Visual search for real-world scenes in patients with Alzheimer's disease and amnestic mild cognitive impairment.

BACKGROUND: Visual attention-related processes that underlie visual search behavior are impaired in both the early stages of Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI), which is considered a risk factor for AD. Although traditional computer-based array tasks have been used to investigate visual search, information on the visual search patterns of AD and MCI patients in real-world environments is limited. AIM: The objective of this study was to evaluate the differences in visual search behaviors among individuals with AD, aMCI, and healthy controls (HCs) in real-world scenes. MATERIALS AND METHODS: A total of 92 participants were enrolled, including 28 with AD, 32 with aMCI, and 32 HCs. During the visual search task, participants were instructed to look at a single target object amid distractors, and their eye movements were recorded. RESULTS: The results indicate that patients with AD made more fixations on distractors and fewer fixations on the target, compared to patients with aMCI and HC groups. Additionally, AD patients had longer fixation durations on distractors and spent less time looking at the target than both patients with aMCI and HCs. DISCUSSION: These findings suggest that visual search behavior is impaired in patients with AD and can be distinguished from aMCI and healthy individuals. For future studies, it is important to longitudinally monitor visual search behavior in the progression from aMCI to AD. CONCLUSION: Our study holds significance in elucidating the interplay between impairments in attention, visual processes, and other underlying cognitive processes, which contribute to the functional decline observed in individuals with AD and aMCI.

Antisaccade error rates in first-episode psychosis, ultra-high risk for psychosis and unaffected relatives of schizophrenia: A systematic review and meta-analysis.

BACKGROUND: Antisaccade, which is described as looking at the opposite location of the target, is an eye movements paradigm used for assessing cognitive functions in schizophrenia. Initiation and sustainment of saccades in antisaccade are managed by frontal and parietal cortical areas. Antisaccade abnormalities are well-established findings in schizophrenia. However, studies in the early phases of psychotic disorders and clinical/familial risk for psychosis reported inconsistent findings. The current systematic review aimed to review the results of studies investigating antisaccade error rates in first-episode psychosis (FEP), individuals with ultra-high-risk for psychosis (UHRP), and familial-high-risk for psychosis (FHRP) compared to healthy controls. METHOD: A meta-analysis of 17 studies was conducted to quantitatively review antisaccade errors in FEP, UHR-P and FHRP. The error rate (Hedges'g) was compared between the total of 860 FEP, UHRP, FHRP, and 817 healthy controls. Hedges' g for effect size, I2 for estimating the percentage of variability, and publication bias were evaluated through the R software. RESULTS: The outcomes of this meta-analysis suggested that FEP is associated with a robust deficit in the antisaccade error rate (g = 1.16, CI = 0.95-1.38). Additionally, both the clinical and familial high-risk groups showed small but significant increases in AS errors (g = 0.26, CI = 0.02-0.52 and g = 0.34, CI = 0.13-0.55, respectively). CONCLUSION: The large effect size estimated for FEP was compatible with previously reported results in chronic schizophrenia patients. Additionally, relatives had abnormalities with small to medium effect sizes and significant differences. The current findings suggest that antisaccade errors might be a potential endophenotype for psychotic disorders.

Uncorrected errors and correct saccades in the antisaccade task distinguish between early-stage Alzheimer's disease dementia, amnestic mild cognitive impairment, and normal aging.

Alzheimer's disease (AD) dementia is a degenerative illness that is characterized by a gradual decline in cognitive abilities. Amnestic mild cognitive impairment (aMCI) is seen as a precursor to AD. The changes in antisaccade performance that can be seen in MCI may provide important clues in the early detection of AD. Therefore, the antisaccade deficits in AD and aMCI remain a research question. This study aimed to examine antisaccade responses and the relationship between antisaccade and cognitive function in AD, aMCI, and healthy controls (HC). This study included 30 patients with early-stage AD, 34 with aMCI, and 32 HC. Patients with AD showed higher rates of uncorrected error, anticipatory saccades and corrected errors, as well as decreased correct saccade rates, and shortened saccade latency compared to aMCI and HC in this study. Patients with aMCI exhibited increased rates of express saccades relative to HC. The antisaccade task and cognitive domains were found to be significantly related. Our study showed that the rate of correct saccades has the capacity to distinguish AD from HC with 87% sensitivity and 86% specificity (AUC = 0.93, p < 0.001). In addition, the rate of uncorrected errors was found to be capable of distinguishing AD from HC with 84% sensitivity and 83% specificity (AUC = 0.91, p < 0.001). This study presented promising findings that these parameters can be used clinically to differentiate AD and aMCI from healthy older individuals.

Visual search in Alzheimer's disease and amnestic mild cognitive impairment: An eye-tracking study.

