Biomarkers, Dementia, and Public Health

Optical coherence tomography and angiography in Alzheimer's disease and other cognitive disorders

AIMS

The aims of this study were to analyze retinal and choroidal changes on optical coherence tomography (OCT) and OCT-Angiography (OCT-A) in Alzheimer's disease (AD) patients and compare them to other forms of major dementia. We also aimed to analyze the correlation between clinical severity of global cognitive deficiency assessed by the mini-mental state exam (MMSE) score and OCT/OCT-A parameters.

METHODS

Retrospective cross-sectional evaluative study of AD, and age-and gender-matched patients with other dementias. Fundus examination, OCT and OCT-A were compared.

RESULTS

Ninety-one eyes of AD patients and 53 eyes of patients with other dementias were included. Retinal deposits were found in 6.59% of AD cases. OCT highlighted the presence of hyperreflective deposits and localized areas of outer retina and ellipsoid zone disruption, respectively in 20.87% and 15.38% of AD cases. Hyperreflective foci were noted within inner retinal layers in 4.39% of AD cases. Quantitative analysis revealed a thicker nasal retinal nerve fiber layer (p = 0.001) and ganglion cell complex in superior (p = 0.011) and temporal quadrants (p = 0.009) in eyes of AD patients, compared to other dementias. OCT-A showed a significantly higher fractal dimension of both superficial and deep capillary plexus (p = 0.005), with lower choriocapillaris density (p = 0.003) in AD patients.

CONCLUSIONS

Structural OCT could highlight the presence of hyperreflective deposits in AD, probably reflecting beta-amyloid deposits, associated to outer retinal disruptions. Quantitative OCT analysis showed structural differences between AD patients and other dementias, and combined OCT-A could identify microvascular changes in AD patients representing new potential differential diagnosis criteria.

The application of optical coherence tomography angiography in Alzheimer's disease: A systematic review

INTRODUCTION

Discovering non-invasive and easily acquired biomarkers that are conducive to the accurate diagnosis of dementia is an urgent area of ongoing clinical research. One promising approach is retinal imaging, as there is homology between retinal and cerebral vasculature. Recently, optical coherence tomography angiography (OCT-A) has emerged as a promising new technology for imaging the microvasculature of the retina.

METHODS

A systematic review and meta-analysis was conducted to examine the application of OCT-A in dementia.

RESULTS

Fourteen studies assessing OCT-A in preclinical Alzheimer's disease (AD), mild cognitive impairment, or AD were included. Exploratory meta-analyses revealed a significant increase in the foveal avascular zone area and a significant decrease in superficial parafoveal and whole vessel density in AD, although there was significant heterogeneity between studies.

DISCUSSION

Although certain OCT-A metrics may have the potential to serve as biomarkers for AD, the field requires further standardization to allow conclusions to be reached regarding their clinical utility.

Changes in retinal microvasculature and retinal layer thickness in association with apolipoprotein E genotype in Alzheimer's disease

Biomarker tests of Alzheimer’s disease (AD) are invasive and expensive. Recent developments in optical coherence tomography (OCT) and OCT angiography (OCTA) have enabled noninvasive, cost-effective characterization of retinal layer vasculature and thickness. Using OCTA and OCT, we characterized retinal microvascular changes in the mild cognitive impairment (MCI) stage of AD and assessed their correlation with structural changes in each retinal neuronal layer. We also evaluated the effect of the APOE-ε4 genotype on retinal microvasculature and layer thickness. Retinal layer thickness did not differ between MCI patients (40 eyes) and controls (37 eyes, all p > 0.05). MCI patients had lower vessel density (VD) (p = 0.003) of the superficial capillary plexus (SCP) and larger foveal avascular zone area (p = 0.01) of the deep capillary plexus (DCP) than those of controls. VD of the SCP correlated with the ganglion cell layer (r = 0.358, p = 0.03) and inner plexiform layer thickness (r = 0.437, p = 0.007) in MCI patients. APOE-ε4-carrying MCI patients had a lower VD of the DCP than non-carriers (p = 0.03). In conclusion, retinal microvasculature was reduced in patients with AD-associated MCI, but retinal thickness was not changed; these changes might be affected by the APOE genotype. OCTA of the retinal microvasculature may be useful to detect vascular changes in AD.

