Does emotional memory enhancement assist the memory-impaired?

The days we never forget: Flashbulb memories across the life span in Alzheimer's disease

Alzheimer's disease (AD) is characterized by autobiographical memory deficits, with the ability to retrieve episodic-rich memories being particularly affected. Here, we investigated the influence of AD on a specific subtype of episodic memories known as flashbulb memories (i.e., the ability to remember the personal circumstances for the reception of important news events). We examined the frequency, characteristics, and the temporal distribution of flashbulb memories across the life span. To this aim, 28 older adults diagnosed with AD and a matched sample of 29 healthy older controls were probed for flashbulb memories for two historical events from each decade of their lives. They also estimated the subjective degree of reexperiencing for the memories reported. AD participants showed impaired access to flashbulb memories, the frequency of reported memories being lower than for healthy older adults. However, qualitative aspects of AD participants' flashbulb memories were quite similar to those of the controls, as no group differences were obtained with respect to the canonical categories or degree of reexperience. AD participants' flashbulb memories clustered during the early years of their life, consistent with a reminiscence bump, whereas healthy controls also reported memories dated to later lifetime periods. Our results suggest that probing for personal memories of important public events may serve as a powerful cue for detailed episodic memories in AD.

Positive Emotional Responses to Socially Assistive Robots in People With Dementia: Pilot Study

Background

Interventions and care that can evoke positive emotions and reduce apathy or agitation are important for people with dementia. In recent years, socially assistive robots used for better dementia care have been found to be feasible. However, the immediate responses of people with dementia when they are given multiple sensory modalities from socially assistive robots have not yet been sufficiently elucidated.

Objective

This study aimed to quantitatively examine the immediate emotional responses of people with dementia to stimuli presented by socially assistive robots using facial expression analysis in order to determine whether they elicited positive emotions.

Methods

This pilot study adopted a single-arm interventional design. Socially assistive robots were presented to nursing home residents in a three-step procedure: (1) the robot was placed in front of participants (visual stimulus), (2) the robot was manipulated to produce sound (visual and auditory stimuli), and (3) participants held the robot in their hands (visual, auditory, and tactile stimuli). Expression intensity values for "happy," "sad," "angry," "surprised," "scared," and "disgusted" were calculated continuously using facial expression analysis with FaceReader. Additionally, self-reported feelings were assessed using a 5-point Likert scale. In addition to the comparison between the subjective and objective emotional assessments, expression intensity values were compared across the aforementioned 3 stimuli patterns within each session. Finally, the expression intensity value for "happy" was compared between the different types of robots.

Results

A total of 29 participants (mean age 88.7, SD 6.2 years; n=27 female; Japanese version of Mini-Mental State Examination mean score 18.2, SD 5.1) were recruited. The expression intensity value for "happy" was the largest in both the subjective and objective assessments and increased significantly when all sensory modalities (visual, auditory, and tactile) were presented (median expression intensity 0.21, IQR 0.09-0.35) compared to the other 2 patterns (visual alone: median expression intensity 0.10, IQR 0.03-0.22; P<.001; visual and auditory: median expression intensity 0.10, IQR 0.04-0.23; P<.001). The comparison of different types of robots revealed a significant increase when all stimuli were presented by doll-type and animal-type robots, but not humanoid-type robots.

Conclusions

By quantifying the emotional responses of people with dementia, this study highlighted that socially assistive robots may be more effective in eliciting positive emotions when multiple sensory stimuli, including tactile stimuli, are involved. More studies, including randomized controlled trials, are required to further explore the effectiveness of using socially assistive robots in dementia care.

Amygdala activity and amygdala-hippocampus connectivity: Metabolic diseases, dementia, and neuropsychiatric issues

With rapid aging of the population worldwide, the number of people with dementia is dramatically increasing. Some studies have emphasized that metabolic syndrome, which includes obesity and diabetes, leads to increased risks of dementia and cognitive decline. Factors such as insulin resistance, hyperglycemia, high blood pressure, dyslipidemia, and central obesity in metabolic syndrome are associated with synaptic failure, neuroinflammation, and imbalanced neurotransmitter levels, leading to the progression of dementia. Due to the positive correlation between diabetes and dementia, some studies have called it "type 3 diabetes". Recently, the number of patients with cognitive decline due to metabolic imbalances has considerably increased. In addition, recent studies have reported that neuropsychiatric issues such as anxiety, depressive behavior, and impaired attention are common factors in patients with metabolic disease and those with dementia. In the central nervous system (CNS), the amygdala is a central region that regulates emotional memory, mood disorders, anxiety, attention, and cognitive function. The connectivity of the amygdala with other brain regions, such as the hippocampus, and the activity of the amygdala contribute to diverse neuropathological and neuropsychiatric issues. Thus, this review summarizes the significant consequences of the critical roles of amygdala connectivity in both metabolic syndromes and dementia. Further studies on amygdala function in metabolic imbalance-related dementia are needed to treat neuropsychiatric problems in patients with this type of dementia.

