The 33rd European Clinical Neuropsychopharmacology Congress (ECNP) virtual congress covered key topics and issues in ADHD, such as transition from child to adult services, adult ADHD, comorbid psychiatric conditions and tips and tricks to facilitate virtual care of individuals with ADHD during the COVID-19 pandemic.

Are dietary interventions for ADHD effective and feasible?

Professor J Antoni Ramos-Quiroga (Department of Psychiatry, Hospital Universitari Vall d’Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain) began by stating that interventions for ADHD must be: (1) effective in producing the desired or intended result; and (2) feasible such that they can be easily and conveniently implemented.

Professor Ramos-Quiroga then stated that gut microbiota and diet have an important role in the development and symptoms of different psychiatric disorders;1 therefore, investigating the brain–gut axis may be relevant for mental health. Moreover, he proposed that if the brain–gut axis can be modified then this may have implications for neurodevelopmental disorders, including ADHD.

Professor Ramos-Quiroga then discussed several possible dietary interventions for ADHD, including: introduction and elimination diets; micronutrients and omega 3 polyunsaturated fatty acids (PUFAs); and prebiotics/probiotics. He highlighted that there are inconsistencies in the data regarding the efficacy of diet interventions for ADHD and presented results from a systematic review of meta-analyses of double-blinded, placebo-controlled clinical trials that evaluated the effectiveness of these interventions in reducing ADHD symptoms in children.

The findings from these meta-analyses highlighted that due to the minimal effect of PUFA supplementation on ADHD symptoms, this does not appear to be an effective contributor to treatment of ADHD. Moreover, further studies are required to understand the effects of artificial food colour elimination on ADHD symptoms in children before this can be recommended as an intervention for ADHD treatment. However, Professor Ramos-Quiroga highlighted that the impact of a Few Foods diet on reducing ADHD symptoms in children was shown to be substantial in these meta-analyses, suggesting that this intervention could provide treatment opportunities in subgroups of children with ADHD who are either not responding to, or are too young to receive, ADHD-specific treatment. Professor Ramos-Quiroga highlighted that these meta-analyses suggested that further research into the effect of a Few Foods diet should be performed to simplify this intervention in children with ADHD.2

Professor Ramos-Quiroga then presented data from a separate systemic review and meta-analysis of clinical trials and biological studies that suggested omega 3 PUFA supplementation monotherapy improves the clinical symptoms and cognitive performance of children and adolescents with ADHD.3 Professor Ramos-Quiroga also discussed results from a study which suggested that adults with ADHD who were administered a symbiotic (a mixture of prebiotics and probiotics) demonstrated improvements in emotional regulation, particularly in goal-directed behaviour.4 Similarly, a study of children and adolescents with ADHD was presented which showed that supplementation with the probiotic strain Lactobacillus rhamnosus GG improved health-related quality of life, indicating that this could be a beneficial treatment for ADHD. Nevertheless, Professor Ramos-Quiroga emphasised that some study modifications were recommended by the authors, including a longer study observation period.5

Professor Ramos-Quiroga concluded his presentation by discussing the Eat2beNICE project which is a medical consortium funded by the European Union that investigates the connections between the gut microbiota, diet and exercise. The purpose of this medical consortium is to formulate nutrition and lifestyle recommendations for brain health. Eat2beNICE currently comprises of four clinical trials that will investigate the effects of elimination diets, broad-spectrum supplementation, probiotics and energy-restricted Mediterranean diets in conjunction with physical activity in children and adolescents or adults with ADHD.

Professor J Antoni Ramos-Quiroga: “Modification of the brain–gut axis may be relevant for modulating the symptoms of ADHD.”

Industry-sponsored symposium: An evidence-based approach to adult ADHD

(Educational financial support provided by Global Medical Education/Takeda)

Are we missing the diagnosis of adult ADHD?

Professor Alexandra Philipsen (Department of Psychiatry and Psychotherapy, University of Bonn, Bonn, Germany) opened this industry-sponsored symposium by stating that ADHD is a lifespan disorder. In her opinion, she felt there is a gap between the prevalence of ADHD described in population-based studies and the number of individuals who receive a clinical diagnosis of ADHD. Professor Philipsen stated that although diagnosis of ADHD among children, adolescents and adults has risen over the years, trends of diagnosis and pharmacotherapy in Germany, for example, suggest that adults with ADHD may still be underdiagnosed and undertreated.6 Professor Philipsen indicated that she feels adults with ADHD are “lost in transition” and clinicians should carefully monitor adolescents with ADHD during transition from child to adult mental health services.

