Hallucinations in Alzheimer's disease: failure to suppress irrelevant memories

On hallucinations and memory: the relationship between hallucinations and autobiographical overgenerality in Alzheimer's Disease

OBJECTIVES

Alzheimer's disease (AD) has been associated with autobiographical overgenerality (i.e. a tendency of patients to retrieve general rather than specific personal memories). AD has also been associated with hallucinations. We investigated the relationship between autobiographical overgenerality and hallucinations in AD.

METHODS

We invited 28 patients with mild AD to retrieve autobiographical memories, and we also evaluated the occurrence of hallucinations in these patients.

RESULTS

Analysis demonstrated significant correlations between hallucinations and autobiographical overgenerality in the patients.

CONCLUSION

AD patients who are distressed by hallucinations may demonstrate autobiographical overgenerality as a strategy to avoid retrieving distressing information that may be related with hallucinations. However, hallucinations as observed in our study can be attributed to other factors such as the general cognitive decline in AD.

Involuntary Autobiographical Memory in Alzheimer's Disease: A Double-Edged Way of Remembering the Past?

Background

Alzheimer's disease (AD) is characterized by severe memory alterations, affecting especially memories of personal past events. Until now, autobiographical memory impairments have been characterized using formal memory assessments, requiring patients to strategically and deliberately recall past events. However, contrary to this highly cognitively demanding mode of memory recall, autobiographical memories frequently come to mind unexpectedly based on automatic associative processes. The involuntary recall of personal memories is effortless and possibly represents a preserved way for AD patients to remember past events.

Objective

This study aimed to investigate involuntary autobiographical memory in AD patients and compare the characteristics of these memories with those of healthy controls.

Methods

Involuntary autobiographical memory was measured in 24 AD patients and 24 matched control participants using self-report measures. Participants were asked to report the frequency with which involuntary autobiographical memories were experienced in their daily life and to describe and self-assess one example of an involuntary memory.

Results

We showed that AD patients and control participants did not differ in terms of the frequency or subjective characteristics of their involuntary autobiographical memories in daily life, except for feelings of intrusiveness. Compared to control participants, AD patients reported their involuntary autobiographical memories as being more intrusive. In addition, more negative and vague involuntary autobiographical memories were associated with greater depressive symptoms.

Conclusions

These findings open up a new avenue for research to better understand the extent to which involuntary autobiographical memory might be preserved in AD patients and why these memories may in turn become intrusive to patients.

A Multimodal Neuroimaging and Neuropsychological Study of Visual Hallucinations in Alzheimer’s Disease

Background: Hallucinations in Alzheimer’s disease (AD) have been linked to more severe cognitive and functional decline. However, research on visual hallucinations (VH), the most common type of hallucinations in AD, is limited. Objective: To investigate the cognitive and cerebral macrostructural and metabolic features associated with VH in AD. Methods: Twenty-four AD patients with VH, 24 with no VH (NVH), and 24 cognitively normal (CN) matched controls were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Differences in regional gray matter (GM) volumes and cognitive performance were investigated with whole brain voxel-based morphometry analyses of MRI structural brain scans, and analyses of neuropsychological tests. Glucose metabolic changes were explored in a subsample of patients who had FDG-PET scans available. Results: More severe visuoconstructive and attentional deficits were found in AD VH compared with NVH. GM atrophy and hypometabolism were detected in occipital and temporal areas in VH patients in comparison with CN. On the other hand, NVH patients had atrophy and hypometabolism mainly in temporal areas. No differences in GM volume and glucose metabolism were found in the direct comparison between AD VH and NVH. Conclusion: In addition to the pattern of brain abnormalities typical of AD, occipital alterations were observed in patients with VH compared with CN. More severe visuoconstructive and attentional deficits were found in AD VH when directly compared with NVH, and might contribute to the emergence of VH in AD.

