This study reports an increasing trend in Finland of diagnosis of ADHD, particularly among boys, and encourages clinicians to screen for ADHD among children diagnosed with other psychiatric disorders.
Using several Finnish nationwide patient registers,* all children/adolescents born in Finland between 1991 and 2005 and diagnosed with ADHD by 2011 were identified with a view to describing their demographic characteristics and psychiatric comorbidities. In addition, the validity of register-based diagnoses was tested via telephone interviewing a small sample of parents of children diagnosed with ADHD according to out-/inpatient records.
Of 10,409 children/adolescents diagnosed with ADHD and referred to specialist health centres, the majority were male (84.0%; male:female ratio 5.3:1). An increasing trend of ADHD diagnosis in the later birth cohorts compared with those born in 1991–1993 was observed; and the proportion of males with ADHD increased significantly between ages 5–15 years (in the cohort born in 1994–1996; p<0.001). Most patients (76.7%) with ADHD had at least one other psychiatric diagnosis, the most common of which were disorders related to learning and co-ordination (48.1%), conduct (28.1%), anxiety (13.6%), autism spectrum (12.0%) and depression (8.9%). Notably, while conduct disorders and autism spectrum disorders were significantly more common among males than females (p<0.05), learning and co-ordination, anxiety and depression disorders were significantly more common among females (p<0.05). Results of the telephone-based diagnostic validation study indicated that 61/69 (88%) of children met the full diagnostic criteria for ADHD.
The authors of this study highlight that with an increasing trend in ADHD diagnosis among children/adolescents in Finland, particularly in males, there is a need to more carefully examine females with hyperactivity and impulsivity. They also relay the clinical importance of screening for ADHD among patients with other psychiatric disorders. Although the study population was derived from specialist mental health centres and thus potentially represents those with more severe ADHD, and given that some patients may have been missed due to lack of adequate follow-up (i.e. children born in 2005 were only 6 at the end of the study in 2011), the results of this study provide a robust basis for future epidemiological studies in ADHD.
*Finnish Hospital Discharge Register; Finnish Central Population Register; Finnish Medical Birth Register
Joelsson P, Chudal R, Gyllenberg D, et al. Demographic characteristics and psychiatric comorbidity of children and adolescents diagnosed with ADHD in specialized healthcare. Child Psychiatry Hum Dev 2016; 47: 574-582.