INTRODUCTION: Visual search impairment is a potential cognitive marker for Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI). The aim of this study is to compare eye movements during visual tracking in AD and aMCI patients versus healthy controls (HCs). METHODS: A prospective cohort study included 32 AD and 37 aMCI patients, and 33 HCs. Each participant was asked to look at the target object in a visual stimulus containing one target and eight distractors, and eye movements were recorded with EyeLink 1000 Plus. RESULTS: AD patients had fewer fixations and shorter target fixation duration than aMCI patients and HCs. Fixation durations were also shorter in aMCI patients compared to HCs. Also, AD patients were more fixated on distractors than HCs. DISCUSSION: Our findings revealed that visual search is impaired in the early stages of AD and even aMCI, highlighting the importance of addressing visual processes in the Alzheimer's continuum. HIGHLIGHTS: AD patients looked to distractors more and longer than the target compared to aMCI patients and older healthy individuals. aMCI patients had an impaired visual search pattern compared to healthy controls, just like patients with AD. The visual search task differentiated AD and aMCI patients from healthy individuals without dementia.

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.

Antisaccade and memory-guided saccade in individuals at ultra-high-risk for bipolar disorder.

BACKGROUND: Ultra-high-risk for bipolar disorder (UHR-BD) is an important paradigm to investigate the potential early-stage biomarkers of bipolar disorder, including eye-tracking abnormalities and cognitive functions. Antisaccade (AS) described as looking in the opposite direction of the target, and memory-guided saccade (MGS), identified as maintaining fixation, and remembering the location of the target, were used in this study. The aim of this study was to evaluate the differences in saccadic eye movements between UHR-BD and healthy controls (HCs) via AS-MGS. METHODS: The study included 28 UHR-BD and 29 HCs. Participants were selected using a structured clinical interview for prodromal symptoms of BD. AS-MGS were measured with parameters like uncorrected errors, anticipatory saccades, and latency. Eye movements were recorded with the EyeLink 1000-Plus eye-tracker. RESULTS: In the AS, the number of correct saccades was significantly decreased in UHR-BD (p = 0.020). Anticipatory (p = 0.009) and express saccades (p = 0.040) were increased in UHR-BD. In the MGS paradigm, the correct saccades were reduced in UHR-BD (p = 0.031). In addition, anticipatory (p = 0.004) and express saccades (p = 0.012) were significantly increased in cue-screen in UHR-BD. CONCLUSIONS: To our knowledge, this is the first study to evaluate cognitive functions with eye movements in individuals at UHR-BD. The current findings showed that eye movement functions, particularly in saccadic parameters related to inhibition and spatial perception, may be affected in the UHR-BD group. Therefore, assessment of oculomotor functions may provide observation of clinical and cognitive functions in the early-stage of bipolar disorder. However, further research is needed because the potential effects of medication may affect saccadic results.

Examination of eye movements during visual scanning of real-world images in Alzheimer's disease and amnestic mild cognitive impairment.

Available evidence shows that Alzheimer's disease (AD) patients display inefficiencies in visual scanning of their surroundings, directing their attention towards non-relevant aspects of scenes. Not much is known about eye movements during visual scanning in individuals with amnestic mild cognitive impairment (aMCI). Notably, a consensus has yet to be reached on this issue. Furthermore, prior research has indicated the existence of visual attention deficits in individuals diagnosed with AD and aMCI. The objective of this study was to examine the visual scanning patterns of individuals diagnosed with AD, aMCI, and healthy controls (HC) when viewing various scenes. Thirty patients with AD, 32 aMCI, and 32 HC were included in the study. A set of 30 real-life scene images were presented to the participants in the visual scanning task. Participants' eye events were monitored using the EyeLink 1000 Plus in this task. The results indicate a significant reduction in total fixation duration, number of scanned areas, fixation counts, and saccade counts in AD as compared to those with aMCI and HC. The research did not reveal any significant statistical differences in eye parameters between the aMCI and HC groups. This study found abnormalities in visual scanning in AD compared to aMCI and HC. Visual scanning patterns of aMCI patients were not different from HC. Previous studies have specifically shown visual attention difficulties in AD and MCI. Our findings may be related to visual attention difficulties in AD. In addition, this study is the first to examine visual scanning behaviour with real-world images in AD and aMCI.

The influence of stimulus eccentricity on prosaccade outcomes in patients with Alzheimer's Disease dementia at an early stage and amnestic mild cognitive impairment.

INTRODUCTION: Prosaccade task is a widely used objective method to evaluate reflexive saccade and visual attention. The study aimed to investigate prosaccade stimulus eccentricity, compare prosaccade parameters in patients with Alzheimer's disease dementia (AD), amnestic mild cognitive impairment (aMCI), and neurotypical adults (NA), and examine the relationship between prosaccade and neuropsychological tests. METHODS: Thirty patients with AD, 34 with aMCI, and 32 NA were included in the study. Eye movements were recorded with the EyeLink 1000 Plus in the prosaccade task, and this study evaluated cognitive function with comprehensive neuropsychological tests assessing attention, memory, executive function, visuospatial function, and language domains. RESULTS: The correct saccade rates of patients with AD were significantly lower than NA in the 5° and 10° stimulus eccentricities. Patients with AD had significantly longer latencies in the 10° stimulus eccentricity than those with aMCI and NA. Patients with aMCI did not differ in prosaccade performance compared to NA. Prosaccade parameters were significantly correlated with all cognitive domains. As the amplitude of the stimuli increased, the rate of correct saccades decreased, while the express saccade rate, latency, amplitude, and peak velocity increased. CONCLUSION: Our findings that correct saccade rates and latency may be distinguishing parameters of early AD are promising. This study also found that stimulus eccentricity affects prosaccade measures in AD, MCI, and NA.