The fabricated past: intentionally fabricated autobiographical memories in Alzheimer's disease

OBJECTIVE

We investigated intentionally fabricated autobiographical memories in Alzheimer's Disease (AD).

METHOD

We invited AD patients and control participants to construct real events as well as fabricated events describing fictitious personal events that occurred in the past.

RESULTS

Results demonstrated slower retrieval time for intentionally fabricated memories than for real ones in both AD patients and control participants. The analysis also showed similar vividness for intentionally fabricated memories and real ones in AD patients but lower vividness for intentionally fabricated memories than for real ones in control participants.

CONCLUSIONS

The slow retrieval time of intentionally fabricated memories may be attributed to the cognitive effort required to retrieve elements from autobiographical memory and edit them to construct a new memory. We suggest that the vividness of intentionally fabricated memories observed in AD may induce confusion with real memories. In addition to the experimental approach of our study, we offer a theoretical rationale for intentionally fabricated autobiographical memories by situating them in the wider context of different facets of false memories in AD (e.g. confabulations, source monitoring errors).

Hallucinations and Covid-19: Increased Occurrence of Hallucinations in Patients with Alzheimer's Disease During Lockdown

We investigated the effects of lockdown, as implemented by retirement homes to cope with the spread of Covid-19, on hallucinatory experiences in patients with Alzheimer's disease (AD). The study included 47 patients with AD living in retirement homes and who were already experiencing hallucinations prior to the lockdown. We invited caregivers to rate hallucinatory experiences in these patients during the lockdown, and compared this rating with that provided by the same caregivers prior to the lockdown. Results demonstrated increased hallucinatory experiences in patients with AD during the lockdown, compared with before the lockdown. The decrease in social and physical activities during the lockdown, and especially, the physical separation of residents from family members, might have led to decreased sensory stimulation and increased loneliness, and consequently, to the hallucinatory experiences in patients with AD living in retirement homes during the lockdown. While the restrictive measures were necessary to cope with the spread of Covid-19, these measures have increased hallucinations in patients with AD living in retirement homes, at least in those who were already experiencing hallucinations prior to the lockdown.

Behavioural effects of the ACE insertion/deletion polymorphism in Alzheimer's disease depend upon stratification according to APOE-ϵ4 carrier status

Introduction: The inherited risk of late-onset Alzheimer's disease (AD) is genetically determined. We aimed to examine associations of genetic variants of APOE and ACE with age at AD onset and with neuropsychiatric symptoms according to each dementia stage.Methods: Consecutive outpatients with AD were assessed for demographic features, Clinical Dementia Rating scores, and the 10-item Neuropsychiatric Inventory, and genotyped for rs7412 and rs429358 (APOE haplotypes, Real-Time Polymerase Chain Reactions), and the ACE insertion/deletion polymorphism (Polymerase Chain Reactions). Combined genetic variants of APOE and ACE were associated with age at dementia onset, and with neuropsychiatric symptoms in each dementia stage (adjusted for sex and age at dementia onset).Results: Over two-thirds of the 238 patients were women, whereas the mean age at dementia onset was 73.82 ± 6.2 years-old. APOE-ϵ4/ϵ4 carriers had earlier dementia onset (p<.001). The ACE insertion/deletion polymorphism was in Hardy-Weinberg equilibrium (p=.37) but was not associated with age at dementia onset, regardless of APOE-ϵ4 carrier status. The only results that survived corrections for false discovery rates were higher scores of dysphoria for APOE-ϵ4 carriers (n=122) who also carried ACE deletion/deletion (p=.031). No results survived corrections for false discovery rates for APOE-ϵ4 non-carriers (n=116).Conclusions: Though only the APOE-ϵ4/ϵ4 haplotype affected AD onset, effects of the ACE insertion/deletion polymorphism over behavioural features might differ according to APOE-ϵ4 carrier status in genetic associations.

