I field many questions from parents who are concerned with their child's ability to read. Indeed, there are many confusing pieces of information on the internet that have the potential to mislead parents or teachers in understanding the reasons why one should (or should not) be concerned with a child or adolescent s reading skill development. Other parents ask me to describe the ways that a neuropsychological or psychoeducational evaluation may help their child if indeed a reading difficulty is identified. This piece is intended to define dyslexia and discuss the process and value of a comprehensive evaluation process.
Dyslexia is another term for Reading Disorder, which is the technical term for reading difficulties used in the Diagnostic and Statistical Manual-IV-TR ( DSM : the manual used by psychologists and social workers which lists and describes all possible diagnoses). In order to meet DSM-IV-TR criteria for reading disorder/dyslexia, a child's reading skills must be substantially below what would be expected given her/his age, intelligence level, and education (as noted below, this objective discrepancy is NOT the only nor the most important criterion to consider). In addition, the child's reading difficulty must interfere to a noticeable degree with both his/her academic performance and any general life skills that require reading proficiency. Finally, if the child has a sensory problem (e.g., vision difficulty), his/her reading difficulties must be over and above what would be expected based on the sensory difficulty alone.
There are two types of dyslexia: developmental dyslexia (e.g., an individual is born with difficulties) and acquired dyslexia (e.g., an individual acquires reading difficulties secondary to a sudden occurrence such as a neurological injury). Developmental dyslexia is common among individuals with first-degree relatives with learning disorders. Thus, although dyslexia appears to be highly heritable, a child's environment (e.g., how much the child's parents encourage or model reading behaviors, how many books or reading materials are in the home) also seems to play an important role in the development of different types of reading profiles (Haiyou-Thomas, 2008).
Recent research shows that there are clear functional differences in the brain systems of children and young adults diagnosed with developmental dyslexia (Richlan, Kronbichler, & Wimmer, 2011). Research has also demonstrated that the functionality of disrupted brain systems has the potential to change upon exposure to high quality reading remediation (Shaywitz, Lyon, & Shaywitz, 2006). In other words, research suggests that with proper and timely reading intervention, the brains of children with dyslexia can change to function more similarly to the brains of children without dyslexia. This suggests that it is very important to identify early vulnerabilities to reading difficulties in children so that high quality programming may be initiated as soon as possible. In general, a younger child's brain is more plastic or malleable than an older child's brain, and thus, there is greater potential for more efficient change in younger children. (Identification of reading vulnerabilities before age six or seven is ideal.)
3. Although recent research indicates that there may be different subtypes of dyslexia which include or do not include phonologic weakness (O Brien, Wolf, & Lovett, 2011), the traditional understanding of dyslexia includes this clinical feature (e.g., clear and consistent difficulty linking sounds to letters). Thus, a thorough evaluation of dyslexia must thoroughly investigate the presence/absence of this quality in a child's reading skill set via standardized tests of decoding. Other aspects of a child's developing reading skills such as oral reading fluency, spelling skills, and reading comprehension are also central to an evaluation of dyslexia.
It is common for schools to rely heavily on the essence of criteria one or a discrepancy model (i.e., a 15-standard score point gap between a child's intelligence level and reading level) to identify reading difficulties in children. This is concerning not only because there are important variations among testing materials between schools, but also because this approach does not necessarily capture the presence or absence of the phonologic component of dyslexia. Elimination of this component of an evaluation compromises accurate identification of children with these difficulties and the provision of a clear description of specific learning needs (e.g., type of intervention program, intensity of intervention format), leading to the possibility that a child will be matched with a reading program does not address his/her needs. Pairing a child with the wrong type of services may lead to what seems to be a lack of success when the true reason for difficulty is that his/her needs are not being appropriately supported.