Summary: A large register-based study from Karolinska Institutet finds that adults with ADHD face an elevated risk of many physical illnesses — notably disorders of the nervous system, respiratory system, musculoskeletal system, and metabolism. The study also observed modestly increased risks for Parkinson’s disease, dementia, and cardiovascular disease.
Source: Karolinska Institutet
A comprehensive Swedish register study published in The Lancet Psychiatry shows that adults diagnosed with attention-deficit/hyperactivity disorder (ADHD) have higher rates of a wide range of physical conditions compared with adults without ADHD.
“Recognising co-occurring physical illnesses is crucial for optimising treatment and improving long-term health and quality of life for adults with ADHD,” says lead author Ebba Du Rietz, postdoctoral researcher at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.
ADHD is a common neurodevelopmental condition marked by inattention, impulsivity and hyperactivity. In adults it is frequently treated with stimulant medications such as methylphenidate and amphetamines, which can require careful monitoring when other physical conditions are present.
Study of more than four million people
While prior research had linked ADHD to some physical health problems, many potential associations were underexplored and clinical guidance for managing comorbid physical illness in adults with ADHD is limited. To address this gap, researchers used Swedish national registers to investigate connections between ADHD and 35 categories of physical disease, and to explore whether genetic or environmental factors contributed to these overlaps.
The study identified over 4.7 million individuals born between 1932 and 1995, forming more than 4.2 million sibling pairs (including full siblings and maternal half-siblings). Participants were followed using data from inpatient (1973–2013) and outpatient (2001–2013) records in the Swedish National Patient Register. The analysis compared the lifetime presence of 35 physical diagnoses in people with ADHD versus those without, and contrasted risks among siblings of individuals with and without ADHD to estimate familial influences.
Widespread associations with physical illness
Adults with ADHD showed a statistically significant increased risk for 34 of the 35 physical conditions examined; arthritis was the only condition without a clear association. The strongest links were with nervous system disorders (including sleep disorders, epilepsy and other neurological problems), respiratory diseases (such as asthma and chronic obstructive pulmonary disease), musculoskeletal conditions and metabolic disorders. Specific diagnoses most strongly associated with ADHD included alcohol-related liver disease, sleep disorders, COPD, epilepsy, fatty liver disease and obesity. The analysis also found slightly elevated risks for cardiovascular disease, Parkinson’s disease and dementia.
“These findings are important for clinical care,” says senior author Henrik Larsson, professor at Örebro University and affiliated researcher at Karolinska Institutet. “Stimulant treatment in ADHD requires extra caution in patients who have cardiac disease, hypertension or liver dysfunction.”
Genetic and environmental contributions
Quantitative genetic analysis indicated that much of the increased risk for physical illnesses in people with ADHD can be attributed to shared genetic factors that influence both ADHD and the physical condition. This genetic overlap explained a large part of the associations for respiratory, musculoskeletal and metabolic diseases. Associations involving nervous system disorders and age-related illnesses, however, were less influenced by shared genes and appeared to be more affected by non-shared environmental factors.
Full siblings of people with ADHD had a higher risk of many of the same physical conditions than did half-siblings, which supports a role for familial (largely genetic) influences in the observed overlaps.
The research team intends to follow up by investigating the mechanisms and risk pathways that link ADHD with specific physical conditions, and to study how ADHD affects the management and prognosis of these illnesses in adulthood.
Funding: Swedish Research Council; Swedish Brain Foundation; Swedish Research Council for Health, Working Life and Welfare; Region Stockholm; StratNeuro (Karolinska Institutet); EU Horizon 2020 research and innovation programme; National Institute of Mental Health.
Conflict of interest disclosures in the original article note that Ebba Du Rietz has provided lectures for Shire Sweden AB outside the submitted work; Henrik Larsson has provided lectures for Evolan Pharma and Shire/Takeda and received research grants from Shire/Takeda; and co-author Marica Leone is employed by Janssen Pharmaceutical Companies of Johnson & Johnson. The full paper lists additional declarations.
About this ADHD research news
Source: Karolinska Institutet
Contact: Press Office – Karolinska Institutet
Image: The image is credited to Karolinska Institutet
Original Research: Open access. “Mapping phenotypic and aetiological associations between ADHD and physical conditions in adulthood in Sweden: a genetically informed register study” by Ebba Du Rietz, Isabell Brikell, Agnieszka Butwicka, Marica Leone, Zheng Chang, Samuele Cortese, Brian M. D’Onofrio, Catharina A. Hartman, Paul Lichtenstein, Stephen V. Faraone, Ralf Kuja-Halkola, Henrik Larsson. Published in The Lancet Psychiatry.
Abstract
Mapping phenotypic and aetiological associations between ADHD and physical conditions in adulthood in Sweden: a genetically informed register study
Background
Increasing evidence indicates that people with ADHD are at higher risk of several physical health conditions, but many potential links remain underexplored, especially in older adults. The study aimed to map both phenotypic associations and their aetiological sources across a broad range of physical conditions throughout adulthood.
Methods
This register study used Swedish population and family registers to identify full-sibling and maternal half-sibling pairs born between 1932 and 1995. Individuals who died or emigrated before 2005 were excluded. ICD diagnoses from inpatient (1973–2013) and outpatient (2001–2013) records were used to record lifetime presence or absence of 35 physical conditions after age 18. Logistic regression estimated associations between ADHD and each condition at the individual and sibling-pair levels, and quantitative genetic models estimated how much of the overlap could be attributed to genetic versus environmental factors.
Findings
The cohort included 4,789,799 individuals (51% men, 49% women) forming 4,288,451 sibling pairs. Mean age at end of follow-up was 47 years (range 18–81). Adults with ADHD had increased risk for 34 of 35 physical conditions examined; the strongest associations involved nervous system disorders (including sleep disorders, epilepsy and dementia) and respiratory diseases (including asthma and COPD). Sex-specific analyses showed similar patterns for men and women. Greater cross-disorder similarity among full-siblings than half-siblings for several condition groups pointed to shared familial (mainly genetic) influences, which quantitative modelling estimated accounted for roughly 60–69% of the observed correlations for many conditions. Associations with nervous system disorders were more influenced by non-shared environmental factors.
Interpretation
These findings map the aetiological sources of overlap between ADHD and many physical illnesses, guiding future research to identify specific mechanisms and targets for prevention or lifestyle interventions. Clinically, the results emphasise the importance of assessing physical health conditions in adults with ADHD to improve care and long-term outcomes.
Funding
Swedish Research Council; Swedish Brain Foundation; Swedish Research Council for Health, Working Life, and Welfare; Stockholm County Council; StratNeuro; EU Horizon 2020 research and innovation programme; National Institute of Mental Health.