Professor Philipsen then discussed why adult ADHD can often be missed and stated that she feels it has many overlapping clinical symptoms with other psychiatric disorders, such as borderline personality disorder. Professor Philipsen also noted that a diagnosis of ADHD can be overlooked as it is highly comorbid with other psychiatric disorders. She then presented data from a population-based cross-sectional study which showed that both males and females with adult ADHD were more likely to present with comorbid anxiety, bipolar disorder, depression and substance use disorder compared with adults without ADHD. Moreover, the prevalence of somatic disorders such as hypertension and type II diabetes mellitus were also higher in individuals with ADHD.7 Professor Philipsen highlighted that ADHD can also be comorbid with developmental disorders. For example, she indicated that the pooled prevalence of ADHD and autism spectrum disorders is 28% (95% confidence interval [CI], 25‒32).8

Professor Philipsen concluded her presentation by stating that, in her opinion, systematically screening for ADHD in high-risk populations is important. As an example, she stated that individuals presenting with substance use disorder should also be screened for comorbid ADHD, and evidence suggests that a diagnosis of ADHD can still be made, even during active substance use.9

Comorbid illnesses in adult ADHD

Professor Michael Huss (Child and Adolescent Psychiatry, Johannes Gutenburg University Mainz, Mainz, Germany) began his presentation by stating that ADHD is highly comorbid with other psychiatric disorders and overlapping symptoms may be exhibited. For instance, symptoms related to depression in adults (such as restlessness or psychomotor agitation and decreased attention or distractibility) exhibit symptomatic overlap with ADHD-related hyperactivity and inattention, respectively.10 Professor Huss then questioned whether ADHD could be a risk factor for depression and presented results from a study which suggested that methylphenidate may reduce the risk of suicide attempts during continuous treatment in a population-based study.11 In his opinion, Professor Huss highlighted that stressful life events could lead to depression which may be precipitated by comorbid ADHD; however, treating ADHD could have a modulatory effect on other comorbid psychiatric disorders such as depression.

Professor Huss also discussed the link between ADHD and eating disorders. He presented data from a systematic review that aimed to evaluate the potential association between ADHD symptoms and disordered eating behaviours. Results from this analysis highlighted that evidence exists for a positive association between ADHD and overeating behaviour and bulimia nervosa.12 Professor Huss then discussed the effects of ADHD treatment on comorbid psychiatric disorders or behaviours. He presented data from a meta-analysis which suggested that treatment of ADHD with stimulants is neither protective against nor increases the risk of later substance use disorders.13 However, stimulant treatment has been shown to reduce criminality in both males and females with ADHD. Professor Huss explained that in one study, ADHD treatment reduced the criminality rate by 32% in males and 41% in females with ADHD compared with non-treated periods.14 Professor Huss concluded his presentation by stating that together these studies suggest that, in his opinion, causality between ADHD and comorbid psychiatric disorders or behaviours is highly relevant.

Managing adult ADHD by the evidence

Professor J Antoni Ramos-Quiroga (Department of Psychiatry, Hospital Universitari Vall d’Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain) began his presentation by reiterating that ADHD is a lifespan disorder. He also highlighted that the mortality rate is higher in individuals with ADHD compared with those without ADHD (mortality rate ratio, 1.50 [95% CI 1.11‒1.98). Moreover, individuals with ADHD and comorbid psychiatric disorders, such as substance use disorder, oppositional defiant disorder and/or conduct disorder, have a higher mortality rate compared with individuals with a diagnosis of only ADHD.15

Professor Ramos-Quiroga then stated that the European Consensus Statement for the diagnosis and treatment of adult ADHD had recently been updated in 2019. He indicated that, according to these guidelines, treatment of adult ADHD should follow a multimodal and multidisciplinary approach, comprising of psychoeducation, pharmacotherapy, cognitive behaviour therapy and coaching for ADHD. Professor Ramos-Quiroga also stated, according to these guidelines, the first treatment step for adults with ADHD is psychoeducation. He then noted that first-line recommended pharmacotherapy for adult ADHD is stimulants. Long-lasting, extended-release formulations for stimulants are preferred due to:

  • Better adherence to treatment.
  • Protection against abuse.
  • Avoidance of rebound symptoms.
  • Safer driving.
  • Provision of cover throughout the day without the need for multiple dosing.

