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

Rumination in dementia and its relationship with depression, anxiety, and attentional biases

Rumination (self-referential and repetitive thinking), attentional biases (AB), and impaired cognitive control are theorized as being integral factors in depression and anxiety. Yet, research examining the relationship between rumination, mood, and AB for populations with reduced cognitive control, e.g., people living with dementia (PwD), is lacking. To explore whether literature-based relationships are demonstrated in dementia, PwD (n = 64) and healthy controls (HC) (n = 75) completed an online self-report survey measuring rumination and mood (twice), and a telephone cognitive status interview (once). Rumination was measured as an emotion-regulation style, thinking style, and response to depression. We examined the test-retest reliability of PwD's (n = 50) ruminative-scale responses, ruminative-scale internal consistency, and correlations between rumination, age, cognitive ability, and mood scores. Also, nine participants (PwD = 6, HC = 3) completed an AB measure via eye-tracking. Participants fixated on a cross, naturally viewed pairs of facial images conveying sad, angry, happy, and neutral emotions, and then fixated on a dot. Exploratory analyses of emotional-face dwell-times versus rumination and mood scores were conducted. Except for the HC group's reflective response to depression measure, rumination measures were reliable, and correlation strengths between rumination and mood scores (.29 to .79) were in line with literature for both groups. For the AB measure subgroup, ruminative thinking style scores and angry-face metrics were negatively correlated. The results of this study show that literature-based relationships between rumination, depression, and anxiety are demonstrated in dementia, but the relationship between rumination and AB requires further investigation.

Emotion Processing Dysfunction in Alzheimer's Disease: An Overview of Behavioral Findings, Systems Neural Correlates, and Underlying Neural Biology

We described behavioral studies to highlight emotional processing deficits in Alzheimer's disease (AD). The findings suggest prominent deficit in recognizing negative emotions, pronounced effect of positive emotion on enhancing memory, and a critical role of cognitive deficits in manifesting emotional processing dysfunction in AD. We reviewed imaging studies to highlight morphometric and functional markers of hippocampal circuit dysfunction in emotional processing deficits. Despite amygdala reactivity to emotional stimuli, hippocampal dysfunction conduces to deficits in emotional memory. Finally, the reviewed studies implicating major neurotransmitter systems in anxiety and depression in AD supported altered cholinergic and noradrenergic signaling in AD emotional disorders. Overall, the studies showed altered emotions early in the course of illness and suggest the need of multimodal imaging for further investigations. Particularly, longitudinal studies with multiple behavioral paradigms translatable between preclinical and clinical models would provide data to elucidate the time course and underlying neurobiology of emotion processing dysfunction in AD.

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.