Excess mortality

Using UK primary care data from approximately 30 000 adults with ADHD and matched controls, O’Nions et al (Reference O’Nions, El Baou and John2025) estimated a reduction in life expectancy of 6.78 years (95% CI 4.50–9.11) for males and 8.64 years (95% CI 6.55–10.91) for females. The study drew on data from 792 general practices serving approximately 9.5 million people. Although socioeconomic status and race/ethnicity were not adjusted for, the findings provide one of the strongest contemporary estimates of reduced life expectancy among adults with ADHD.

Similar findings have been reported internationally. In a systematic review and meta-analysis of neurodevelopmental disorders, Catalá-López et al (Reference Catalá-López, Hutton and Page2022) identified eight ADHD studies, involving 396 488 participants, and found that ADHD was associated with a twofold increase in all-cause mortality (RR = 2.13, 95% CI 1.13–4.02). Mortality from natural causes was not significantly increased (RR = 1.62, 95% CI 0.89–2.96), whereas mortality from unnatural causes, including injury and suicide, was substantially increased (RR = 2.81, 95% CI 1.73–4.55). The authors also reported a more than fourfold increase in mortality risk by midlife. Mortality appeared higher among females (RR = 2.84, 95% CI 1.02–7.89) than males (RR = 2.43, 95% CI 1.01–5.83). The included studies were drawn from the USA, Denmark, Finland, Sweden and Taiwan, although heterogeneity across studies was considerable.

Suicide risk

Suicide appears to be an important contributor to this excess mortality. In a Danish prospective cohort study of 1.92 million individuals, including 32 061 people with ADHD, Dalsgaard et al (Reference Dalsgaard, Østergaard and Leckman2015, cited in Faraone Reference Faraone, Banaschewski and Coghill2021) reported a 5.85-fold increased risk of suicide compared with 2.21 in those without ADHD, even after adjustment for comorbid depression and substance misuse. A meta-analysis by Septier et al (Reference Septier, Stordeur and Zhang2019, cited in Faraone Reference Faraone, Banaschewski and Coghill2021) similarly found elevated risks of suicidal ideation (OR = 3.53, 95% CI 2.94–4.25), suicide attempts (OR = 2.37, 95% CI 1.64–3.43) and completed suicide (OR = 6.69, 95% CI 3.24–17.39). Austgulen et al’s systematic review (Reference Austgulen, Skram and Haavik2023) identified ADHD symptom severity and persistence, female gender, family history of ADHD, childhood and parental factors, and impaired social functioning as risk factors for suicidal behaviours. Importantly, elevated risk persisted after adjustment for psychiatric comorbidity.

It is worth clarifying that the evidence of association between ADHD and completed suicide is less clear compared with the evidence of association with suicide attempts. Registry studies show that taking ADHD medication is associated with lower rates of suicide attempts (Zhang Reference Zhang, Zhu and Sjölander2025).

Summary

Taken together, the literature on life expectancy in ADHD is relatively recent but warrants urgent policy attention. The available evidence suggests that adults with ADHD are at increased risk of premature mortality compared with the general population. The excess mortality appears to be largely attributable to unnatural causes, particularly injury and suicide, and to have been observed across various high-income countries. Although the evidence remains limited, females may be at particularly high risk.

Changing epidemiology

Recent studies suggest that the epidemiology of diagnosed adult ADHD may be changing. In the UK, McKechnie et al (Reference McKechnie, O’Nions and Dunsmuir2023) reported substantial increases in ADHD diagnoses and prescribing for females in primary care between 2000 and 2018. Similar trends have been observed elsewhere. Hu et al (Reference Hu, Desai and Au2025) found increasing rates of incident adult ADHD diagnoses among females in British Columbia, Canada, between 2013 and 2023, and Westman et al (Reference Westman, Prami and Kallio2025) reported increasing rates of ADHD diagnosis across age groups in Finland, with particularly marked increases among females. Martin et al (Reference Martin, Langley and Cooper2024), using population healthcare records from Wales, found that sex differences in ADHD diagnosis varied according to age at diagnosis. The highest male:female ratio was observed among those diagnosed before the age of 12 years (4.8:1), whereas the lowest ratio was observed among those diagnosed after the age of 18 years (1.9:1). Collectively, these findings suggest that females are increasingly being recognised and diagnosed with ADHD in adulthood.

Diagnostic and treatment delays

Despite these trends, evidence suggests that females continue to experience delays in diagnosis and treatment. In a Swedish population register study involving approximately 85 000 individuals with ADHD, Skoglund et al (Reference Skoglund, Sundström Poromaa and Leksell2024) found that females were diagnosed and treated approximately 4 years later than males (95% CI 3.74–4.11). Thus, although the gap in rates of diagnosis may be narrowing, females continue to experience delays in gaining access to diagnosis and treatment.

