DIFFERENTIAL DIAGNOSIS IN LEARNING DISABILITIES

The long-range objectives of this Learning Disabilities Research Center are
the identification, characterization, validation, and amelioration of
etiologically distinct subtypes or dimensions of learning disabilities. To
accomplish these objectives, test batteries that include measures of
cognitive abilities (Research Project I), reading and language processes
(Research Project II), and ADHD and executive functions (Research Project
III) will be administered to a unique sample of 50 pairs of identical twins
and 50 pairs of fraternal twins in which at least one member of each pair
has a significant difficulty in the acquisition and use of mathematics, to
an independent sample of 50 pairs of identical twins and 50 pairs of
fraternal twins in which at least one member of each pair is reading
disabled, and to a comparison group of 50 pairs of identical twins and 50
pairs of fraternal twins with a school history of no significant difficulty
in mathematics or reading. Resulting data will be used to assess the
genetic and environmental etiologies of deficits in mathematics and
reading, as well as their covariation with measures of phonological and
orthographic coding, ADHD, and executive functions. In order to search for
major genes and/or quantitative trait loci that may influence learning
disabilities, blood samples will be drawn from fraternal twin pairs and
subjected to genetic linkage analyses (Research Project IV). Concurrently,
a sample of 100 twin pairs will be administered differential computer-based
remediation to assess possible subtype-by-treatment interactions (Research
Project V). An administrative core unit will be responsible for
coordinating the activities of the five research projects; maintaining
communication among the participating investigators; ascertaining and
scheduling subjects; obtaining questionnaire data from families of twins;
compiling and managing i a master file of combined data sets; and
administering the Center budget and other fiscal matters.