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The latest issue of “Perspectives,” the quarterly publication of the International Dyslexia Association, is themed “Controversial Therapies for Dyslexia.”
According to theme editor Bruce Pennington the goal of this issue is to illustrate how to evaluate treatments for students with dyslexia.
Contributors review treatments that have many advocates (and clients) but have not been proven scientifically to be effective. One clear message is that there is an important distinction between “process-focused” and “performance-based” therapies.
Process-focused therapies are based on the theory that what underlies a given learning disorder is a deficit in a simple sensory or motor process.
Performance-based therapies target symptoms directly and treat them. For example, performance-based therapies for dyslexia would provide instruction and guided practice in reading itself.
As the articles suggest, it is easier to provide evidence of effectiveness for performance-based therapies than it is for those that are process-focused.
Controversial, process-focused therapies for learning disorders (including dyslexia) have a common logic: they claim that
- … a disorder in some higher aspect of cognition, such as reading, language, attention or social cognition, is caused by a lower-level deficit in a modality of perception (auditory, tactile, or visual); or in some aspect of motor skill;
- …that the lower-level deficit is present in children with the learning disorder;
- …that the lower-level deficit can be remediated with practice because of brain plasticity;
- …that fixing the lower-level deficit transfers and thus improves the deficit in higher cognition.
Training in a particular skill rarely transfers to other skills, so it is particularly important that research meets the final criterion.
These four assumptions need to be empirically tested before a therapy can be accepted. Is it theoretically plausible, associated with the learning disorder, treatable and directly transferable?
By definition, a performance-based therapy just has to satisfy the treatable test (#3), since it is by definition theoretically plausible (#1), reading problems are associated with dyslexia by definition (#2), and because we are training the skill itself, transferability is not applicable (#4).
The three types of therapies evaluated in Perspectives are 1) speed of word processing interventions, 2) vision efficiency interventions and 3) exercise-based interventions. They have all not passed the empirical tests. They should not be used to treat children.
Pennington writes that the two most critical issues for evaluating a therapy for dyslexia are its theoretical plausibility and its demonstrated efficacy for improving reading through random controlled trials (RCTs).
Because the science of both normal reading and dyslexia are well-developed, any new theory of what causes dyslexia has to be plausible given what we already know about the causes of dyslexia.
The further away the proposed cause is from reading itself, the more skeptical you should be. So, a new theory that says the cause of dyslexia is — say — in the balance system of the brain, is much less plausible than the established theory that dyslexia is caused by a problem in the phonological aspect of language development.
But the most important thing is this: any treatment for dyslexia, or any disorder, whether it is based on a new or established theory, must also be demonstrated to be effective in random controlled trials.
This is true whether they are process-focused or performance-based. Being performance-based doesn’t mean it is effective. Demonstrating efficacy through RCTs makes a therapy an empirically supported therapy (an EST).
“Best practices” consist of ESTs and empirically supported assessments.
Visit the IDA Web site to find its “Knowledge and Practice Standards for Teacher of Reading.”
RESOURCES FOR PROVEN THERAPIES
Anyone considering a new therapy for a child should compare the claims made with the objective valuations of that therapy on these Web sites:
- What Works Clearinghouse (http://www.whatworks.ed.gov)
- The Cochrane Collaboration (http://www.cochrane.org)
- TRIP Database for Evidence Based Medicine (http://www.tripdatabase.com)
- Quackwatch (http://www.quackwatch.com)
If a therapy has not been evaluated, that in itself is a bad sign. Treatments with efficacy based solely on clinical observations, uncontrolled studies or anecdotes are not empirically validated. Pennington says it would be unprofessional and unethical to disseminate them.
Sole source: article by Bruce Pennington in the Winter 2011 issue of Perspectives on Language and Literacy.
Pennington is a John Evans Professor of Psychology at the University of Denver and a Fellow at AAAS and APS. He is an award-winning researcher and writer on dyslexia and other neurodevelopmental disorders. His “Diagnosing Learning Disorders” is published by Guilford Press.
“Perspectives on Language and Learning,” a quarterly publication, is a benefit of membership in the International Dyslexia Association (IDA). Visit http://www.interdys.org
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