Amnesic disorders

Associations Between Free and Cued Selective Reminding Test and Cerebrospinal Fluid Biomarkers in Amnestic Mild Cognitive Impairment

Background

The Free and Cued Selective Reminding Test (FCSRT), assessing verbal episodic memory with controlled learning and semantic cueing, has been recommended for detecting the genuine encoding and storage deficits characterizing AD-related memory disorders.

Objective

The present study aims at investigating the ability of FCSRT in predicting cerebrospinal fluid (CSF) evidence of amyloid-β positivity in subjects with amnestic mild cognitive impairment (aMCI) and exploring its associations with amyloidopathy, tauopathy and neurodegeneration biomarkers.

Methods

120 aMCI subjects underwent comprehensive neurological and neuropsychological examinations, including the FCSRT assessment, and CSF collection; CSF Aβ42/40 ratio, p-tau181, and total-tau quantification were conducted by an automated CLEIA method on Lumipulse G1200. Based on the Aβ42/40 ratio value, subjects were classified as either A+ or A-.

Results

All FCSRT subitem scores were significantly lower in A+ group and significantly predicted the amyloid-β status, with Immediate Total Recall (ITR) being the best predictor. No significant correlations were found between FCSRT and CSF biomarkers in the A- aMCI group, while in the A+ aMCI group, all FCSRT subitem scores were negatively correlated with CSF p-tau181 and total-tau, but not with the Aβ42/40 ratio.

Conclusions

FCSRT confirms its validity as a tool for the diagnosis of AD, being able to predict the presence of amyloid-β deposition with high specificity. The associations between FCSRT subitem scores and CSF p-tau-181 and total-tau levels in aMCI due to AD could further encourage the clinical use of this simple and cost-effective test in the evaluation of individuals with aMCI.

Behavioral, neurological, and psychiatric frailty of autobiographical memory

Autobiographical-episodic memory is considered to be the most complex of the five long-term memory systems. It is autonoetic, which means, self-reflective, relies on emotional colorization, and needs the features of place and time; it allows mental time traveling. Compared to the other four long-term memory systems-procedural memory, priming, perceptual, and semantic memory-it develops the latest in phylogeny and ontogeny, and is the most vulnerable of the five systems, being easily impaired by brain damage and psychiatric disorders. Furthermore, it is characterized by its fragility and proneness to distortion due to environmental influences and subsequent information. On the brain level, a distinction has to be made between memory encoding and consolidating, memory storage, and memory retrieval. For encoding, structures of the limbic system, with the hippocampus in its center, are crucial, for storage of widespread cortical networks, and for retrieval again a distributed recollection network, in which the prefrontal cortex plays a crucial role, is engaged. Brain damage and psychiatric diseases can lead to what is called "focal retrograde amnesia." In this context, the clinical picture of dissociative or functional or psychogenic amnesia is central, as it may result in autobiographical-emotional amnesia of the total past with the consequence of an impairment of the self as well. The social environment therefore can have a major impact on the brain and on autobiographical-episodic memory processing. This article is categorized under: Psychology > Memory.

Two Cases of Malingered Crime-Related Amnesia

Amnesia is a frequent claim in major crimes, and it is estimated that the complete or partial absence of memory following a crime ranges from 25% to 50% of total cases. Although some cases may constitute a genuine form of amnesia, due to organic-neurological defects or psychological causes, and possibly combined with a dissociative or repressive coping style after an extreme experience, malingering is still fairly common in offenders. Therefore, one of the main goals in medico-legal proceedings is to find methods to determine the credibility of crime-related amnesia. At present, a number of lie and memory detection techniques can assist the forensic assessment of the reliability of declarative proof, and have been devised and improved over the past century: for example, modern polygraphs, event-related potentials, thermal imaging, functional magnetic resonance imaging, kinematic, and facial analysis. Other ad hoc psychological tests, such as the so-called Symptom Validity Test (SVT) and Performance Validity Test (PVT), as well as the autobiographical Implicit Association Test (aIAT), can also be used. To date, however, there is little evidence or case reports that document their real usefulness in forensic practice. Here, we report two cases of crime-related amnesia, whereby both defendants, who were found guilty of homicide, appeared to exhibit dissociative amnesia but where the application of SVTs, PVTs, and aIAT detected a malingered amnesia.

A neurostructural biomarker of dissociative amnesia: a hippocampal study in dissociative identity disorder

BACKGROUND

Little is known about the neural correlates of dissociative amnesia, a transdiagnostic symptom mostly present in the dissociative disorders and core characteristic of dissociative identity disorder (DID). Given the vital role of the hippocampus in memory, a prime candidate for investigation is whether total and/or subfield hippocampal volume can serve as biological markers of dissociative amnesia.

METHODS

A total of 75 women, 32 with DID and 43 matched healthy controls (HC), underwent structural magnetic resonance imaging (MRI). Using Freesurfer (version 6.0), volumes were extracted for bilateral global hippocampus, cornu ammonis (CA) 1-4, the granule cell molecular layer of the dentate gyrus (GC-ML-DG), fimbria, hippocampal-amygdaloid transition area (HATA), parasubiculum, presubiculum and subiculum. Analyses of covariance showed volumetric differences between DID and HC. Partial correlations exhibited relationships between the three factors of the dissociative experience scale scores (dissociative amnesia, absorption, depersonalisation/derealisation) and traumatisation measures with hippocampal global and subfield volumes.