DMapp: a developing promising approach to monitor symptoms progression and stimulate memory in Italian people with cognitive impairments

BACKGROUND

Based on recent researches on the use of natural language processing techniques for very early detection of cognitive decline and the benefits of cognitive stimulation for people with cognitive impairments, the Dementia Monitoring application (DMapp) is developed inside the Memento project.

AIMS

The aims of this work are: (1) to present DMapp; (2) to report the results of two preliminary studies on DMapp; (3) to describe the clinical and experimental potentiality of DMapp.

METHODS

Italian people with the diagnosis of mild cognitive impairment due to Alzheimer's disease or dementia due to Alzheimer's Disease with a Mini-Mental-State-Examination between 24 and 28 (inclusive) were involved in the DMapp development prototype during the Lab Trial (4 subjects) and Filed Trial (5 subjects) of the Memento project. Qualitative and quantitative data were collected to evaluate participants' opinions, the DMapp ability to perform the automatic analysis of the speech and participants' visible emotional state effective. Ad hoc interviews, the Observed Emotion Rating Scale and performance metrics to solve different tasks were used. The relation between cognitive measures (global cognitive measures) and linguistic indexes values was considered using Euclidean distances between the participants.

RESULTS

Linguistic indexes were calculated and seemed to classify the participants' performance as expected from cognitive measures. The DMapp was appreciated by people with cognitive impairment. Positive emotions were present.

CONCLUSION

DMapp seems an interesting approach to monitor dementia symptoms progression and stimulate memory. Possible developments and open questions are discussed.

Aesthetic Preference for Negatively-Valenced Artworks Remains Stable in Pathological Aging: A Comparison Between Cognitively Impaired Patients With Alzheimer's Disease and Healthy Controls

Background

Despite severe cognitive dysfunction in Alzheimer's disease (AD), aesthetic preferences in AD patients seem to retain some stability over time, similarly to healthy controls. However, the underlying mechanisms of aesthetic preference stability in AD remain unclear. We therefore aimed to study the role of emotional valence of stimuli for stability of aesthetic preferences in patients with AD compared to cognitively unimpaired elderly adults.

Methods

Fifteen AD patients (Mini-Mental State Examination (MMSE) score 12–26) without visual impairment and/or psychiatric disorder, as well as 15 healthy controls without cognitive impairment (MMSE ≥ 27) matched in age, sex, art interest and highest level of education were included in this study. All participants were asked to rank-order eight artworks per stimulus category (positive, negative, neutral in emotional valence) according to their preference twice with a 2-week span in-between. Based on these two rankings a preference change score was calculated. In order to assess explicit recognition memory of the artworks in the second testing session, four artworks of each stimulus category used in the preference ranking task were presented together with a content-matched distractor artwork painted by the same artist. Participants had to indicate which of the stimuli they had seen 2 weeks previously.

Results

AD patients [MMSE (M) = 18.9 ± 3.6; Age (M) = 85.4 ± 6.9; 33.3% male] had no explicit recognition memory of the artworks (recognition at chance level), whereas healthy controls [MMSE (M) = 27.7 ± 1.4; Age (M) = 84.3 ± 6.7; 33.3% male] correctly recognized 85% of stimuli after 2 weeks. AD patients had equally stable preferences compared to the control group for negative artworks, but less stable preferences for positive and neutral images (Bonferroni-corrected significance levels; p < 0.017).

Conclusion

Even in cognitively impaired AD patients, aesthetic preference for negatively-valenced artworks remains relatively stable. Our study provides novel evidence that AD patients may have a somewhat preserved implicit valence system for negative compared to neutral or positive visual information, especially in the domain of aesthetics. However, more studies need to further uncover the details of the underlying neurocognitive mechanisms of preference stability in pathological aging.

