Face Recognition Deficits in a Patient With Alzheimer's Disease: Amnesia or Agnosia? The Importance of Electrophysiological Markers for Differential Diagnosis

Eye movement patterns during viewing face images with neutral expressions in patients with early-stage Alzheimer's disease and amnestic mild cognitive impairment

BACKGROUND

Alzheimer's disease (AD) neuropathology affects the brain regions responsible for visuospatial skills. Accumulating evidence points to visual difficulties involving face processing in AD and amnestic mild cognitive impairment (aMCI). No study has so far examined eye movement patterns when viewing faces with neutral expressions in patients with AD.

AIM

The objective of this study aimed to examine the eye movements of patients with early-stage AD, aMCI, and healthy controls (HC) during viewing face images.

MATERIALS&METHODS

Thirty-one AD, 37 aMCI, and 33 HC were included in the study. Eye movements in facial stimuli were recorded with the EyeLink 1000 Plus eye-tracker.

RESULTS

Our findings showed that AD patients looked less at the eye area of interest than the nose and mouth areas of interest compared to aMCI and HC. Regardless of the group, all participants looked at the eye and nose areas of interest more and longer in the mouth area of interest. In addition, the first fixation duration to the eye area of interest of all participants was shorter than that of the nose and mouth.

DISCUSSION

Consistent with our study, studies in healthy adults revealed eye movement patterns that focused more on the eyes and nose. AD patients are unable to pay attention to the salient parts of faces, tending to focus instead on the non-informative parts.

CONCLUSION

Our study is the first to reveal eye movement differences in face processing in AD.

Variation in Group Composition Alters an Early-Stage Social Phenotype in hAPP-Transgenic J20 Mice

BACKGROUND

Altered social behavior is one of the symptoms of Alzheimer's disease (AD) that results in social withdrawal and loneliness and provides a major burden on patients and their relatives. Furthermore, loneliness is associated with an increased risk to develop AD and related dementias.

OBJECTIVE

We aimed to investigate if altered social behavior is an early indicator of amyloid-β (Aβ) pathology in J20 mice, and if co-housing with wild type (WT) mice can positively influence this social phenotype.

METHODS

The social phenotype of group-housed mice was assessed using an automated behavioral scoring system for longitudinal recordings. Female mice were housed in a same-genotype (4 J20 or WT mice per colony) or mixed-genotype (2 J20 mice + 2 WT mice) colony. At 10 weeks of age, their behavior was assessed for five consecutive days.

RESULTS

J20 mice showed increased locomotor activity and social sniffing, and reduced social contact compared to WT mice housed in same-genotype colonies. Mixed-genotype housing reduced the social sniffing duration of J20 mice, increased social contact frequency of J20 mice, and increased nest hide by WT mice.

CONCLUSION

Thus, altered social behavior can be used as an early indicator of Aβ-pathology in female J20 mice. Additionally, when co-housed with WT mice, their social sniffing phenotype is not expressed and their social contact phenotype is reduced. Our findings highlight the presence of a social phenotype in the early stages of AD and indicate a role for social environment variation in the expression of social behavior of WT and J20 mice.

Jatrorrhizine can improve nerve cell injury induced by Aβ 25-35, acting through miR-223-3p/HDAC4 axis

OBJECTIVE

The purpose of this research is to probe the mechanism of Jatrorrhizine (JAT) improving Aβ 25-35-induced nerve cell injury through the miR-223-3p/HDAC4 axis.

METHODS

SH-SY5Y cells were treated with Aβ 25-35 to simulate nerve injury in the pathogenesis of Alzheimer's disease (AD), and JAT-treated SH-SY5Y cells were assessed for HDAC4 and miR-223-3p. The HDAC4 and miR-223-3p levels were tested by qRT-PCR. Proliferation was determined through MTT. Apoptosis was assessed by flow cytometry, and the related indexes of oxidative stress (OS) were examined by an OS kit.

RESULTS

Compared with AD group, OD value increased, apoptosis rate decreased, and OS was inhibited in the AD+JAT group (all P<0.05). In SH-SY5Y cells, miR-223-3p can specifically inhibit the HDAC4 expression. The miR-223-3p expression increased and HDAC4 decreased after JAT acted on SH-SY5Y cells stimulated by Aβ 25-35 (all P<0.05). The addition of over-expression HDAC4 vector or miR-223-3p inhibitor could inhibit proliferation, and promote apoptosis and OS on the basis of JAT (all P<0.05). In addition, over-expressing miR-223-3p can suppress over-expressed HDAC4's effects on proliferation, apoptosis, and OS of SH-SY5Y cells (all P<0.05).

CONCLUSION

JAT can improve the nerve injury induced by Aβ 25-35 by up-regulating miR-223-3p and inhibiting the HDAC4 expression, suppress apoptosis and OS, and induce proliferation. This research further clarified the mechanism of JAT in AD.