Primary Prevention of Dementia: An Ethical Review

Dementia poses important medical and societal challenges, and of all health risks people face in life, dementia is one of the most feared. Recent research indicates that up to about 40% of all cases of dementia might be preventable. A series of environmental, social, and medical risk-factors have been identified that should be targeted from midlife onwards when people are still cognitively healthy. At first glance, this seems not merely advisable, but even imperative. However, these new developments trigger a series of new ethical questions and concerns which have hardly been addressed to date. Pro-active ethical reflection, however, is crucial to ensure that the interests and well-being of those affected, ultimately all of us, are adequately respected. This is the goal of the current contribution. Against the background of a concrete case in primary dementia prevention, it provides a systematic overview of the current ethical literature and sketches an ethical research agenda. First, possible benefits of increased well-being must be balanced with the burdens of being engaged in particularly long-term interventions for which it is unclear whether they will ever pay out on a personal level. Second, while knowledge about one's options to maintain brain health might empower people, it might also undermine autonomy, put high social pressure on people, medicalize healthy adults, and stigmatize those who still develop dementia. Third, while synergistic effects might occur, the ideals of dementia prevention might also conflict with other health and non-health related values people hold in life.

Ethical Arguments Concerning the Use of Alzheimer's Disease Biomarkers in Individuals with No or Mild Cognitive Impairment: A Systematic Review and Framework for Discussion

BACKGROUND

The shift to defining Alzheimer's disease (AD) as a biological continuum, which is characterized by the presence of biomarkers instead of clinical symptoms, has sparked a widespread debate. Insight into the given arguments and their underlying moral values is crucial to ensure well-considered and appropriate AD biomarker testing in the future.

OBJECTIVE

To critically review the arguments in favor of or against AD biomarker testing in people with no or mild cognitive impairment and to explicate their underlying moral values.

METHODS

Seven databases were systematically searched for publications mentioning arguments of interest. Arguments are identified using qualitative data-analysis and evaluated within an ethical framework.

RESULTS

Our search yielded 3,657 articles of which 34 met the inclusion criteria. We discuss the clusters of arguments separate from their evaluation and the assessment of the debate as a whole. The right to know, which derives from the moral value of respect for autonomy, is a central argument in favor of biomarker testing. On the other hand, fear of the disease and lack of a disease-modifying treatment may result in a negative balance of good over inflicted harms, which argues against its use.

CONCLUSION

Critical evaluation and weighing of the given arguments in a specific context, within an ethical framework, demonstrates the necessity to differentiate between what we hope or expect from research and where we currently stand. While AD biomarkers may have an indispensable value for research, the current advantage for clinical practice appears limited.

Plasma Biomarkers: Potent Screeners of Alzheimer's Disease

Alzheimer's disease (AD), a neurological disorder, is as a complex chronic disease of brain cell death that usher to cognitive decline and loss of memory. Its prevalence differs according to risk factors associated with it and necropsy performs vital role in its definite diagnosis. The stages of AD vary from preclinical to severe that proceeds to death of patient with no availability of treatment. Biomarker may be a biochemical change that can be recognized by different emerging technologies such as proteomics and metabolomics. Plasma biomarkers, 5-protein classifiers, are readily being used for the diagnosis of AD and can also predict its progression with a great accuracy, specificity, and sensitivity. In this review, upregulation or downregulation of few plasma proteins in patients with AD has also been discussed, when juxtaposed with control, and thus serves as potent biomarker in the diagnosis of AD.

Spectral-Domain OCT Measurements in Alzheimer's Disease: A Systematic Review and Meta-analysis

TOPIC

OCT is a noninvasive tool to measure specific retinal layers in the eye. The relationship of retinal spectral-domain (SD) OCT measurements with Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains unclear. Hence, we conducted a systematic review and meta-analysis to examine the SD OCT measurements in AD and MCI.

CLINICAL RELEVANCE

Current methods of diagnosing early AD are expensive and invasive. Retinal measurements of SD OCT, which are noninvasive, technically simple, and inexpensive, are potential biomarkers of AD.