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.

Emotional Valence Affects Word Retrieval During Verb Fluency Tasks in Alzheimer's Dementia

Individuals with amnestic Alzheimer's disease (AD) often demonstrate preserved emotional processing skills despite the neurodegenerative disease that affects their limbic system. Emotional valence encompasses the encoding and retrieval of memory and it also affects word retrieval in healthy populations, but it remains unclear whether these effects are preserved in individuals with amnestic AD. Previous studies used a variety of encoding procedures and different retrieval methods that resulted in mixed findings. Therefore, the purpose of the current study is to investigate whether emotional enhancement of memory effects is observed in an experimental condition where the memory encoding process is not required, namely verb (action) fluency tasks. Seventeen participants who were cognitively healthy older adults (CHOA) and 15 participants with amnestic AD were asked to complete verb fluency tasks, and the relative degree of emotional valence observed in their responses was compared between the two groups. A neuropsychological test battery was administered to determine the participants' cognitive and linguistic profiles, and correlational analyses were conducted to delineate relationships between emotional valence, verbal memory, and learning abilities. The results indicated that the participants with amnestic AD produced words with higher emotional valence (i.e., more pleasant words) compared to CHOA during action fluency testing. In addition, the degree of emotional valence in the words was negatively correlated with verbal memory and learning skills, showing that those with poorer memory skills tend to retrieve words with higher emotional valence. The findings are consistent with those previous studies that stressed that individuals with AD have preserved emotional enhancement of memory effects and may benefit from them for retrieval of information, which may offer some insight into the development of novel rehabilitative strategies for this population.

Age-related Differences in Mu rhythm during Emotional Destination Memory

BACKGROUND

Destination memory, defined as the ability to remember to whom we addressed a piece of information, is found to be impaired in normal aging. Theories on development of affect and research findings have shown that emotional charge improves performance in memory tasks, and also that Mu rhythm is desynchronized as an index of mirror neuron activation during such tasks.

OBJECTIVE

In this paper, we sought to investigate the differences in Mu rhythm during an emotional destination memory task between younger and older adults.

METHODS

16 cognitively normal older adults, recruited from Alzheimer's disease day center and 16 young adults, recruited via advertisements, participated in this experimental study. We investigated the destination memory of emotionally charged faces (Emotional Destination Memory, EDM) while applying electroencephalograph (EEG) in real-time in young versus older adults. We measured Mu rhythm in frontal, fronto-temporal and central areas. EEG data has been pre-processed, segmented in non-overlapping epochs, and independent component analysis (ICA) has been conducted to reject artifacts.

RESULTS

Results showed that young adults performed better than older adults in remembering facts associated with angry faces. Also, a difference in neurophysiological activation was found, with older adults showing Mu suppression in frontal and fronto-temporal regions, specifically in F3, F7 and F8 electrodes, in contrast with young adults who showed Mu enhancement. With regard to the within-group differences, it was found that in the older adults group, electrodes F8 and central C3 were the most activated, while in the young adults group, C3 was the most activated electrode.

CONCLUSION

The findings suggest better behavioral performance of young adults as a result of a better cognitive state and adaptive bias. On a neurophysiological level, it is suggested that older adults employ Mu suppression, thus activation of mirror neurons is a possible compensatory mechanism while mirroring properties are not spontaneously activated in young adults.

Eye contact effects on social preference and face recognition in normal ageing and in Alzheimer's disease

Perceiving a direct gaze (i.e. another individual's gaze directed to the observer leading to eye contact) influences positively a wide range of cognitive processes. In particular, direct gaze perception is known to stimulate memory for other's faces and to increase their likeability. Alzheimer's disease (AD) results in social withdrawal and cognitive decline. However, patients show preserved eye contact behaviours until the middle stage of the disease. The eye contact effects could be preserved in AD and be used to compensate for cognitive and social deficits. Yet, it is unknown whether these effects are preserved in normal ageing. The aim of this study was to address whether the positive effects of eye contact on memory for faces and likeability of others are preserved in healthy older adults and in patients with early to mild AD. Nineteen AD patients, 20 older adults and 20 young adults participated in our study. Participants were first presented with faces displaying either direct or averted gaze and rated each face's degree of likeability. They were then asked to identify the faces they had previously seen during a surprise recognition test. Results showed that the effect of eye contact on other's likeability was preserved in normal ageing and in AD. By contrast, an effect of eye contact on memory for faces seems to emerge only in young participants, suggesting that this effect declines with ageing. Interestingly, however, AD patients show a positive correlation between ratings of likeability and recognition scores, suggesting that they implicitly allocated their encoding resources to most likeable faces. These results open a new way for a "compensating" therapy in AD.

