Disordered speech in dementia.

What is the effect on language of the progressive degenerative disorder, Alzheimer's \ndisease (AD)? What are the functional consequences of this illness, particularly for \nspeech? The majority of accounts interpret speech disorder in AD as reflecting \nunderlying semantic disruption. In contrast I apply current theories of lexicalization \nin speech production to the speech disorder. Four competing hypotheses are derived \nfrom a two-stage model of lexicalization in speech production. This model contains \nseparate semantic, lexical and phonological representations. Data are collected from \npatients with probable AD and age-matched controls using standard psycholinguistic \ntechniques. The data support an explanation of progressively impaired higher level \ncognitive processing which interacts with impaired semantic to lexical processing in \nspeech production.