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作者：Caroline Cassels  
出處：WebMD醫學新聞

　　February 11, 2010 —一篇大型族群基礎研究認為，母親的年紀越大，孩童有自閉症的風險增加，這與父親的年紀無關。
　　
　　加州Sacramento UC Davis健康體系之研究者進行的此篇研究顯示，母親的年紀每增加5歲，則孩童的自閉症風險增加達18%。
　　
　　資深研究者Irva-Hertz-Picciotto博士等人寫道，這些資料顯示，孩童有完整自閉症狀的風險隨著母親的年紀增加而增加，而年輕母親(<30歲)中，風險隨著父親的年紀增加。
　　
　　根據主要研究作者、博士生Janie Shelton表示，該研究挑戰「父親的年紀是增加自閉症風險的關鍵因素」這個假設。
　　
　　Shelton小姐在聲明中表示，研究顯示母親的年紀與自閉症風險增加一致，父親的年紀只有在母親年紀30歲以下時對風險增加有影響，母親年紀30歲以上者中，父親的年紀與自閉症風險增加無關。
　　
　　這篇研究線上登載於2月8日的自閉症研究(Autism Research)期刊。
　　
　　根據該研究，之前有關自閉症與父親年紀之研究獲得的結果互相矛盾，無法確定是母親或父親或兩者的年紀與孩童自閉症風險增加有關。
　　
　　為了確認雙親之一的年紀是否有關，研究者蒐集了1990年1月1日至1999年12月31日間，加州的所有出生電子資料，這些紀錄納入了詳細的人口統計學資訊，包括雙親的年紀。
　　
　　為了確認後續發生自閉症的孩童，研究者獲得研究期間內出生之孩童，接受加州發展服務部之自閉症診斷的電子紀錄，本研究的自閉症定義為在一個加州區域中心診斷為完整自閉症症狀者。
　　
　　最後的研究樣本包括了490萬例出生以及12,159件自閉症，研究者報告指出，對於年紀較大的母親，隨著年紀增加則孩童後來診斷有自閉症的風險也增加，這部份與父親的年紀無關。
　　
　　研究者寫道，我們發現，母親的年紀增加會增加(孩童)自閉症風險，且與父親年紀無關，只有母親年紀小於30歲時，父親的年紀增加才與自閉症風險有關。30歲以上的母親中，我們觀察發現，只有父親年紀40歲以上者的風險略為增加；即使是年紀最大的一組中，增加程度也比年輕母親組中、父親30-34歲者小且較不明確。
　　
　　目前，父親年紀影響自閉症風險的原因依舊不清楚，Hertz-Picciotto博士在聲明中表示，我們仍需要釐清為何年長雙親會讓孩童有較高的自閉症風險與其他不良結果，如此才可以開始研究介入對策。
　　
　　研究作者們皆宣告沒有相關財務關係。
　　
　　Autism Res. 線上發表於2010年2月8日。


Older Maternal Age Linked to Increased Risk for Autism in Children

By Caroline Cassels
Medscape Medical News

February 11, 2010 — Advanced maternal age significantly increases the risk of having a child with autism irrespective of paternal age, a large population-based study suggests.

The research, conducted by investigators at UC Davis Health System, Sacramento, California, shows that the incremental risk of having a child with autism increased by 18% for every 5-year increase in maternal age.

"These data show that the risk of having a child with full-syndrome autism increases with maternal age, but increased risk from advancing paternal age primarily occurs among younger mothers (<30)," the researchers, led by senior investigator Irva-Hertz-Picciotto, PhD, MPH, write.

According to lead study author Janie Shelton, a doctoral student, the study challenges the hypothesis that the father's age is a key factor in increasing autism risk.

"It shows that while maternal age consistently increases the risk of autism, the father's age only contributes an increased risk when the father is older and the mother is under 30 years old. Among mothers over 30, increases in the father's age do not appear to further increase the risk of autism," Ms. Shelton said in a statement.

The study was published online February 8 in Autism Research.

According to the study, previous research on autism and paternal age have yielded conflicting results on whether mothers, fathers, or both contribute to an increased risk for autism in children.

To determine the independent or dependent effect from each parent, the researchers gathered electronic records for all births in California between January 1, 1990, and December 31, 1999. The records incorporated detailed demographic information, including the age of both parents.

To identify which children would subsequently develop autism, the investigators obtained electronic records identifying children born during the study period who later received an autism diagnosis from California's Department of Developmental Services. For the study, autism was defined as a diagnosis of full-syndrome autism at a California regional center.

The final study sample included 4.9 million births and 12,159 cases of autism. The researchers report that for older mothers there was a stepwise progression in the risk of having a child who would later be diagnosed as having autism, irrespective of the father's age.

"We demonstrate that advancing maternal age increases the risk of autism independent of father's age, while advancing father's age increases the risk of autism primarily for mothers under 30. Among mothers over 30, we observed a small increased risk only among fathers 40+; even at the highest age group, the increase was smaller and less precise than that for fathers 30-34 among younger mothers," the researchers write.

At this point, the reason parental age influences autism risk is not clear. "We still need to figure out what it is about older parents that puts their children at greater risk for autism and other adverse outcomes, so we can begin to design interventions," Dr. Hertz-Picciotto said in a statement.

The study authors have disclosed no relevant financial relationships.

Autism Res. Published online February 8, 2010.