Professor Ramos-Quiroga noted that according to the updated European Consensus Statement 2019, the recommended second-line pharmacotherapy for adult ADHD is non-stimulants.16

Professor Ramos-Quiroga then noted that there are few head-to-head comparative studies of treatments for ADHD and discussed results of a systematic review and network meta-analyses that aimed to compare the efficacy and tolerability of ADHD-specific treatments for children, adolescents and adults with ADHD. The purpose of this analysis is to help inform individuals with ADHD, their families, clinicians, guideline developers and policymakers on the choice of ADHD treatment across age groups.17 Professor Ramos-Quiroga concluded his presentation by indicating that, in his opinion, adult ADHD is an under-treated disorder but specific guidelines are available to clinicians to provide stepwise management of ADHD.

Professor Alexandra Philipsen: “There is a gap in our healthcare systems, adolescents with ADHD are lost in the system when they transition from child to adult mental health services.”

Education update session: Suicidality in children and adolescents with externalising disorders

ADHD, suicide and non-suicidal self-injury

Dr Judit Balázs (Institute Psychology Eotvos Lorand University, Department of Developmental and Clinical Child Psychology, Budapest, Hungary) opened her presentation by highlighting that there are >800,0000 suicide deaths per year and that it is the second leading cause of death among 15–29 years olds.18 She went on to describe suicide as a “multifactorial event” with impulsivity and psychiatric comorbidities as key contributors. She noted that in the MTA study, only one third of the patients included had ADHD alone, and that oppositional defiant disorder, anxiety/depression and conduct disorder were the most common psychiatric comorbidities.19 She went on to explain that in Hungary, results from a study conducted at Vadaskert Child Psychiatry Hospital in Budpest found that the most common comorbid diagnoses with ADHD in children and adolescents were oppositional defiant disorder, conduct disorder and suicidal behaviour; and in adolescents the number of comorbid diagnoses with ADHD was higher than in children.20

Dr Balázs explained there is limited research on suicidality in children and adolescents with ADHD. A review of the literature by James et al. (2004)21 found an association between ADHD and completed suicide, however, the evidence for any direct or independent link was modest and that ADHD appeared to increase the risk of suicide in male patients via increasing severity of comorbid conditions, such as conduct disorder and depression. However, no studies have found a direct link between ADHD and suicide or investigated the effect of multiple psychiatric comorbidities on suicide. In a subsequent study of children and adolescents with treatment-naïve ADHD conducted at Vadaskert Child Psychiatry Hospital in Budpest, results showed that ADHD had an indirect effect on suicidality, which was moderated by age, and that in children under 12 years significant mediators were anxiety disorders; whilst in the adolescent group mood disorders and symptoms of substance abuse/dependence were significant mediators.22 Dr Balázs concluded from these studies the importance of early recognition of ADHD, as well as the importance of screening for comorbid psychiatric disorders, including suicidal behaviour, in children and adolescents.20,22

In the second half of the presentation, Dr Balázs discussed the relationship between ADHD and non-suicidal self-injury (NSSI), which she described as the deliberate, non-suicidal purpose of self-injury, which is not a culturally sanctioned behaviour.23 She went on to describe results from a study of 52 adolescents with ADHD at the Vadaskert Child Psychiatry Hospital in Budpest, which showed that 67% of them experienced NSSI and that it was more common in females than males. Multiple mediation analyses demonstrated that the relationship between ADHD symptoms and the prevalence of current NSSI was mediated by the comorbid symptoms in both males and females and that significant mediators were affective and psychotic disorders and suicidality in both genders, and the symptoms of alcohol abuse/dependence disorder in females.24 She concluded by stating that in order to prevent NSSI, clinicians should routinely screen for symptoms of ADHD and comorbidity, specifically focussing on the symptoms of affective disorders, psychotic disorders and alcohol abuse/dependence.

Risk factors for suicidality in children and adolescents with externalising disorders

Dr Tomer Levy (The Geha Mental Health Center Tel Aviv University, Behavioral Regulation Services, Petah Tikva, Israel) opened his presentation by describing the possible risk factors for suicidality in externalising disorders such as ADHD:

  • Direct effects: impulsivity, conduct problems, aggression and irritability.
  • Indirect effects: suicide-related comorbidities, substance use, family problems, social marginalisation, negative self-image, poor academic achievement and poor problem solving.

