Since the 2004 re-authorization of the IDEA, twice exceptional students (students with gifted abilities or talents and LDs) have qualified for individualized educational support in the form of 504 accommodations or an IEP. That said, twice exceptional students are often overlooked in conventional school settings because their gifts may compensate enough to avoid identification for help, but not enough to avoid emotional problems and often gross academic achievement.
From Successful Strategies for Twice Exceptional Students above, it's easy to see how students' gifted abilities might be missed; often it is only parents or teachers who develop a close relationship with a student who notice advanced conceptual ability, abstract reasoning, self-initiated creative activities in the presence of otherwise lackluster academic performances. It's also worthwhile noting how often secondary social, emotional, or behavioral problems erupt making the sources of school underachievement difficult to identify.
Advances in our understanding of brain biology provide helpful insights into how twice exceptional abilities arise; also they raise important issues about how they should best be identified, accommodated, and taught.
1. Twice Exceptionality Often Runs in Families - Structural Brain Differences
Although parents don't always think about their extended family tree when they are thinking about why their son or daughter is having trouble in school, it's important that they should. It's a rare teacher or doctor who will think to ask about whether a child's learning problems or "underachievement" runs in the family, and if parents or grandparents don't think about it, it may be highly likely that no one will. In addition to individual inherited factors contributing to giftedness and learning disability, assortative mating (tendency of like to marry like) can dramatically increase the likelihood of adults' learning differences being inherited by children (6-40x higher chance of a person with a reading disability marrying another with a reading disability! - see Hynd).
With advanced imaging and morphometric methods, its becoming easier to identify familial differences in brain organization (see Asymmetry and Dyslexia). Looking at Einstein's brain at left, is it any wonder that he found his most successful life's work using visual and spatial problem solving methods, and that he had an undistinguished start to his schooling and was a late talking child?
2. Dynamic Reorganization Ability in the Brain - Alternate Brain Pathways Can Compensate for Weakness
In the past 30 years, there have been dramatic advances in our understanding of how dynamic pathway remodeling exists in the brain. Partially redundant systems help us to accurately sense our environments, learn and remember, and plan and act.
Gifts Secondary to Disabilities
Partial redundancy provides a buffer system in the event of injury; if one system is injured, another increases its activity to take its place. At right, Shibata and colleagues found that the part of the brain that normal hears in congenitally deaf subjects was reorganized to 'see' - so although the deaf were unable to hear, their visual sensitivity was greater than normal hearing subjects because more brain resources were now devoted to seeing.
It is likely, then, that some twice exceptional abilities many occur as the result of the brain's compensatory drive from a deficit or injury. One practical implication for this idea is that a thorough search for strengths and gifts should be made in the setting of any disability.
Disabilities Secondary to Gifts
But in some cases, there is a suggestion that some disabilities or delays in development are secondary to gifts. In a study from Port Townsend (Sweetland), researchers found that the higher the IQ, the greater the likelihood of high VIQ/PIQ discrepancies (17% of a control sample had IQ subtest discrepancies of 18 points or more vs. 55% of a gifted sample). And there's that data from Giedd and colleagues showing that the higher the IQ in young children, the slower the development of prefrontal cortical thickness. Extreme ability or talent may result in slower time courses of development or stunting of other systems or pathways if resources are limited.
Different developmental time courses should also (in the best of all worlds) warrant appropriate curricular and other educational accommodations. For instance, if young gifted children were found to present as mixed dominant "late-bloomers", shouldn't demands for heavy bihemispheric activities be individualized (e.g. note-taking, writing to open-ended prompts) and instruction optimized for what we know to be well-developed?
Twice Exceptional Guidebook, Montgomery County
Eides Presentation: Twice Exceptional - Life at the Extremes pdf
Hynd: Neurobiological Reseach in Reading Disabilities and Implications for Autism Spectrum pdf
Superior nonverbal abilities in families with dyslexia - ppt
Eide Neurolearning Blog: Blessings and Burdens of High IQ