Evaluation of P300 components for emotion-loaded visual event-related potential in elderly subjects, including those with dementia

Deficits in facial emotional valence processing in older people with subjective memory complaints: Behavioral and electrophysiological evidence

Subjective memory complaints (SMCs), which occur in the absence of clinical memory deficits, may precede mild cognitive impairment (MCI) or Alzheimer's disease (AD). Some studies have reported a deficit in facial emotion processing in people with MCI or AD. However, it is unclear whether this deficit is also present in older people with SMCs. The present study used behavioral measurements and event-related potentials (ERPs) to investigate the facial emotion processing of 41 older people with SMCs and 38 without SMCs. The task contained 204 images displaying facial emotions (positive, negative, and neutral). In terms of behavior, our results showed that participants with SMCs were slower and less accurate than controls. In terms of ERPs, the N170 latency was longer in men with SMCs than in controls, whereas no differences were observed between groups in the P300 and late positive potential (LPP) latencies or amplitudes. Moreover, in participants with SMCs, higher P300 and LPP amplitudes were related to better performance on working memory, psychomotor speed, and attention. Additionally, women were faster and more accurate than men on the facial emotion-processing task. In sum, these results suggest that older people with SMCs may have deficits in the processing of facial expressions of emotion. However, this deficit seems to affect the structural encoding of faces, rather than the late stages of processing.

A systematic review of cognitive event-related potentials in mild cognitive impairment and Alzheimer's disease

This systematic review examined whether event-related potentials (ERPs) during higher cognitive processing can detect subtle, early signs of neurodegenerative disease. Original, empirical studies retrieved from PsycINFO and PubMed were reviewed if they analyzed patterns in cognitive ERPs (≥150 ms post-stimulus) differentiating mild cognitive impairment (MCI), Alzheimer's disease (AD), or cognitively intact elders who carry AD risk through the Apolipoprotein-E ε4 allele (ε4+) from healthy older adult controls (HC). The 100 studies meeting inclusion criteria (MCI = 47; AD = 47; ε4+ = 6) analyzed N200, P300, N400, and occasionally, later components. While there was variability across studies, patterns of reduced amplitude and delayed latency were apparent in pathological aging, consistent with AD-related brain atrophy and cognitive impairment. These effects were particularly evident in advanced disease progression (i.e., AD > MCI) and in later ERP components measured during complex tasks. Although ERP studies in intact ε4+ elders are thus far scarce, a similar pattern of delayed latency was notable, along with a contrasting pattern of increased amplitude, consistent with compensatory neural activation. This limited work suggests ERPs might be able to index early neural changes indicative of future cognitive decline in otherwise healthy elders. As ERPs are also accessible and affordable relative to other neuroimaging methods, their addition to cognitive assessment might substantively enhance early identification and characterization of neural dysfunction, allowing opportunity for earlier differential diagnosis and targeting of intervention. To evaluate this possibility there is urgent need for well-powered studies assessing late cognitive ERPs during complex tasks, particularly in healthy elders at risk for cognitive decline.

Impact of emotionally negative information on attentional processes in normal aging and Alzheimer's disease

Impairments of emotional processing have been reported in Alzheimer's disease (AD), consistently with the existence of early amygdala atrophy in the pathology. In this study, we hypothesized that patients with AD might show a deficit of orientation toward emotional information under conditions of visual search. Eighteen patients with AD, 24 age-matched controls, and 35 young controls were eye-tracked while they performed a visual search task on a computer screen. The target was a vehicle with implicit (negative or neutral) emotional content, presented concurrently with one, three, or five non-vehicle neutral distractors. The task was to find the target and to report whether a break in the target frame was on the left or on the right side. Both control groups detected negative targets more efficiently than they detected neutral targets, showing facilitated engagement toward negative information. In contrast, patients with AD showed no influence of emotional information on engagement delays. However, all groups reported the frame break location more slowly for negative than for neutral targets (after accounting for the last fixation delay), showing a more difficult disengagement from negative information. These findings are the first to highlight a selective lack of emotional influence on engagement processes in patients with AD. The involvement of amygdala alterations in this behavioral impairment remains to be investigated.