He went on to present results from the National Comorbidity Survey Replication – Adolescent Supplement, which showed that lifetime prevalence of psychiatric disorders in suicidal adolescents was highest in those patients with comorbid externalising disorder such as major depressive disorder, oppositional defiant disorder and conduct disorders.25

Dr Levy then went on to specifically discuss ADHD and suicidality. He began by highlighting that ADHD confers a greater risk of suicidality and that comorbidities play a major role in the ADHD–suicidality association.22 He went on to explain that it is both the inattention and impulsivity/hyperactivity symptoms associated with this risk; and that this association was indirect and fully mediated by symptoms of depression, irritability and anxiety. He concluded that assessing these symptoms may enable an estimate of suicidality and help managing suicidal risk in ADHD.26

Dr Balázs: “Patients with ADHD can be a risk group for suicidality and NSSI and we should consider this in diagnosis and in further research.”

Industry-Sponsored Symposium: Discovering ADHD in adults: transition and comorbidities

(Educational financial support provided by Global Medical Education/Takeda)

Achieving optimal transition in ADHD

Professor Swaran Singh (Department of Mental Health and Wellbeing, Warwick Medical School, University of Warwick, Warwick, UK) began his presentation by stating that, in his opinion, the fields of child and adult psychiatry have developed in two different trajectories such that their respective services may operate differently. Professor Singh highlighted that as a result of these differences in services, he became interested in what happens when adolescents with mental health problems transition from child and adolescent mental health services (CAMHS) to adult mental health services (AMHS). He then presented conclusions from the TRACK study which evaluated the process, outcomes and user and carer experience of adolescents’ transition from CAMHS to AMHS. The results of this study showed that adolescents with neurodevelopmental disorders (such as ADHD), emerging anxiety disorders and mood disorders fell through the gap when transitioning from CAMHS to AMHS. Moreover, for adolescents who were transferred to AMHS, the transition care was poorly planned, poorly executed and poorly experienced. Professor Singh highlighted that in this study, “optimal transition” was defined as adequate transition planning, good transfer between CAMHS and AMHS, joint working between CAMHS and AMHS teams and continuity of care following transition. Professor Singh indicated that for adolescents who did transition successfully from CAMHS to AMHS (<5%), most stayed engaged with AMHS and reported improvements in their mental health.27

Professor Singh then discussed the National Institute for Health and Care Excellence guidance on supporting adolescents with mental health problems in their transition to AMHS,28 and emphasised that this is an important aspect of clinical care for adolescents with ADHD. Professor Singh then presented data from a study that assessed the characteristics and activities of CAMHS in 28 countries in the European Union. The findings from this study indicated considerable variations in the following between countries:29

  • Availability of services.
  • Number of inpatient beds.
  • Number of clinicians.
  • Number of organisations.
  • Delivery of specific CAMHS.
  • Availability of treatments.

Professor Singh highlighted that the transition age from CAMHS to AMHS did vary between these countries but for the majority of adolescents, transition between services occurred at the age of 18 years. The findings from this study, as emphasised by Professor Singh, highlighted that for example, the number of CAMHS ranged from 12.9 per 100,000 adolescents in Finland to 0.5 per 100,000 adolescents in Bulgaria.29 Professor Singh concluded his presentation by stating that, in his opinion, this does not reflect the difference in epidemiology of mental health problems in adolescents across these countries but instead reflects how services are differently resourced across countries.

ADHD and substance use disorder in adult patients

Dr Vanesa Richarte (Department of Psychiatry, Hospital Universitari Vall d’Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain) began her presentation by stating that ADHD is a complex and multifactorial disorder. Dr Richarte stated that “a single piece of the puzzle could not explain ADHD” as a combination of environmental risk factors and genes give rise to ADHD. She then highlighted that ADHD varies across the lifespan and that, in her opinion, smoking, alcohol and drug experimentation in adolescents with ADHD could lead to alcohol and substance misuse during adulthood. Dr Richarte then opined that for many psychiatric disorders, ADHD is an underlying hidden disorder.

