Dyslexia

Dyslexia: A Specific Learning Disorder in Reading

What is Dyslexia?

Dyslexia is a specific reading disorder affecting 8–12% of the population. It has a neurological origin and a genetic cause. Because dyslexia is a permanent condition that can have a devastating impact on academic performance, it is one of the leading causes of learning disorders. The most significant manifestation of dyslexia is a lack of reading fluency. Two main factors disrupt reading fluency: accuracy and speed. Thus, dyslexia is characterized by imprecise or slow reading.

What are the Diagnostic Criteria for Identifying Dyslexia?

The criteria for identifying specific reading disorders (commonly referred to as dyslexia) have been established by the American Psychiatric Association (APA) and published in the DSM-5-TR diagnostic manual. The APA comprises a group of experts (researchers and clinicians) who rely on scientific evidence to develop precise diagnostic criteria. These criteria are internationally recognized by legal, scientific, and medical authorities. (European scientific and clinical communities use similar diagnostic criteria published in the ICD-11.)

The criterion for diagnosing dyslexia is a gap of at least two years between intellectual performance and reading skills (accuracy or speed) that significantly interferes with academic success and daily activities requiring reading. This specific reading disorder cannot be explained by:
a) intellectual disability,
b) psycho-emotional disorders,
c) sensory deficits (vision or hearing),
d) lack of educational opportunities, or
e) lack of motivation and interest.

Therefore, diagnosing dyslexia requires a comprehensive analysis of the overall profile of the child or adult, including academic history, intellectual assessment, and psycho-emotional profile. Only neuropsychologists or psychologists specializing in learning disorders are qualified to conduct this comprehensive evaluation. These specialists have the necessary expertise to assess intellectual abilities, emotional and psychological disorders, and academic skills, including reading.

The Cause of Dyslexia

Although the exact cause of dyslexia remains unknown, several studies suggest it is hereditary, with links to chromosomes 2, 3, 6, 15, and 18. This genetic connection is widely recognized in the scientific and clinical communities.

Research over the past decade indicates that dyslexia stems from a neurological impairment. Brain imaging studies, which capture the brain in action, show that individuals with dyslexia do not use the same brain regions for reading as those without reading disorders. Moreover, in individuals with dyslexia, the brain areas typically involved in reading are underactivated.

What are the Manifestations of Dyslexia in Children?

The impact of dyslexia varies from person to person, depending on its severity and type. In children, dyslexia results in reading that is very difficult and disorganized, often significantly disrupting or even preventing text comprehension. The following factors frequently characterize the reading of children with dyslexia:

• Reading is very slow.
• Reading is hesitant (transforming letters into sounds or breaking words into syllables can feel insurmountable).
• Words with less frequent usage are read even more slowly and in a highly segmented way.
• Irregular words (e.g., “knight” or “thought”) are not read accurately.
• Sounds are altered.
• Words are guessed based on their visual appearance (e.g., reading “never” instead of “fever”).

What are the Manifestations of Dyslexia in Adults?

Some of these difficulties persist into adulthood. If reading has been diligently practiced during childhood and adolescence, adults may achieve greater reading accuracy. However, despite improved accuracy, reading remains hindered by significant slowness and lack of fluency. Reading never becomes fully automatic, meaning dyslexic readers may be two to three times slower than non-dyslexic readers. For instance, a dyslexic student may need 6–8 hours to read what their peers can finish in 3 hours. This can be not only discouraging but also exhausting. Because reading is not automated, it demands much more effort from the reader. As a result, individuals with dyslexia are often fatigued after just one hour of reading.

Associated Difficulties Include:

• Short-term verbal memory deficits.
• Short-term non-verbal memory deficits.
• Attention deficit (co-occurs in 30–50% of dyslexic individuals).
• Dysorthographia (difficulty acquiring spelling skills).
• Executive function impairments (e.g., planning and organization).
• Arithmetic difficulties.

Given the significant individual differences, dyslexia interventions may require varied approaches. If dyslexia is suspected in a child or adult, a comprehensive evaluation can clarify the nature of the dyslexia and identify associated neuropsychological disorders. This, in turn, enables the development of appropriate intervention strategies.

While dyslexia is a lifelong condition, research shows that individuals with dyslexia can benefit from evidence-based remediation programs when rigorously applied.

Accommodations and Support

Increasingly, tools are being developed to address the challenges associated with dyslexia. Neuropsychological evaluations can also identify accommodations that schools can implement as part of an adapted intervention plan (e.g., classroom and exam accommodations) to help dyslexic individuals overcome learning barriers.