Adolescents with Developmental Disabilities and Their Families

INTRODUCTION A comprehensive understanding of adolescent development requires investigation into both normative patterns and individual differences in the full range of developmental domains. Extensive research in adolescent development has focused on delineating trajectories of typi· cal development and understanding how those vary based on gender, culture, and socioeco­ nomic context. Very few studies, however, consider such trajectories in adolescents with developmental disabilities (i.e., biologically based delays or impairments in one or more areas of development). Investigations of indi­ viduals with developmental disabilities usu­ ally require cross-disciplinary collaboration among such fields as psychology, sociology, biology, medicine, public health, special edu­ cation, social work; and psychopathology, and therefore the study of adolescents with devel­ opmental disabilities has not found a primary home. (ndeed, some researchers point out that adolescence is not even considered an actual subdiscipline within the field of intelleetual impairment (Hodapp, Kazemi, Rosner, & Dykens, 2006). Cross-disciplinary work, how­ ever, can provide critical insight into such investigations. For example, current research emanat­ ing from the fields of molecular biology and behavioral genetics has stimulated thinking about the complex interplay between genetic disorders (such as Down syndrome or fragile X syndrome) and developmental changes in indi­ viduals with those disorders (Inlow & Restifo, 2004). Such work is essential to mapping the variation within typieal development. locating biological differences in atypical development (e.g., in the synthesis of proteins), and forming testable hypotheses about gene~nvironment interaction and potential therapeutic interven­ tions (Gardiner, 2006). Currently, the grow­ ing knowledge base on the cont1uence of gene~nvironment complexity along with the biological changes and psychosocial demands that typically occur during the adolescent period makes the study of this developmen­ tal phase for individuals with developmental disabilities essential to a full understanding of adolescent development. For example, stud­ ies on those with fragile X syndrome, the most common form of hereditary intellectual dis­ ability, indicate that the disorder is due to a mutation of the FMRI gene on the X chromo­ some, a condition that has been simulated in mice. Restivo et al. (2005) conducted a study on such mice (termed knockout mice since the FMRI gene is deleted) comparing those reared in enriched and standard caged environment They reported that the transgenic mice raised in the enriched environment showed fewer behavioral abnormalities (such as hyperac­ tivity and lack of habituation) and displayed