RESULTS

Hippocampal volumes were found to be smaller in DID as compared with HC in bilateral global hippocampus and bilateral CA1, right CA4, right GC-ML-DG, and left presubiculum. Dissociative amnesia was the only dissociative symptom that correlated uniquely and significantly with reduced bilateral hippocampal CA1 subfield volumes. Regarding traumatisation, only emotional neglect correlated negatively with bilateral global hippocampus, bilateral CA1, CA4 and GC-ML-DG, and right CA3.

CONCLUSION

We propose decreased CA1 volume as a biomarker for dissociative amnesia. We also propose that traumatisation, specifically emotional neglect, is interlinked with dissociative amnesia in having a detrimental effect on hippocampal volume.

Utility of Amyloid Positron Emission Tomography Imaging in Older Adults With Epilepsy and Cognitive Decline

In older adults with cognitive decline and epilepsy, diagnosing the etiology of cognitive decline is challenging. We identified 6 subjects enrolled in the Imaging Dementia-Evidence of Amyloid Imaging Scanning (IDEAS) study and nonlesional epilepsy. Three cognitive neurologists reviewed each case to determine the likelihood of underlying Alzheimer's disease (AD) pathology. Their impressions were compared to amyloid PET findings. In 3 cases the impression was concordant with PET findings. In 2 cases "possibly suggestive," the PET reduced diagnostic uncertainty, with 1 having a PET without elevated amyloid and the other PET with intermediate amyloid. In the remaining case with lack of reviewer concordance, the significance of PET with elevated amyloid remains uncertain. This case series highlights that in individuals with a history of epilepsy and cognitive decline, amyloid PET can be a useful tool in evaluating the etiology of cognitive decline when used in an appropriate context.

Wheatgrass extract imparts neuroprotective actions against scopolamine-induced amnesia in mice

The rich and diverse phytoconstituents of wheatgrass have established it as a natural antioxidant and detoxifying agent. The anti-inflammatory potential of wheatgrass has been studied extensively. However, the neuroprotective potential of wheatgrass has not been studied in depth. In this study, we investigated the neuroprotective response of wheatgrass against age-related scopolamine-induced amnesia in mice. Scopolamine is an established anticholinergic drug that demonstrates the behavioural and molecular characteristics of Alzheimer's disease. In the current study, wheatgrass extracts (prepared from 5 and 7 day old plantlets) were administered to scopolamine-induced memory deficit mice. The Morris water maze (MWM) and Y-maze tests demonstrated that wheatgrass treatment improves the behavior and simultaneously enhances the memory of amnesic mice. We further evaluated the expression of neuroinflammation related genes and proteins in the hippocampal region of mice. Wheatgrass significantly upregulated the mRNA and protein expression of neuroprotective markers such as BDNF and CREB in scopolamine-induced mice. Simultaneously, wheatgrass also downregulated the expression of inflammatory markers such as TNF-α and tau genes in these mice. The treatment of scopolamine-induced memory impaired mice with wheatgrass resulted in an elevation in the level of the phosphorylated form of ERK and Akt proteins. Wheatgrass treatment of mice also regulated the phosphorylation of tau protein and simultaneously prevented its aggregation in the hippocampal region of the brain. Overall, this study suggests the therapeutic potential of wheatgrass in the treatment of age-related memory impairment, possibly through the involvement of ERK/Akt-CREB-BDNF pathway and concomitantly ameliorating the tau-related pathogenesis.

Risk of ischaemic stroke in patients with transient global amnesia: a propensity-matched cohort study

BACKGROUND

The exact pathophysiological mechanism of transient global amnesia (TGA) is unknown. It is debatable whether TGA is a risk factor for stroke. Therefore, here we investigated the possibility of TGA as a risk factor for stroke in a real-world setting using large-scale nationwide health claims data.

METHODS

We used health claims data from the Korean National Health Insurance Service (NHIS). Patients diagnosed with TGA between 2007 and 2013 were selected. We initially extracted patients without TGA who were preferentially matched for age and sex with the patients with TGA at a ratio of 10:1 from the whole dataset. Further, we performed 1:2 propensity score matching analysis to balance the baseline characteristics between the two groups. In the propensity score-matched dataset, we performed multivariable Cox regression analysis to investigate the association between TGA and stroke type, including ischaemic, haemorrhagic and all stroke types.

RESULTS

Patients with TGA (n=14 673) were selected from the NHIS database. After extracting from the whole database (n=140 486) and propensity score matching their data at a 1:2 ratio, a total of 10 448 and 20 442 patients were finally assigned to the TGA and control groups, respectively. The multivariable Cox regression analysis demonstrated that the TGA group had a higher risk of ischaemic stroke and all types of stroke (adjusted HR=1.194; 95% CI: 1.043 to 1.368; and HR=1.197; 95% CI: 1.056 to 1.357, respectively).

CONCLUSIONS

Analysis of the nationwide claims database showed that TGA could be an important risk factor for stroke, especially for ischaemic stroke.

Potential Roles of Glucagon-Like Peptide-1 and Its Analogues in Dementia Targeting Impaired Insulin Secretion and Neurodegeneration

Dementia is a chronic, irreversible condition marked by memory loss, cognitive decline, and mental instability. It is clinically related to various progressive neurological diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington’s. The primary cause of neurological disorders is insulin desensitization, demyelination, oxidative stress, and neuroinflammation accompanied by various aberrant proteins such as amyloid-β deposits, Lewy bodies accumulation, tau formation leading to neurofibrillary tangles. Impaired insulin signaling is directly associated with amyloid-β and α-synuclein deposition, as well as specific signaling cascades involved in neurodegenerative diseases. Insulin dysfunction may initiate various intracellular signaling cascades, including phosphoinositide 3-kinase (PI3K), c-Jun N-terminal kinases (JNK), and mitogen-activated protein kinase (MAPK). Neuronal death, inflammation, neuronal excitation, mitochondrial malfunction, and protein deposition are all influenced by insulin. Recent research has focused on GLP-1 receptor agonists as a potential therapeutic target. They increase glucose-dependent insulin secretion and are beneficial in neurodegenerative diseases by reducing oxidative stress and cytokine production. They reduce the deposition of abnormal proteins by crossing the blood-brain barrier. The purpose of this article is to discuss the role of insulin dysfunction in the pathogenesis of neurological diseases, specifically dementia. Additionally, we reviewed the therapeutic target (GLP-1) and its receptor activators as a possible treatment of dementia.