Dr Richarte stated that individuals with childhood ADHD have a 1.8 times higher risk for developing psychoactive substance use disorder and a 8.6 times higher risk for nicotine dependence compared with individuals without ADHD.30 She also noted that individuals with comorbid ADHD and substance use dependence have a higher severity of substance use dependence, more frequent polysubstance dependence and an increased risk for other psychiatric disorders such as mood or borderline personality disorder.31 Dr Richarte then discussed the results of a meta-analyses of genome-wide association studies of ADHD and lifetime cannabis use. The findings from this study indicated that there is a causal relationship between ADHD and subsequent cannabis use (odds ratio 7.9 [95% CI 3.72‒15.51] versus individuals without ADHD). Dr Richarte also highlighted that this study suggested there is a genetic overlap between ADHD and cannabis use, with 29% of the genetic basis of ADHD sharing likelihood of cannabis consumption. Moreover, four new genome-wide significant loci were identified in the meta-analyses linking ADHD and cannabis use. Based on the results from this study, Dr Richarte summarised the following conclusions:32

  • Children and adolescents with ADHD have an increased risk of future cannabis use.
  • Preventative programmes for cannabis use in the context of psychiatric disorders should be established.
  • Research into the underlying biological mechanisms of ADHD and cannabis use should be continued.
  • Using genetic information to identify individuals with ADHD most vulnerable for cannabis use would enable prevention, early detection and treatment.

Dr Richarte then highlighted that, in her opinion, the results of the meta-analyses act as a starting point for future research, which has the potential to make a positive impact on public health. However, she stated that the number of studies in this field of research must increase, this type of research must be extended to other substance use disorders and research is warranted to find effective therapies for both substance use disorder and ADHD.

Next, Dr Richarte mentioned the International Consensus Statement on the screening, diagnosis and treatment of substance use disorder in individuals with comorbid ADHD. She went on to emphasise that individuals with substance use disorder should always be screened for ADHD using appropriate screening scales. Dr Richarte also highlighted that in up to 20% of cases, a diagnosis of ADHD can be missed when only a single ADHD screening scale is used; therefore, using two screening scales is recommended when possible. Dr Richarte also indicated that symptoms associated with an individual’s substance use may be incorrectly identified as ADHD-related symptoms; therefore, it is important for clinicians to focus on alcohol- and drug-free periods in an individual’s life when assessing for ADHD.33

Dr Richarte then discussed statements from other guidelines available for the management of individuals with ADHD and comorbid substance use disorder. For example, the Canadian ADHD Practice Guidelines which state that:34

  • In most cases, ADHD and substance use disorder need to be treated concurrently and independently when comorbid.
  • Psychostimulants taken orally do not have the same abuse liability as illicit stimulants (e.g. cocaine) due to slower dissociation from the site of action, slower uptake into the striatum and slower binding and dissociation with the dopamine transporter.
  • Non-stimulant and long-acting psychostimulants have less abuse potential than immediate-release preparations of psychostimulants.

Dr Richarte concluded her presentation by highlighting that the risk for stimulant misuse and diversion may be higher in individuals with ADHD and comorbid substance use disorder; therefore, an individualised risk–benefit assessment must be performed by the treating clinician.35

Professor Singh: “ADHD fell through the care gap…when we looked at individual experiences, some of the most shocking and the most extraordinary outcomes, in terms of poor outcomes, were for young people with ADHD…they had nowhere to go. They receive all of this [mental health] care until they are aged 18 years and then suddenly it disappears.”

ADHD: Virtual diagnosis and follow-up in adult women with depression/anxiety

Dr Pratap Chokka (University of Alberta, Edmonton, Canada) began his presentation by stating that, in his opinion, the majority of children and adolescents with ADHD do not outgrow the disorder during adulthood. He opined that ADHD is the most common psychiatric disorder in childhood and adolescence which progresses through the lifespan. Dr Chokka expressed that one of the greatest tragedies of ADHD is that the disorder is either not diagnosed, misdiagnosed or not adequately treated. He then presented data highlighting that children with ADHD are at a greater risk of poor long-term outcomes in adulthood and have a greater risk of mortality compared with the general population.15,36 Dr Chokka also emphasised that ADHD is highly comorbid with other psychiatric disorders, resulting in a higher disease burden and greater severity of illness.37