Low Arousal Positive Emotional Stimuli Attenuate Aberrant Working Memory Processing in Persons with Mild Cognitive Impairment

Emotional enhancement effects on memory have been reported to mitigate the pathophysiology of Alzheimer's disease (AD). However, relative to their manifestation in persons without pathologic aging, these effects may be reduced in magnitude or even deleterious, especially in tasks that more closely model ecologic memory performance. Based upon a synthesis of such reports, we hypothesized that in persons with AD low arousal positive stimuli would evoke relatively intact emotional enhancement effects, but that high arousal negative stimuli would evoke disordered emotional enhancement effects. To assess this, participants with and without mild cognitive impairment (MCI) presumed to be due to AD performed an emotionally-valenced short-term memory task while encephalography was recorded. Results indicated that for persons with MCI, high arousal negative stimuli led to working memory processing patterns previously associated with MCI presumed due to AD and dementia of the Alzheimer-type. In contrast, low arousal positive stimuli evoked a processing pattern similar to MCI participants' unaffected spouses. Our current findings suggest that low arousal positive stimuli attenuate working memory deficits of MCI due to AD.

Spared behavioral repetition effects in Alzheimer's disease linked to an altered neural mechanism at posterior cortex

OBJECTIVE

Individuals with dementia of the Alzheimer type (AD) classically show disproportionate impairment in measures of working memory, but repetition learning effects are relatively preserved. As AD affects brain regions implicated in both working memory and repetition effects, the neural basis of this discrepancy is poorly understood. We hypothesized that the posterior repetition effect could account for this discrepancy due to the milder effects of AD at visual cortex.

METHOD

Participants with early AD, amnestic mild cognitive impairment (MCI), and healthy controls performed a working memory task with superimposed repetition effects while electroencephalography was collected to identify possible neural mechanisms of preserved repetition effects.

RESULTS

Participants with AD showed preserved behavioral repetition effects and a change in the posterior repetition effect.

CONCLUSION

Visual cortex may play a role in maintained repetition effects in persons with early AD.

Variation in the corticotropin-releasing hormone receptor 1 (CRHR1) gene modulates age effects on working memory

Decline in working memory (WM) functions during aging has been associated with hippocampal dysfunction mediated by age-related changes to the corticotropin-releasing hormone (CRH) system. Recent reports suggest that GG-homozygous individuals of single nucleotide polymorphisms (rs110402 and rs242924) in the CRH receptor 1 (CRHR1) gene show increased stress vulnerability and decreased BOLD responses in WM relevant regions. However, until now, no study investigated the interaction effects of variation in the CRHR1 gene and age on individual differences in WM. Here, young, middle-aged and old subjects (N = 466) were genotyped for rs110402 and rs242924 within the CRHR1 gene and an n-back task was used to investigate the hypothesis that vulnerable genotypes (GG-homozygotes) would show impaired WM functions that might be magnified by increased CRH production with advancing age. Our results show an impact of genotype already in middle-age with significantly better performance in AT-carriers. Working memory performance in AT-carriers did not differ between young and middle-aged subjects, but was significantly impaired in old age. In GG-homozygotes, severe working memory dysfunction occurred already in middle age. Our data indicate that GG-homozygotes of CRHR1 rs110402 and rs242924 represent a genetically driven subtype of early WM impairments due to alterations in hippocampal CRHR1 activation. Early interventions that have proven effective in delaying cognitive decline appear to be particularly important for these subjects at risk for premature memory decline, who are in the prime of their personal and professional lives.

Feelings without memory in Alzheimer disease

Background:

Patients with Alzheimer disease (AD) typically have impaired declarative memory as a result of hippocampal damage early in the disease. Far less is understood about AD’s effect on emotion.

Objective:

We investigated whether feelings of emotion can persist in patients with AD, even after their declarative memory for what caused the feelings has faded.

Methods:

A sample of 17 patients with probable AD and 17 healthy comparison participants (case-matched for age, sex, and education) underwent 2 separate emotion induction procedures in which they watched film clips intended to induce feelings of sadness or happiness. We collected real-time emotion ratings at baseline and at 3 post-induction time points, and we administered a test of declarative memory shortly after each induction.

