01 NRDC Dyslexia 1-88 update - Texthelp

Developmental dyslexia in adults: a research review 71
The framework accommodates multiple routes to the final common pathway of difficulty in
acquiring a specific skill such as reading. It takes into account the unlikelihood that one
common factor alone will explain a significant majority of nonsyndromic cases of
developmental learning disability in the population. Similarly, it holds that no single gene is
responsible for the majority of cases or deficit of any particular form of developmental
learning disability and that, for example, genes putting individuals at risk do not necessarily
correspond to specific cognitive aspects of reading ability. It thus contests the assumption
that any genetic effect on reading ability will be focused, singular and direct.
With respect to theories associating dyslexia with abnormal neural migration, the concept of
atypical brain development accommodates the possibility that such an effect could affect
multiple brain areas, not just those associated with reading and that even a specific singlegene
effect will show great variation between individuals. For this reason, it is suggested that
the search for genes should be redirected towards those that cause brain variation in the
population at large rather than towards those that might cause a specific defect. The concept
of atypical brain development is not confined to gene effects, however; it embraces the effects
of harmful substances in the environment, such as lead, drugs taken during pregnancy and
impoverished postnatal environments.
It remains to be seen whether the concept of atypical brain dysfunction will lead to new
strategies for research. At the very least, it provides an incentive to dispense with univariate
contrasting-groups strategies. It also offers an opportunity to explore differential patterns of
function and dysfunction across five large-scale neurocognitive networks: spatial awareness,
language, memory and emotion, working memory and executive functions and face and object
identification (Mesulam, 1998). It might also be an appropriate conceptual framework within
which to explore (and perhaps also to rename) the concept of ‘dyslexia’ without literacy
problems (Miles et al., 2003).
The concept of atypical brain development provides a framework for the development of
theory.
The concept questions the validity of discrete categories and syndromes in the diagnosis of
developmental disabilities.
Atypical development may not have a single specific cause but may happen as the extreme of
a continuously-distributed trait.
Although the concept was formulated as a perspective for researchers, it might alert
practitioners to student characteristics that would otherwise have escaped their notice.