Dr Chokka then discussed ADHD in females and presented evidence suggesting symptoms of ADHD may vary across the menstrual cycle in response to hormone changes.38 Dr Chokka indicated that, in his opinion, these findings could have implications on the development of gender-specific treatment strategies for ADHD. Next, Dr Chokka discussed ADHD and comorbid eating disorders, and highlighted that females with ADHD are 3.6 times more likely to meet the criteria for an eating disorder compared with females without ADHD. Dr Chokka highlighted that eating disorders in females with ADHD also further increases the risk of anxiety, depression and disruptive behaviour disorders.39 Therefore, in his opinion, Dr Chokka said that it is important for clinicians to screen for ADHD in individuals presenting with an eating disorder. Dr Chokka then highlighted that the menopausal transition is a time of increased vulnerability to cognitive decline and aspects of executive functioning.40 Dr Chokka stated that, in line with published studies, optimal management of ADHD should continue in older adults,41 and in his opinion, clinicians should not be afraid of diagnosing ADHD in the elderly. The next topic of discussion was ADHD and pregnancy. Dr Chokka indicated that hormonal fluctuations during pregnancy has the potential to exacerbate symptoms of ADHD.42 Dr Chokka presented results from a cohort study of 1,813,894 pregnancies in the United States which suggested that there was a small increase in the risk of foetal cardiac malformations as a result of intrauterine exposure to methylphenidate but not amfetamine.43 Dr Chokka stated that, in his opinion, the risk–benefit ratio of keeping individuals with ADHD on stimulant medication during pregnancy must be considered.

The next section of Dr Chokka’s presentation included tips and tricks to facilitate virtual care of individuals with ADHD during the COVID-19 pandemic. He emphasised that Telehealth enables clinicians to continue to provide treatment to both existing and new individuals with ADHD remotely; however, some adaptations to practice may be required. Dr Chokka highlighted that the Canadian ADHD Resource Alliance has developed a document of frequently asked questions to aid management of individuals with ADHD during the pandemic.44 Briefly, Dr Chokka highlighted the following points:

  • Prior to consultation, any ADHD assessment rating scales should be sent in advance to the patient with instructions. If video conferencing software is used, the clinician should make sure the patient understands how to access the system.
  • It is important for clinicians to consider patient confidentiality when at home and also patient safety when providing a virtual consultation.
  • Clinicians should still provide patient education and encourage the patient to maintain a structured schedule, eat nutritious meals and engage in physical activity to aid attention and reduce anxiety.
  • Access to medications can still be facilitated virtually and longer prescriptions may be required for patients; dose adjustments can also still be made during this time.
  • It may be challenging to monitor the effectiveness of ADHD treatment in patients virtually, particularly as patients may not be in school or work due to COVID-19. Nevertheless, rating scales for ADHD should still be completed periodically by the patient to monitor treatment responses.
  • It is important for clinicians to connect with the patient and/or their family every few weeks, even for a short period of time.

Dr Chokka concluded his presentation by showing data from two studies, which highlighted that adequate treatment of ADHD in adolescence leads to improvements in functioning and reduced risk of psychiatric comorbidities.45,46 Dr Chokka then emphasised that early identification of ADHD in childhood and adolescence can prevent the development of secondary impairment and comorbidity in adulthood.

Dr Chokka: “ADHD can be a launching pad for prevention, especially secondary prevention. I think more than any other brain disorder in psychiatry, treating ADHD early may actually prevent morbidity, mortality and decrease the impact of secondary comorbidities.”

Disclaimer: The views expressed here are the views of the presenting physicians and not those of Takeda