Results:

As expected, the patients with AD had severely impaired declarative memory for both the sad and happy films. Despite their memory impairment, the patients continued to report elevated levels of sadness and happiness that persisted well beyond their memory for the films. This outcome was especially prominent after the sadness induction, with sustained elevations in sadness lasting for more than 30 minutes, even in patients with no conscious recollection for the films.

Conclusions:

These findings indicate that patients with AD can experience prolonged states of emotion that persist well beyond the patients’ memory for the events that originally caused the emotion. The preserved emotional life evident in patients with AD has important implications for their management and care, and highlights the need for caretakers to foster positive emotional experiences.

What do temporal lobe epilepsy and progressive mild cognitive impairment have in common?

Temporal lobe epilepsy (TLE) and mild cognitive impairment (MCI) are both subject to intensive memory research. Memory problems are a core characteristic of both conditions and we wonder if there are analogies which would enrich the two distinct research communities. In this review we focus on memory decline in both conditions, that is, the most feared psychosocial effect. While it is clear that memory decline in MCI is highly likely and would lead to the more severe diagnosis of Alzheimer's disease, it is a debate if TLE is a dementing disease or not. As such, like for MCI, one can differentiate progressive from stable TLE subtypes, mainly depending on the age of onset. Neuroimaging techniques such as volumetric analysis of the hippocampus, entorhinal, and perirhinal cortex show evidence of pathological changes in TLE and are predictive for memory decline in MCI. Several studies emphasize that it is necessary to extend the region of interest—even whole-brain characteristics can be predictive for conversion from MCI to Alzheimer's disease. Electroencephalography is increasingly subject to computational neuroscience, revealing new approaches for analyzing frequency, spatial synchronization, and information content of the signals. These methods together with event-related designs that assess memory functions are highly promising for understanding the mechanisms of memory decline in both TLE and MCI populations. Finally, there is evidence that the potential of such markers for memory decline is far from being exhausted. Similar structural and neurophysiological characteristics are linked to memory decline in TLE and MCI. We raise the hope that interdisciplinary research and cross-talk between fields such as research on epilepsy and dementia, will shed further light on the dementing characteristics of the pathological basis of MCI and TLE and support the development of new memory enhancing treatment strategies.

The emotional memory effect in Alzheimer's disease: emotional words enhance recollective experience similarly in patients and control participants

The purpose of the present study was to investigate emotional memory enhancement (EME) in Alzheimer's disease (AD). In particular, we were interested in exploring which memory process (i.e., recollection or familiarity) could be improved by emotional information in the course of the disease. Eighteen AD patients were compared with 15 normal controls on the Remember/Know/Guess paradigm following encoding of emotional and neutral words. AD patients' recollective experience was improved for emotional compared to neutral words to the same extent as that of normal controls, whereas emotion had no effect on participants' memory performance involving familiarity processes. Our results showed that AD patients' memory can be enhanced qualitatively but not quantitatively by an emotional material. Furthermore, we found that AD patients were as able as normal controls to benefit from the emotional content of information to improve the recollection of details.

Memory for the 2008 presidential election in healthy ageing and mild cognitive impairment

The present study examined memory accuracy and confidence for personal and public event details of the 2008 presidential election in healthy older adults and those with mild cognitive impairment (MCI). Participants completed phone interviews within a week after the election and after a 10-month delay. MCI patients and healthy older adults had comparable emotional reactions to learning the outcome of the election, with most people finding it to be a positive experience. After the delay period, details about the election were better remembered by all participants than a less emotionally arousing comparison event. However, MCI patients had more difficulty than healthy older adults correctly recalling details of public information about the election, although often the MCI patients could recognise the correct details. This is the first study to show that MCI patients' memory can benefit from emotionally arousing positive events, complementing the literature demonstrating similar effects for negative events.

