Executive functioning among Finnish adolescents with attention-deficit/hyperactivity disorder.

OBJECTIVE: The present study examined cognitive functioning in a population sample of adolescents with and without attention-deficit/hyperactivity disorder (ADHD) from the Northern Finland Birth Cohort 1986. METHOD: The sample consisted of 457 adolescents ages 16 to 18 who were assessed using a battery of cognitive tasks. Performance according to diagnostic group (control, behavior disorder, and ADHD) and sex was compared. Then, the effect of executive function deficit (EFD) was assessed by diagnostic group status on behavioral and cognitive measures. RESULTS: When compared to non-ADHD groups, adolescents with ADHD exhibited deficits on almost all of the cognitive measures. The behavior disorder group obtained scores that were generally intermediate between the ADHD and control groups, but exhibited deficits in intelligence and executive function similar to the ADHD group. Approximately half the ADHD sample had EFD; however, the type and presence of EFDs were not differentially related to cognitive performance as a function of diagnosis. CONCLUSIONS: These findings indicate that EFDs are more frequent in ADHD than control or behavior disorder groups. EFDs are a general risk factor for poor cognitive functioning across multiple domains, irrespective of diagnostic status.

Prevalence and psychiatric comorbidity of attention-deficit/hyperactivity disorder in an adolescent Finnish population.

OBJECTIVE: The purpose of the study was to estimate the prevalence of attention-deficit/hyperactivity disorder (ADHD) and its clinical characteristics in the Northern Finland Birth Cohort 1986. METHOD: A general population Northern Finland Birth Cohort 1986 of 9,432 children followed prospectively from the early fetal period was surveyed at adolescence (ages 16-18) for ADHD behaviors. Among 6,622 respondents to the survey, a subset of 457 likely cases and controls were evaluated for ADHD and other psychiatric disorders. Chi-square and descriptive statistics were used to examine clinical characteristics of ADHD in the subset, and logistic regression was used to estimate prevalence by weighted extrapolation in the larger cohort. RESULTS: The estimated prevalence of ADHD among adolescents in the Northern Finland Birth Cohort 1986 is 8.5% with a male/female ratio of 5.7:1. The distribution of ADHD subtypes among the ADHD adolescents is 28% Combined, 64% Inattentive, and 8% Hyperactive-Impulsive. A lifetime diagnosis of a broadly defined ADHD (probable or definite) had a prevalence of 18.2% with a male/female odds ratio (OR) of 3.2. This lifetime diagnosis of ADHD is significantly associated with anxiety (OR 2.4), mood (OR 2.9), and disruptive behavioral disorders (OR 17.3) in the cohort. CONCLUSIONS: ADHD is a common neurobehavioral disorder among Northern Finnish adolescents and significantly associated with psychiatric comorbidity in adolescence.