Independent effect of Aβ burden on cognitive impairment in patients with small subcortical infarction

BACKGROUND

The effect of amyloid-β (Aβ) on cognitive impairment in patients with small subcortical infarction remains controversial, although a growing body of evidence shows a substantial overlap between Alzheimer's disease (AD) and subcortical ischemic vascular dementia, another form of cerebral small vessel disease (cSVD). Therefore, we investigated the relationships between Aβ positivity and the development of post-stroke cognitive impairment (PSCI) in patients with small subcortical infarction.

METHODS

We prospectively recruited 37 patients aged ≥ 50 years, with first-ever small subcortical infarction, who underwent amyloid positron emission tomography, 3 months after stroke at Korea University Guro Hospital. We also enrolled CU participants matched for age and sex with stroke patients for comparison of Aβ positivity. Patients were followed up at 3 and 12 months after the stroke to assess cognitive decline. Logistic and linear mixed-effect regression analyses were performed to identify the effect of Aβ positivity on PSCI development and long-term cognitive trajectories.

RESULTS

At 3 months after stroke, 12/37 (32.4%) patients developed PSCI, and 11/37 (29.7%) patients had Aβ deposition. Aβ positivity (odds ratio [OR] = 72.2, p = 0.024) was predictive of PSCI development regardless of cSVD burden. Aβ positivity (β = 0.846, p = 0.014) was also associated with poor cognitive trajectory, assessed by the Clinical Dementia Rating-Sum of Box, for 1 year after stroke.

CONCLUSIONS

Our findings highlight that Aβ positivity is an important predictor for PSCI development and cognitive decline over 1 year. Furthermore, our results provide evidence that anti-AD medications may be a strategy for preventing cognitive decline in patients with small subcortical infarctions.

Functional gradients reveal altered functional segregation in patients with amnestic mild cognitive impairment and Alzheimer's disease

Alzheimer's disease and amnestic mild cognitive impairment are associated with disrupted functional organization in brain networks, involved with alteration of functional segregation. Connectome gradients are a new tool representing brain functional topological organization to smoothly capture the human macroscale hierarchy. Here, we examined altered topological organization in amnestic mild cognitive impairment and Alzheimer's disease by connectome gradient mapping. We further quantified functional segregation by gradient dispersion. Then, we systematically compared the alterations observed in amnestic mild cognitive impairment and Alzheimer's disease patients with those in normal controls in a two-dimensional functional gradient space from both the whole-brain level and module level. Compared with normal controls, the first gradient, which described the neocortical hierarchy from unimodal to transmodal regions, showed a more distributed and significant suppression in Alzheimer's disease than amnestic mild cognitive impairment patients. Furthermore, gradient dispersion showed significant decreases in Alzheimer's disease at both the global level and module level, whereas this alteration was limited only to limbic areas in amnestic mild cognitive impairment. Notably, we demonstrated that suppressed gradient dispersion in amnestic mild cognitive impairment and Alzheimer's disease was associated with cognitive scores. These findings provide new evidence for altered brain hierarchy in amnestic mild cognitive impairment and Alzheimer's disease, which strengthens our understanding of the progressive mechanism of cognitive decline.

Amyloid PET across the cognitive spectrum in former professional and college American football players: findings from the DIAGNOSE CTE Research Project

BACKGROUND

Exposure to repetitive head impacts (RHI) in American football players can lead to cognitive impairment and dementia due to neurodegenerative disease, particularly chronic traumatic encephalopathy (CTE). The pathognomonic lesion of CTE consists of perivascular aggregates of hyper-phosphorylated tau in neurons at the depths of cortical sulci. However, it is unclear whether exposure to RHI accelerates amyloid-β (Aβ) plaque formation and increases the risk for Alzheimer's disease (AD). Although the Aβ neuritic plaques characteristic of AD are observed in a minority of later-stage CTE cases, diffuse plaques are more common. This study examined whether former professional and college American football players, including those with cognitive impairment and dementia, have elevated neuritic Aβ plaque density, as measured by florbetapir PET. Regardless of cognitive and functional status, elevated levels of florbetapir uptake were not expected.