  1. Richarte V, Rosales K, Corrales M, et al. The gut-brain axis in attention deficit hyperactivity disorder: the role of the microbiota. Rev Neurol 2018; 66: S109-S114.
  2. Pelsser LM, Frankena K, Toorman J, et al. Diet and ADHD, reviewing the evidence: a systematic review of meta-analyses of double-blind placebo-controlled trials evaluating the efficacy of diet interventions on behavior of children with ADHD. PLoS One 2017; 12: e0169277.
  3. Chang JP-C, Su K-P, Mondelli V, et al. Omega-3 polyunsaturated fatty acids in youths with attention deficit hyperactivity disorder: a systematic review and meta-analysis of clinical trials and biological studies. Neuropsychopharmacology 2018; 43: 534-545.
  4. Skott E, Yang LL, Stiernborg M, et al. Effects of a synbiotic on symptoms, and daily functioning in attention deficit hyperactivity disorder – A double-blind randomized controlled trial. Brain Behav Immun 2020; S0889-1591(20)30057.
  5. Kumperscak HG, Gricar A, Űlen A, et al. A pilot randomized control trial with the probiotic strain Lactobacillus rhamnosus GG (LGG) in ADHD: children and adolescents report better health-related quality of life. Front Psychiatry 2020; 11: 181.
  6. Bachmann CJ, Philipsen A, Hoffmann F. ADHD in Germany: trends in diagnosis and pharmacotherapy. Dtsch Arztebl Int 2017; 114: 141-148.
  7. Chen Q, Hartman CA, Haavik J, et al. Common psychiatric and metabolic comorbidity of adult attention-deficit/hyperactivity disorder: A population-based cross-sectional study. PLoS One 2018; 13: e0204516.
  8. Lai M-C, Kassee C, Besney R, et al. Prevalence of co-occurring mental health diagnoses in the autism population: a systematic review and meta-analysis. Lancet Psychiatry 2019; 6: 819-829.
  9. van Emmerik-van Oortmerssen K, Vedel E, Kramer FJ, et al. Diagnosing ADHD during active substance use: feasible or flawed? Drug Alcohol Depend 2017; 180: 371-375.
  10. Kooij JJS, Huss M, Asherson P, et al. Distinguishing comorbidity and successful management of adult ADHD. J Atten Disord 2012; 16: 2S-19S.
  11. Man KKC, Coghill D, Chan EW, et al. Association of risk of suicide attempts with methylphenidate treatment. JAMA Psychiatry 2017; 74: 1048-1055.
  12. Kaisari P, Dourish CT, Higgs S. Attention deficit hyperactivity disorder (ADHD) and disordered eating behaviour: a systematic review and a framework for future research. Clin Psychol Rev 2017; 53: 107-121.
  13. Humphreys KL, Eng T, Lee SS. Stimulant medication and substance use outcomes: a meta-analysis. JAMA Psychiatry 2013; 70: 740-749.
  14. Lichtenstein P, Halldner L, Zetterqvist J, et al. Medication for attention deficit-hyperactivity disorder and criminality. N Engl J Med 2012; 367: 2006-2014.
  15. Dalsgaard S, Østergaard SD, Leckman JF, et al. Mortality in children, adolescents, and adults with attention deficit hyperactivity disorder: a nationwide cohort study. Lancet 2015; 385: 2190-2196.
  16. Kooij JJS, Bijlenga D, Salerno L, et al. Updated European Consensus Statement on diagnosis and treatment of adult ADHD. Eur Psychiatry 2019; 56: 14-34.
  17. Cortese S, Adamo N, Del Giovane C, et al. Comparative efficacy and tolerability of medications for attention-deficit hyperactivity disorder in children, adolescents, and adults: a systematic review and network meta-analysis. Lancet Psychiatry 2018; 5: 727-738.
  18. World Health Organization. Mental health – Suicide data. Available at Last accessed September 2020.
  19. Jensen PS, Hinshaw SP, Swanson JM, et al. Findings from the NIMH Multimodal Treatment Study of ADHD (MTA): implications and applications for primary care providers. J Dev Behav Pediatr 2001; 22: 60-73.
  20. Keresztény A, Dallos G, Miklósi M, et al. A gyeremek és serdülkokori Figyelemhiányos-hiperaktivvitás zavar kmorbiditásainak összehasonlitása [Comparing the comorbidity of attention-deficit/hyperactivity disorder in childhood and adolescence]. Psychiatr Hung 2012; 27: 165-173.
  21. James A, Lai FH, Dahl C. Attention deficit hyperactivity disorder and suicide: a review of possible associations. Acta Psychiatr Scand 2004; 110: 408-415.
  22. Balazs J, Miklósi M, Keresztény A, et al. Attention-deficit hyperactivity disorder and suicidality in a treatment naïve sample of children and adolescents. J Affect Disord 2014; 152-154: 282-287.
