Processing of emotionally toned pictures in dementia

Apathy is a common symptom in dementia and is often associated with reduced emotional reactivity. This study examined whether reduced emotional reactivity can be demonstrated in dementia patients using a picture viewing task.

The viewing time of three different types of visual stimuli was measured in 24 elderly participants, half of which suffered from dementia. The participants had to make a target response to an emotionally neutral target stimulus that was intermixed with a frequently occurring non-target or 'background' stimulus and infrequently presented emotional stimuli. All participants could control the presentation time of each stimulus, but one half of the participants were explicitly instructed to perform the task quickly.

The main measure was a ratio score in which the viewing time for emotional stimuli was expressed relative to the viewing time for the neutral non-target stimulus. Using this measure, the instigation of a time-pressure condition proved to significantly reduce the viewing time for emotional stimuli in the healthy subjects. Irrespective of time-pressure condition, the dementia patients showed a similar short viewing time for emotional stimuli as did the healthy subjects in the time-pressure condition. However, both dementia patients and healthy controls displayed longer viewing times for unpleasant than for pleasant stimuli.

These results suggest the ability of the present task to reveal the simultaneous occurrence of an overall reduced interest for novel stimuli and an intact differential emotional reactivity to stimuli with a negative versus positive valence in the dementia patients.