METHODS

We examined 237 men ages 45-74, including 119 former professional (PRO) and 60 former college (COL) football players, with and without cognitive impairment and dementia, and 58 same-age men without a history of contact sports or TBI (unexposed; UE) and who denied cognitive or behavioral symptoms at telephone screening. Former players were categorized into four diagnostic groups: normal cognition, subjective memory impairment, mild cognitive impairment, and dementia. Positive florbetapir PET was defined by cortical-cerebellar average SUVR of ≥ 1.10. Multivariable linear regression and analysis of covariance (ANCOVA) compared florbetapir average SUVR across diagnostic and exposure groups. Multivariable logistic regression compared florbetapir positivity. Race, education, age, and APOE4 were covariates.

RESULTS

There were no diagnostic group differences either in florbetapir average SUVR or the proportion of elevated florbetapir uptake. Average SUVR means also did not differ between exposure groups: PRO-COL (p = 0.94, 95% C.I. = [- 0.033, 0.025]), PRO-UE (p = 0.40, 95% C.I. = [- 0.010, 0.029]), COL-UE (p = 0.36, 95% CI = [0.0004, 0.039]). Florbetapir was not significantly associated with years of football exposure, cognition, or daily functioning.

CONCLUSIONS

Cognitive impairment in former American football players is not associated with PET imaging of neuritic Aβ plaque deposition. These findings are inconsistent with a neuropathological diagnosis of AD in individuals with substantial RHI exposure and have both clinical and medico-legal implications.

TRIAL REGISTRATION

NCT02798185.

[Dementia : current guidelines for clinical management]

Dementia is an umbrella term used to describe a group of symptoms associated with a decline in cognitive abilities that are severe enough to interfere with daily functioning and independence. While Alzheimer's disease (AD) is the most frequent cause, dementia in old aged persons represents rather a syndrome caused by various underlying conditions and diseases. Successful treatment allows for the individual clinical picture, and should be aimed at helping the patient regarding his cognitive deficits, behavioral and psychiatric complaints, sleep disorders, as well as management of daily life. Recently published promising study results on the use of monoclonal antibody therapies in AD give reason to believe that treatments will be available soon that can modulate disease progression at the neurobiological level.

Association Between Socioeconomic Factors, Race, and Use of a Specialty Memory Clinic

BACKGROUND AND OBJECTIVES

The capacity of specialty memory clinics in the United States is very limited. If lower socioeconomic status or minoritized racial group is associated with reduced use of memory clinics, this could exacerbate health care disparities, especially if more effective treatments of Alzheimer disease become available. We aimed to understand how use of a memory clinic is associated with neighborhood-level measures of socioeconomic factors and the intersectionality of race.

METHODS

We conducted an observational cross-sectional study using electronic health record data to compare the neighborhood advantage of patients seen at the Washington University Memory Diagnostic Center with the catchment area using a geographical information system. Furthermore, we compared the severity of dementia at the initial visit between patients who self-identified as Black or White. We used a multinomial logistic regression model to assess the Clinical Dementia Rating at the initial visit and t tests to compare neighborhood characteristics, including Area Deprivation Index, with those of the catchment area.

RESULTS

A total of 4,824 patients seen at the memory clinic between 2008 and 2018 were included in this study (mean age 72.7 [SD 11.0] years, 2,712 [56%] female, 543 [11%] Black). Most of the memory clinic patients lived in more advantaged neighborhoods within the overall catchment area. The percentage of patients self-identifying as Black (11%) was lower than the average percentage of Black individuals by census tract in the catchment area (16%) (p < 0.001). Black patients lived in less advantaged neighborhoods, and Black patients were more likely than White patients to have moderate or severe dementia at their initial visit (odds ratio 1.59, 95% CI 1.11-2.25).

DISCUSSION

This study demonstrates that patients living in less affluent neighborhoods were less likely to be seen in one large memory clinic. Black patients were under-represented in the clinic, and Black patients had more severe dementia at their initial visit. These findings suggest that patients with a lower socioeconomic status and who identify as Black are less likely to be seen in memory clinics, which are likely to be a major point of access for any new Alzheimer disease treatments that may become available.

