Cognitive predictors of language impairment in Down syndrome

描述（由申请人提供）：唐氏综合症患者通常是智力最低的2%人群，但他们的语言能力远远低于他们的智力能力。严重的语言障碍对退行性痴呆患者的生活功能有着深刻而普遍的影响。尽管人们已经做了很多工作来理解唐氏综合症患者的语言能力模式，但人们对导致这种模式的潜在过程或机制的本质知之甚少。本研究的长远目标是确定残疾儿童语言障碍的认知预测因素，尤其是句法障碍。我们预测，内隐学习和语音记忆的障碍共同导致了这一群体的语言障碍。该研究采用比较/纵向联合设计，其中年龄在10-21岁的DS组和2个对照组（CA和混合病因ID）在第1时间进行测试，DS和混合病因ID组在2年后的第2时间再次进行测试。具体目的1是为了证明，除了已知的语音记忆障碍外，退行性障碍还存在严重的内隐学习障碍。我们预计，与CA组和ID组相比，DS组的参与者在内隐学习和语音记忆方面的表现更差。本研究还包括一个典型的发展轨迹，以评估内隐学习在DS和混合ID组。具体目标2是证明内隐学习和语音记忆障碍与退行性残疾的语言障碍有关。如果是这样的话，那么(a)内隐学习和语音记忆将与DS的并发语言能力相关，(b)时间1的内隐学习和语音记忆将预测DS两年内的语言发展速度。具体目的3是检验内隐学习对幼儿语言尤其是句法影响的部分中介模型。我们认为内隐学习直接影响语言，因为它限制了语言习得所必需的复杂规则系统和协变的习得，但也间接影响，通过语音记忆。内隐学习母语语音单位间共变的能力差，导致语音记忆的局限性，从而制约了语言习得。我们将在两年内并发地、纵向地测试部分中介模型。

DESCRIPTION (provided by applicant): People with Down syndrome (DS) are usually in the lowest 2% of the population in intellectual ability, yet their language ability is far lower than their intellectual ability. Severe language limitations have a profound and pervasive impact on life functioning of people with DS. Though much work has been done to understand the pattern of language abilities in individuals with DS, little is known about the nature of the underlying processes or mechanisms that result in this pattern. The broad, long-term objective of the proposed research is to identify cognitive predictors of language impairment in DS, especially syntax. We predict that impairments in implicit learning and phonological memory together lead to impairments in language in this group. The study uses a combined comparative/longitudinal design in which a DS group, age 10-21, and 2 control groups (CA and mixed etiology ID) are tested at Time 1 and the DS and mixed ID groups are tested again 2 years later at Time 2. Specific Aim 1 is to demonstrate that, in addition to the known impairment in phonological memory, there is also a severe impairment in implicit learning in DS. We expect participants with DS to perform more poorly than CA and ID groups on measures of implicit learning and phonological memory. The study also includes a typical developmental trajectory to evaluate implicit learning in the DS and mixed ID groups. Specific Aim 2 is to demonstrate that implicit learning and phonological memory impairments are linked to language impairment in DS. If so, then (a) implicit learning and phonological memory will correlate with concurrent language ability in DS and (b) implicit learning and phonological memory at Time 1 will predict rate of language development over two years in DS. Specific Aim 3 is to test a partial mediation model of the influence of implicit learning on language in DS, especially syntax. We suggest that implicit learning affects language directly, because it limits the acquisition of complex rule systems and covariations necessary for language acquisition, but also indirectly, through phonological memory. Poor implicit learning of covariations among phonologic units in one's native language leads to limitations in phonological memory, which constrain language acquisition. We will test the partial mediation model concurrently and longitudinally over two years.