Emotional face recognition deficit in amnestic patients with mild cognitive impairment: behavioral and electrophysiological evidence

Psilocybin for the treatment of Alzheimer's disease

Alzheimer's disease (AD) stands as a formidable neurodegenerative ailment and a prominent contributor to dementia. The scarcity of available therapies for AD accentuates the exigency for innovative treatment modalities. Psilocybin, a psychoactive alkaloid intrinsic to hallucinogenic mushrooms, has garnered attention within the neuropsychiatric realm due to its established safety and efficacy in treating depression. Nonetheless, its potential as a therapeutic avenue for AD remains largely uncharted. This comprehensive review endeavors to encapsulate the pharmacological effects of psilocybin while elucidating the existing evidence concerning its potential mechanisms contributing to a positive impact on AD. Specifically, the active metabolite of psilocybin, psilocin, elicits its effects through the modulation of the 5-hydroxytryptamine 2A receptor (5-HT2A receptor). This modulation causes heightened neural plasticity, diminished inflammation, and improvements in cognitive functions such as creativity, cognitive flexibility, and emotional facial recognition. Noteworthy is psilocybin's promising role in mitigating anxiety and depression symptoms in AD patients. Acknowledging the attendant adverse reactions, we proffer strategies aimed at tempering or mitigating its hallucinogenic effects. Moreover, we broach the ethical and legal dimensions inherent in psilocybin's exploration for AD treatment. By traversing these avenues, We propose therapeutic potential of psilocybin in the nuanced management of Alzheimer's disease.

Features of event-related potentials during retrieval of episodic memory in patients with mild cognitive impairment due to Alzheimer's disease

Objective

To provide a rigorous comparison between patients with mild cognitive impairment due to Alzheimer's disease (MCI-AD) and healthy elderly, as well as to assess the value of electroencephalography (EEG) in terms of early diagnosis, we conducted a neutral image recognition memory task involving individuals with positive biomarkers including β amyloid deposition, pathologic tau or neurodegeneration.

Methods

The task involving study and test blocks was designed to evaluate participants' recognition memory. Electroencephalogram was recorded synchronously to elicit event-related potentials in patients with MCI-AD and healthy control subjects. We further analyzed differences between groups or conditions in terms of behavioral performance, time domain, and time-frequency domain.

Results

The MCI-AD cohort showed a slower response time to old/new images and had low accuracy regarding behavioral performance. The amplitude of the late positive complex for the old/new effects was significantly suppressed in the MCI-AD cohort when compared with that in the HC cohort. The amplitude of the late old/new effects was correlated with the Auditory Verbal Learning Test recognition score in all participants. The time-frequency domain analysis revealed that correct recognition of old items elicited a decrease in beta power, mainly limited to the HC cohort. Moreover, the combination of behavioral (processing speed and accuracy) and electrophysiological (average amplitude and relative power of delta band) measures contributes to classifying patients with MCI-AD from healthy elderly people.

Conclusion

Changes of old/new effects, accuracy and response time are sensitive to the impairment of recognition memory in patients with MCI-AD and have moderate value in predicting the incipient stage of AD.

Emotional characteristics of socially isolated older adults with MCI using tablet administered NIH toolbox: I-CONECT study

Introduction

Examining the emotional functioning of individuals with mild cognitive impairment (MCI) could help describe their cognitive status and inform the development of interventions. This study compared the emotional characteristics of socially isolated older adults with and without MCI.

Methods

We used baseline data from the Internet-based Conversational Engagement Clinical Trial. Emotional characteristics were assessed with the National Institutes of Health Toolbox Emotion Battery (NIHTB-EB). MCI status was determined with a consensus clinical diagnosis.

Results

This study included 163 participants (mean age = 81.2 years, non-Hispanic Black = 20.7%, MCI = 52.8%). MCI was associated with higher negative affect and lower psychological well-being. Non-Hispanic Black participants scored lower in sadness, higher in positive affect, and higher in meaning and purpose than non-Hispanic White participants.

Conclusion

Older adults with MCI experience more negative emotions and worse psychological well-being than those with normal cognition. The NIHTB-EB appears to be a sensitive tool to detect emotional characteristics associated with cognitive decline.

