Typically, neuropsychological testing helps medical experts situate a given patient in continuum of the Alzheimer's disease (AD) spectrum, especially in the continuum between cognitively normal controls (CN) and the prodromal stage of mild cognitive impairment (MCI). As a well-known early symptom, some linguistic complexity changes of language have been associated with the progression of AD. Currently, the investigations of linguistic manifestations of MCI do mostly rely on manual analysis, yet linguistic complexity-based neuropsychological assessment cannot be effectively attained by using manual approaches. Taking advantage of the existing natural language processing (NLP) techniques to extract key features in linguistic complexity changes associated with the progression of MCI, this study develops an NLP-oriented computerized neuropsychological assessment to automatically analyze the distinguishing characteristics of data in the MCI group versus those in cognitively normal control (CN) group. By using the transcripts of news conferences from President Ronald Reagan, who was diagnosed with Alzheimer's disease in 1994, and President Dwight D. Eisenhower (DE), and President George H. W. Bush (GB), who have no known diagnosis of AD, this study found the significantly different patterns of the linguistic complexity changes between CN and MCI subjects, which can be applied into the diagnosis of MCI.