Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder with estimated worldwide prevalence of 7.2 % in children and adolescents. Comorbidity of psychiatric disorders is considered common in ADHD and has been found to contribute to poorer prognosis. Despite decades of research, the actual prevalence of comorbid psychiatric disorders in children and adolescents with ADHD is unclear. The purpose of this systematic review and meta-analysis was to investigate the prevalence of comorbid disorders in children and adolescents with ADHD. Embase OVID, Ovid MEDLINE and PsycINFO were systematically searched for eligible studies published up to February 2025. In total 121 studies involving 39,894 children and adolescents with ADHD diagnosis were included. The most common comorbid disorders were Oppositional Defiant Disorder (34.7 %), Behavior Disorders (30.7 %), Anxiety Disorders (18.4 %), Specific phobias (11.0 %), Enuresis (10.8 %), and Conduct Disorder (CD) (10.7 %). All individual disorders studied had a higher prevalence among children and adolescents with ADHD than in the general population. Few gender differences were found; higher prevalence of CD among boys and higher of OCD in girls. The findings indicate that comorbid psychiatric disorders are highly prevalent in children and adolescents with ADHD and must be considered in both assessment and treatment of ADHD. PROSPERO registration: ID CRD42022359965.

Objective: Studies on comorbidity in children diagnosed with ADHD have relied more on parent/teacher reports instead of self-reported data and have focused on the frequency of comorbid symptoms instead of scores above clinical cutoffs. The purpose of this study was to examine the prevalence of oppositional defiant disorder (ODD), anxiety, and depression in children with ADHD, using self-report measures for internalizing symptoms and parent-reported measures for externalizing symptoms for increased accuracy. Gender differences were also assessed. Method: Parents of 197 children diagnosed with ADHD answered the Disruptive Behavior Rating Scale, and 112 of the children filled out the Multidimensional Anxiety Scale for Children and the Children’s Depression Inventory. Results: Results revealed that 19.28% of the children met cut-off criteria for ODD, 41.96% for anxiety, and 21.43% for depression. Conclusion: Our findings indicate a relatively lower prevalence of ODD and a slightly higher prevalence of anxiety symptoms than previously reported. Possible explanations and future directions are discussed.

Background: More than 500 million people worldwide live within exposure range of an active volcano and children are a vulnerable subgroup of such exposed populations. However, studies on the effects of volcanic eruptions on children’s health beyond the first year are sparse. Objective: To examine the effect of the 2010 Eyjafjallajökull eruption on physical and mental health symptoms among exposed children in 2010 and 2013 and to identify potential predictive factors for symptoms. Method: In a population-based prospective cohort study, data was collected on the adult population (N = 1615) exposed to the 2010 Eyjafjallajökull eruption and a non-exposed group (N = 697). The exposed group was further divided according to exposure level. All participants answered questionnaires assessing their children´s and their own perceived health status in 2010 and 2013. Results: In 2010, exposed children were more likely than non-exposed children to experience respiratory symptoms (medium exposed OR 1.47; 95% CI 1.07–2.03; high exposed OR 1.52; 95% CI 1.03–2.24) and anxiety/worries (medium exposed OR 2.39; 95% CI 1.67–3.45; high exposed OR 2.77; 95% CI 1.81–4.27). Both genders had an increased risk of symptoms of anxiety/worries but only exposed boys were at increased risk of experiencing headaches and sleep disturbances compared to non-exposed boys. Within the exposed group, children whose homes were damaged were at increased risk of experiencing anxiety/worries (OR 1.62; 95% CI 1.13–2.32) and depressed mood (OR 1.55; 95% CI 1.07–2.24) than children whose homes were not damaged. Among exposed children, no significant decrease of symptoms was detected between 2010 and 2013. Conclusions: Adverse physical and mental health problems experienced by the children exposed to the eruption seem to persist for up to a three-year period post-disaster. These results underline the importance of appropriate follow-up for children after a natural disaster.