Emotion recognition and processing in patients with mild cognitive impairment: A systematic review

The purpose of this study was to investigate emotion recognition and processing in patients with mild cognitive impairment (MCI) in order to update the state of current literature on this important but undervalued topic. We identified 15 papers published between 2012 and 2022 that meet the inclusion criteria. Paper search, selection, and extraction followed the PRISMA guidelines. We used a narrative synthesis approach in order to report a summary of the main findings taken from all papers. The results collected are still ambiguous: some studies did not find any differences between MCI and healthy controls (HC) groups in emotion recognition and processing, and other results reported emotion-specific deficits in emotion recognition regarding MCI patients (both regarding negative and neutral emotions). It is essential to underline that these findings could not be generalized to the whole MCI population due to the heterogeneous use of measures and composition of the sample. This does not allow us to make a comprehensive comparison between the results. Our suggestion for future research is to align the results using the same type of tests and emotion recognition assessment.

Deficient Novelty Detection and Encoding in Early Alzheimer’s Disease: An ERP Study

Patients with early Alzheimer’s disease (AD) have difficulty in learning new information and in detecting novel stimuli. The underlying physiological mechanisms are not well known. We investigated the electrophysiological correlates of the early (< 400 ms), automatic phase of novelty detection and encoding in AD. We used high-density EEG Queryin patients with early AD and healthy age-matched controls who performed a continuous recognition task (CRT) involving new stimuli (New), thought to provoke novelty detection and encoding, which were then repeated up to 4 consecutive times to produce over-familiarity with the stimuli. Stimuli then reappeared after 9–15 intervening items (N-back) to be re-encoded. AD patients had substantial difficulty in detecting novel stimuli and recognizing repeated ones. Main evoked potential differences between repeated and new stimuli emerged at 180–260 ms: neural source estimations in controls revealed more extended MTL activation for N-back stimuli and anterior temporal lobe activations for New stimuli compared to highly familiar repetitions. In contrast, AD patients exhibited no activation differences between the three stimulus types. In direct comparison, healthy subjects had significantly stronger MTL activation in response to New and N-back stimuli than AD patients. These results point to abnormally weak early MTL activity as a correlate of deficient novelty detection and encoding in early AD.

Performance of facial expression classification tasks in patients with obstructive sleep apnea

STUDY OBJECTIVES

People show a facial recognition speed advantage, termed positive classification advantage (PCA), when judging whether a facial expression is happy compared to angry or sad. This study investigated emotional face recognition by patients with obstructive sleep apnea (OSA) with impaired neurocognition.

METHODS

Thirty-four patients with OSA and 26 healthy control patients who underwent 1 night of polysomnographic evaluation before recruitment were asked to complete an emotion recognition task. Accuracy rates and reaction times were recorded and analyzed using repeated-measures analysis of variance.

RESULTS

When participants were asked to classify positive (happy) versus negative (sad) emotional expressions, the phenomenon of PCA disappeared. Importantly, however, compared with the control patients who showed PCA, patients with OSA identified sad faces faster but were similar in processing happy faces.

CONCLUSIONS

In accordance with previous studies that showed depressive emotion in patients with OSA, our results indicate that patients with OSA show negative bias in facial expression recognition, which might lead to decline in ability of social communication.

Memory deficits for facial identity in patients with amnestic mild cognitive impairment (MCI)

Faces are among the most relevant social stimuli revealing an encounter's identity and actual emotional state. Deficits in facial recognition may be an early sign of cognitive decline leading to social deficits. The main objective of the present study is to investigate if individuals with amnestic mild cognitive impairment show recognition deficits in facial identity. Thirty-seven individuals with amnestic mild cognitive impairment, multiple-domain (15 female; age: 75±8 yrs.) and forty-one healthy volunteers (24 female; age 71±6 yrs.) participated. All participants completed a human portrait memory test presenting unfamiliar faces with happy and angry emotional expressions. Five and thirty minutes later, old and new neutral faces were presented, and discrimination sensitivity (d') and response bias (C) were assessed as signal detection parameters of cued facial identity recognition. Memory performance was lower in amnestic mild cognitive impairment as compared to control subjects, mainly because of an altered response bias towards an increased false alarm rate (favoring false OLD ascription of NEW items). In both groups, memory performance declined between the early and later testing session, and was always better for acquired happy than angry faces. Facial identity memory is impaired in patients with amnestic mild cognitive impairment. Liberalization of the response bias may reflect a socially motivated compensatory mechanism maintaining an almost identical recognition hit rate of OLD faces in individuals with amnestic mild cognitive impairment.