Spontaneous speech of patients with dementia of the Alzheimer type and mild cognitive impairment.

This article discusses the potential of three assessments of language function in the diagnosis of Alzheimer-type dementia (DAT). A total of 115 patients (mean age 65.9 years) attending a memory clinic were assessed using three language tests: a picture description task (Boston Cookie-Theft picture), the Boston Naming Test, and a semantic and phonemic word fluency measure. Results of these assessments were compared with those of clinical diagnosis including the Global Deterioration Scale (GDS). The patients were classified by ICD-10 diagnosis and GDS stage as without cognitive impairment (n = 40), mild cognitive impairment (n = 34), mild DAT (n = 21), and moderate to severe DAT (n = 20). Hypotheses were (a) that the complex task of a picture description could more readily identify language disturbances than specific language tests and that (b) examination of spontaneous speech could help to identify patients with even mild forms of DAT. In the picture description task, all diagnostic groups produced an equal number of words. However, patients with mild or moderate to severe DAT described significantly fewer objects and persons, actions, features, and localizations than patients without or with mild cognitive impairment. Persons with mild cognitive impairment had results similar to those without cognitive impairment. The Boston Naming Test and both fluency measures were superior to the picture description task in differentiating the diagnostic groups. In sum, both hypotheses had to be rejected. Our results confirm that DAT patients have distinct semantic speech disturbances whereas they are not impaired in the amount of produced speech.