2026-07-01 コペンハーゲン大学（UCPH）
◆デンマークの全国規模の医療・行政データを解析した結果、近年は以前より軽度の症状や多様な特性を持つ人々も診断対象となるようになり、診断範囲が広がったことが診断件数増加の大きな要因であることが明らかになった。一方で、重症例の割合は大きく変化しておらず、診断の増加が必ずしも疾患そのものの増加を意味するわけではないことが示された。
◆研究は、診断基準の変化や社会的認知の向上、医療へのアクセス改善などを考慮して診断統計を解釈する重要性を指摘している。また、診断数の増加を適切に理解することは、医療・教育・福祉サービスの計画や資源配分を検討する上でも重要であると結論付けている。
＜関連情報＞
- https://news.ku.dk/all_news/2026/06/adhd-and-autism-diagnoses-have-increased.-new-study-points-to-broader-diagnoses-as-an-explanation/
- https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2850079
診断年によるASDおよびADHDへの遺伝的寄与の変化 Changes in Genetic Contributions to ASD and ADHD by Year of Diagnosis
Sonja LaBianca, MD, PhD; Mette Lise Lousdal, PhD; Morten Dybdahl Krebs, MD, PhD;et al
JAMA Psychiatry Published:June 10, 2026
DOI:10.1001/jamapsychiatry.2026.1450
Key Points
Question Has the genetic risk profile of individuals diagnosed with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) changed as diagnostic rates have increased?
Findings In this cohort study among 17 071 individuals with incident diagnosis of ASD and 20 111 individuals with incident diagnosis of ADHD, genetic contributions to ASD and ADHD diagnoses weakened over the past 2 decades.
Meaning These results suggest that recent increases in ASD and ADHD diagnoses coincided with a broadening of diagnostic criteria.
Abstract
Importance The incidences of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) have increased markedly over recent decades, raising concerns about the emergence of new risk factors. Current literature typically attributes increased rates to changes in diagnostic practice, stigmatization, and awareness, but critically few studies have explored changes in underlying risk factors.
Objective To assess changes in the genetic risk profile of individuals diagnosed with ASD or ADHD by year of incident diagnosis and explore results in comparison with those expected under simulated scenarios.
Design, Setting, and Participants This cohort study used data from the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH2015) study, a population-based case-cohort in Denmark among individuals with incident diagnoses for ASD and ADHD made from 1994 to 2016. Data were analyzed from January 2024 until September 2025.
Exposure Year of incident diagnosis. Regression models tested changes in the mean genetic risk profile of individuals diagnosed in each consecutive year (1994-2016), adjusting for age, sex, and ancestry.
Main Outcomes Polygenic scores for psychiatric (ADHD, ASD, depression, bipolar, and schizophrenia) and cognitive-behavioral (addiction, educational attainment, IQ, neuroticism, and risk-taking) outcomes were used to capture genetic risk profiles of diagnosed individuals. Empirical trends were compared with those expected under different simulated drivers of increasing rates.
Results A total of 17 071 individuals with incident diagnoses for ASD (4196 female [24.6%]; mean [SD] age at diagnosis, 9.7 [4.6] years) and 20 111 with diagnoses for ADHD (5960 female [29.6%]; mean [SD] age at diagnosis, 11.0 ([4.7] years) were analyzed. A more recent ADHD diagnosis was associated with decreased genetic risk for ADHD as shown by difference in mean polygenic score (β estimate per 10-year increase, −0.06 SDs; 95% CI, −0.09 to −0.03 SDs; P = .001) and other disorders, including ASD, bipolar, and schizophrenia (eg, ASD: β per 10-year increase, −0.07 SDs; 95% CI, −0.10 to −0.03 SDs; P < .001). Similarly, a more recent ASD diagnosis was associated with decreased genetic risk for ASD (β per 10-year increase, −0.07 SDs; 95% CI, −0.10 to −0.04 SDs; P < .001) and other disorders and traits, including bipolar disorder, schizophrenia, and educational attainment (eg, bipolar disorder: β per 10-year increase, −0.05 SDs; 95% CI, −0.08 to −0.02 SDs; P = .001).
Conclusions and Relevance By analyzing multiple polygenic scores together with simulated expectations, this study could disambiguate among competing hypotheses about scenarios that may be associated with increased rates of ADHD and ASD diagnoses. Findings support broadening diagnostic criteria as an explanation for increasing rates, with implications for understanding changes in risk factors and clinical practice.
