ic conditions as medical/neurological disorders are added diagnostic overshadowing. Resolving these issues requires a high index of suspicion and a reasonable working knowledge of neuropsychiatry. Such awareness can improve our understanding of the complex nature of differential diagnosis and help us empathize with the problems faced by colleagues working in the field of dual diagnosis (IDD and MH) (2).
A second set of challenges may be as complicated as those outlined above. Understanding and treating individuals with dual diagnosis also forces the clinician to integrate multiple clinical perspectives. For example:
Behavioral therapy and learning theory: This system is based on target behaviors rather than syndromes (e.g. aggression in response to changes in key environmental factors or escape from task demands) (8). The challenge to mental health professionals is to determine when appropriate target symptoms are identified with specific psychiatric syndromes, e.g. dysphoric mood in major depressive disorder.
Nomenclature issues: Clinicians need to adapt our current nomenclature to better fit adult patients with IDD. The Diagnostic Manual-Intellectual Disability (DM-ID) and the Diagnostic Criteria-Learning Disorders respectively represent attempts to adapt the DSM-IV-TR and ICD-9 uniquely to these differences in nosology.
Adapting to multidisciplinary teams. Best practices in the field of dual diagnosis include mental health professionals as part of a team that includes behavioral psychologists, occupational therapists, physical therapists, pediatric neurology, medicine, psychiatry, educators, family members, and direct support professionals and others. The goal is to integrate different points of view and treatment models into a coherent treatment plan (5–7).
A third challenge arises from an information explosion in the clinical neurosciences of IDD and mental illness. At a practical level we need to translate new information into clinical practice. At a theoretical level we need to update the biopsychosocial model to include:
Genetics: Genes serve as the blueprint for brain development. Our older models were deterministic, hence a nature-nurture debate; current models are probabilistic and interactional. Clinical researchers moved beyond Mendelian (autosomal dominant, recessive inheritance) analysis and now emphasize the sequence and integration of gene activation and de-activation during critical periods of development. As a result the focus instead is on epigenetics and gene-environmental interactions. In this world, the nature-nurture argument is an anachronism (9–11).
Neurosciences: Rapid advances in the neurosciences are deepening our understanding of central coherence, executive functions and adaptive behaviors, theory of mind, social communication, memory, attention, impulse control and affect regulation (11). Our challenge is to understand how errors in brain development (errors in neuronal migration, maturation, neuroplasticity, myelinization and interactive specialization and regional interconnections) relate to cognitive, social and emotional development; and how these errors translate into real life problems for adults with dual diagnoses.
Translational research needs: Clinicians concentrate on challenging behaviors and mental disorders and often eschew molecules as well as policy. But we cannot lose sight of the interactions between macrocosmic forces such as socio-cultural, governmental and economic forces and microcosmic ones related to genetics and neurobiology.
As a result, we need to redefine our understanding of the biopsychosocial model to incorporate this new knowledge (12). The challenge for the 21st century is to adapt the biopsychosocial model in order to make sure that our ideas about the multidirectional and systemic forces underlying this concept are kept up to date with scientific and clinical reality. Translating the innovations in the neurosciences into best practices, positive practice models, and evidence-based and outcome-based treatment for busy clinicians is one of our greatest chall