Hallucinations and Delusions Signal Alzheimer's Associated Cognitive Dysfunction More Strongly Compared to Other Neuropsychiatric Symptoms

OBJECTIVES

Neuropsychiatric symptoms (NPS) are common among individuals with dementia of the Alzheimer's type (DAT). We sought to characterize which NPS more purely relate to cognitive dysfunction in DAT, relative to other NPS.

METHOD

Demographic, neurocognitive, neuroimaging, and NPS data were mined from the Alzheimer's Disease Neuroimaging Initiative database (n = 906). Using factor analysis, we analyzed the degree to which individual NPS were associated with DAT-associated cognitive dysfunction. We also employed item response theory to graphically depict the ability of individual NPS to index DAT-associated cognitive dysfunction across a continuum ranging from cognitively normal to mild DAT.

RESULTS

Psychotic symptoms (hallucinations and delusions) were more strongly related to the continuum of DAT-associated cognitive dysfunction than other NPS, with the strength of the relationship peaking at high levels of disease severity. Psychotic symptoms also negatively correlated with brain volume and did not relate to the presence of vision problems. Aberrant motor behavior and apathy had relatively smaller associations with DAT-associated cognitive dysfunction, while other NPS showed minimal associations.

DISCUSSION

Psychotic symptoms most strongly indexed DAT-associated cognitive dysfunction, whereas other NPS, such as depression and anxiety, were not as precisely related to the DAT-associated cognitive dysfunction.

Hallucinations in a Patient with Alzheimer's Disease During the COVID-19 Crisis: A Case Study

While social distancing may be deemed necessary in order to avoid COVID-19 infections, the lockdown may impact mental health of patients with Alzheimer’s disease (AD). We present a case study involving hallucinations in a patient with AD who lives in a nursing home during the COVID-19 crisis. We compared this patient’s hallucination scores before and during the lockdown. We observed increased hallucinations during, compared to before, the lockdown. These increased hallucinations can be attributed to a number of elements such as the decreased in daily activities, social distancing, lack of physical contact with family members, and loneliness during the lockdown.

Tailoring cognitive behavioural therapy to subtypes of voice-hearing using a novel tabletised manual: a feasibility study

BACKGROUND

Cognitive behavioural therapy for psychosis (CBTp) is a recommended treatment for psychotic experiences, but its effectiveness has been questioned. One way of addressing this may be to tailor therapy materials to the phenomenology of specific psychotic experiences.

AIM

In this study, we investigated the acceptability of a novel treatment manual for subtypes of 'voice-hearing' experiences (i.e. auditory verbal hallucinations). An uncontrolled, single-arm design was used to assess feasibility and acceptability of using the manual in routine care for people with frequent voice-hearing experiences.

METHOD

The manual was delivered on a smart tablet and incorporated recent research evidence and theory into its psychoeducation materials. In total, 24 participants completed a baseline assessment; 19 started treatment, 15 completed treatment and 12 participants completed a follow-up assessment (after 10 sessions of using the manual).

RESULTS

Satisfaction with therapy scores and acceptability ratings were high, while completion rates suggested that the manual may be more appropriate for help with participants from Early Intervention in Psychosis services rather than Community Mental Health Teams.

CONCLUSION

Within-group changes in symptom scores suggested that overall symptom severity of hallucinations - but not other psychosis features, or beliefs about voices - are likely to be the most appropriate primary outcome for further evaluation in a full randomised controlled trial.

Hallucinations in Older Adults: A Practical Review

Older adults experience hallucinations in a variety of social, physical, and mental health contexts. Not everyone is open about these experiences, as hallucinations are surrounded with stigma. Hence, hallucinatory experiences in older individuals are often under-recognized. They are also commonly misunderstood by service providers, suggesting that there is significant scope for improvement in the training and practice of professionals working with this age group. The aim of the present article is to increase knowledge about hallucinations in older adults and provide a practical resource for the health and aged-care workforce. Specifically, we provide a concise narrative review and critique of (1) workforce competency and training issues, (2) assessment tools, and (3) current treatments and management guidelines. We conclude with a brief summary including suggestions for service and training providers and future research.

