A recent study from the Université de Montréal, published in the Journal of Alzheimer’s Disease, has demonstrated that Alzheimer’s also impairs visual face perception.
The study set out to determine if Alzheimer's impaired the perceptual level for faces, more specifically at extracting a visual representation of an individual face.
To address this question the researchers investigated the matching of simultaneously presented individual faces and that of the familiar shape of cars. Both were presented in both upright and inverted orientation to a group of people living with mild Alzheimer's and in a group of healthy older controls matched for age and education.
While the healthy control group showed a much larger decrease in performance for faces than for cars when images were inversed, those living with Alzheimer showed a reduced inversion effect (i.e., larger performance for upright than inverted stimuli) for faces, but not for cars, both in terms of error rates and response times and the inversion effect did not differ significantly for faces and cars in Alzheimer's.
This abnormal inversion effect for faces was observed in a large subset of individuals living with Alzheimer's. These results suggest a deficit in higher-level visual processes, more specifically at perceiving individual faces, a function that relies on holistic representations specific to upright face stimuli. These deficits, combined with memory impairment, may contribute to the difficulties in recognizing familiar people that are often reported in patients with Alzheimer's and by their caregivers.
Full article of the research conducted by the team of Dr. Sven Joubert, PhD, a researcher at the Centre de recherche de l’Institut universitaire de gériatrie de Montréal and a Professor with the Department of Psychology at Université de Montréal, in the Journal of Alzheimer’s Disease. A Qualitative Impairment in Face Perception in Alzheimer’s Disease: Evidence from a Reduced Face Inversion Effect