A behavioral study of the nature of verb production deficits in Alzheimer's disease.

Patients with Alzheimer's disease (AD) may experience greater difficulty with verb production than with noun production. In this study, we sought to assess the nature of verb production deficits in AD by using verb fluency and verb naming tasks. We designed two hypotheses for this verb deficit: (1) executive impairment drives the deficit; (2) semantic impairment drives the deficit. Thirty-five patients with AD and 35 matched healthy controls participated in the study. Both groups performed a verb naming task composed of 45 pictures (low-, medium-, and high-frequency subsets) and a verb fluency task (scored for total correct words and for mean word frequency). Patients with AD were equally impaired in verb naming and verb fluency, with an effect of disease severity on verb naming. Word frequency influenced verb naming, but not verb fluency, performance. Our results indicate that verb production deficits in AD seem to be driven more by semantic than by executive impairment.