Exploring longitudinal changes in implicit awareness of dementia: An investigation of the emotional Stroop effect in healthy ageing and mild dementia

The aim of the study was to investigate responses to dementia-relevant words in healthy older people and to investigate changes in response over 20-months in people with early-stage dementia. An emotional Stroop task, using colour-naming dementia-relevant words, was used as an indicator of implicit awareness of dementia. Overall, 24 people with dementia and 24 healthy older people completed an emotional Stroop task (T1). People with dementia completed the same task again after 12 (T2) and 20 (T3) months. For people with dementia emotional Stroop performance was contrasted with ratings of explicit awareness based on a detailed interview at T1 and at T2. For healthy older people and people with dementia response times to dementia-relevant words were significantly longer than those for neutral words. The effect was absent for people with dementia at T3. This decline in the emotional Stroop effect was not associated with cognitive decline as measured by the MMSE. Ratings of explicit awareness showed no significant change over time. There was no association between explicit awareness and implicit awareness. Implicit awareness of the condition is evident in early-stage dementia and can be elicited even where there is reduced explicit awareness. The emotional Stroop effect for dementia-relevant words in people with dementia appears to decline over time, independently of changes in MMSE score, suggesting that implicit awareness fades as time progresses.

Antidepressant medications in dementia: evidence and potential mechanisms of treatment-resistance

Depression in dementia is common, disabling and causes significant distress to patients and carers. Despite widespread use of antidepressants for depression in dementia, there is no evidence of therapeutic efficacy, and their use is potentially harmful in this patient group. Depression in dementia has poor outcomes and effective treatments are urgently needed. Understanding why antidepressants are ineffective in depression in dementia could provide insight into their mechanism of action and aid identification of new therapeutic targets. In this review we discuss why depression in dementia may be a distinct entity, current theories of how antidepressants work and how these mechanisms of action may be affected by disease processes in dementia. We also consider why clinicians continue to prescribe antidepressants in dementia, and novel approaches to understand and identify effective treatments for patients living with depression and dementia.

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.

Executive Functions in Alzheimer Disease: A Systematic Review

Alzheimer's disease is a severe irreversible syndrome, characterized by a slow and progressive cognitive decline that interferes with the standard instrumental and essential functions of daily life. Promptly identifying the impairment of particular cognitive functions could be a fundamental condition to limit, through preventive or therapeutic interventions, the functional damages found in this degenerative dementia. This study aims to analyse, through a systematic review of the studies, the sensitivity of four experimental paradigms (Wisconsin Card Sorting Test, Stroop Task, Go/No-Go Task, and Flanker Task) considered as golden standard instruments for executive functions assessment in elderly subjects affected by Alzheimer dementia. This review was carried out according to the PRISMA method. Forty-five studies comparing the executive performance of patients with Alzheimer's dementia (diagnosed according to different classification criteria for dementia) and healthy elderly patients both over the age of sixty, were selected. For the research, PubMed, PsycINFO, PsycArticles databases were used. The study highlighted the importance of using standard protocols to evaluate executive dysfunction in Alzheimer's disease. The Stroop task allows discriminating better between healthy and pathological aging.

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.

Affective false memories in Dementia of Alzheimer's Type

This study examined the production of inferential false memories for complex pictorial stimuli and the implications of affective content in Alzheimer's disease (AD). A group of 24 AD patients and a group of 24 healthy older adults studied a sequence of pictures depicting stories that included positive, negative or neutral consequences of an unseen action, and then completed an old-new picture recognition test. The number of causal errors was higher in healthy older adults compared to AD patients but affective content attenuated the effect. Causal errors increased in AD patients when stories included affective (positive or negative) outcomes. In addition, negative content produced a larger number of errors than positive content across groups. This data confirms that although memory processing is poorer in AD, it is sensitive to affective content. Accordingly, the nature of affective false memory errors suggest the need to consider the use of affective information in the development of new cognitive training procedures.

Understanding the world of dementia. How do people with dementia experience the world?

BACKGROUND

There is growing awareness that the subjective experience of people with dementia is important for understanding behavior and improving quality of life. This paper reviews and reflects on the currently available theories on subjective experience in dementia and it explores the possibility of a knowledge gap on the influence of neurological deficits on experience in late stage dementia.

