Mutual gaze in Alzheimer's disease, frontotemporal and semantic dementia couples

Abstract

Alzheimer's disease (AD), frontotemporal dementia (FTD) and semantic dementia (SD) are neurodegenerative diseases that differ in their socioemotional presentations. Mutual gaze (i.e. when two individuals make eye contact) is a building block of social behavior that may be differentially affected by these diseases. We studied 13 AD patients, 11 FTD patients, 9 SD patients and 22 normal controls as they engaged in conversations with partners about relationship conflicts. Physiological reactivity was monitored during the conversations and trained raters coded mutual gaze from videotaped recordings. Results indicated that mutual gaze was preserved in AD couples. Mutual gaze was diminished in FTD couples while SD couples showed evidence of greater mutual gaze. SD couples also showed lower physiological reactivity compared to controls. Across patient groups, reduced mutual gaze was associated with greater behavioral disturbance as measured by the Neuropsychiatric Inventory, especially on the disinhibition and apathy subscales. These results point to subtle differences between the three types of dementia in the social realm that help to illuminate the nature of the disease process and could aid in differential diagnosis.

Fig. 1

Means plot for total gaze at the level of the couples and the level of the individual participants (at the couple-level, ‘mean gaze’ refers to the mean number of mutual gaze segments; at the participant-level, ‘mean gaze’ refers to the mean number of segments that participants looked at their partners’ eyes). Similar patterns among the groups were seen at the level of the couples and individuals. Error bars reflect the standard errors for each group.