Gestures analysis during a picture description task: Capacity to discriminate between healthy controls, mild cognitive impairment, and Alzheimer's disease

Abstract

The main objective of this study is to compare the gesticulation of the five study groups that conform the evolution from healthy ageing to a moderate stage of Alzheimer's disease (AD). As a secondary aim we intend to assess the capacity of co-speech gestures to discriminate between the two main groups of amnestic Mild Cognitive Impairment (MCI), executive MCI (ex-MCI) and temporo-medial MCI (tm-MCI), since this last group is the one with the highest rate of progression to AD. 52 participants were divided into five groups, according to their global cognition state (healthy controls, ex-MCI, tm-MCI, mild AD, and moderate AD). They were videotaped during a picture description task and their verbal (speech fluency and lexical diversity measures) and non-verbal communication (gestural production) performances were analysed. Statistical analysis confirmed that the global cognition performance was worse in patients with greater cognitive impairment, and MCI groups differ from each other in delayed recall memory. Concerning verbal communication, time of speech was lower in the healthy control group when compared with the rest of the groups. In the non-verbal communication aspect, a trend toward statistical significance was found in iconic gestures per minute, iconic gestures per word and iconic gestures for word substitution. Pairwise comparison highlighted these variables as potential differentiating factor between ex-MCI, tm-MCI and mild AD groups. As for the first objective, our study results demonstrated there was not a linear progression in gestural production among groups. In relation to the second objective, outcomes pointed to a great value, since iconic gestures variables have been identified as a potential marker for the specific identification of tm-MCI individuals, who are a subgroup of amnestic MCI with a greater predisposition to progress to Alzheimer's disease.