METHODS

A literature review on current commonly used theories on experience in dementia was supplemented with a systematic review in PubMed and Psychinfo. For the systematic review, the terms used were Perception and Dementia and Behavior; and Awareness and Dementia and Long term care.

RESULTS

Current models emphasize the psychosocial factors that influence subjective experience, but the consequences of neurological deficits are not elaborated upon. The systematic literature search on the neuropsychological functioning in dementia resulted in 631 papers, of which 94 were selected for review. The current knowledge is limited to the early stages of Alzheimer's disease. Next to memory impairments, perception of the direct environment, interpretation of the environment, and inhibition of own responses to the environment seem to be altered in people with dementia.

CONCLUSIONS

Without knowledge on how perception, interpretation and the ability for response control are altered, the behavior of people with dementia can easily be misinterpreted. Research into neuropsychological functioning of people in more severe stages and different forms of dementia is needed to be able to develop a model that is truly biopsychosocial. The proposed model can be used in such research as a starting point for developing tests and theories.

Emotional working memory and Alzheimer's disease

A number of recent studies have reported that working memory does not seem to show typical age-related deficits in healthy older adults when emotional information is involved. Differently, studies about the short-term ability to encode and actively manipulate emotional information in dementia of Alzheimer's type are few and have yielded mixed results. Here, we review behavioural and neuroimaging evidence that points to a complex interaction between emotion modulation and working memory in Alzheimer's. In fact, depending on the function involved, patients may or may not show an emotional benefit in their working memory performance. In addition, this benefit is not always clearly biased (e.g., towards negative or positive information). We interpret this complex pattern of results as a consequence of the interaction between multiple factors including the severity of Alzheimer's disease, the nature of affective stimuli, and type of working memory task.

Dissociation between implicit and explicit manifestations of awareness in early stage dementia: evidence from the emotional Stroop effect for dementia-related words

OBJECTIVE

To determine whether people with dementia (PwD), and carers of PwD, show a processing bias to dementia-related words in an emotional Stroop task, and if so, whether the presence of such a bias is related to level of explicit awareness of the condition.

METHOD

Seventy-nine people with early stage Alzheimer's disease (AD), vascular or mixed dementia, and their carers, completed an emotional Stroop task. Time taken to colour-name dementia-related and neutral words was compared within and between groups. Additionally, as a comparison, ratings of the awareness of the condition shown by PwD were made on the basis of a detailed interview with each PwD and his/her carer.

RESULTS

PwD and carers showed the same level of increase in response times to salient compared to neutral words. In the PwD this effect was unrelated to the degree of awareness that they demonstrated regarding the condition.

CONCLUSIONS

The emotional Stroop effect in response to dementia-related words in PwD indicates that preserved implicit awareness of the condition can be elicited even where there is reduced explicit awareness.

Differential age-related decline in conflict-driven task-set shielding from emotional versus non-emotional distracters

While normal aging is associated with a marked decline in cognitive abilities, such as memory and executive functions, recent evidence suggests that control processes involved in regulating responses to emotional stimuli may remain well-preserved in the elderly. However, neither the precise nature of these preserved control processes, nor their domain-specificity with respect to comparable non-emotional control processes, are currently well-established. Here, we tested the hypothesis of domain-specific preservation of emotional control in the elderly by employing two closely matched behavioral tasks that assessed the ability to shield the processing of task-relevant stimulus information from competition by task-irrelevant distracter stimuli that could be either non-emotional or emotional in nature. The efficacy of non-emotional versus emotional task-set shielding, gauged via the 'conflict adaptation effect', was compared between cohorts of healthy young adults, healthy elderly adults, and individuals diagnosed with probable Alzheimer's disease (PRAD), age-matched to the elderly subjects. It was found that, compared to the young adult cohort, the healthy elderly displayed deficits in task-set shielding in the non-emotional but not in the emotional task, whereas PRAD subjects displayed impaired performance in both tasks. These results provide new evidence that healthy aging is associated with a domain-specific preservation of emotional control functions, specifically, the shielding of a current task-set from interference by emotional distracter stimuli. This selective preservation of function supports the notion of partly dissociable affective control mechanisms, and may either reflect different time-courses of degeneration in the neuroanatomical circuits mediating task-set maintenance in the face of non-emotional versus emotional distracters, or a motivational shift towards affective processing in the elderly.