Characteristics and comorbidity of ADHD sib pairs in the Central Valley of Costa Rica.

BACKGROUND: While genetic epidemiological studies demonstrate a substantial degree of genetic predisposition for attention-deficit/hyperactivity disorder (ADHD), they also suggest that the genetics are complex and may differ between populations or ethnic groups. OBJECTIVE: This study describes the phenomenology of siblings with ADHD from the genetically isolated population of the Central Valley of Costa Rica. METHODS: Rates of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)-defined ADHD subtypes and comorbid conditions were calculated in a sample of 157 ADHD-affected children (probands and siblings) recruited for genetic studies using standardized approaches. Sib-sib comparisons and logistic regressions were conducted to identify significant patterns of concordance. RESULTS: Combined-type ADHD (69.5%) was the most common subtype among probands, followed by the inattentive (27.4%), and hyperactive-impulsive (3.2%) subtypes. Anxiety disorders were prevalent (55.9%), as were disruptive behavior disorders (30.9%) and Tourette disorder (17.0%). Probands and siblings showed high sib-sib concordance for anxiety disorders. CONCLUSIONS: ADHD in Costa Rica is similar in clinical and demographic characteristics to ADHD seen in other parts of the world, although the rates of co-occurring psychiatric disorders differ somewhat from those previously reported in Latin American samples. Comorbid anxiety is prevalent, with high rates of sib-sib concordance, and may represent a distinct, homogeneous subgroup suitable for genetic studies.

[Prevalence of and screening for ADHD in Costa Rica]. / Prevalencia y tamizaje del Trastorno por Déficit de Atención con Hiperactividad en Costa Rica.

This research project sought to estimate the prevalence of Attention-Deficit/Hyperactivity Disorder (ADHD) and to determine if the Swanson Nolan and Pelham Rating Scale IV (SNAP-IV) Spanish version is a useful screening tool in a population of Costa Rican school children. The SNAP-IV Spanish version was given to the parents and teachers of 425 children aged 5 to 13 (mean 8.8). All subjects were also assessed with the Swanson, Kotkin, Agler, M-Flynn and Pelham Scale (SKAMP), along with diagnostic confirmation by clinical interview. The sensitivity and specificity of the SNAP-IV was assessed as a predictor of DSM-IV ADHD diagnosis. The point prevalence of Attention Deficit Hyperactivity Disorder (ADHD) in this sample was 5%. The prevalence of ADHD among girls was 7%, while that among boys was 4%. The optimal screen was the teacher-rated SNAP-IV at a 20% cutoff, which had a sensitivity of 96% and specificity of 82%. Parent sensitivities were lower than teacher sensitivities. SNAP-IV teacher ratings with a cutoff isolating the top 20% of scores correctly categorized 87% of children.