Processing Facial Expressions That Conflict With Their Meanings to an Observer: An Event Related Potential Study

As social signals, identical facial expressions can be perceived differently, even oppositely, depending on the circumstances. Fast and accurate understanding of the information conveyed by others’ facial expressions is crucial for successful social interaction. In the current study, we used electroencephalographic analysis of several event-related potentials (ERPs) to investigate how the brain processes the facial expressions of others when they indicate different self-outcomes. In half of the trial blocks, a happy face indicated “Win” and an angry face indicated “Lose.” In the other half of the blocks, the rule was reversed. The results showed that the N170 could distinguish expression valence and the N300 could distinguish outcome valence. The valence of the expression (happy or angry) and the valence of the outcome (Win or Loss) interacted with each other in the early, automatic perceptual processing stage (N1) as well as in the later, cognitive evaluation stage (P300). Standardized Low-Resolution Electromagnetic Tomography (sLORETA) results indicated that the N1 modulation only occurred for happy faces, which may relate to automatic emotion regulation, while the interaction on P300 was significant only for angry faces, which might be associated with the regulation of negative emotions.

Visual Event-Related Potentials in Mild Cognitive Impairment and Alzheimer's Disease: A Literature Review

BACKGROUND

Cognitive deficits are correlated with increasing age and become more pronounced for people with mild cognitive impairment (MCI) and dementia caused by Alzheimer's disease (AD). Conventional methods to diagnose cognitive decline (i.e., neuropsychological testing and clinical judgment) can lead to false positives. Tools such as electroencephalography (EEG) offer more refined, objective measures that index electrophysiological changes associated with healthy aging, MCI, and AD.

OBJECTIVE

We sought to review the EEG literature to determine whether visual event-related potentials (ERPs) can distinguish between healthy aging, MCI, and AD.

METHOD

We searched Medline and PyscInfo for articles published between January 2005 and April 2018. Articles were considered for review if they included participants aged 60+ who were healthy older adults or people with MCI and AD, and examined at least one visually elicited ERP component.

RESULTS

Our search revealed 880 records, of which 34 satisfied the inclusion criteria. All studies compared cognitive function between at least two of the three groups (healthy older adults, MCI, and AD). The most consistent findings related to the P100 and the P3b; while the P100 showed no differences between groups, the P3b showed declines in amplitude in MCI and AD.

CONCLUSION

Visually elicited ERPs can offer insight into the cognitive processes that decline in MCI and AD. The P3b may be useful in identifying older adults who may develop MCI and AD, and more research should examine the sensitivity and specificity of this component when diagnosing MCI and AD.

On the use of the P300 as a tool for cognitive processing assessment in healthy aging: A review

Changes in patterns of performance for the cognitive functions of memory, processing speed, and focused attention are expected in old age.

Efficacy of electrical acupuncture on vascular cognitive impairment with no dementia: study protocol for a randomized controlled trial

BACKGROUND

Vascular cognitive impairment with no dementia (VCIND), manifested mainly as mild impairment of concentration and executive function, is the early phase of vascular dementia (VD). Currently, there is no specific treatment for VCIND. We hypothesize that electrical acupuncture can improve the mental and motor functions of patients with VCIND. Thus, we designed this randomized controlled trial to test this hypothesis by comparing the therapeutic effect of electrical acupuncture versus sham acupuncture in patients with VCIND.

METHOD/DESIGN

In this single-center 3-year study, 120 eligible patients will be recruited and randomly assigned to receive electrical acupuncture treatment (n = 60) or sham acupuncture (n = 60) for 8 consecutive weeks (24 sessions in total), with the same acupoint prescription (DU20, EX-HN3, DU24, DU17, DU26, EX-HN1, HT7, PC6, GB20, SP6). The primary assessment is the Montreal Cognitive Assessment. The secondary assessments are the Modified Barthel Index and Event-Related Potential. All outcomes will be assessed at baseline, endpoint, and follow-up at 8 and 24 weeks after the end of treatment.

DISCUSSION

If the outcome confirms the effectiveness and safety of electrical acupuncture in treating VCIND, this treatment is expected to be promoted in clinical practice to treat such patients.

TRIAL REGISTRATION

Chinese Clinical Trial Registry identifier: ChiCTR-IIR-17011513 ; Registered on 27 May 2017.

Early Emotional Attention is Impacted in Alzheimer's Disease: An Eye-Tracking Study

Emotional deficits have been repetitively reported in Alzheimer's disease (AD) without clearly identifying how emotional processing is impaired in this pathology. This paper describes an investigation of early emotional processing, as measured by the effects of emotional visual stimuli on a saccadic task involving both pro (PS) and anti (AS) saccades. Sixteen patients with AD and 25 age-matched healthy controls were eye-tracked while they had to quickly move their gaze toward a positive, negative, or neutral image presented on a computer screen (in the PS condition) or away from the image (in the AS condition). The age-matched controls made more AS mistakes for negative stimuli than for other stimuli, and triggered PSs toward negative stimuli more quickly than toward other stimuli. In contrast, patients with AD showed no difference with regard to the emotional category in any of the tasks. The present study is the first to highlight a lack of early emotional attention in patients with AD. These results should be taken into account in the care provided to patients with AD, since this early impairment might seriously degrade their overall emotional functioning.

