(Cheuk, Wong & Leung 2005) 特異性言語障害と多言語への暴露

家庭内での多言語への暴露はSLI発症の独立したリスク因子であり、そのオッズ比は2.94。バイリンガルにSLIが多いことを科学的に証明した研究。一方で、学童期の第二言語の曝露のほうがSLIの危険性が高いと言われており、その場合の相対リスクははるかに高い値が予想される。

Paediatr Perinat Epidemiol. 2005 Jul;19(4):303-14.

Multilingual home environment and specific language impairment: a case-control study in Chinese children.

Cheuk DK, Wong V, Leung GM.
Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China. cheukkl@hkusua.hku.hk
Abstract
Specific language impairment (SLI) is a common developmental disorder in young children. To investigate the association between multilingual home environment and SLI, we conducted a case-control study in Hong Kong Chinese children over a 4-year period in the Duchess of Kent Children's Hospital. Consecutive medical records of all new referrals below 5 years of age were reviewed and children diagnosed with SLI (case) were compared with those referred with other developmental and behavioural problems who had been assessed as having normal language and overall development (control) using the Griffiths Mental Developmental Scale. SLI was defined as those with a language quotient more than one standard deviation below the mean and below the general developmental quotient in children with normal general developmental quotient, but without neurological or other organic diseases. We used binary and ordinal logistic regression to assess any association between SLI and multilingual exposure at home, adjusting for age and gender of subjects, parental age, education level and occupational status, number of siblings, family history of language delay and main caregiver at home. Multivariable linear regression was used to examine the effect of covariates on the language comprehension and expression standard scores assessed by the Reynell Developmental Language Scale. A total of 326 cases and 304 controls were included. The mean ages of cases and controls were 2.56 and 2.89 years respectively. Boys predominated in both groups (cases, 75.2%; controls, 60.2%). The children were exposed to between one and four languages at home, the major ones being Cantonese Chinese followed by English. The adjusted odds ratio (OR) of SLI was 2.94; [95% confidence interval (CI) 1.82, 4.74] for multilingual compared with monolingual exposure. A significant linear dose-response relationship was found (OR of SLI = 2.58 [1.72, 3.88] for each additional language to which the child was exposed). Male gender (OR = 1.88 [1.24, 2.87]), positive family history (OR = 2.01 [1.17, 3.47]), lower education levels of parents (P = 0.028 for father, P = 0.038 for mother) and lower occupational status of father (P = 0.005) were also risk factors for SLI. Multilingual exposure also significantly reduced the language quotient (P = 0.012) and language comprehension standard score (P = 0.016) of children with SLI, but not of normal children. We concluded that multilingual home environment is associated with SLI with a dose-response relationship. Exposure to multiple languages might adversely affect subsequent language ability.
PMID: 15958153 [PubMed - indexed for MEDLINE]
Multilingual home environment and specific language impairment: a case-control study in Chinese children. - PubMed - NCBI

多言語家庭環境と特異性言語障害：中国人小児の症例対照研究
特異性言語障害は、若い小児における一般的な発達障害である。多言語家庭環境とSLIとの関連性を検討するため、ケント公爵夫人小児病院にて、香港の中国人小児の4年間以上に渡っての症例対照研究を行った。年齢5歳以下の全ての新規紹介患者の連続した医療記録をレビューし、SLIと診断された小児（症例）と、言語と全般的発達の正常な他の発達・行動問題をともなう紹介患者（対照）とをGMDスケールを用いて比較した。SLIを、言語指数が平均値よりも1標準偏差以上下回り、全般的発達指数が正常な全般発達指数を下回るが、神経学的・その他の器質的疾患を伴わないものと定義した。SLIと家庭内多言語曝露の関連性の評価には、二値、あるいは順序ロジスティック回帰を用い、対象の年齢と性別、親の年齢、教育水準、職業状態、兄弟の数、言語遅滞の家族歴、家庭における主な介護者で調整した。ライネル発達言語スコアで評価した言語理解表現標準化スコアの共変量の効果を検討するため、多変量線形回帰を使った。総計で326の症例と304の対照が含まれた。症例と対照の平均年齢はそれぞれ2.54歳と2.89歳だった。両群で、男子が数的優位であった。小児は家庭で1から4言語にさらされていた。広東語が最多で、次が英語であった。マルチリンガルとモノリンガルの曝露を比較すると、SLIの修正オッズ比は2.94[1.82-4.74]であった。小児がさらされた言語が追加されるごとに、有意な線形の用量反応関係が認められた。男性(OR 1.88[1.24-2.87])、家族歴(OR 2.01[1.17-3.47])、親の教育レベル、父親の就労状態がSLIのさらなるリスクファクターであった。多言語の曝露は、言語指数、言語理解標準化スコアを有意に低下させた。多言語家庭環境は、用量反応関係をもってSLIと関連していると結論づけた。多言語への曝露は、その後の言語能力に不利に働く可能性がある。