METHODS

We conducted a literature search in PubMed and Excerpta Medica Database to identify studies published before December 31, 2017, that assessed the associations between AD, MCI, and measurements of SD OCT: ganglion cell-inner plexiform layer (GC-IPL), ganglion cell complex (GCC), macular volume, and choroidal thickness, in addition to retinal nerve fiber layer (RNFL) and macular thickness. We used a random-effects model to examine these relationships. We also conducted meta-regression and assessed heterogeneity, publication bias, and study quality.

RESULTS

We identified 30 eligible studies, involving 1257 AD patients, 305 MCI patients, and 1460 controls, all of which were cross-sectional studies. In terms of the macular structure, AD patients showed significant differences in GC-IPL thickness (standardized mean difference [SMD], -0.46; 95% confidence interval [CI], -0.80 to -0.11; I² = 71%), GCC thickness (SMD, -0.84; 95% CI, -1.10 to -0.57; I² = 0%), macular volume (SMD, -0.58; 95% CI, -1.03 to -0.14; I² = 80%), and macular thickness of all inner and outer sectors (SMD range, -0.52 to -0.74; all P < 0.001) when compared with controls. Peripapillary RNFL thickness (SMD, -0.67; 95% CI, -0.95 to -0.38; I² = 89%) and choroidal thickness (SMD range, -0.88 to -1.03; all P < 0.001) also were thinner in AD patients.

CONCLUSIONS

Our results confirmed the associations between retinal measurements of SD OCT and AD, highlighting the potential usefulness of SD OCT measurements as biomarkers of AD.

Review of the Ethical Issues of a Biomarker-Based Diagnoses in the Early Stage of Alzheimer's Disease

BACKGROUND

Today, many healthcare or dementia organizations, clinicians, and companies emphasize the importance of detection of Alzheimer's disease in an early phase. This idea has gained considerable momentum due to the development of biomarkers, the recent FDA and EMA approval of three amyloid tracers, and the failure of a number of recent therapeutic trials conducted in the early dementia phase. On the one hand, an early etiological diagnosis can lead to early and more efficacious intervention. On the other hand, it is questioned how early an etiological diagnosis is beneficial to the patient. Here we consider ethical issues related to the process of biomarker testing and the impact on the diagnostic disclosure to patients with mild cognitive impairment due to prodromal Alzheimer's disease.

METHODS

A systematic review of the theoretical bioethics literature was performed by using electronic databases. The review was limited to articles published in English between 2003 and 2016.

RESULTS

A total of twenty articles were included in our effort to make an analysis of the ethical challenges. One of the biggest challenges was the uncertainty and the predictive value of the biomarker-based diagnosis where patients can be amyloid positive without full certainty whether or when they will develop symptomatic decline due to Alzheimer's disease. Another challenge was the tension between the right to know versus the wish not to know, the limited efficacy of currently available treatment options, and the opportunities and consequences after receiving such an early diagnosis.

CONCLUSION

Based on the results and the additional comments in the discussion, several unanswered questions emerged. Therefore, careful consideration of all these ethical issues is required before the disclosure of a biomarker-based diagnosis to the patient with mild cognitive impairment due to Alzheimer's disease.

Amnestic MCI patients' experiences after disclosure of their amyloid PET result in a research context

BACKGROUND

Biomarkers such as amyloid imaging are increasingly used for diagnosis in the early stages of Alzheimer's disease. Very few studies have examined this from the perspective of the patient. To date, there is only limited evidence about how patients experience and value disclosure in an early disease stage.

METHODS

Semistructured interviews were carried out with 38 patients with amnestic mild cognitive impairment as part of an investigator-driven diagnostic trial (EudraCT, 2013-004671-12; registered on 20 June 2014) in which participants could opt to know the binary outcome (positive/negative) result of their amyloid positron emission tomography (PET) scan. Verbatim transcripts of the interviews were evaluated using qualitative content analysis and NVivo 11 software.

RESULTS

Eight of 38 patients received a positive amyloid PET scan result, and the remaining 30 patients received a negative amyloid PET scan result. After disclosure of the result to the patients, we interviewed each patient twice: 2 weeks after disclosure and 6 months after disclosure. Patients had difficulties in repeating the exact words used during disclosure of their amyloid PET scan result by the neurologist; yet, they could recall the core message of the result in their own words. Some patients were confused by the terminology of an amyloid-positive/negative test result. At 6 months, two of eight patients with a positive amyloid PET scan result experienced emotional difficulties (sadness, feeling worried). Three of 30 patients with a negative amyloid PET scan result started to doubt whether they had received the correct result. Patients reported that they experienced advantages after the disclosure, such as information about their health status, the possibility of making practical arrangements, medication, enjoying life more, and a positive impact on relationships. They also reported disadvantages following disclosure, such as having emotional difficulties, feeling worried about when their symptoms might worsen, the risk of a more patronizing attitude by relatives, and the possibility of a wrong diagnosis.

