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