Objective: Eighteen extended multigenerational families were recruited from the genetically isolated Paisa community in Colombia to conduct genetic studies of attention-deficit/hyperactivity disorder (ADHD). This report describes the inclusion strategy and clinical features of participants to facilitate comparisons with other data sets.
Method: Families were selected through a fixed-sampling scheme beginning with child probands referred for clinical evaluation for ADHD. Direct structured psychiatric interviews were conducted with 433 informative individuals, including 92 children aged 4 to 11, 57 adolescents aged 12 to 17, and 284 adults. Best estimate ADHD diagnoses were established for each informative pedigree member.
Results: These families contained a high proportion of individuals affected with ADHD (32.8%), which was highly comorbid with conduct disorder (50%; odds ratio 11.5, 95% confidence interval = 6.4-20.9), oppositional defiant disorder (25.4%; odds ratio 2.7, confidence interval = 1.5-4.8), and associated conditions including nicotine dependence and alcohol abuse and/or dependence.
Conclusions: ADHD in these extended Paisa families is highly comorbid with conduct and oppositional defiant disorders. This pattern of comorbidity, as well as the large dense pedigrees of the sample, suggests that it will be particularly useful for molecular genetic studies that are currently under way.