CONCLUSIONS

This exploratory study shows that the majority of patients can accurately recall the information received during disclosure. The experienced advantages and disadvantages reported by our patients depended on the outcome of the result (positive or negative) and the interval of the conducted interview (2 weeks or 6 months after amyloid PET disclosure). Discrepancies were found between patients' expectations according to the interview prior to amyloid PET disclosure (Vanderschaeghe et al. [Neuroethics. 2017;10:281-97]) and their actual experiences after their amyloid PET disclosure.

The application of retinal fundus camera imaging in dementia: A systematic review

Introduction

The ease of imaging the retinal vasculature, and the evolving evidence suggesting this microvascular bed might reflect the cerebral microvasculature, presents an opportunity to investigate cerebrovascular disease and the contribution of microvascular disease to dementia with fundus camera imaging.

Methods

A systematic review and meta-analysis was carried out to assess the measurement of retinal properties in dementia using fundus imaging.

Results

Ten studies assessing retinal properties in dementia were included. Quantitative measurement revealed significant yet inconsistent pathologic changes in vessel caliber, tortuosity, and fractal dimension. Retinopathy was more prevalent in dementia. No association of age-related macular degeneration with dementia was reported.

Discussion

Inconsistent findings across studies provide tentative support for the application of fundus camera imaging as a means of identifying changes associated with dementia. The potential of fundus image analysis in differentiating between dementia subtypes should be investigated using larger well-characterized samples. Future work should focus on refining and standardizing methods and measurements.

Cognition, even in the normal range, predicts disability: cross-sectional and prospective analyses of a population-based sample

OBJECTIVE

To determine if the modified mini-mental state examination (3MS) predicts functional status and if any effect on function is observed within the normal range of cognition.

DESIGN

Cohort study.

SETTING

Community-dwelling older adults in the Canadian province of Manitoba sampled in 1991 and followed in 1996.

PARTICIPANTS

Baseline sample of 1751 adults aged 65+ from a representative registry. Five years later, 1028 participants remained in the community and had no missing data.

MEASUREMENTS

The 3MS, age, gender, education, living arrangements, self-rated health, and depressive symptoms were self-reported. Functional status was assessed using the Older Americans Resource Survey, which was dichotomized into no/mild disability versus moderate/severe disability.

RESULTS

Baseline 3MS score predicted baseline functional status. This effect was a gradient across the entire 3MS score, extending into the normal range with no apparent threshold. In logistic regression models, the unadjusted odds ratio (OR, 95% confidence interval) for the association of 3MS score with disability was 0.94 (0.93, 0.95); the adjusted OR was 0.96 (0.95, 0.98) in models including age, gender, education, and other covariates. Baseline 3MS score also predicted functional status 5 years later: The unadjusted OR for disability was 0.94 (0.92, 0.95); the adjusted OR was 0.97 (0.95, 0.99). Again, the risk of functional impairment at time 2 was a gradient effect, extending into the normal range of baseline 3MS score.

CONCLUSIONS

The 3MS predicts functional decline, and this effect is a gradient effect. These results support the hypothesis that cognition is a continuum in risk.

Before it is too late: professional responsibilities in late-onset Alzheimer's research and pre-symptomatic prediction

The development of a wide array of molecular and neuroscientific biomarkers can provide the possibility to visualize the course of Alzheimer's disease (AD) at early stages. Many of these biomarkers are aimed at detecting not only a preclinical, but also a pre-symptomatic state. They are supposed to facilitate clinical trials aiming at treatments that attack the disease at its earliest stage or even prevent it. The increasing number of such biomarkers currently tested and now partly proposed for clinical implementation calls for critical reflection on their aims, social benefits, and risks. This position paper summarizes major challenges and responsibilities. Its focus is on the ethical and social problems involved in the organization and application of dementia research, as well as in healthcare provision from a cross-national point of view. The paper is based on a discussion of leading dementia experts from neuroscience, neurology, social sciences, and bioethics in the United States and Europe. It thus reflects a notable consensus across various disciplines and national backgrounds. We intend to initiate a debate on the need for actions within the researchers' national and international communities.

