RESUMO
Objective To explore the features of connected speech produced by Chinese mild Alzheimer's disease (AD) patients.Methods Thirty Chinese mild AD patients (eight males and 22 females,and the age was (72.73 ± 7.78) years) and 30 age and education matched normal controls from three communities were recruited in Xuanwu Hospital from January 2018 to May 2018.All subjects completed tasks of picture naming,semantic fluency (animal),and Cookie Theft picture description.Picture description was analyzed for speech production (total word output,speech rate,sound errors),lexical content (number of nouns and verbs,proportion of pronouns and verbs,semantic errors),information content (information unit,idea density,efficiency),syntactic structure and complexity (mean length of utterance,words in sentences,syntactic errors).Differences between groups were calculated.Association between picture naming,semantic fluency,and measures in picture descriptions was analyzed.Results Compared with the controls,mild AD patients achieved lower scores on the picture naming task (74.45±8.04 vs 79.60± 1.73,t=-2.800,P=0.010) as well as on the semantic fluency task (10.35±3.08 vs 18.50±4.66,t=-6.520,P＜0.01) and produced lower speech rate (131.80±36.40 vs 149.64±26.69,t=-2.095,P=0.041),less number of nouns (7.52±2.55 vs 9.67±3.58,t=-2.509,P=-0.015) and verbs (4.40±2.24 vs 5.73±1.92,t=-2.375,P=0.021),increased proportion of pronouns (0.286 (0.319) vs 0.039 (0.122),Z=3.602,P＜0.01) and semantic errors (0.629 (1.396) vs 0 (0.779),Z=2.386,P=0.017),less information units (11.00±3.63 vs 13.70±3.53,t=-2.787,P=0.007),decreased idea density (0.11±0.04 vs 0.16±0.05,t=-3.946,P＜0.01),decreased efficiency (14.23±7.56 vs 22.95±7.14,t=-4.738,P＜0.01),shorter mean length of utterance (6.64± 1.27 vs 8.25± 1.70,t=-3.928,P＜0.01),and less words in sentence (0.84±0.10 vs 0.95±0.06,t=-4.625,P＜0.01).Group differences in total word output,sound errors,proportion of verbs,and syntactic errors did not reach statistical significance.Scores on picture naming task were negatively associated with the proportion of pronouns (r=-0.737,P=0.003),and positively associated with the idea density (r=0.540,P=0.046) and efficiency (r=0.592,P=0.026) in the AD group.Scores on semantic fluency task were negatively associated with the proportion of pronouns (r=-0.554,P=0.011).Conclusions Connected speech in mild AD patients was characterized by decreased naming accuracy,decreased sematic fluency,decreased content words,information units,conciseness,efficiency,and syntactic complexity,but motoric aspects of speech and sentence structure remained relatively preserved.Decreased content words and increased pronouns in mild AD may relate to semantic impairment.