Differential regulation of STP, LTP and LTD by structurally diverse NMDA receptor subunit-specific positive allosteric modulators

Different types of memory are thought to rely on different types of synaptic plasticity, many of which depend on the activation of the N-Methyl-D Aspartate (NMDA) subtype of glutamate receptors. Accordingly, there is considerable interest in the possibility of using positive allosteric modulators (PAMs) of NMDA receptors (NMDARs) as cognitive enhancers. Here we firstly review the evidence that NMDA receptor-dependent forms of synaptic plasticity: short-term potentiation (STP), long-term potentiation (LTP) and long-term depression (LTD) can be pharmacologically differentiated by using NMDAR ligands. These observations suggest that PAMs of NMDAR function, depending on their subtype selectivity, might differentially regulate STP, LTP and LTD. To test this hypothesis, we secondly performed experiments in rodent hippocampal slices with UBP714 (a GluN2A/2B preferring PAM), CIQ (a GluN2C/D selective PAM) and UBP709 (a pan-PAM that potentiates all GluN2 subunits). We report here, for the first time, that: (i) UBP714 potentiates sub-maximal LTP and reduces LTD; (ii) CIQ potentiates STP without affecting LTP; (iii) UBP709 enhances LTD and decreases LTP. We conclude that PAMs can differentially regulate distinct forms of NMDAR-dependent synaptic plasticity due to their subtype selectivity.

This article is part of the Neuropharmacology Special Issue on ‘Glutamate Receptors – NMDA receptors’.

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NMDAR-dependent STP, LTP and LTD can be dissociated pharmacologically

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GluN2A/2B PAM UBP714 potentiates LTP and reduces LTD

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GluN2C/D PAM CIQ potentiates STP without affecting LTP

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NMDAR pan-PAM UBP709 potentiates LTD and reduces LTP

Hemochromatosis Mutations, Brain Iron Imaging, and Dementia in the UK Biobank Cohort

Background:

Brain iron deposition occurs in dementia. In European ancestry populations, the HFE p.C282Y variant can cause iron overload and hemochromatosis, mostly in homozygous males.

Objective:

To estimate p.C282Y associations with brain MRI features plus incident dementia diagnoses during follow-up in a large community cohort.

Methods:

UK Biobank participants with follow-up hospitalization records (mean 10.5 years). MRI in 206 p.C282Y homozygotes versus 23,349 without variants, including T2^* measures (lower values indicating more iron).

Results:

European ancestry participants included 2,890 p.C282Y homozygotes. Male p.C282Y homozygotes had lower T2^* measures in areas including the putamen, thalamus, and hippocampus, compared to no HFE mutations. Incident dementia was more common in p.C282Y homozygous men (Hazard Ratio HR = 1.83; 95% CI 1.23 to 2.72, p = 0.003), as was delirium. There were no associations in homozygote women or in heterozygotes.

Conclusion:

Studies are needed of whether early iron reduction prevents or slows related brain pathologies in male HFE p.C282Y homozygotes.

Memory for public events in amnestic mild cognitive impairment: The role of hippocampus and ventro-medial prefrontal cortex

BACKGROUND

Current theories assume that retrograde memory deficits for semantic information in amnestic mild cognitive impairment (aMCI) are temporally graded and partially sparing most remote memories. Moreover, these models assume a prevalent role of the hippocampus in early phases of memory consolidation and of the prefrontal mesial neocortical areas in permanent consolidation of traces.

PURPOSE

To explore the relationship between hippocampus and memory accuracy for the most recent public events and between the ventro-medial prefrontal cortex (vmPFC) and memory accuracy irrespective of the memory age, we investigated in aMCI patients the retrograde memory for public events and its relationship with grey matter volume reductions in the hippocampus and vmPFC.

METHODS

18 aMCI patients and 13 healthy subjects (HS) underwent a modified version of the Famous Events questionnaire (FEq) to assess their memory performance for public events. Patients underwent 3T-MRI scanning to assess correlations between FEq's scores and grey matter volumes.

RESULTS

aMCI showed significantly reduced performances on FEq compared to HS in the recollection of most recent events, while no significant difference was observed for more remote memories, thus demonstrating a temporal gradient. Moreover, hippocampal volumes predicted accuracy scores for most recent, but not older, public events. Finally, an area in the subcallosal portion of the vmPFC, corresponding to BA32, predicted accuracy scores on FEq irrespective of the period examined.

CONCLUSIONS

Pathological changes in a neural circuit linking hippocampal to medial prefrontal cortical regions are responsible for impaired recollection of retrograde memories in aMCI.

