Elderly people with mild cognitive impairment have an unusually weakened capacity for memorizing human faces in the short term, compared to healthy elderly people, a Japanese research group reports. The finding may help lead to the early detection of dementia.
Brain imaging studies show that areas of the brain for memory and visually processing human faces in people with mild cognitive impairment (MCI) are structurally and functionally transformed. To investigate these specific and yet unstudied areas, a research group from Kumamoto University in Japan conducted comparative experiments with normal elderly subjects and MCI patients (18 each) using a delayed-matching task with face and house stimuli in independent blocks.
In each block, they asked subjects to remember a single image and then, after a short delay, select a memorized image from a set new of images. The researchers also recorded subject gaze trends during the image memorization process.
Reduced Short-term Face Memorization
The results showed that the memorization performance of MCI patients was lower for facial images than for house images, but found no performance difference in normal subjects.
Face-specific memory deficits and changes in eye scanning patterns among patients with amnestic mild cognitive impairment. (a) Illustration of each area of interest (AOI) on an averaged face image. (b) Eye fixation duration for each AOI. Fixation duration per fixation (upper row) and Total fixation duration (lower row) are visualized separately for each condition. Credit: Toshikazu Kawagoe et al, CC-BY
The research also demonstrated that, during the process of memorizing, MCI patient gaze concentration on the eyes of an image decreased but the time spent looking at the mouth increased in comparison to normal subjects. In essence, MCI patients had reduced short-term memorization ability and a different gaze pattern for faces when compared to normal people.
“Looking at the eyes is important for remembering the entirety of the face,” said Emeritus Professor Kaoru Sekiyama. “MCI patients probably have an abnormality in the cognitive processing of faces due to the deterioration of brain function. It is possible that the distributed gaze pattern is compensation for this decreased function. We hope to shed some light on this possibility in future work.”
Alzheimer’s disease is considered to be the most common type of dementia, and early detection of preliminary stages is important to halt its progression into a more serious form of the disease. Mild cognitive impairment, believed to be a preliminary stage of Alzheimer’s, is a state in which cognitive functions, such as memory or thinking ability, decrease at a level that do not affect daily life.
Top Image: Patients with mild cognitive impairment, on the left. On the right, gaze pattern of MCI patients (yellow) is focused over a greater area of the face, possibly as compensation for cognitive degradation, compared to the gaze pattern of healthy people, which is more focused on the eyes. Credit: Toshikazu Kawagoe