Comorbidity and psychological science: Does one size fit all?

Identifying subtypes among children with developmental coordination disorder and mathematical learning disabilities, using model-based clustering

A relationship between motor and mathematical skills has been shown by previous research. However, the question of whether subtypes can be differentiated within developmental coordination disorder (DCD) and/or mathematical learning disability (MLD) remains unresolved. In a sample of children with and without DCD and/or MLD, a data-driven model-based clustering was used to identify subgroups of individuals with relatively homogeneous profiles on measures associated with motor and mathematical skills. One subgroup of children with motor problems was found based on motor variables. Based on mathematical variables, two clinical clusters were found: a subtype with number fact retrieval problems and a subtype with procedural calculation problems. Clustering with motor and mathematical skills revealed two clinical clusters: a cluster with number fact retrieval as well as procedural calculation problems and below average motor and visual-motor integration skills. A second cluster of children had only procedural calculation and visual-motor problems. Our results raise questions about the usefulness of placing children who have below average mathematical skills into a single diagnostic category. Furthermore, we inform ongoing debates about the overlap between DCD and MLD, as below average motor skills were found in both MLD subgroups, although a different motor profile is linked to a different mathematical profile.

The conceptualization and measurement of comorbidity: a review of the interprofessional discourse

Background. Chronic medical conditions often occur in combination. Understanding underlying mechanisms causing diseases and their interactions may make it possible to address multiple complex conditions with single or consolidated treatment approaches and improve patients' health outcomes while reducing costs. Objectives. We present a synthesis of the current interprofessional discourse on the issues surrounding comorbidities. Methods. A targeted review of the literature was conducted using published editorials, commentaries, and review articles. Results. Errors in conceptualization and measurement plague our current understanding of comorbidities. Two potential paths to generating knowledge involve the use of etiological or epidemiological approach. An etiological approach investigates the risk factors and underlying mechanisms potentially leading to consolidation of diagnosis and treatments. Because of the rudimentary stage of knowledge development in this area, this approach will require time and significant research investments. In contrast, the epidemiological approach relies on statistical identification of disease entities that cooccur beyond random chance; this approach carries an accompanying risk of diagnostic and treatment proliferation. Discussion. The concept of comorbidity, its nature, and measurement is in need of meaningful debate by the scientific and clinical communities. Recommendations in the domains of conceptualization, research, and measurement are discussed.

Diagnostic Profiles among Urban Adolescents with Unmet Treatment Needs: Comorbidity and Perceived Need for Treatment

The goal of this study was to document comorbidity profiles of psychiatric disorder and perceived need for treatment among urban adolescents with unmet behavioral health needs. Participants were 303 community-referred adolescents and their primary caregivers. Adolescents included both boys (54%) and girls and were primarily Hispanic (58%), African American (23%), and multiracial (13%). Home-based interviews with both adolescents and caregivers were used to assess DSM-IV diagnoses and perceived treatment needs. Most adolescents (80%) were diagnosed with multiple disorders and most families (66%) reported a need to treat more than one disorder. Latent class analysis of endorsed DSM-IV disorders identified five distinct diagnostic profiles: Parental Concern, Adolescent Distress, Basic Externalizers, Severely Distressed, and Comorbid Externalizers. Diagnostic profiles were compared on perceived treatment need and related psychosocial risk characteristics. Implications for behavioral health care policy and practice for youth with unmet treatment needs are discussed.