Chronic Traumatic Encephalopathy: A Comparison with Alzheimer's Disease and Frontotemporal Dementia

The clinical diagnosis of chronic traumatic encephalopathy (CTE) is challenging due to heterogeneous clinical presentations and overlap with other neurodegenerative dementias. Depending on the clinical presentation, the differential diagnosis of CTE includes Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), Parkinson's disease, amyotrophic lateral sclerosis, primary mood disorders, posttraumatic stress disorder, and psychotic disorders. The aim of this article is to compare the clinical aspects, genetics, fluid biomarkers, imaging, treatment, and pathology of CTE to those of AD and bvFTD. A detailed clinical evaluation, neurocognitive assessment, and structural brain imaging can inform the differential diagnosis, while molecular biomarkers can help exclude underlying AD pathology. Prospective studies that include clinicopathological correlations are needed to establish tools that can more accurately determine the cause of neuropsychiatric decline in patients at risk for CTE.

Acute amnestic syndromes

Acute amnestic syndromes are usually rare clinical events occurring in emergency situations. Etiological diagnosis can be challenging and underlying causes diverse. They can be transient and totally reversible, or accompanied by other neurological symptoms resulting in serious and irreversible brain damage. Pathophysiology of these syndromes mainly corresponds to structural or functional alteration of memory circuits, including those in the hippocampus. One of the most frequent forms is transient global amnesia (TGA), characterized by sudden onset of anterograde amnesia lasting less than 24  hours, in the absence of other neurological signs or symptoms. Another acute and transient memory disorder is transient epileptic amnesia (TEA), due to focal crisis activity. Stroke injuries occurring at strategic memory-related sites can also present as sudden episodes of amnesia. In addition to neurological etiologies, amnesia may be a symptom of a psychiatric disorder (dissociative amnesia). Traumatic brain injuries, autoimmune encephalitis and acute toxic metabolic disorders can also cause amnesia and should be included among the differential diagnoses. In this review, we summarize the most relevant clinical findings in acute amnestic syndromes, and discuss the different ancillary tests needed to establish a correct diagnosis and management as well the best treatment options. Relevant anatomical and pathophysiological aspects underlying these conditions will be also be presented.

Stress- and trauma-related blockade of episodic-autobiographical memory processing

Memory disorders without a direct neural substrate still belong to the riddles in neuroscience. Although they were for a while dissociated from research and clinical arenas, risking becoming forgotten diseases, they sparked novel interests, paralleling the refinements in functional neuroimaging and neuropsychology. Although Endel Tulving has not fully embarked himself on exploring this field, he had published at least one article on functional amnesia (Schacter et al., 1982) and ignited a seminal article on amnesia with mixed etiology (Craver et al., 2014). Most importantly, the research of Endel Tulving has provided the researchers and clinicians in the field of dissociative or functional amnesia with the best framework for superiorly understanding these disorders through the lens of his evolving concept of episodic memory and five long term memory systems classification, which he developed and advanced. Herein we use the classification of long-term memory systems of Endel Tulving as well as his concepts and views on autonoetic consciousness, relationships between memory systems and relationship between episodic memory and emotion to describe six cases of dissociative amnesia that put a challenge for researchers and clinicians due to their atypicality. We then discuss their possible triggering and maintaining mechanisms, pointing to their clinical heterogeneity and multifaceted causally explanatory frameworks.

Impairments to Consolidation, Reconsolidation, and Long-Term Memory Maintenance Lead to Memory Erasure

An enduring problem in neuroscience is determining whether cases of amnesia result from eradication of the memory trace (storage impairment) or if the trace is present but inaccessible (retrieval impairment). The most direct approach to resolving this question is to quantify changes in the brain mechanisms of long-term memory (BM-LTM). This approach argues that if the amnesia is due to a retrieval failure, BM-LTM should remain at levels comparable to trained, unimpaired animals. Conversely, if memories are erased, BM-LTM should be reduced to resemble untrained levels. Here we review the use of BM-LTM in a number of studies that induced amnesia by targeting memory maintenance or reconsolidation. The literature strongly suggests that such amnesia is due to storage rather than retrieval impairments. We also describe the shortcomings of the purely behavioral protocol that purports to show recovery from amnesia as a method of understanding the nature of amnesia.

Alzheimer's and Hyperglycemia: Role of the Insulin Signaling Pathway and GSK-3 Inhibition in Paving a Path to Dementia

In this project, we are trying to review the articles that discuss the relationship between insulin signaling and Alzheimer's disease (AD). Another focus of this project is to find the best treatment regimen that can reduce the progression of AD in patients with impaired glucose metabolism. We used Pubmed database to collect our data and used the following keywords: Alzheimer’s disease, insulin signaling pathway, type 3 diabetes, type 2 diabetes, insulin, and insulin resistance in our revision; we included free articles that were published in the last 10 years and excluded articles that were written in any language other than English. We reviewed 68 articles. Forty-nine out of 68 articles were containing materials that are relevant for this project. We found that there is a relation between AD and the insulin signaling pathway. Insulin signaling pathway impairment leads to hyperphosphorylation of Tau protein, which plays a vital role in AD pathology. The effect of insulin on cognition is bidirectional; the intranasal route of insulin showed to have a promising effect on cognition improvement. Subcutaneous and intravenous insulin can increase the risk of dementia. Further studies are encouraged to use a specific anti-diabetic medication that can reduce the progression of AD.

Quo vadis 'episodic memory'? - Past, present, and perspective

The term 'episodic memory' was coined by Endel Tulving, who also created a classification in several memory systems. This classification is presented, and it is described which predecessors existed for the partition of memory into systems. The 'episodic memory system' is discussed as being in general equivalent with the 'episodic-autobiographical memory system'. It is seen as an emotionally colorized system. A special paragraph is devoted to the 'perceptual memory system', as this was not included in Tulving's previous schemes of memory systems. More recent sub-categorizations of the 'episodic memory system' are presented and a perspective on the future of the episodic memory system is developed.

