This systematic review aims to synthesize current findings on the syntactic abilities of individuals with Down Syndrome from childhood into adolescence and adulthood and discuss them in terms of the delayed or deviant pattern of development as well as in terms of the critical period for syntactic development. This literature search was conducted using research articles written only in the English language, but concerning syntax in any language, after a thorough search in the web databases, following the inclusion criteria set for this review. Studies which examine any syntactic domain of language via particular and targeted materials were included. The findings show that individuals with Down Syndrome lag behind typically developing and present a delayed pattern of syntactic development. The Down Syndrome population presents difficulties with both comprehension and production of syntax, a fact which is observed in various syntactic structures and becomes apparent in more complex ones, such as subordinate clauses, passivisation and pronouns.
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