Life Expectancy and Years of Life Lost for Adults with Diagnosed ADHD in the UK

Briefing Document: Life Expectancy and Years of Life Lost for Adults with Diagnosed ADHD in the UK

1. Introduction & Background

Problem: Adults with ADHD, a neurodevelopmental condition affecting approximately 3% of adults, experience poorer life outcomes including worse educational and employment opportunities, physical and mental health issues, and increased risk of premature death.
Gap in Knowledge: Prior to this study, no research had specifically used UK mortality data to estimate the life expectancy deficit for adults diagnosed with ADHD using the life-table method.
Study Aim: This study sought to estimate the average "years of life lost" associated with a diagnosis of ADHD in UK adults using data from primary care records between 2000 and 2019.
2. Methodology

Study Design: A matched retrospective cohort study.
Data Source: Electronic primary care health records from the IQVIA Medical Research Data (IMRD) database, which is largely representative of the UK population and includes data from 794 primary care practices.
Participants: The study included 30,039 adults aged 18+ with a recorded diagnosis of ADHD, along with a comparison group of 300,390 adults matched 1:10 on age, sex, and primary care practice.
Key Considerations:The study only included individuals with a diagnosed ADHD, acknowledging that most adults with ADHD are undiagnosed.
The start of the observation period (cohort entry) for ADHD participants was the later of their diagnosis date, their practice's qualification for data collection or Jan 1, 2000. This avoids "immortal time bias"
The end of the observation period (cohort exit) was the earliest of death, de-registration from practice, practice ceased data contribution or Jan 16, 2019.
Data Analysis:
Poisson regression was used to estimate age-specific mortality rates.
Life tables were used to estimate life expectancy at age 18 for those with and without ADHD.
95% Confidence Intervals (CIs) were calculated for all estimates using simulations.
Ethical Approval: Data collection and use of IMRD was approved by the relevant ethics boards.
3. Key Findings

Prevalence of Diagnosis: Only 0.32% of adults in the study cohort had an ADHD diagnosis, representing roughly 1 in 9 of the estimated number of adults with the condition (2.8%).
Comorbidities: Adults with diagnosed ADHD had higher rates of diagnosed physical and mental health conditions at baseline than the comparison group (Table 2):
Mental Health: Significantly higher rates of anxiety ("2.78 (2.65–2.91)" times more likely for men; "2.38 (2.24–2.54)" times more likely for women), depression ("3.08 (2.96–3.21)" for men; "2.63 (2.48–2.78)" for women), severe mental illness ("6.70 (6.08–7.38)" for men; "8.35 (7.15–9.76)" for women), self-harm/suicide ("5.80 (5.51–6.10)" for men; "4.83 (4.49–5.18)" for women), autism ("9.00 (8.51–9.52)" for men; "22.01 (18.61–26.03)" for women), intellectual disability ("6.68 (6.24–7.15)" for men; "10.93 (9.47–12.63)" for women), and personality disorder ("12.17 (10.64–13.93)" for men; "12.51 (10.52–14.86)" for women).
Physical Health: Higher rates of diabetes, hypercholesterolemia, hypertension, ischaemic heart disease, chronic respiratory disease and epilepsy.
Lifestyle: Higher rates of smoking ("2.67 (2.60–2.75)" for men; "2.15 (2.04–2.27)" for women) and potentially harmful alcohol use ("2.16 (2.04–2.28)" for men; "1.76 (1.59–1.96)" for women).
Increased Mortality Rates: Individuals with diagnosed ADHD had significantly higher mortality rates compared to the matched comparison group, rates increased exponentially with age (Fig. 1). Males with diagnosed ADHD were 1.89 times more likely to die and females with ADHD were 2.13 times more likely to die during the study period.
Reduced Life Expectancy: The study estimated a significant reduction in life expectancy for adults diagnosed with ADHD:
Males: 6.78 years of life lost (95% CI: 4.50 to 9.11). Estimated life expectancy of 73.26 years compared with 80.03 for the comparison group.
Females: 8.64 years of life lost (95% CI: 6.55 to 10.91). Estimated life expectancy of 75.15 years compared with 83.79 for the comparison group.
Sensitivity Analysis: Including potentially fatal incidents did not significantly change the results.
4. Discussion and Implications

Key Conclusion: Adults with diagnosed ADHD live significantly shorter lives than expected, with a deficit of approximately 7 years for men and 9 years for women.
Quote: "Adults with diagnosed ADHD are living shorter lives than they should."
Probable Causes: This reduced life expectancy is not thought to be a direct result of ADHD itself but is likely due to modifiable risk factors and unmet support and treatment needs. These factors may include:
Co-occurring mental and physical health conditions.
Unhealthy lifestyle choices (smoking, substance use, poor diet, etc.).
Increased risk-taking behaviours.
Inequalities and adversity (educational underachievement, unemployment, financial instability).
Urgent Need for Action: The findings highlight a critical health inequity that requires urgent attention, including:
Improving access to specialist services for adults with ADHD.
Quote: "At present, there is a dearth of specialist services to support adults with ADHD in the UK."
Developing initiatives to address physical and mental health conditions prevalent in the ADHD population.
Promoting timely access to mental health support and services that help reduce risk factors (e.g., smoking cessation).
Comparison with other studies Mortality ratios derived from this study are similar to that reported in other countries.
Limitations Lack of information about cause of death. The wide confidence intervals. Diagnosed adults may overrepresent those with higher support needs, and these results may not generalise to the entire ADHD population or to other settings and times. This study did not adjust for socioeconomic status, as this was considered a mediator and part of the causal pathway from ADHD to premature death.
5. Strengths and Limitations

Strengths:Large, representative sample from UK primary care.
Matched comparison group from the same practices, controlling for regional variations.
Use of the life-table method for estimating life expectancy, and inclusion of "immortal time".
Limitations:Lack of cause-of-death data, so the reasons for decreased life expectancy could not be fully determined.
Wide confidence intervals due to relatively small proportion of people with ADHD.
Potential over-representation of those with comorbid conditions in the diagnosed sample.
Missing ethnicity data was a confounder that could not be controlled for.
Generalizability is limited, as the data is specific to the UK, and the period in which it was collected.
The study did not include gender diverse individuals.
The diagnosed population might overrepresent more severe cases of ADHD.
6. Conclusion

This study provides compelling evidence that adults with diagnosed ADHD in the UK experience a significant reduction in life expectancy. These findings demand urgent attention from policymakers, healthcare providers, and researchers to address the unmet needs of this vulnerable population and reduce the observed health inequities.

7. Future Directions

Further research should examine mortality in gender diverse people with ADHD.
Further estimates of life expectancy should be made using population-based surveys including diagnosed and undiagnosed individuals.
Future research should address questions around ADHD, ethnicity and premature mortality.