There are now hundreds of systematic reviews on attention deficit hyperactivity disorder (ADHD) of variable quality. To help navigate this literature, we have reviewed systematic reviews on any topic on ADHD.

We searched MEDLINE, PubMed, PsycINFO, Cochrane Library, and Web of Science and performed quality assessment according to the Joanna Briggs Institute Manual for Evidence Synthesis. A total of 231 systematic reviews and meta-analyses met the eligibility criteria.

The prevalence of ADHD was 7.2% for children and adolescents and 2.5% for adults, though with major uncertainty due to methodological variation in the existing literature. There is evidence for both biological and social risk factors for ADHD, but this evidence is mostly correlational rather than causal due to confounding and reverse causality. There is strong evidence for the efficacy of pharmacological treatment on symptom reduction in the short-term, particularly for stimulants. However, there is limited evidence for the efficacy of pharmacotherapy in mitigating adverse life trajectories such as educational attainment, employment, substance abuse, injuries, suicides, crime, and comorbid mental and somatic conditions. Pharmacotherapy is linked with side effects like disturbed sleep, reduced appetite, and increased blood pressure, but less is known about potential adverse effects after long-term use. Evidence of the efficacy of nonpharmacological treatments is mixed.

Despite hundreds of systematic reviews on ADHD, key questions are still unanswered. Evidence gaps remain as to a more accurate prevalence of ADHD, whether documented risk factors are causal, the efficacy of nonpharmacological treatments on any outcomes, and pharmacotherapy in mitigating the adverse outcomes associated with ADHD.

In 2017, a capacity-based criterion was added to the Norwegian Mental Health Act, stating that those with capacity to consent to treatment cannot be subjected to involuntary care unless there is risk to themselves or others. This was expected to reduce incidence and prevalence rates, and the duration of episodes of involuntary care, in particular regarding community treatment orders (CTOs).

The aim was to investigate whether the capacity-based criterion had the expected impact on the use of CTOs.

This retrospective case register study included two catchment areas serving 16% of the Norwegian population (aged ≥18). In total, 760 patients subject to 921 CTOs between 1 January 2015 and 31 December 2019 were included to compare the use of CTOs 2 years before and 2 years after the legal reform.

CTO incidence rates and duration did not change after the reform, whereas prevalence rates were significantly reduced. This was explained by a sharp increase in termination of CTOs in the year of the reform, after which it reduced and settled on a slightly higher leven than before the reform. We found an unexpected significant increase in the use of involuntary treatment orders for patients on CTOs after the reform.

The expected impact on CTO use of introducing a capacity-based criterion in the Norwegian Mental Health Act was not confirmed by our study. Given the existing challenges related to defining and assessing decision-making capacity, studies examining the validity of capacity assessments and their impact on the use of coercion in clinical practice are urgently needed.

Norway authorised out-patient commitment in 1961, but there is a lack of representative and complete data on the use of out-patient commitment orders.

To establish the incidence and prevalence rates on the use of out-patient commitment in Norway, and how these vary across service areas. Further, to study variations in out-patient commitment across service areas, and use of in-patient services before and after implementation of out-patient commitment orders. Finally, to identify determinants for the duration of out-patient commitment orders and time to readmission.

Retrospective case register study based on medical files of all patients with an out-patient commitment order in 2008–2012 in six catchment areas in Norway, covering one-third of the Norwegian population aged 18 years or more. For a subsample of patients, we recorded use of in-patient care 3 years before and after their first-ever out-patient commitment.

Annual incidence varied between 20.7 and 28.4, and prevalence between 36.5 and 48.9, per 100 000 population aged 18 years or above. Rates differed significantly between catchment areas. Mean out-patient commitment duration was 727 days (s.d. = 889). Use of in-patient care decreased significantly in the 3 years after out-patient commitment compared with the 3 years before. Use of antipsychotic medication through the whole out-patient commitment period and fewer in-patient episodes in the 3 years before out-patient commitment predicted longer time to readmission.

Mechanisms behind the pronounced variations in use of out-patient commitment between sites call for further studies. Use of in-patient care was significantly reduced in the 3 years after a first-ever out-patient commitment order was made.

None.