Episodic memory is emotionally laden memory, requiring amygdala involvement

The memory impairment of neurological and psychiatric patients is seen as occurring mainly in the autobiographical-episodic memory domain and this is considered to depend on limbic structures such as the amygdala or the septal nuclei. Especially the amygdala is a hub for giving an emotional flavor to personal memories. Bastin et al. fail to include the amygdala in their integrative memory model.

Differential executive functioning in the topology of Spirit possession or dissociative disorders: an explorative cultural study

BACKGROUND

In Oman, anecdotal and impressionistic observation have helped parse and categorize various manifestations of spirit possession into two broad and distinct categories: intermittent dissociative phenomenon and transitory dissociative phenomenon. The primary aim of the present study was to compare the performance of participants on neuropsychological tests among different grades of possession. Other correlates were also sought.

METHODS

Assessment criteria for the two groups included measures examining executive functioning: controlled oral word association test Verbal Fluency, Wisconsin Card Sorting Test (Perseverative error and the number of categories achieved), Trail Making Test and the Tower of London Test (number of correctly solved problems). Sociodemographic variables and the history of trauma were also sought.

RESULT

Among 84 participants, one third of them presented the intermittent possession type and two thirds, the transitory possession type. Their mean age was 34.17 ± 11.82 and 56% of them were female. Nearly 35% of them endorsed a history of a traumatic experience. Both the multivariate models showed statistical significance (F (5, 78) = 5.57, p < 0.001, R² = 0.22), F (5, 78) = 11.38, p < 0.001, R² = 0.39) with an independent predictor of intermittent dissociative phenomenon (β = - 3.408, p < 0.001), (β = 63.88, p < 0.001) for Verbal Fluency and Trail Making Test, respectively. The history of the traumatic event was also statistically significant with the results of the Trail Making Test (β = - 26.01, p < 0.041. Furthermore, the subtype of Pathogenic Possession turned out to be an independent predictor across all models: Wisconsin Card Sorting Test perseverative error, Wisconsin card sorting test categories achieved and the number of problems solved in the Tower of London Test (OR = 3.70, 95% C.I. 2.97-4.61; p < 0.001), (OR = 0.57, 95% C.I.0.39-0.84; p = 0.004) and (OR = 0.80, 95% C.I. 0.65-0.99; p < 0.037) respectively.

CONCLUSIONS

This study suggests that typology of spirit possession found in Oman tends to differ on indices of executive function. Those with 'diagnosis' of intermittent possession showed impairment in many indices of executive functioning. Despite its wide prevalence, spirit possession has not been examined in terms of its neuropsychological functioning. We believe that this study will be instrumental in laying the groundwork for a more robust methodology.

Anomalies of Autobiographical Memory

OBJECTIVES

In this paper, I review three 'anomalies' or disorders in autobiographical memory: neurological retrograde amnesia (RA), spontaneous confabulation, and psychogenic amnesia.

METHODS

Existing theories are reviewed, their limitations considered, some of my own empirical findings briefly described, and possible interpretations proposed and interspersed with illustrative case-reports.

RESULTS

In RA, there may be an important retrieval component to the deficit, and factors at encoding may give rise to the relative preservation of early memories (and the reminiscence bump) which manifests as a temporal gradient. Spontaneous confabulation appears to be associated with a damaged 'filter' in orbitofrontal and ventromedial frontal regions. Consistent with this, an empirical study has shown that both the initial severity of confabulation and its subsequent decline are associated with changes in the executive function (especially in cognitive estimate errors) and inversely with the quantity of accurate autobiographical memories retrieved. Psychogenic amnesia can be 'global' or 'situation-specific'. The former is associated with a precipitating stress, depressed mood, and (often) a past history of a transient neurological amnesia. In these circumstances, frontal control mechanisms can inhibit retrieval of autobiographical memories, and even the sense of 'self' (identity), while compromised medial temporal function prevents subsequent retrieval of what occurred during a 'fugue'. An empirical investigation of psychogenic amnesia and some recent imaging studies have provided findings consistent with this view.

CONCLUSIONS

Taken together, these various observations point to the importance of frontal 'control' systems (in interaction with medial temporal/hippocampal systems) in the retrieval and, more particularly, the disrupted retrieval of 'old' memories.

The Detection of Malingered Amnesia: An Approach Involving Multiple Strategies in a Mock Crime

The nature of amnesia in the context of crime has been the subject of a prolonged debate. It is not uncommon that after committing a violent crime, the offender either does not have any memory of the event or recalls it with some gaps in its recollection. A number of studies have been conducted in order to differentiate between simulated and genuine amnesia. The recognition of probable malingering requires several inferential methods. For instance, it typically involves the defendant's medical records, self-reports, the observed behavior, and the results of a comprehensive neuropsychological examination. In addition, a variety of procedures that may detect very specific malingered amnesia in crime have been developed. In this paper, we investigated the efficacy of three techniques, facial thermography, kinematic analysis, and symptom validity testing in detecting malingering of amnesia in crime. Participants were randomly assigned to two different experimental conditions: a group was instructed to simulate amnesia after a mock homicide, and a second group was simply asked to behave honestly after committing the mock homicide. The outcomes show that kinematic analysis and symptom validity testing achieve significant accuracy in detecting feigned amnesia, while thermal imaging does not provide converging evidence. Results are encouraging and may provide a first step towards the application of these procedures in a multimethod approach on crime-specific cases of amnesia.