Comprehension of acoustically degraded speech in Alzheimer's disease and primary progressive aphasia

Successful communication in daily life depends on accurate decoding of speech signals that are acoustically degraded by challenging listening conditions. This process presents the brain with a demanding computational task that is vulnerable to neurodegenerative pathologies. However, despite recent intense interest in the link between hearing impairment and dementia, comprehension of acoustically degraded speech in these diseases has been little studied. Here we addressed this issue in a cohort of 19 patients with typical Alzheimer's disease and 30 patients representing the three canonical syndromes of primary progressive aphasia (non-fluent/agrammatic variant primary progressive aphasia; semantic variant primary progressive aphasia; logopenic variant primary progressive aphasia), compared to 25 healthy age-matched controls. As a paradigm for the acoustically degraded speech signals of daily life, we used noise-vocoding: synthetic division of the speech signal into frequency channels constituted from amplitude-modulated white noise, such that fewer channels convey less spectrotemporal detail thereby reducing intelligibility. We investigated the impact of noise-vocoding on recognition of spoken three-digit numbers and used psychometric modelling to ascertain the threshold number of noise-vocoding channels required for 50% intelligibility by each participant. Associations of noise-vocoded speech intelligibility threshold with general demographic, clinical and neuropsychological characteristics and regional grey matter volume (defined by voxel-based morphometry of patients' brain images) were also assessed. Mean noise-vocoded speech intelligibility threshold was significantly higher in all patient groups than healthy controls, and significantly higher in Alzheimer's disease and logopenic variant primary progressive aphasia than semantic variant primary progressive aphasia (all P < 0.05). In a receiver operating characteristic analysis, vocoded intelligibility threshold discriminated Alzheimer's disease, non-fluent variant and logopenic variant primary progressive aphasia patients very well from healthy controls. Further, this central hearing measure correlated with overall disease severity but not with peripheral hearing or clear speech perception. Neuroanatomically, after correcting for multiple voxel-wise comparisons in predefined regions of interest, impaired noise-vocoded speech comprehension across syndromes was significantly associated (P < 0.05) with atrophy of left planum temporale, angular gyrus and anterior cingulate gyrus: a cortical network that has previously been widely implicated in processing degraded speech signals. Our findings suggest that the comprehension of acoustically altered speech captures an auditory brain process relevant to daily hearing and communication in major dementia syndromes, with novel diagnostic and therapeutic implications.

Association between stress-related disorders and the risk of dementia using the Korean National Sample Cohort: a matched cohort study

Post-traumatic stress disorder (PTSD) is associated with the development of dementia; however, the association of dementia risk with overall stress-related disorders is less known. This study investigated the association between stress-related disorders and the risk of dementia in a Korean nationwide sample cohort. The data analyzed in this study were acquired from the Korean National Health Insurance Service National Sample Cohort between 2002 and 2013. Using a 1:3 propensity score matching, 8906 patients with stress-related disorders and 26,718 control participants were included in the analysis. Patients with stress-related disorders had a higher risk of developing dementia after adjusting for covariates (hazard ratio [HR] = 1.15; 95% confidence interval [CI] 1.01-1.30) than control participants. Patients with PTSD showed the highest risk of increase (HR = 1.78) than those with other types of stress-related disorders. Patients with stress-related disorders showed the highest and significantly increased risk for Alzheimer's dementia (HR = 1.22, 95% CI 1.04-1.56). These results indicated an association between a history of stress-related disorders and the risk of dementia in the South Korean population. Further research investigating the causal mechanisms is needed.

Dysregulation of Ruminococcaceae and Megamonas could be predictive markers for rapid progression of mild cognitive impairment

BACKGROUND

Intestinal flora dysregulation may affect the development of Alzheimer's disease (AD). However, the correlation between intestinal flora and rapid progression of mild cognitive impairment (MCI) is rarely reported. Our aim was to investigate the features of the intestinal flora in patients with rapidly progressive MCI.

METHOD

A total of 1013 participants were screened, in which 87 patients with MCI were followed up for two years. At the baseline time point, fecal samples of the patients were sequenced via the microbial diversity high-throughput 16 s-rDNA.

RESULTS

After a two-year follow-up, 30 patients with MCI presented rapidly progressive cognitive impairment, whereas the 57 patients remained unprogressive. Analyses of their fecal samples showed that the abundance of 11 intestinal microflora were significantly different between the two groups at the baseline time point. Further analyses revealed that the decrease of Ruminococcaceae abundance and the increase of Megamonas abundance were significantly correlated with the progression of MCI. Also, the decreased Ruminococcaceae was independently associated with several factors such as P-tau181, and the increased Megamonas was independently associated with diabetes, low-density lipoprotein, median cell count.

CONCLUSION

The decrease of Ruminococcaceae and the increase of Megamonas could act as predictive markers for the rapidly progressive MCI.