  23. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. 2013
  24. Balázs J, Győri D, Horváth LO, et al. Attention-deficit hyperactivity disorder and nonsuicidal self-injury in a clinical sample of adolescents: the role of comorbidities and gender. BMC Psychiatry 2018; 18: 34.
  25. Nock MK, Green JG, Hwang I, et al. Prevalence, correlates, and treatment of lifetime suicidal behavior among adolescents: results from the National Comorbidity Survey Replication Adolescent Supplement. JAMA Psychiatry 2013; 70: 300-310.
  26. Levy T, Kronenberg S, Crosbie J, Schachar RJ. Attention-deficit/hyperactivity disorder (ADHD) symptoms and suicidality in children: The mediating role of depression, irritability and anxiety symptoms. J Affect Disord. 2020; 265: 200-206.
  27. Singh SP, Paul M, Ford T, et al. Process, outcome and experience of transition from child to adult mental healthcare: multiperspective study. Br J Psychiatry 2010; 197: 305-312.
  28. Singh S, Anderson B, Liabo K, et al. Supporting young people in their transition to adults’ services: a summary of NICE guidance. BMJ 2016; 11: i2225.
  29. Signorini G, Singh S, Boricevic-Marsanic V, et al. Architecture and functioning of child and adolescent mental health services: a 28-country survey in Europe. Lancet Psych 2017; 4: 715-724.
  30. Groenman AP, Oosterlaan J, Rommelse N, et al. Substance use disorder in adolescents with attention deficit hyperactivity disorder: a four-year follow-up study. Addiction 2013; 108: 1503-1511.
  31. Icick R, Moggi F, Slobodin O, et al. Attention deficit/hyperactivity disorder and global severity profiles in treatment-seeking patients with substance use dependence. Eur Addict Res 2020; 26: 201-210.
  32. Solar Artigas M, Sánchez-Mora C, Rovira P, et al. Attention-deficit/hyperactivity disorder and lifetime cannabis use: genetic overlap and causality. Mol Psychiatry 2019; Epub ahead of print.
  33. Crunelle CL, van de Brink W, Moggi F, et al. International Consensus Statement on Screening, Diagnosis and Treatment of Substance Use Disorder Patients with Comorbid Attention Deficit/Hyperactivity Disorder. Eur Addict Res 2018; 24: 43-51.
  34. Canadian ADHD Resource Alliance (CADDRA): Canadian ADHD Practice Guidelines, Edition 4.1, Toronto ON; CADDRA, 2020.
  35. Mariani JJ and Levin FR. Treatment strategies for co-occurring ADHD and substance use disorders. Am J Addict 2007; 16: 45-56.
  36. Klein RG, Mannuzza S, Ramos Olazagasti MA, et al. Clinical and functional outcome of childhood attention-deficit/hyperactivity disorder 33 years later. Arch Gen Psych 2012; 69: 1295-1303.
  37. Katzman MA, Bilkey TS, Chokka PR, et al. Adult ADHD and comorbid disorders: clinical implications of a dimensional approach. BMC Psych 2017; 17: 302.
  38. Roberts B, Eisenlohr-Moul T, Martel MM. Reproductive steroids and ADHD symptoms across the menstrual cycle. Psychoneuroendocrinology 2018; 88: 105-114.
  39. Biederman J, Ball SW, Monuteaux MC, et al. Are girls with ADHD at risk for eating disorders? Results from a controlled, five-year prospective study. J Dev Behav Pediatr 2007; 28: 302-307.
  40. Weber MT, Maki PM, McDermott MP. Cognition and mood in perimenopause: a systematic review and meta-analysis. J Steriod Biochem Mol Biol 2014; 142: 90-98.
  41. Torgersen T, Gjervan B, Lensing MB, et al. Optimal management of ADHD in older adults. Neuropsychiatr Dis Treat 2016; 12: 79-87.
  42. Freeman M. ADHD and pregnancy. Am J Psychiatry 2014; 171: 723-728.
  43. Huybrechts KF, Bröms G, Christensen LB, et al. Association between methylphenidate and amphetamine use in pregnancy and risk of congenital malformations: A cohort study from the International Pregnancy Safety Study Consortium. JAMA Psychiatry 2018; 75: 167-175.
  44. Canadian ADHD Resource Alliance (CADDRA). ADHD and COVID-19: Frequently asked questions (FAQ). Accessed September 2020.
  45. Biederman J, Monuteaux MC, Spencer T, et al. Do stimulants protect against psychiatric disorders in youth with ADHD? A 10-year follow-up study. Pediatrics 2009; 124: 71-78.
  46. Biederman J, DiSalvo M, Fried R, et al. Quantifying the protective effects of stimulants on functional outcomes in attention-deficit/hyperactivity disorder: A focus on number needed to treat statistic and sex effects. J Adolesc Health 2019; 65: 784-789.