Impairment in recognition of emotional facial expressions in Alzheimer's disease is represented by EEG theta and alpha responses

Abstract

Behavioral studies have shown that the recognition of facial expressions may be impaired in patients with Alzheimer's disease (AD). The identification and recognition of a facial expression might be represented by event‐related brain oscillations. The present study aims to analyze EEG event‐related oscillations and determine the electrophysiological indicators of impaired facial expression recognition in AD patients. EEGs of 30 healthy controls and 30 AD patients were recorded during their perception of three different facial expressions (angry, happy, neutral). Event‐related power spectrum and phase locking were analyzed in the theta (4‒7) and alpha (8‒13 Hz) frequency bands with the EEGLAB open toolbox. There was a significant facial Expression × Group interaction (p < 0.05) for the theta power spectrum; the healthy control group had higher theta power than the AD group during the perception of angry facial expressions (p < 0.05). There was a significant hemisphere difference between the two groups (p < 0.05). There was a right hemisphere alpha power dominance in healthy subjects. However, AD patients did not have this alpha power asymmetry. The present study, for the first time in the literature, presents the electrophysiological indicators of impaired recognition of facial expression in AD patients. The current study could be a basis for future studies that will analyze emotional processing in different kinds of dementia patients, and this study may have provided indicators of electrophysiological correlates of behavioral problems observed in clinical practice.

Event-related EEG oscillatory responses elicited by dynamic facial expression

“…According to the valence hypothesis [ 49 , 50 , 54 ], increased left anterior activity is associated mostly with positive emotions, while increased right anterior activity is associated with negative emotions. However, in this study, we see that the hemispheric difference is in posterior regions rather than anterior regions, and this hemispheric difference is not between the emotions (joyful vs. fearful), which is in line with Güntekin et al [ 8 ]. Therefore, rather than the valence hypothesis, the results support the right hemisphere hypothesis [ 51 , 55 ], which suggests that the right hemisphere is important in processing emotions irrespective of their valence.…”

“…Furthermore, several studies related FE perception to widespread neuronal processing in the right hemisphere, with an organization similar to language processing in the left hemisphere [ 45 – 48 ]. Aside from pioneering functional magnetic resonance imaging (fMRI) studies on FE processing, there are also EEG studies demonstrating this hemispheric lateralization during FE processing [ 8 , 49 – 52 ]. However, such results were obtained with stimulus sets that mostly used static photographs, where the temporal dynamics of face processing were not considered [ 45 , 46 , 53 ].…”

“…Facial expressions of basic emotions can be recognized irrespective of culture or geographical location [ 1 – 3 ], underlining the evolutionary value of recognizing others' emotions and inferring their intentions. This ability to recognize emotions in FEs can be impaired in certain pathologies, including Alzheimer's disease [ 4 – 8 ], schizophrenia [ 9 – 11 ], or autism spectrum disorders [ 12 – 14 ], and is subject to change throughout the lifespan [ 15 , 16 ]. Given its fundamental social function, it is important to understand what the neural mechanisms of FE processing are.…”

Empathy and Theory of Mind in Alzheimer’s Disease: A Meta-analysis

“…Failures of ToM refer to difficulties understanding the mental states of others and appreciating that these mental states might differ from our own (Poletti et al, 2012). In AD, these social cognitive deficits have been linked to both volumetric loss and white matter pathology (Dermody et al, 2016;Guntekin et al, 2019;Kanske et al, 2015;Lee et al, 2013;Park et al, 2017;Poletti et al, 2012;Sturm et al, 2013). Consequently, it is unsurprising that both types of impairment grow more severe with disease progression (Fliss et al, 2016;Kumfor et al, 2014;Sturm et al, 2013;Torres et al, 2015).…”

Similar Theory of Mind Deficits in Community Dwelling Older Adults with Vascular Risk Profile and Patients with Mild Cognitive Impairment: The Case of Paradoxical Sarcasm Comprehension

“…As regards a possible brain substrate for the deficits of MCI patients in sarcasm comprehension, in many studies on ADD and ToM abilities, social cognitive deficits have been linked to white matter pathology [ 27 , 28 , 29 , 70 , 71 , 72 ]. The same pathology is also presented in older adults with VRF [ 73 ], indicating that metabolic syndrome is associated with brain abnormalities.…”