Response

We appreciate the cohort study ‘Life expectancy and years of life lost for adults with diagnosed ADHD in the UK’ recently published in the British Journal of Psychiatry. ^{Reference El Baou, John, Lewer, Mandy and McKechnie1} This research offers substantial insights into the reduced estimated life expectancy (ELE) of individuals diagnosed with attention-deficit hyperactivity disorder (ADHD). The authors have have made an impressive effort to collect extensive data-sets and draw conclusions that could shape future advancements in ADHD diagnosis and treatment.

The matched cohort study, analysing data from over 9.5 million individuals, confirmed 30 039 cases of ADHD using primary care records from 792 general practices. The investigation interprets a significant reduction in life expectancy of adults who have ADHD, with males losing 6.78 years and females losing 8.64 years compared with the non-ADHD population. Through precise subgroup analyses and employing a 1:10 matched control design, the study stresses the influence of physical health (diabetes mellitus, hypertension and ischemic heart disease) and mental health/neurodevelopmental comorbidities (anxiety, depression, autism, intellectual disability), as well as lifestyle variables (smoking and alcoholism), on ADHD individuals. Using Poisson regression models and life table methods enhances the study’s reliability.

Attention-deficit hyperactivity disorder is a neurodevelopmental condition defined by persistent patterns of inattention, hyperactivity and impulsivity that hinder everyday activities. ^{Reference Tripp and Wickens2} While it is commonly related to childhood, ADHD persists repeatedly into adulthood with notable outcomes for both well-being and lifespan. ^{Reference Zalsman and Shilton3} Research has increasingly underscored the glaring truth that adults with ADHD deal with a considerably diminished life expectancy. Higher rates of mental health conditions, cardiovascular disease, substance use and risky behaviours, as well as healthcare disparities and social inequities, increase the risk for individuals with ADHD. A prompt response, improved mental health support and fundamental shifts are needed to mitigate exposures.

However, like any research, this cohort study has certain limitations. These limitations urgently call for extended research to revolutionise the diagnostic and treatment approaches for ADHD. Accordingly, the following limitations have been identified to facilitate a critical study analysis.

First, the study mainly represents a population of younger adults, limiting its capacity to observe trends in the life expectancy of older adults with ADHD. Given the exponential escalation of mortality risk during midlife, the recent literature proposes that lifespan reduction may extend to 12.7 years with persistent ADHD. ^{Reference Barkley and Fischer4} Second, while the study attributes early mortality primarily to physical and psychiatric health comorbidities, emerging studies suggest that there is a hereditary component to the association of reduced ELE with ADHD. Nineteen distinct gene loci have been found to simultaneously predispose individuals to developing ADHD and a shorter lifespan. ^{Reference Vilar-Ribó, Cabana-Domínguez, Martorell, Ramos-Quiroga, Sanchez-Roige and Palmer5}

Third, the analysis does not take into account the rectifying impact of ADHD pharmacotherapy on the severity of symptoms, because individuals receiving sustained treatment exhibit a marked decrease in both all-cause and unnatural-cause mortality, which suggests a hopeful potential for improvement in ADHD treatment. ^{Reference Li, Zhu, Zhang, Kuja-Halkola, D’Onofrio and Brikell6} Stimulant medications such as amphetamine and methylphenidate have, in particular, been shown to decrease the risk of suicide in ADHD patients. ^{Reference Rice, Peltzman, Gottlieb, Shiner and Watts7}

Last, despite mentioning the influence of lifestyle variables such as smoking and alcoholism, this study does not examine the negative impact of other crucial modifiable lifestyle factors including poor nutritional habits, disturbed sleep patterns, insufficient physical activity and excessive screen exposure. Understanding and managing these factors can empower individuals in managing their ADHD. Exercise provides a significant positive effect against compulsive behaviour, poor impulse control, anxiety and depression, as well as hypothalamic–pituitary–adrenal disruptions. Brain-derived neurotrophic factor, generally deficient in ADHD, is a vital element of a typically developed brain; it can be markedly increased by incorporating regular physical activity for ADHD subjects. ^{Reference Archer and Kostrzewa8} Similarly, a healthy diet has been shown to decrease detrimental ADHD symptoms; in contrast, a ‘junk food’ diet with processed and sweetened items worsens these. ^{Reference Shareghfarid, Sangsefidi, Salehi-Abargouei and Hosseinzadeh9}

Despite profound understanding, several questions remain regarding the impact of ADHD on life expectancy: What effect does undiagnosed ADHD have on life expectancy? Future research should use population-based studies to apprehend undiagnosed and self-diagnosed individuals, establishing a more extensive apprehension of ADHD-related mortality. How does ADHD compare with other neurodevelopmental conditions in regard to mortality rate? Cohort studies should include individuals with autism spectrum disorder and other intellectual disabilities to provide a broader context. Does treatment reduce the life expectancy gap? Longitudinal studies following pharmacological and behavioural measures are essential to appraise their role in alleviating mortality risks. What role does genetic predisposition play? Future research should incorporate genetic data to distinguish hereditary risk factors and modifiable influences. How do comorbid conditions such as cardiovascular disease, psychiatric disorders and substance use add to early mortality in ADHD? Assessing their separate and collective impact can help determine fundamental points. Could healthcare access, early initiatives and lifestyle changes, such as mental health support and smoking cessation, refine sustained results? Prospective cohort studies and sibling-controlled analysis will be imperative in answering these questions and informing targeted public health initiatives.