Mismatch negativity as a potential neurobiological marker of early-stage Alzheimer disease and vascular dementia

Alzheimer's disease (AD) and vascular dementia (VD) are serious, irreversible forms of cognitive impairment, which means that an early diagnosis is essential to slow down their progression. One potential neurophysiological biomarker of these diseases is the mismatch negativity (MMN) event-related potentials (ERP) component, which reflects an automatic detection mechanism at the pre-attentive stages of information processing. We evaluated the auditory MMN response in individuals from two patient groups: those in the prodromal stages of AD (P-AD) and those in the prodromal stages of VD (P-VD). Thirty patients (15 P-AD patients and 15 P-VD patients) and 30 age-matched controls were recruited to undergo electrophysiological recordings during the presentation of an auditory deviant-standard-reverse oddball paradigm that was used to elicit genuine MMN responses. We show that over the frontal-central area, the mean amplitude of the MMN was significantly reduced in both the P-AD (p=0.017) and P-VD groups (p=0.013) compared with controls. The MMN peak latency in P-VD patients was significantly shorter than in controls (p=0.027). No MMN response differences between the P-AD and P-VD were found in either the frontal-central or the temporal areas. These results indicate that P-AD and P-VD patients exhibit impaired pre-attentive information processing mechanisms as revealed by the frontal-central area MMN response, which is associated with sensory memory and cognitive deficits.

Human Brain Reacts to Transcranial Extraocular Light

Transcranial extraocular light affects the brains of birds and modulates their seasonal changes in physiology and behavior. However, whether the human brain is sensitive to extraocular light is unknown. To test whether extraocular light has any effect on human brain functioning, we measured brain electrophysiology of 18 young healthy subjects using event-related potentials while they performed a visual attention task embedded with emotional distractors. Extraocular light delivered via ear canals abolished normal emotional modulation of attention related brain responses. With no extraocular light delivered, emotional distractors reduced centro-parietal P300 amplitude compared to neutral distractors. This phenomenon disappeared with extraocular light delivery. Extraocular light delivered through the ear canals was shown to penetrate at the base of the scull of a cadaver. Thus, we have shown that extraocular light impacts human brain functioning calling for further research on the mechanisms of action of light on the human brain.

Menopause Analytical Hormonal Correlate Outcome Study (MAHCOS) and the association to brain electrophysiology (P300) in a clinical setting

Various studies have demonstrated that increased leptin levels and obesity are inversely related to cognitive decline in menopausal women. It is hypothesized that adiposity is inversely correlated with cognitive decline, as women with increased weight are less vulnerable to diminishing cognition. However, it is increasingly observed that menopausal women, even with increased adiposity, experience significant cognitive decline. Positron emission tomography (PET) has been used to analyze cognitive function and processing in menopausal women. Evoked potentials (P300) and neurophysiologic tests have validated brain metabolism in cognitively impaired patients. Post-hoc analyses of 796 female patients entering PATH Medical Clinic, between January 4, 2009 and February 24, 2013, were performed as part of the "Menopause Analytical Hormonal Correlate Outcome Study" (MAHCOS). Patient age range was 39-76 years (46.7 ± 0.2). P300 latency and amplitude correlated with a number of hormones: follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, estrone, estriol, DHEA, pregnenolone, progesterone, free and total testosterone, thyroid stimulating hormone (TSH), Vitamins D 1.25 and D 25OH, leptin, and insulin-like growth factor-binding protein 3 (IGF-BP3). Corrected statistics did not reveal significant associations with P300 latency or amplitude for these hormones except for leptin plasma levels. However, factor analysis showed that FSH and LH clustered together with Vitamin D1.25 and Vitamin D25OH, P300 latency (not amplitude), and log leptin were found to be associated in the same cluster. Utilizing regression analysis, once age adjusted, leptin was the only significant predictor for latency or speed (p = 0.03) with an effect size of 0.23. Higher plasma leptin levels were associated with abnormal P300 speed (OR = 0.98). Our findings show a significant relationship of higher plasma leptin levels, potentially due to leptin resistance, and prolonged P300 latency. This suggests leptin resistance may delay electrophysiological processing of memory and attention, which appears to be the first of such an association.