A longitudinal study that used imaging to compare brain activation patterns has identified two types of reading disability:
- a primarily inherent type with higher cognitive ability (poor readers who compensate for disability), and
- a more environmentally influenced type with lower cognitive skills and attendance at more disadvantaged schools (persistently poor readers).
It seems, compensated poor readers are able to overcome some of the disability, improving their ability to read words accurately and to understand what they read, while persistently poor readers continue to experience difficulties.Brain activation patterns showed a disruption in the neural systems for reading in compensated readers (specifically, a relative underactivation in posterior neural systems for reading located in left parietotemporal and occipitotemporal regions), while persistently poor readers had the neural circuitry for reading real words, but it had not been properly activated.These results point to the importance of providing early interventions aimed at stimulating both the ability to sound out words and to understand word meanings for children at risk for reading difficulties associated with disadvantage.
The importance of childhood environment is also emphasized by a study of older adults that found that the larger a person's head in adulthood, the less likely their cognitive abilities are to decline in later years. Head size in adulthood is determined in infancy: during the first year of life, babies' brains double in size, and by the time they are six, their brain weight has tripled. These, it appears, are the crucial years for laying down brain cells and neural connections — pointing to the importance of providing both proper nourishment and intellectual stimulation in these early years.
Impaired reading skills are found in some 20% of children - in boys, more than girls. Dyslexia - a disability which is found across all socioeconomic classes and all ethnicities - may be thought of as the low end of a continuum of reading ability. Training that helps dyslexics can also help those whose problems with reading are of lesser magnitude.
It has been suggested that the reason reading disabilities are more common among boys is that teachers simply tend to recognize the problem in boys more often, but it does now seem clear that boys really do have more reading difficulties than girls. Analysis of four large-scale studies of reading in children, involving some 9,800 children, found about 20% of the boys had reading disabilities compared with about 11% of the girls.
An EEG study of gender differences in the emerging connectivity of neural networks associated with phonological processing, verbal fluency, higher-level thinking and word retrieval (skills needed for beginning reading) in preschoolers confirms different patterns of growth in building connections between boys and girls. These differences point to the different advantages each gender brings to learning to read, and suggests the need for different emphases in teaching boys and girls to read. Boys favor vocabulary sub-skills needed for comprehension while girls favor fluency and phonic sub-skills needed for the mechanics of reading.
No educational system in the world has mastered the problem of literacy; every existing system produces an unacceptably high level of failures. So, we cannot point to a particular program of instruction and say, this is the answer. Indeed, I am certain that such an aim would be foredoomed to failure - given the differences between individuals, how can anyone believe that there is some magic bullet that will work on everyone?
Having said that, we have a far greater idea now of the requirements of an effective literacy program. One of the reasons for that is the work of the National Reading Panel in the United States, which spent some three years analyzing a huge number of studies into various aspects of reading instruction. I have summarized their findings here.
Direct instruction in specific components of reading skills is clearly only part, albeit a major part, of improving literacy. There is also the role of providing a stimulating environment, most particularly in the very early years. Little is known about the precise nature of the stimulation that would be most productive for providing the foundation for later literacy, but we may speculate that, apart form the obvious (being read to, etc), music may also be beneficial. Although I am not aware of any studies specifically looking at the possible benefits of music training for developing reading skills in children, recent research does provide evidence that giving children music instruction benefits their verbal memory.
Dyslexics who are identified at a very early age (1st grade or earlier) have significantly fewer problems in learning to read than those who are not diagnosed until later. About 74%of the children with dyslexia who are poor readers in 3rd grade remain poor readers in the 9th grade, and often can’t read well as adults either. The earlier dyslexia is recognized and proper instruction given the better. Dyslexia tends to run in families.
Other research also points to the importance of early intervention.The brains of children with learning problems not only appear to develop more slowly than those of their unaffected counterparts but also actually may stop developing around the time of puberty's onset. In the study, children with impairments started out about three years behind, but their rate of improvement was very similar to that of the children without impairments — until around 10 years, when further development in the children with learning problems stopped.
We always want simple answers, but, as so often, it seems likely that there is no single, simple answer to the problem of dyslexia. Imaging studies have revealed that different phonological skills relate to activity in different parts of the brain when children read.There are probably several neurobiological profiles that correspond to different subtypes of dyslexia, each associated with varying deficits in different phonological skills.
For example, a key predictor of reading problems is lack of a skill called "rapid naming" - basically, being able to quickly retrieve the names of very familiar letters and numbers. It's been suggested that inability to rapidly name, and inability to differentiate between sounds, may be separate causes of dyslexia.
Interestingly, confirming a very old theory of dyslexia, it seems that normally developing readers learn to suppress the visual images reported by the right hemisphere of the brain - these images potentially interfere with input from the left. Dyslexic readers also appear to process auditory and visual sensory cues differently than do normal readers. During an auditory matching task, dyslexic readers showed increased activity in the visual pathway of the brain, while that same region deactivated in normal readers.
The tendency for dyslexia to run in families points to a genetic aspect. It has been found that brain images of people with a family history of dyslexia show significant reduction of gray matter in centers associated with language processing.
A number of educational tools have been developed to teach people with dyslexia to read. Remembering that dyslexia is a label for a variety of different skill deficits, it is not surprising that an effective training program is not the same for everyone. The dyslexic person’s individual strengths and weaknesses must be assessed to find the program that will help best.
What is exciting is the converging evidence in recent years that it is indeed possible to re-train dyslexic brains. Clearly, the earlier the better, but one encouraging recent study found clear evidence for the benefits of a comprehensive reading program for dyslexic children aged 11-12 years. The study mapped the brain activation patterns of dyslexic children and good readers of the same age during two types of reading tests: phoneme mapping (which tests the ability to make correct associations between letters or letter combinations and sounds in nonsense words - e.g., if oa in ploat stands for the same sound as ow in crow) and morpheme mapping (having to decide if one word comes from another word - e.g., builder and build (yes); corner and corn (no)).
Both groups of children were found to use the same specific parts of their brains to perform the reading tasks, however, the activation of these regions was much weaker in the dyslexic children. The children with dyslexia then received a three-week training program based on principles outlined by the National Reading Panel Research findings of the NRP). After this program the levels of brain activation were found to be essentially the same in the two groups.The improvement in activation in the dyslexics was mirrored in improved reading scores.
Another recent study used an interactive computer game called MovingToRead (MTR) to significantly improve reading skills in poor second-grade readers within three months by practicing left-right movement discrimination for 5 to 10 minutes once or twice a week. It has been suggested that immature motion pathways — the circuit of neurons that helps readers determine the location of letters of a word and words on a page — may be related to reading problems in children. The therapy appears to be most effective with second-graders (age 7).
Other studies, such as Fast ForWord, and the Lindamood Phoneme Sequencing program (LiPS), also appear to have had good results. The point is not so much that any one specific program is the answer. Remember that different dyslexics will have different impairments, and accordingly, different programs will be effective for different individuals. Having said that, there are some common aspects to these programs. In particular, any such program should emphasize phoneme awareness.