Plasminogen activator inhibitor-1 as an early potential diagnostic marker for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in individuals over 65 years old. However, to date, no useful early diagnostic markers for AD have been discovered. We examined the utility of plasminogen activator inhibitor-1 (PAI-1) as a potential biomarker for AD in subjects with mild cognitive impairment (MCI) or AD, as well as in nondemented healthy controls. Plasma PAI-1 levels were measured by enzyme-linked immunosorbent assays (ELISAs) in samples collected from 76 patients with MCI, 74 patients with AD, and 76 healthy controls. Our results show that plasma PAI-1 levels gradually increased as dementia progressed. The mean levels of plasma PAI-1 in patients with MCI and AD patients were significantly higher than those of in healthy controls. Consistently, neuropsychological examination (e.g., MMSE, CDR) also demonstrated significant correlations between the plasma PAI-1 levels and cognitive function. In conclusion, the level of plasma PAI-1 is a potential biomarker for the early detection and diagnosis of AD.

Evaluation of annexin A5 as a biomarker for Alzheimer's disease and dementia with lewy bodies

Background: Alzheimer's disease (AD) differs from other forms of dementia in its relation to amyloid beta peptide (Aβ₄₂). Using a cell culture model we previously identified annexin A5, a Ca²⁺, and phospholipid binding protein, as an AD biomarker. Plasma level of annexin A5 was significantly higher in AD patients compared to that in a control group. On the other hand, AD has been identified to share a number of clinical and pathological features with Dementia with Lewy bodies (DLB). The present study was done to examine whether or not plasma annexin A5 is a specific marker for AD, when being compared with the levels of DLB patients. As Apolipoprotein E (ApoE) gene subtype ε4 (ApoE-ε4) has been noticed as the probable genetic factor for AD, we also examined and compared ApoE genotype in both AD and DLB.

Methods: Blood samples were obtained from 150 patients with AD (aged 77.6 ± 6.5 years), 50 patients of DLB (79.4 ± 5.0) and 279 community-dwelling healthy elderly individuals of comparable age and sex (75.6 ± 8.1). All AD patients met NINCDS-ADRDA criteria and all DLB patients were diagnosed as probable DLB according to the latest consensus diagnostic criteria. Quantification was done using the Chemiluminescent Enzyme Immunoassay (CLEIA) Technique (SphereLight assay) using the monoclonal antibodies against annexin A5. DNA genotyping of ApoE was performed by distinguishing unique combinations of Hha1 fragments of PCR-amplified genomic DNA products.

Results: The plasma level of annexin A5 was significantly higher in AD patients than in the healthy individuals (control) (P < 0.0001). The plasma annexin A5 level was also significantly higher in DLB patients than in the control group (P < 0.0001). From the ROC curves with plasma annexin A5 concentrations, the mean areas under the curve were 0.863 and 0.838 for the AD/control and DLB/control, respectively. The rate of ApoE4 carrier status and the frequency of the ε4 allele were significantly higher in AD or DLB than in control and there was no significant difference between AD and DLB.

Conclusions: These results suggest that both annexin A5 and ApoE4 are common markers for AD and DLB.

Brain oscillations as biomarkers in neuropsychiatric disorders: following an interactive panel discussion and synopsis