The role of hippocampus in the retrieval of autobiographical memories in patients with amnestic Mild Cognitive Impairment due to Alzheimer's disease

The role of the hippocampus and neocortical areas in the retrieval of past memories in pre-dementia Alzheimer's disease (AD) patients was investigated. The aim was to assess whether the hippocampus has a temporary role in memory trace formation, according to the Cortical Reallocation Theory (CRT), or whether it continuously updates and enriches memories, according to the Multiple Trace Theory. According to the former theory, hippocampal damage should affect more recent memories, whereas the association cortex is expected to affect memories of the entire lifespan. In the second case, damage to either the hippocampus or the association cortices should affect memories of the entire lifespan. Seventeen patients with amnestic Mild Cognitive Impairment due to AD were submitted to autobiographical (i.e., episodic and semantic personal) memory assessment. Patients underwent MRI for the acquisition of T1-weighted brain volumes. Voxel-based morphometry was used to assess correlations between grey matter (GM) volumes and autobiographical memory. Correlation analyses revealed a strict association between GM volumes in the hippocampus and patients' ability to retrieve the most recent but not the oldest autobiographical memories in both aspects, episodic and semantic. Moreover, patients' GM volumes in the pre-frontal and temporal polar areas were associated with recollection of episodic and semantic events, respectively. Finally, GM volumes in the precuneus and occipital cortex were associated with retrieval of the most recent episodic events. These findings indicate that the hippocampus has a specific time-dependent role; thus, they support the CRT.

Neural correlates of free recall of "famous events" in a "hypermnestic" individual as compared to an age- and education-matched reference group

BACKGROUND

Memory performance of an individual (within the age range: 50-55 years old) showing superior memory abilities (protagonist PR) was compared to an age- and education-matched reference group in a historical facts ("famous events") retrieval task.

RESULTS

Contrasting task versus baseline performance both PR and the reference group showed fMRI activation patterns in parietal and occipital brain regions. The reference group additionally demonstrated activation patterns in cingulate gyrus, whereas PR showed additional widespread activation patterns comprising frontal and cerebellar brain regions. The direct comparison between PR and the reference group revealed larger fMRI contrasts for PR in right frontal, superior temporal and cerebellar brain regions.

CONCLUSIONS

It was concluded that PR generally recruits brain regions as normal memory performers do, but in a more elaborate way, and furthermore, that he applied a memory-strategy that potentially includes executively driven multi-modal transcoding of information and recruitment of implicit memory resources.

United states of amnesia: rescuing memory loss from diverse conditions

Amnesia - the loss of memory function - is often the earliest and most persistent symptom of dementia. It occurs as a consequence of a variety of diseases and injuries. These include neurodegenerative, neurological or immune disorders, drug abuse, stroke or head injuries. It has both troubled and fascinated humanity. Philosophers, scientists, physicians and anatomists have all pursued an understanding of how we learn and memorise, and why we forget. In the last few years, the development of memory engram labelling technology has greatly impacted how we can experimentally study memory and its disorders in animals. Here, we present a concise discussion of what we have learned about amnesia through the manipulation of engrams, and how we may use this knowledge to inform novel treatments of amnesia.

Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases

Neurodegenerative diseases are a common cause of morbidity and cognitive impairment in older adults. Most clinicians who care for the elderly are not trained to diagnose these conditions, perhaps other than typical Alzheimer's disease (AD). Each of these disorders has varied epidemiology, clinical symptomatology, laboratory and neuroimaging features, neuropathology, and management. Thus, it is important that clinicians be able to differentiate and diagnose these conditions accurately. This review summarizes and highlights clinical aspects of several of the most commonly encountered neurodegenerative diseases, including AD, frontotemporal dementia (FTD) and its variants, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and Huntington's disease (HD). For each condition, we provide a brief overview of the epidemiology, defining clinical symptoms and diagnostic criteria, relevant imaging and laboratory features, genetics, pathology, treatments, and differential diagnosis.

Dissoziative Amnesie und Migration

Zusammenfassung. Dissoziative Amnesie verläuft unter Umständen chronisch und kann zu lebenslanger Arbeitsunfähigkeit führen. Die Krankheit tritt gehäuft im Zusammenhang mit Migration auf und verläuft dann schwerer als in anderen Fällen. Sie ist im Grunde reversibel, d. h., der Abruf der Gedächtnisinhalte ist nur blockiert. Betroffen sind Patienten, die nicht verarbeitete Stress- und Traumaerlebnisse als Hintergrund haben und dann ein erneutes Stresserlebnis erfahren, welches zum dissoziativen Amnesiezustand führt. Es wird postuliert, dass in erster Linie Patienten betroffen sind, die im neuen Heimatland nicht ausreichend und ihrem Anspruch entsprechend Fuß fassen konnten. Mangelnde Sprachkenntnisse und eine nicht den Erwartungen entsprechende neue Arbeitssituation sind am ehesten als Gründe anzuführen.