The consequences of missed or delayed diagnosis may be considerable. In a systematic review of qualitative studies, Attoe & Climie (Reference Attoe and Climie2023) found that females with ADHD commonly reported low self-esteem, anxiety, stress and difficulties in interpersonal relationships prior to diagnosis. Receiving a diagnosis was frequently associated with relief, improved self-understanding and reduced self-criticism. However, the available evidence remains limited by relatively small sample sizes and a predominance of studies conducted in high-income countries.

Summary

Overall, the available evidence suggests differences in how adult females may experience ADHD, including more complex clinical presentations and greater psychiatric and emotional comorbidity. These factors may contribute to delayed recognition and treatment. Herein lies a gap where greater awareness among clinicians, alongside ongoing refinement of diagnostic frameworks and clinical guidance, may help reduce inequities in access to timely assessment and treatment.

Diagnosis

Asian, Black and Hispanic youths are thought to be underdiagnosed relative to White youths, despite similar symptom levels. Shi et al (Reference Shi, Hunter Guevara and Dykhoff2021) examined data on 238 011 insured children in the USA and found that ADHD was diagnosed significantly less often in Asian (3.2%), Black (6.0%) and Hispanic (9.1%) children than in White children (78.8%) (P < 0.001).

Chung et al (Reference Chung, Jiang and Paksarian2019) examined adult ADHD prevalence and incidence across seven racial and ethnic groups in the USA. Among more than five million adults aged 25–34 years, prevalence increased across all groups over the 10-year study period. White adults consistently had the highest prevalence rates, whereas Asian American adults had the lowest. White race was associated with significantly greater odds of receiving an ADHD diagnosis (e.g. Asian versus White patients: OR = 0.248, 95% CI 0.240–0.257; P < 0.001). However, participants were drawn from a single healthcare organisation in Northern California, limiting generalisability.

Shalaby et al (Reference Shalaby, Sengupta and Williams2024) analysed 41 million anonymised electronic health records from a US insurance database. Aside from the hyperactive subtype, ADHD diagnoses were significantly less common in Black than in White individuals. Diagnosis rates declined after adolescence in the Black population, whereas White individuals showed disproportionately higher rates of diagnosis between 18 and 40 years of age. The study did not adjust for socioeconomic or insurance status, both of which may influence access to diagnosis. These findings are consistent with underrecognition of ADHD in some Black and minority ethnic populations rather than over-diagnosis among White populations. They may also reflect implicit biases that contribute to service-seeking behaviours being misinterpreted as stimulant-seeking behaviours.

Treatment

Following diagnosis, disparities in treatment persist, at least in the USA. Black, Hispanic and Asian children in the USA are less likely than White children to receive ADHD-specific care, including medication and mental health visits (Yang Reference Yang, Flores and Carson2022). Similarly, Shi et al (Reference Shi, Hunter Guevara and Dykhoff2021) found lower odds of treatment among Asian (OR = 0.54, 95% CI 0.42–0.70), Hispanic (OR = 0.57, 95% CI 0.48–0.67) and Black children (OR = 0.79, 95% CI 0.64–0.98). Medication patterns also differ, with Black and Asian children receiving fewer ADHD medications, while Black and Hispanic children show higher rates of treatment discontinuation (Yang Reference Yang, Flores and Carson2022; Cummings Reference Cummings, Ji and Allen2017). Although ethnic differences are less pronounced for psychosocial interventions, Black and Hispanic adolescents remain less likely to receive psychosocial therapy (Adams et al Reference Adams, Riley and Quinn2024). In educational settings, behavioural symptoms in Black children are more likely to result in disciplinary action, whereas White children with similar presentations are more often referred for therapeutic or behavioural interventions (Skiba Reference Skiba, Michael and Nardo2002).

However, these findings remain contested. Cénat et al (Reference Cénat, Blais-Rochette and Morse2021) reported a pooled ADHD prevalence of 14.54% (95% CI 10.64%–19.56%) among Black individuals in the USA. The authors suggested that this may reflect the inclusion of studies involving youths from lower socioeconomic backgrounds. Only two studies included adults, precluding conclusions regarding adult populations. In a subsequent meta-analysis, Cénat et al (Reference Cénat, Kokou-Kpolou and Blais-Rochette2024) found no significant difference in ADHD prevalence between Black and White youths, suggesting that prevalence may be more similar than previously thought.