This survey covers the potential use of neurophysiological changes as a biomarker in four neuropsychiatric diseases (attention deficit hyperactivity disorder (ADHD), Alzheimer's disease (AD), bipolar disorder (BD), and schizophrenia (SZ)). Great developments have been made in the search of biomarkers in these disorders, especially in AD. Nevertheless, there is a tremendous need to develop an efficient, low-cost, potentially portable, non-invasive biomarker in the diagnosis, course, or treatment of the above-mentioned disorders. Electrophysiological methods would provide a tool that would reflect functional brain dynamic changes within milliseconds and also may be used as an ensemble of biomarkers that is greatly needed in the evaluation of cognitive changes seen in these disorders. The strategies for measuring cognitive changes include spontaneous electroencephalography (EEG), sensory evoked oscillation (SEO), and event-related oscillations (ERO). Further selective connectivity deficit in sensory or cognitive networks is reflected by coherence measurements. Possible candidate biomarkers discussed in an interactive panel can be summarized as follows: for ADHD: (a) elevation of delta and theta, (b) diminished alpha and beta responses in spontaneous EEG; for SZ: (a) decrease of ERO gamma responses, (b) decreased ERO in all other frequency ranges, (c) invariant ERO gamma response in relation to working memory demand; for euthymic BD: (a) decreased event-related gamma coherence, (b) decreased alpha in ERO and in spontaneous EEG; for manic BD: (a) lower alpha and higher beta in ERO, (b) decreased event-related gamma coherence, (c) lower alpha and beta in ERO after valproate; and for AD: (a) decreased alpha and beta, and increased theta and delta in spontaneous EEG, (b) hyperexcitability of motor cortices as shown by transcortical magnetic stimulation, (c) hyperexcitability of visual sensory cortex as indicated by increased SEO theta responses, (d) lower delta ERO, (e) lower delta, theta, and alpha event-related coherence, (f) higher theta synchrony and higher alpha event-related coherence in cholinergically treated AD subjects. In further research in the search for biomarkers, multimodal methods should be introduced to electrophysiology for validation purposes. Also, providing the protocols for standardization and harmonization of user-friendly acquisition or analysis methods that would be applied in larger cohort populations should be used to incorporate these electrophysiologic methods into the clinical criteria. In an extension to conventional anatomical, biochemical and brain imaging biomarkers, the use of neurophysiologic markers may lead to new applications for functional interpretrations and also the possibility to monitor treatments tailored for individuals.

Predicting Alzheimer's disease: neuropsychological tests, self-reports, and informant reports of cognitive difficulties

OBJECTIVES

To investigate the independent and combined contributions to the risk of Alzheimer's disease (AD) of three important domains of cognitive assessment: neuropsychological measurement, self-reports, and informant reports.

DESIGN

Longitudinal, community-based sample.

SETTING

Einstein Aging Study.

PARTICIPANTS

Six hundred twenty-seven individuals without dementia aged 70 and older systematically recruited from the Bronx, New York.

MEASUREMENTS

Comprehensive assessment included neurological examination, behavioral questions, and neuropsychological testing. AD diagnoses were based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria assigned at a multidisciplinary consensus case conference. The major statistical analyses used Cox proportional hazards models (with age as the time scale) adjusted for sex, education, and depressive symptoms.

RESULTS

Forty-eight participants developed incident AD during a median of 3.3 years of follow-up. Self- and informant reports of cognitive status and baseline scores on tests of episodic memory and psychomotor speed predicted the onset of AD, but in models examining all the variables simultaneously, only the episodic memory tests and informant reports were associated with risk of AD. A likelihood ratio test confirmed the incremental effect of informant reports in addition to the neuropsychological test scores (P = .03).

CONCLUSION

Informant ratings improved the prediction of AD conversion in addition to objective memory impairment in older adults without dementia. Combining these cognitive measures may provide a useful, empirical method for identifying individuals at high risk of future AD.

Using informant reports to detect cognitive decline in mild cognitive impairment

BACKGROUND

The use of informant rating scales in older adults at risk of dementia may assist with early detection and intervention strategies. This study aims to evaluate whether informants rate greater cognitive change in patients with mild cognitive impairment (MCI) compared to cognitively intact individuals, and to determine the relationship between informant ratings of cognitive change and neuropsychological performance.

METHODS

One hundred and nine health-seeking older adults underwent clinical and neuropsychological assessments, and informants completed the Cambridge Behavioral Inventory-Revised (CBI-R). Patients were rated according to MCI criteria, including amnestic and non-amnestic subtypes, or as being cognitively intact. CBI-R ratings were evaluated with respect to MCI diagnosis and neuropsychological performance.