Neurocognitive Effect of Nootropic Drug Brahmi (Bacopa monnieri) in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease of the elderly. The rapid increase in its incidence has necessitated development of newer drugs. Ayurvedic herbal medications are increasingly researched due to their biosafety profile and usefulness in cognitive impairment. In this article, we critically reviewed one such Medhya Rasayana (nootropic drug) Brahmi-derived from extract of Bacopa monnieri (EBm). Studies have shown that EBm promotes free radical scavenger mechanisms and protects cells in prefrontal cortex, hippocampus, and striatum against cytotoxicity and DNA damage implicated in AD. It also reduces lipoxygenase activity reducing lipid peroxidation, increases glutathione peroxidase and chelates iron. Administration of EBm was seen to protect the cholinergic neurons and reduce anticholinesterase activity comparable to donepezil, rivastigmine, and galantamine. It also reduces hippocampal β-amyloid deposition and stress-induced hippocampal damage. The neuroprotective effect of EBm is also due to nitric oxide-mediated cerebral vasodilation. EBm improved the total memory score and maximum improvement was seen in logical memory and paired associate learning in humans and reversed phenytoin-induced memory impairment in experimental model. EBm has not shown any serious clinical, neurological, hematological complications, or vital organs damage in experimental studies. Rats showed marked reduction in fertility; however, libido was unaffected. There is no experimental evidence of genotoxicity or teratogenesis by use of EBm. Mild nausea and gastrointestinal upset are seen in humans. Brahmi promises to be a novel agent in AD; however, further human trials are recommended to verify the efficacy and rule out any side effects as evidenced by the experimental models.

Neuropsychological Profiles Differentiate Alzheimer Disease from Subcortical Ischemic Vascular Dementia in an Autopsy-Defined Cohort

BACKGROUND/AIMS

The aim of this study was to assess the ability of neuropsychological tests to differentiate autopsy-defined Alzheimer disease (AD) from subcortical ischemic vascular dementia (SIVD).

METHODS

From a sample of 175 cases followed longitudinally that underwent autopsy, we selected 23 normal controls (NC), 20 SIVD, 69 AD, and 10 mixed cases of dementia. Baseline neuropsychological tests, including Memory Assessment Scale word list learning test, control oral word association test, and animal fluency, were compared between the three autopsy-defined groups.

RESULTS

The NC, SIVD, and AD groups did not differ by age or education. The SIVD and AD groups did not differ by the Global Clinical Dementia Rating Scale. Subjects with AD performed worse on delayed recall (p < 0.01). A receiver operating characteristics analysis comparing the SIVD and AD groups including age, education, difference between categorical (animals) versus phonemic fluency (letter F), and the first recall from the word learning test distinguished the two groups with a sensitivity of 85%, specificity of 67%, and positive likelihood ratio of 2.57 (AUC = 0.789, 95% CI 0.69-0.88, p < 0.0001).

CONCLUSION

In neuropathologically defined subgroups, neuropsychological profiles have modest ability to distinguish patients with AD from those with SIVD.

Post-traumatic amnesia and confusional state: hazards of retrospective assessment

Retrospective assessment of post-traumatic amnesia (PTA) must take into account factors other than traumatic brain injury (TBI) which may impact on memory both at the time of injury and subsequent to the injury. These include analgesics, anaesthesia required for surgery, and the development of acute or post-traumatic stress disorder. This is relevant in clinical and medicolegal settings. Repeated assessments of the post-injury state, involving tests for continuing amnesia, risk promoting recall of events suggested by the examiner, or generating confabulations. The PTA syndrome affects the categorical autobiographical memory, and is accompanied by confusion as an essential component; this should be suspected from the initial or early Glasgow Coma Scale score (13-14/15) if not directly recorded by clinical staff. PTA by itself is only one of several indices of severity of TBI. The nature of the head injury, including observers' accounts, clinical and neuroimaging data, the possible role of other external injuries, blood loss, acute stress disorder and the potential for hypoxic brain injury, must be taken into account as well as concomitant alcohol or substance abuse, and systemic shock. A plausible mechanism for a TBI must be demonstrable, and other causes of amnesia excluded.

Deconstructing the process of change in cognitive behavioral therapy: An alternative approach focusing on the episodic retrieval mode

Lane et al. view the process of memory reconsolidation as a main ingredient of psychotherapeutic change. They ascertain that in cognitive behavioral therapy (CBT) high priority is given to the "semantic structure." We argue that memory-related mechanisms of change in CBT are more nuanced than the target article presents. Furthermore, we propose to partially shift the focus from the process of reconsolidation to the retrieval operations.

Patterns of Chinese medicine use in prescriptions for treating Alzheimer's disease in Taiwan

BACKGROUND

Certain Chinese medicine (CM) herbs and acupuncture may protect against Alzheimer's disease (AD). However, there is a lack of research regarding the use of CM in patients with AD. The aim of this study was to investigate CM usage patterns in patients with AD, and identify the Chinese herbal formulae most commonly used for AD.

METHODS

This retrospective, nationwide, population-based cohort study was conducted using a randomly sampled cohort of one million patients, selected from the National Health Insurance Research Database between 1997 and 2008 in Taiwan. CM use and the top ten most frequently prescribed formulae for treating AD were assessed, including average formulae dose and frequency of prescriptions. Demographic characteristics, including sex, age and insurance level were examined, together with geographic location. Existing medical conditions with the behavioral and psychological symptoms of dementia, and medications associated with CM were also examined. Factors associated with CM use were analyzed by multiple logistic regressions.

RESULTS

The cohort included 1137 newly diagnosed AD patients, who were given conventional treatment for AD between 1997 and 2008. Among them, 78.2 % also used CM treatments, including Chinese herbal remedies, acupuncture and massage manipulation. Female patients (aOR 1.57 with 95 % CI 1.16-2.13) and those living in urban areas (aOR 3.00 with 95 % CI 1.83-4.90 in the middle of Taiwan) were more likely to use CM. After adjusting for demographic factors, AD patients suffering from the behavioral and psychological symptoms of dementia were more likely to seek CM treatment than those with no symptoms (aOR 2.26 with 95 % CI 1.48-3.43 in patients suffering more than three symptoms). Bu-Zhong-Yi-Qi-Tang and Ji-Sheng-Shen-Qi-Wan were the two formulae most frequently prescribed by CM practitioners for treating AD.