O-GlcNAcylation as a Therapeutic Target for Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia and the number of elderly patients suffering from AD has been steadily increasing. Despite worldwide efforts to cope with this disease, little progress has been achieved with regard to identification of effective therapeutics. Thus, active research focusing on identification of new therapeutic targets of AD is ongoing. Among the new targets, post-translational modifications which modify the properties of mature proteins have gained attention. O-GlcNAcylation, a type of PTM that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to a protein, is being sought as a new target to treat AD pathologies. O-GlcNAcylation has been known to modify the two important components of AD pathological hallmarks, amyloid precursor protein, and tau protein. In addition, elevating O-GlcNAcylation levels in AD animal models has been shown to be effective in alleviating AD-associated pathology. Although studies investigating the precise mechanism of reversal of AD pathologies by targeting O-GlcNAcylation are not yet complete, it is clearly important to examine O-GlcNAcylation regulation as a target of AD therapeutics. This review highlights the mechanisms of O-GlcNAcylation and its role as a potential therapeutic target under physiological and pathological AD conditions.

A look into hallucinations: the relationship between visual imagery and hallucinations in Alzheimer's disease

Introduction: We investigated the relationship between visual hallucinations and vividness of visual imagery in patients with Alzheimer's disease (AD). Method: We recruited 28 patients with AD and 30 healthy control participants, matched for age and education. We evaluated proneness towards hallucinations with the Launay-Slade Hallucinations Scale, which includes items assessing visual and auditory hallucinations. We also evaluated vividness of visual imagery with the Vividness of Visual Imagery Questionnaire on which participants had to imagine four images (i.e., imagining the face of a friend, the rising sun, a familiar shop-front, and a country scene) and report the vividness of the images they generated. Results: Analysis demonstrated significant positive correlations between visual hallucinations and vividness of visual imagery in AD patients, however, no significant correlations were observed between auditory hallucinations and vividness of visual imagery in these participants. No significant correlations were observed between hallucinations and vividness of visual imagery in healthy control participants, probably due to the lack of hallucinations in these participants. Discussion: These results demonstrate a selective relationship between the occurrence of visual (but not auditory) hallucinations and the ability to generate vivid visual images in AD.

Berberine Alleviates Amyloid-beta Pathogenesis Via Activating LKB1/AMPK Signaling in the Brain of APP/PS1 Transgenic Mice

Background:

Liver kinase B1 (LKB1)/5’-adenosine monophosphate-activated protein kinase (AMPK) signaling, a metabolic checkpoint, plays a neuro-protective role in the pathogenesis of Alzheimer’s disease (AD). Amyloid-β (Aβ) acts as a classical biomarker of AD. The aim of the present study was to explore whether berberine (BBR) activates LKB1/AMPK signaling and ameliorates Aβ pathology.

Methods:

The Aβ levels were detected using enzyme-linked immunosorbent assay and immunohistochemistry. The following biomarkers were measured by Western blotting: phosphorylated (p-) LKB1 (Ser334 and Thr189), p-AMPK (AMPKα and AMPKβ1), synaptophysin, post-synaptic density protein 95 and p-cAMP-response element binding protein (p-CREB). The glial fibrillary acidic protein (GFAP) was determined using Western blotting and immunohistochemistry.

Results:

BBR inhibited Aβ expression in the brain of APP/PS1 mice. There was a strong up-regulation of both p-LKB1 (Ser334 and Thr189) and p-AMPK (AMPKα and AMPKβ1) in the brains of APP/PS1 transgenic mice after BBR-treatment (P<0.01). BBR promoted the expression of synaptophysin, post-synaptic density protein 95 and p-CREB(Ser133) in the AD brain, compared with the model mice.

Conclusion:

BBR alleviates Aβ pathogenesis and rescues synapse damage via activating LKB1/AMPK signaling in the brain of APP/PS1 transgenic mice.