RESULTS

Compared to cognitively intact individuals, informants rated patients with MCI as having significantly more change in overall functioning (p < 0.05) as well as in specific domains of memory and orientation (p < 0.01), everyday skills (p < 0.05), and motivation (p < 0.05), even after controlling for depressive symptom severity. In further analyses, the non-amnestic MCI subgroup only had more informant-rated mood changes compared to the amnestic subgroup. In relation to neuropsychological performance, informant ratings were related to poorer visual memory, verbal learning and memory, language, and psychomotor speed, with correlations ranging from -0.19 to -0.43 (p < 0.05).

CONCLUSIONS

These findings indicate that informants are sensitive to subtle early cognitive change in individuals with MCI, and that their ratings are related to objectively measured neuropsychological performance. Thus, the CBI-R may be valuable in assisting early screening and intervention processes.

Association between circulating hemostatic measures and dementia or cognitive impairment: systematic review and meta-analyzes

BACKGROUND AND OBJECTIVES

Hemostasis and thrombosis may be important contributors to cognitive decline and dementia. Certain blood markers may assist in diagnosis or management.

OBJECTIVES

To collate evidence for the association of circulating hemostatic variables and dementia or cognitive impairment.

METHODS

A systematic review of studies describing blood markers of hemostatic function and cognition/dementia. Abstracts were reviewed by two independent assessors and studies selected based on pre-specified criteria. We described methodological quality and performed meta-analyzes where data allowed.

RESULTS

From 7103 titles, 485 abstracts and included 21 studies (n = 32,773) were assessed. In two longitudinal studies, the incident of vascular dementia risk was greater for higher D-dimer [hazard ratio (HR): 1.50, 95% confidence interval (CI): 1.15-1.96]. For case-control data, we calculated standardized mean differences (SMD) and 95% CI. Higher levels of: factor (F)VII (SMD: 0.93; 95% CI: 0.60-1.26), fibrinogen (SMD: 1.53; 95% CI: 1.17-1.87), prothrombin fragment 1 and 2 (SMD: 0.64; 95% CI: 0.32-0.96), plasminogen activator inhibitor (SMD: 0.68; 95% CI: 0.26-1.10), D-dimer (SMD: 2.00; 95% CI: 1.59-2.40) and von Willebrand factor (VWF) (SMD: 1.68; 95% CI: 1.30-2.06) showed modest but significant associations with vascular dementia. For patients with any dementia diagnosis, associations were with higher D-dimer (SMD: 0.36; 95% CI: 0.15-0.56) and VWF (SMD: 0.31; 95% CI: 0.11-0.51). For specific cognitive domains, significant (P < 0.001) positive correlations were fibrinogen and speed of processing (0.76; 95% CI: 0.67-0.84), verbal memory (0.69; 95% CI: 0.59-0.79) and non-verbal reasoning (0.57; 95% CI: 0.49-0.65).

CONCLUSIONS

The present results suggest a modest association between hemostasis and vascular dementia including increased levels of thrombin generation markers (D-dimer and prothrombin fragment 1 + 2) and endothelial dysfunction (VWF and plasminogen activator inhibitor). Associations are weaker for specific cognitive tests and when all dementias are combined.

Dementia screening, biomarkers and protein misfolding: Implications for public health and diagnosis

Misfolded proteins are at the core of many neurodegenerative diseases, nearly all of them associated with cognitive impairment. For example Creutzfeldt-Jacob disease is associated with aggregation of prion protein, Lewy body dementia and Parkinson disease with α-synuclein and forms of frontotemporal dementia with tau, TDP 43 and host of other proteins, Alzheimer disease (AD), the most common cause of dementia, and its prodromal syndrome mild cognitive impairment (MCI) are an increasing public health problem and a diagnostic challenge to may clinicians. AD is characterized pathologically by the accumulation of amyloid β protein (Aβ) as senile plaques and in the walls of blood vessels as amyloid angiopathy. Additionally, there are accumulations of tau-protein as neurofibrillary tangles and dystrophic neurites. Biological markers of AD and MCI can serve as in vivo diagnostic indicators of underlying pathology, particularly when clinical symptoms are mild and are likely present years before the onset of clinical symptoms. Research to discover and refine fluid and imaging biomarkers of protein aggregation has undergone a rapid evolution and combined analysis of different modalities may further increase diagnostic sensitivity and specificity. Multi-center trials are now investigating whether imaging and/or cerebrospinal fluid (CSF) biomarker candidates can be used as outcome measures for use in phase III clinical trials for AD.