CONCLUSION

Most people with AD who consumed herbal products used supplement qi, nourish the blood, and quiet the heart spirit therapy as complementary medicines to relieve AD-related symptoms, in addition to using standard anti-AD treatments.

Functional (dissociative) retrograde amnesia

Retrograde amnesia is described as condition which can occur after direct brain damage, but which occurs more frequently as a result of a psychiatric illness. In order to understand the amnesic condition, content-based divisions of memory are defined. The measurement of retrograde memory is discussed and the dichotomy between "organic" and "psychogenic" retrograde amnesia is questioned. Briefly, brain damage-related etiologies of retrograde amnesia are mentioned. The major portion of the review is devoted to dissociative amnesia (also named psychogenic or functional amnesia) and to the discussion of an overlap between psychogenic and "brain organic" forms of amnesia. The "inability of access hypothesis" is proposed to account for most of both the organic and psychogenic (dissociative) patients with primarily retrograde amnesia. Questions such as why recovery from retrograde amnesia can occur in retrograde (dissociative) amnesia, and why long-term new learning of episodic-autobiographic episodes is possible, are addressed. It is concluded that research on retrograde amnesia research is still in its infancy, as the neural correlates of memory storage are still unknown. It is argued that the recollection of episodic-autobiographic episodes most likely involves frontotemporal regions of the right hemisphere, a region which appears to be hypometabolic in patients with dissociative amnesia.

Mitochondrial Respiration Chain Enzymatic Activities in the Human Brain: Methodological Implications for Tissue Sampling and Storage

Mitochondrial respiratory chain complexes enzymatic (MRCCE) activities were successfully evaluated in frozen brain samples. Epilepsy surgery offers an ethical opportunity to study human brain tissue surgically removed to treat drug resistant epilepsies. Epilepsy surgeries are done with hemodynamic and laboratory parameters to maintain physiology, but there are no studies analyzing the association among these parameters and MRCCE activities in the human brain tissue. We determined the intra-operative parameters independently associated with MRCCE activities in middle temporal neocortex (Cx), amygdala (AMY) and head of hippocampus (HIP) samples of patients (n = 23) who underwent temporal lobectomy using multiple linear regressions. MRCCE activities in Cx, AMY and HIP are differentially associated to trans-operative mean arterial blood pressure, O2 saturation, hemoglobin, and anesthesia duration to time of tissue sampling. The time-course between the last seizure occurrence and tissue sampling as well as the sample storage to biochemical assessments were also associated with enzyme activities. Linear regression models including these variables explain 13-17 % of MRCCE activities and show a moderate to strong effect (r = 0.37-0.82). Intraoperative hemodynamic and laboratory parameters as well as the time from last seizure to tissue sampling and storage time are associated with MRCCE activities in human samples from the Cx, AMYG and HIP. Careful control of these parameters is required to minimize confounding biases in studies using human brain samples collected from elective neurosurgery.

Do statins prevent Alzheimer's disease? A narrative review

Alzheimer's disease is the most common cause of dementia and occurs commonly in patients 65 and older. There is an urgent need to find an effective management that could help prevent or at least slow down the progress of this major public health problem. Cholesterol related pathways might play a role in the pathogenesis of Alzheimer's disease. Treatment with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) has been suggested to promote the prevention of Alzheimer's disease. In this review, we discuss potential pathogenetic pathways for the development of Alzheimer's disease and review the evidence regarding the value of statins as a strategy to prevent or delay progression of Alzheimer's disease.

The nature of the semantic/episodic memory distinction: A missing piece of the “working through” process

The relations between the semantic and episodic-autobiographical memory systems are more complex than described in the target article. We argue that understanding the noetic/autonoetic distinction provides critical insights into the foundation of the delineation between the two memory systems. Clarity with respect to the criteria for classification of these two systems, and the evolving conceptualization of episodic memory, can further neuroscientifically informed therapeutic approaches.

Side of pupillary mydriasis predicts the cognitive prognosis in patients with severe traumatic brain injury

BACKGROUND

Pupils' abnormalities are associated to bad prognosis in traumatic brain injury. We investigated the association between the side of pupil mydriasis and the long-term cognitive performance of patients with severe traumatic brain injury (TBI).

METHODS

We analyzed the cognitive performance of patients admitted at the intensive care unit with isochoric pupils (IP, n = 28), left mydriasis (LM, n = 10), right mydriasis (RM, n = 9) evaluated in mean 2.5 years after the severe TBI and controls (n = 26) matched for age, sex and education level.

RESULTS

Patients and controls had similar scores in the four WAIS-III investigated subtests. In comparison with controls, LM patients had lower scores in Letters and Category Fluency and IP patients in Category Fluency. Among the 10 evaluated memory tests, LM patients had lower scores than controls in eight, RM patients in two and IP in three memory tests. IP and RM were 3.5 to nine times more associated to significant impairment (cognitive scores under the percentile 10 of controls) in six of 16 investigated cognitive tests. LM was six to 15 times more associated to significant impairment in 10 of 16 cognitive tests. The association among the pupil abnormalities and cognitive performances remained significant after the multiple linear regression analysis controlling for age, gender, admission coma Glasgow scale and serum glucose, presence of associated trauma, and cranial computed tomography abnormalities.

CONCLUSION

Side of admission pupil abnormalities may be a useful variable to improve prognostic models for long-term cognitive performance in severe TBI patients.