I don't think that even the MRI researchers themselves believe that there will ever be routine MRI scanning procedures to identify potential dyslexics in the general population. Who would pay for it ? Genetic testing suffers from the same problems. First of all, both are medical procedures, and under existing conditions that means that either the insurance companies would have to include that as a benefit ( not likely ) or the individual would have to pay. Neither are cost effective methods for the identification of dyslexics.
Consider this. If the 5-10% of the population that is dyslexic could be identified by a test, then the effective cost of identifying 1 dyslexic will be 10 to 20 times the cost of the test. If an MRI evaluation costs $2000 then the identification of 1 dyslexic would be $20,000 -40,000.
The reason the researcher in the article said that a combination of MRI and a reading skills test together would increase the ability to identify a dyslexic is that MRI tests alone can not identify individual dyslexics at this time. Only differences between groups of dyslexics and non dyslexics are reported with so much overlap that individuals can not be put into either group with certainty. It does seem to be almost a cheat if ( as far as MRI goes ) to find that someone has good reading skills and so can be removed from the group with dyslexic looking scans and put into the group of non dyslexics or moving someone into the group of dyslexics from the non dyslexic looking scans because of poor results on a reading skills test.
I can understand the frustrations of going into a study with the preconceived idea that a particular part of the brain is going to be able to identify whether a person is dyslexic or not and having the results only be able to tell the difference between groups of dyslexics and non dyslexics. What I really can not understand is the continued fixation with only focusing on one part of the brain for each study.
Common knowledge is that different dyslexics have different dyslexic symptoms. Some dyslexics seem to have auditory problems where they have difficulty hearing the difference between sounds. fMRI studies have determined that this occurs in one part of the brain and when studied the standard results of being able to determine differences between groups of dyslexics and non dyslexics but not individually dyslexic or non dyslexic is found. Some dyslexics seem to have problems making words from letters. This word forming part of the brain has been studied by fMRI studies with the same standard result......................I get tired of writing it all out.................................different groups...............................not able to identify individuals. Some dyslexics have visual processing problems. Again the visual center is identified with the same result............................groups ....................not individuals. Some dyslexics have problems with the meanings of words. Word processing area of the brain identified same fMRI results ...........................groups ....................................not individuals.
Now I suspect that some of you know where I am going with this but I am going to spell it out anyway. Some dyslexics may have problems in all the above areas to different degrees but most function adequately in some areas. Not all dyslexics have auditory problems and so for those dyslexics their results of being in a fMRI study focused on the auditory area of the brain would likely result in a similar analysis as non dyslexics. There are dyslexics without word processing problems that can't be identified by looking at only the word processing area. Dyslexics without visual problems that can't be identified by looking at only the visual processing area of the brain by fMRI.
Now as far as overlap going the other way I am going to use an analogy. Many dyslexics are poor spellers. There must be a spelling part of the brain. Some very good readers are also poor spellers. Any fMRI study that only had a focus on the spelling part of the brain to identify dyslexics would expect to see the same standard results....................groups ...................not individuals.
I am not saying that fMRI research into dyslexia is worthless. The useful information that is being developed by looking at specific areas of the brain is just not ever going to develop into a identification screening procedure for dyslexia by looking at one brain site. I predict that at some point fMRI may be used to determine what specific areas are problem areas for a particular already diagnosed dyslexic so that an intervention may be developed that most effectively addresses his or her dyslexic problem/s.
The economics of fMRI evaluation for the best intervention selection for a diagnosed dyslexic could turn out to be very favorable for the people that can afford $20,000-30,000 a year for dyslexia intervention. Spending $2,000-4,000 to custom design the intervention based on fMRI results could be cost effective.
A more reasonable future screening process for dyslexia from the general population would include some skill tests and include a family's IQ and educational history along with a questionnaire about their reading habits and other questions that might be found to be helpful such as how well oral directions are followed. The goal should be to identify not only dyslexics but all who are likely to need extra help developing reading skills. Some screening tests already exist and are possibly something that could find funding from educational budgets.
My niche in dyslexia is for the minority of dyslexics that describe visual problems such as jumping or missing letters that make reading difficult for them. I sell dyslexia glasses that remove described visual problems at http://www.dyslexiaglasses.com/ . I follow most mainstream dyslexia research and am amazed at the hype that is generated as if dyslexia is caused by a single factor and that the answer has been found. I am also concerned that the % of poor readers is so much higher than any estimate of dyslexics and conclude that the educational system is failing many when it comes to teaching the skills needed to read.
MRI studies have their place in generating information about dyslexia but are not ever going to be used for evaluation on a widespread scale because the cost of testing all the non dyslexics would also need to be absorbed.