自閉症の定義変更にあたり専門家らが慎重に対応（米国）

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自閉症の定義変更にあたり専門家らが慎重に対応

自閉症の新しい定義が今年（2012年）後半にメンタルヘルス専門家に採用されれば、自閉症と診断される人数が減少する可能性が高まる。医師らはこの変更の意義を確信しているわけではないが、自閉症患者の生活や治療にあたる専門家に影響することで意見が一致しており、医療や教育、社会福祉を受ける人数に影響が及ぶ可能性があるという。

新しい定義では、現在用いられているアスペルガー症候群、自閉症スペクトラム障害、広汎性発達障害（PDD-NOS）という3つのサブタイプに代わり、1つの診断カテゴリー、つまり「自閉症スペクトラム障害（autism spectrum disorder）」が採用される。この定義は、米国精神医学会（APA）が指名した専門家委員会が草案を作成中で、今年末までに最終的な形にまとめられる予定の「精神疾患の分類と診断の手引（DSM）」第5版の一部になるとみられる。

米国における自閉症の推定率は1980年代以降急増しており、近年の数値では小児110人あたり1人にみられる。症例数が実際に増加しているという専門家がいる一方で、明確な診断ガイドラインがないためであると指摘する専門家もいる。自閉症は複雑な神経発達障害であり、典型的な症状には他人との意志疎通が困難、社会的関係形成不能、反復運動、自虐行為などがあるが、原因は依然として不明である。

新しい定義では、一般に高機能自閉症とされるアスペルガー症候群とPDD-NOSは削除される。米ニューヨーク・タイムズ紙によれば、最近（1月20日）アイスランド医師会の会議で発表された研究では、1993年の論文で自閉症と診断された小児および成人372人の半数弱（45％）が新しい基準に適合すると推定している。

米オーティズム・スピークスAutism Speaks最高科学責任者であり、米ノースカロライナ大学チャペルヒル校精神医学教授のGeraldine Dawson氏は、「これは学際的な課題（academic exercise）ではない。この診断基準の変更は人々の生活に実際に影響を及ぼすことになる。新基準の実施は非常に慎重に開始し、サービスを受けられる人に対する影響を監視しなければならない。科学的な観点から、診断基準の変更は理にかなっている。サブカテゴリーは病因の点から意味を持たず、推奨される治療を区別する必要もない」と述べている。別の専門家は「偉大な試みだが、近年の自閉症の有病率の推定が正しいかどうか確証はなく、専門家の意見は分かれている。今回の診断基準変更の影響は時間が経過してみないと分からない」としている。（HealthDay News 2012-1月20日）

2012年1月30日 13:53　

（ 英文原文： Experts Weigh Changes to Definition of Autism
The goal: to create a clearer diagnosis of what constitutes the disorder; many could be affected
Please note: This article was published more than one year ago. The facts and conclusions presented may have since changed and may no longer be accurate. Questions about personal health should always be referred to a physician or other health care professional.

By Amanda Gardner
HealthDay Reporter
FRIDAY, Jan. 20 (HealthDay News) -- The number of people diagnosed with autism will likely decrease if a new definition of the disorder is adopted by mental health experts later this year.
Doctors aren't sure what the implications of the changes will be, but they agree there will be an impact on the lives of people with autism and the professionals who treat them. The changes could affect the number of people eligible for health, educational and social services.
But some experts contend that a clearer definition of autism is needed because the current definition is too hazy and may have contributed to an exaggerated number of people with the developmental disorder.
"This is not an academic exercise," said Geraldine Dawson, the chief science officer for Autism Speaks, an advocacy organization, and a professor of psychiatry at the University of North Carolina at Chapel Hill. "These changes in the diagnostic criteria will have a real impact on people's lives and we have to be very careful as we begin to implement the new criteria that we monitor how this is affecting people's ability to obtain services."
The new definition would create just one diagnostic category -- autism spectrum disorder -- that would replace the three subtypes that are used now. Those subtypes are Asperger syndrome, autism spectrum disorder and pervasive developmental disorder-not otherwise specified (PDD-NOS).
The revised definition of autism is being drafted by a panel of experts appointed by the American Psychiatric Association. The new definition will be part of the psychiatric association's Diagnostic and Statistical Manual of Mental Disorders (DSM), the "bible" for psychiatric diagnoses. The manual is currently in its fourth edition, which was released in 1994, but the much-anticipated fifth edition should be final by the end of this year.
Although the new definition of autism isn't final, it's "very likely," Dawson said. "They [the expert panel] are extremely close, so any changes at this point will probably be relatively minor."
Estimated rates of autism in the United States have surged since the 1980s, with some recent figures running as high as one in every 110 children. Some experts say there has been a bona fide increase in the number of cases, while others contend that the lack of clear-cut diagnostic guidelines is to blame.
Autism is a complex neurodevelopment disorder with typical symptoms that include difficulty communicating with others, the inability to form social relationships, and repetitive movements such as rocking and twirling, or even self-abusive behavior such as biting or head-banging, according to the U.S. National Institute of Neurological Disorders and Stroke.
The cause of autism remains unknown.
Under the new definition of autism, Asperger syndrome, which generally describes a higher functioning individual, would be eliminated, as would PDD-NOS, a sort of catch-all category.
A study presented Thursday at a meeting of the Icelandic Medical Association estimated that less than half (45 percent) of 372 children and adults diagnosed with autism in a 1993 paper would qualify under the new criteria, The New York Times reported.
A previous study came to a similar conclusion, Dawson said, with both papers appearing to identify fewer people with autism.
"In particular, they're identifying fewer individuals who are higher functioning, for example, Asperger [syndrome patients]," she said.
From a scientific point of view, the changes in diagnostic criteria make sense, Dawson said. The subcategories don't have any meaning in terms of etiology, or what causes autism. Nor do they necessarily differentiate recommended treatments, she added.
And clinicians don't always agree on diagnoses for particular individuals.
But science aside, Dawson said, "We have to keep in mind the real-world implications. In particular, we have to be very careful that through this process that we're not excluding people from receiving services that they need and deserve."
Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at the Steven and Alexandra Cohen Children's Medical Center of New York in New Hyde Park, said the new definition is "trying to lend some greater precision" to the diagnosis of autism.
But, so far, experts aren't even sure if the recent estimates of autism's prevalence are correct, he said. "There are differences of opinion," he added.
"Only time will tell what kind of impact this will have," Adesman said.
More information
The U.S. National Institute of Neurological Disorders and Stroke has more on autism.
SOURCES: Geraldine Dawson, Ph.D., chief science officer, Autism Speaks, and professor of psychiatry, University of North Carolina at Chapel Hill; Andrew Adesman, M.D., chief, developmental and behavioral pediatrics, Steven and Alexandra Cohen Children's Medical Center of New York, New Hyde Park; Jan. 19, 2012, The New York Times
Last Updated: Jan. 20, 2012 ）