There is a long way to understand the causes of dyslexia
Medical and scientific treatments for the understanding of dyslexia have advanced in the last 5 years, but There is still much work to be done to fully understand the causes of dyslexia, and be able to improve the lives of children struggling to learn to read, according to a seminar published in 'The Lancet'.
In fact, most children are diagnosed with dyslexia, after having encountered serious difficulties in school, at a time when it is much more difficult for them to master new skills.
"Professionals should not wait for children to be formally diagnosed with dyslexia, since the remedy is less effective than early intervention," explain Robin Peterson and Bruce Pennington of the University of Denver, in the USA.
Approximately 7 percent of the population is dyslexic, and children are twice as likely to have dyslexia as girls. It was believed that dyslexia involved problems with visual processing, but growing evidence suggests that the underlying deficit consists of the difficulty of discerning language sounds, assigning letters (phonological deterioration).
"Like all behaviorally defined disorders, the cause of dyslexia is multifactorial, and is associated with multiple genes and environmental risk factors," the authors explain. Despite the recent identification of the six genes that contribute to the disease, very little is known about how these, and other possible genetic determinants, can contribute to dyslexia.
Therefore, further research is needed to reveal undiscovered genes that may contribute to dyslexia, to identify which gene locations are shared and not shared with comorbid disorders -such as attention deficit hyperactivity disorder (ADHD) -, and to examine the effects of environmental risk factors.
"We still have to learn more about the nature of the phonological deficit, and how this problem interacts with other linguistic and non-linguistic risk factors," Peterson and Pennington explain.
The researchers add that much remains to be done to address the issues of treatment, and state that "brain imaging studies have shown that an effective intervention seems to promote the normalization of activity in the reading and language network of the left hemisphere."
Although the diagnosis is usually delayed until school age, common coexistence conditions, such as ADHD, language disorder, and speech disorder, may be evident much earlier, and could be used to help predict a child's risk. of having later problems with reading, according to the authors.