz, MD, and Bennett Shaywitz, MD, of Yale University, the researchers used functional magnetic resonance imaging to examine brain activity patterns in the three groups during two reading tasks, one that asked them to identify rhyming words and one that asked them to judge if two words fit in the same categories, like foods or jobs.
In readers who had shown improvement during schooling, brain activation patterns showed a disruption in the neural systems for reading but also showed development of compensatory pathways. But in persistently poor readers, the neural circuitry for reading was present but improperly connected, Lyon says.
The findings indicate to parents and teachers that activating children's neural circuitry for reading early on is key, Lyon says: "We have to have preschool and early education programs that know how to identify kids at risk and know how to provide them with substantial language and literacy interactions that are warm and nurturing--replicating what ideally they should find at home."