Has your loved one forgotten who you are?
In the United States, more than five million people are living with Alzheimer’s disease. One of the most recognized aspects of the disease is the impairment of memory and specifically, facial recognition. Often, loved ones are left wondering why this disease causes their relative to forget something that was once so familiar. Although definitive treatments have been elusive, a deeper understanding of the condition has grown significantly in the past few years, and a new study from researchers at the University of Montreal may help answer this question.
The study focused on the way the healthy mind perceives normally presented faces, which is called holistic perception – meaning instead of looking for each feature, the brain takes in the whole picture. In contrast, when a face is inverted, it is much more difficult to interpret, and is responded to more slowly.
“The difference in response time and accuracy between upright and inverted faces is termed the face inversion effect. Interestingly, such an effect is not seen when examining upright and inverted pictures of other objects, likely reflecting the intrinsic importance of face processing to our socialization and survival,” explains Dr. Darren Gitelman, senior medical director at the Advocate Memory Center in Park Ridge, Ill. “In patients with Alzheimer’s disease (AD), it has been unclear whether changes in face processing are specific to faces or reflect a deeper underlying perceptual defect.”
To test whether AD patients experienced visual perception differently, researchers worked with two groups: one, a group of actual AD patients, and the other, a controlled group of healthy individuals. All subjects were shown the same images: photographs of cars and faces, some upright and some upside down.
The study demonstrated that both groups, AD patients and healthy elderly individuals, showed relatively equivalent performances for upright versus inverted cars, although AD patients were slower overall.
“This finding suggests that basic visual perception was functioning in AD patients, albeit at a reduced level,” says Dr. Gitelman. “However, there was a striking difference in performance on upright and inverted faces, with healthy elderly participants performing much better when viewing upright than inverted faces, while AD patients showed equivalent reduced performance with both pictures. Thus, AD patients had developed an impairment in the specific visual processes related to face perception.”
The findings of this research confirm that the disease hinders the inherent processing abilities of the mind when it comes to facial recognition, which causes patients to have difficulty recognizing both familiar and famous faces. The study suggests that new methods could be developed in the clinic to identify this problem and perhaps help to develop treatments or strategies to diminish its effects.