2023-02-02 スウェーデン王国・カロリンスカ研究所(KI)
世界人口の1〜5%が摂食障害に苦しんでいると推定されるが、その存在に気づいている人はほとんどいない。回避・制限性食物摂取障害(ARFID)は、栄養失調や栄養欠乏を引き起こす深刻な摂食障害である。
◆拒食症とは異なり、ARFIDは患者さん自身の体感や体重が増えることへの恐怖が原因ではありません。その代わりに、食べ物の特徴や見た目による感覚的な不快感、例えば、窒息の恐れ、食中毒恐怖症、食欲不振などにより、特定の種類の食べ物を避けることが特徴的な病気です。
◆カロリンスカ研究所の研究者たちは、ARFIDの発症における遺伝的要因の重要性を調査しました。1992年から2010年の間に生まれたスウェーデンの約17,000組の双子のコホートが研究に参加しました。6歳から12歳の間にARFIDを発症した計682人の子どもを特定することができた。
◆研究者らは双子法を用いて、病気の発症に及ぼす遺伝子と環境の影響を明らかにしました。
◆研究者たちは、ARFIDを発症するための遺伝的要素が79パーセントと高いことを発見しました。これは、ARFIDの発症リスクの79%が遺伝的要因で説明できることを意味します。
◆「この研究成果によって、摂食障害の大きな問題である偏見や罪悪感を減らすことができればと思います。子供がARFIDを発症することを選ぶわけではありませんし、親が子供に発症させることもできません。そのことを忘れてはいけません」とLisa Dinklerは言います。
◆リサ・ディンクラーの研究の次のステップは、ARFIDが不安やうつ病、神経発達障害、胃腸障害など、他の精神疾患とどの程度関連しているかを調べることである。
<関連情報>
- https://news.ki.se/serious-eating-disorder-arfid-is-highly-heritable-according-to-new-twin-study
- https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2801119
スウェーデンの6歳から12歳の双子における広範な回避的制限的食物摂取障害の表現型の病因について Etiology of the Broad Avoidant Restrictive Food Intake Disorder Phenotype in Swedish Twins Aged 6 to 12 Years
Lisa Dinkler, Marie-Louis Wronski, Paul Lichtenstein, Sebastian Lundström, Henrik Larsson, Nadia Micali, Mark J. Taylor, Cynthia M. Bulik
JAMA Psychiatry Published:February 1, 2023
DOI:doi:10.1001/jamapsychiatry.2022.4612
Key Points
Question To what extent do genetic and environmental factors contribute to the liability to avoidant restrictive food intake disorder (ARFID)?
Findings In this nationwide Swedish twin study including 16 951 twin pairs aged 6 to 12 years, using parent-reported and national health register data, a composite score to identify the ARFID phenotype was developed. The heritability of ARFID was high (79%), and nonshared environmental factors played a smaller but significant role (21%).
Meaning In this study, the heritability of ARFID was comparable with the heritability of other eating disorders and similar to heritability of neurodevelopmental disorders.
Abstract
Importance Avoidant restrictive food intake disorder (ARFID) is characterized by an extremely limited range and/or amount of food eaten, resulting in the persistent failure to meet nutritional and/or energy needs. Its etiology is poorly understood, and knowledge of genetic and environmental contributions to ARFID is needed to guide future research.
Objective To estimate the extent to which genetic and environmental factors contribute to the liability to the broad ARFID phenotype.
Design, Setting, and Participants This nationwide Swedish twin study includes 16 951 twin pairs born between 1992 and 2010 whose parents participated in the Child and Adolescent Twin Study in Sweden (CATSS) at twin age 9 or 12 years. CATSS was linked to the National Patient Register (NPR) and the Prescribed Drug Register (PDR). Data were collected from July 2004 to April 2020, and data were analyzed from October 2021 to October 2022.
Main Outcomes and Measures From CATSS, NPR, and PDR, all parent reports, diagnoses, procedures, and prescribed drugs that were relevant to the DSM–5 ARFID criteria were extracted when twin pairs were aged 6 to 12 years and integrated into a composite measure for the ARFID phenotype (ie, avoidant/restrictive eating with clinically significant impact, such as low weight or nutritional deficiency, and with fear of weight gain as an exclusion). In sensitivity analyses, autism and medical conditions that could account for the eating disturbance were controlled for. Univariate liability threshold models were fitted to estimate the relative contribution of genetic and environmental variation to the liability to the ARFID phenotype.
Results Of 33 902 included children, 17 151 (50.6%) were male. A total of 682 children (2.0%) with the ARFID phenotype were identified. The heritability of ARFID was 0.79 (95% CI, 0.70-0.85), with significant contributions from nonshared environmental factors (0.21; 95% CI, 0.15-0.30). Heritability was very similar when excluding children with autism (0.77; 95% CI, 0.67-0.84) or medical illnesses that could account for the eating disturbance (0.79; 95% CI, 0.70-0.86).
Conclusions and Relevance Prevalence and sex distribution of the broad ARFID phenotype were similar to previous studies, supporting the use of existing epidemiological data to identify children with ARFID. This study of the estimated genetic and environmental etiology of ARFID suggests that ARFID is highly heritable, encouraging future twin and molecular genetic studies.