Summary

Although the evidence remains mixed, racial and ethnic disparities appear to exist in childhood ADHD diagnosis, treatment access and treatment patterns. These differences may extend into adolescence and young adulthood. Evidence regarding disparities in adult ADHD remains limited. Taken together, the findings suggest that Black, Asian and Hispanic adults may be less likely to have ADHD recognised during childhood or early adulthood, increasing their vulnerability to adverse outcomes. Further efforts are needed to improve recognition and access to care in these populations.

Transition to adult services

Adolescents with ADHD form the largest group of patients requiring transition from child and adolescent mental health services (CAMHS) to adult mental health services. However, they remain at risk of falling through gaps in service provision. A systematic review by Price et al (Reference Price, Janssens and Woodley2019) found that the experiences of young people transitioning between services were predominantly negative. These challenges arise largely in healthcare systems where child and adult services are separately commissioned and organised.

Despite growing recognition of ADHD in adults, service provision remains variable. The UK NICE guideline on ADHD (NICE 2018) recommends that adults requiring assessment should be referred to a mental health specialist with training in the diagnosis and treatment of the disorder. Responsibility for ongoing care is placed with healthcare professionals possessing appropriate expertise in ADHD management. This specialist-led model presents challenges when applied to a relatively common condition, particularly in health systems already facing workforce and capacity constraints.

The impact of this can be seen in attitudes to service provision. In a survey of psychiatrists in South Australia, Cao et al (Reference Cao, Deakin and Gill2024) found that some clinicians did not feel adequately equipped, trained or resourced to treat adults with ADHD. Such concerns may contribute to variations in service availability and access to care.

Care pathways and prescribing practices

Care pathways differ internationally. In the Republic of Ireland, the Health Service Executive has developed a National Clinical Programme for ADHD in Adults, whereby referrals from general practitioners are initially assessed within general adult mental health services before onward referral to regional specialist ADHD teams where indicated (Health Service Executive 2021). In contrast, Canadian guidelines permit assessment and management within primary care settings by appropriately trained clinicians and do not restrict key elements of diagnosis or treatment to specialist services alone (Canadian ADHD Resource Alliance 2020). This potentially allows more timely access to care if expertise exists outside specialist services.

Differences are also evident in medication availability and prescribing practices. In Japan, strict controls on amphetamines have resulted in greater reliance on methylphenidate and atomoxetine (Sasaki Reference Sasaki, Tsujii and Sasaki2021). France historically restricted stimulant prescribing because of concerns regarding misuse, with methylphenidate being the only approved stimulant for treatment of ADHD in children since July 1995 (Frances et al Reference Frances, Hoizey and Millart2004). For an extended period in Saudi Arabia, methylphenidate and atomoxetine were the only ADHD-specific medications available (Saudi ADHD Society 2016).

These international differences highlight the absence of a single model for adult ADHD care. These differences extend beyond service organisation and service models to medication availability. Consistent with this, ADHD-specific medications are not currently included in the WHO’s essential medicines list (WHO 2023b).

Service capacity

To address service capacity, the Taskforce called on integrated care boards (ICBs), commissioners and service providers to urgently reduce waiting times and evaluate service performance through ongoing audits and quality improvement processes. It recommended that triage should not rely solely on screening questionnaires, but should be informed by clinical judgement and overseen by appropriately experienced clinicians.

A central recommendation was the adoption of a stepped-care model, with greater involvement of primary care in the assessment and management of ADHD. The report proposed that general practices be supported and incentivised to undertake aspects of ADHD care, alongside more integrated support across health, social care, education and other agencies. It also endorsed task-sharing and task-shifting as potential approaches to expanding workforce capacity and capability.

The stepped-care model appears to be the most practical of the five service models proposed by Smith et al (Reference Smith, Mukherjee and Müller-Sedgwick2024) for the UK. However, Bhattacharya (Reference Bhattacharya2024) argued that implementation may be hindered by the absence of clear definitions of ADHD severity within current diagnostic systems, making it difficult to determine which patients are most appropriately managed at different levels of care.

Regulation and quality assurance

The Taskforce also recommended greater regulation and accountability across ADHD commissioning and service provision, supported by the development of quality standards. It called for waiting-time expectations comparable to those applied to chronic physical health conditions and highlighted the need for greater clarity regarding workforce roles. Specifically, it recommended that NICE clarify what constitutes an ‘appropriately qualified healthcare professional’ for the assessment and management of ADHD (NICE 2018: para. 1.3.1) and specify the competencies required for these roles.

Improving workforce capability

Finally, the report recommended the development of core competencies and training curricula across professional groups, including psychiatrists, paediatricians, psychologists and specialist mental health nurses. It further advocated government-supported training initiatives to expand the workforce capable of assessing and treating ADHD.