Distinct neural systems underlying reduced emotional enhancement for positive and negative stimuli in early Alzheimer's disease

Emotional information is typically better remembered than neutral content, and previous studies suggest that this effect is subserved particularly by the amygdala together with its interactions with the hippocampus. However, it is not known whether amygdala damage affects emotional memory performance at immediate and delayed recall, and whether its involvement is modulated by stimulus valence. Moreover, it is unclear to what extent more distributed neocortical regions involved in e.g., autobiographical memory, also contribute to emotional processing. We investigated these questions in a group of patients with Alzheimer's disease (AD), which affects the amygdala, hippocampus and neocortical regions. Healthy controls (n = 14), patients with AD (n = 15) and its putative prodrome amnestic mild cognitive impairment (n = 11) completed a memory task consisting of immediate and delayed free recall of a list of positive, negative and neutral words. Memory performance was related to brain integrity in region of interest and whole-brain voxel-based morphometry analyses. In the brain-behavioral analyses, the left amygdala volume predicted the immediate recall of both positive and negative material, whereas at delay, left and right amygdala volumes were associated with performance with positive and negative words, respectively. Whole-brain analyses revealed additional associations between left angular gyrus integrity and the immediate recall of positive words as well as between the orbitofrontal cortex and the delayed recall of negative words. These results indicate that emotional memory impairments in AD may be underpinned by damage to regions implicated in emotional processing as well as frontoparietal regions, which may exert their influence via autobiographical memories and organizational strategies.

Exploring the affective dimension of the life review process: Facilitators’ interactional strategies for fostering personhood and social value among older adults with early dementia

We employed an auto-ethnography approach to explore the affective dimension of life review sessions with community-dwelling older military veterans with minor cognitive impairment (MCI) and early dementia. Using researchers’ analytic memos, we identified facilitators’ interactional strategies that fostered the participant’s sense of personal identity, dignity and social self-worth. Interaction among participant, caregiver, and facilitators evoked a range of emotional responses, offering a window into the affective world of MCI and early dementia. Positive emotional responses outnumbered negative emotional responses by a ratio of two-to-one in the life review sessions; however, negative emotions were more revelatory of current struggles with declines in health and function. Facilitators utilized two interactional strategies, in particular, to foster personhood and social value of participants: focusing on the participant and creating an empathic connection with the participant. Further work is needed to understand the role of emotions in research interactions and to examine the psychosocial mechanisms through which positive affect functions in promoting identity, personhood and social value among persons with MCI and early dementia.

Preserved and impaired emotional memory in Alzheimer's disease

Patients with early atrophy of both limbic structures involved in memory and emotion processing in Alzheimer's disease (AD) provide a unique clinical population for investigating how emotion is able to modulate retention processes. This review focuses on the emotional enhancement effect (EEE), defined as the improvement of memory for emotional events compared with neutral ones. The assessment of the EEE for different memory systems in AD suggests that the EEE could be preserved under specific retrieval instructions. The first part of this review examines these data in light of compelling evidence that the amygdala can modulate processes of hippocampus-dependent memory. We argue that the EEE could be a useful paradigm to reduce impairment in episodic memory tasks. In the second part, we discuss theoretical consequences of the findings in favor of an EEE, according to which a compensatory mechanism in patients with AD solicits greater amygdala functioning or additional networks, even when amygdala atrophy is present. These considerations emphasize the relevance of investigating patients with AD to understand the relationship between emotion and memory processes.

Local amplification of glucocorticoids in the aging brain and impaired spatial memory

The hippocampus is a prime target for glucocorticoids (GCs) and a brain structure particularly vulnerable to aging. Prolonged exposure to excess GCs compromises hippocampal electrophysiology, structure, and function. Blood GC levels tend to increase with aging and correlate with impaired spatial memory in aging rodents and humans. The magnitude of GC action within tissues depends not only on levels of steroid hormone that enter the cells from the periphery and the density of intracellular receptors but also on the local metabolism of GCs by 11β-hydroxysteroid dehydrogenases (11β-HSD). The predominant isozyme in the adult brain, 11β-HSD1, locally regenerates active GCs from inert 11-keto forms thus amplifying GC levels within specific target cells including in the hippocampus and cortex. Aging associates with elevated hippocampal and neocortical 11β-HSD1 and impaired spatial learning while deficiency of 11β-HSD1 in knockout (KO) mice prevents the emergence of cognitive decline with age. Furthermore, short-term pharmacological inhibition of 11β-HSD1 in already aged mice reverses spatial memory impairments. Here, we review research findings that support a key role for GCs with special emphasis on their intracellular regulation by 11β-HSD1 in the emergence of spatial memory deficits with aging, and discuss the use of 11β-HSD1 inhibitors as a promising novel treatment in ameliorating/improving age-related memory impairments.