Prevalence of nutrition disorders and nutrition-related conditions in older patients with Alzheimer's disease

BACKGROUNDS

Alzheimer's disease is frequently encountered with nutrition-related conditions such as malnutrition, sarcopenia, frailty, overnutrition, and micronutrient abnormalities in older patients. In this study, we aimed to evaluate the prevalence of nutrition disorders and nutrition-related conditions in the same patient group.

METHODS

A total of 253 older patients with Alzheimer's disease underwent comprehensive geriatric assessment, which included nutrition-related disorders, malnutrition via the Mini Nutritional Assessment-Short Form (MNA-SF), frailty via the Clinical Frailty Scale (CFS), and sarcopenia was diagnosed according to European Working Group on Sarcopenia in Older People-2 criteria.

RESULTS

The patients' mean age was 79.8 ± 6.5 years, and 58.1% were women. In our patients, 64.8% had malnutrition or were at risk of malnutrition; 38.3% had sarcopenia; 19.8% were prefrail; and 80.2% were frail. Malnutrition, frailty, and sarcopenia prevalence increased as the Alzheimer's disease stage progressed. Malnutrition was found to be significantly related with frailty scores via CFS (odds ratio [OR], 1.397; P = 0.0049) and muscle mass via fat-free mass index (FFMI) (OR, 0.793; P = 0.001). In logistic regression analysis, age, MNA-SF, and CFS were included in the model to detect the independent correlates of probable and confirmed sarcopenia. CFS was independently associated with probable and confirmed sarcopenia (OR, 1.822; P = 0.013; OR, 2.671; P = 0.001, respectively). Frailty was similarly related with FFMI (OR, 0.836; P = 0.031). Obesity was independently related with FFMI (OR, 0.688; P < 0.001).

CONCLUSION

In conclusion, nutrition disorders and nutrition-related conditions can present concurrently in patients with all stages of Alzheimer's disease; therefore, these frequent problems should be screened and diagnosed accordingly.

Reproducible Abnormalities and Diagnostic Generalizability of White Matter in Alzheimer's Disease

Alzheimer's disease (AD) is associated with the impairment of white matter (WM) tracts. The current study aimed to verify the utility of WM as the neuroimaging marker of AD with multisite diffusion tensor imaging datasets [321 patients with AD, 265 patients with mild cognitive impairment (MCI), 279 normal controls (NC)], a unified pipeline, and independent site cross-validation. Automated fiber quantification was used to extract diffusion profiles along tracts. Random-effects meta-analyses showed a reproducible degeneration pattern in which fractional anisotropy significantly decreased in the AD and MCI groups compared with NC. Machine learning models using tract-based features showed good generalizability among independent site cross-validation. The diffusion metrics of the altered regions and the AD probability predicted by the models were highly correlated with cognitive ability in the AD and MCI groups. We highlighted the reproducibility and generalizability of the degeneration pattern of WM tracts in AD.

Management of neuropsychiatric symptoms in dementia

PURPOSE OF REVIEW

The purpose is to review the results and clinical implications of recent studies of neuropathology in relation to neuropsychiatric symptoms (NPS) in Alzheimer's disease and related dementias, and discuss new therapeutic approaches based on evidence from clinical trials.

RECENT FINDINGS

In a large autopsy series from a national consortium, multiple neuropathologies of dementia subtypes were common and increased severity of specific NPS during life was associated with greater severity of neuropathology across diagnoses. Based on three clinical trials, brexpiprazole, which is an antipsychotic with dopamine and serotonin receptor partial agonism properties, was recently approved for the treatment of agitation in Alzheimer's dementia by the U.S. Food and Drug Administration (FDA). Its therapeutic profile indicates modest efficacy with high safety. Brexpiprazole has not been compared to other antipsychotics that are commonly prescribed to treat agitation in dementia, though none of them have been approved for this indication. Other drugs that showed positive results in Phase 2 trials are being tested in Phase 3 trials. These include cannabinoids and drug combinations that inhibit dextromethorphan metabolism peripherally, thereby increasing its bioavailability in the brain. Apathy is common in several types of dementia, and there is initial evidence that treatment with methylphenidate, a psychostimulant, may be efficacious with good tolerability.

SUMMARY

Greater understanding of the associations between NPS and dementia subtypes can improve clinical management of these disorders. In addition to the approval of brexpiprazole to treat agitation in Alzheimer's dementia, there is optimism about other medications based on ongoing clinical trials. Along with short-term improvement, altering the adverse impact on NPS on long-term prognosis remains an important challenge for the field.

Longitudinal post-shunt outcomes in idiopathic normal pressure hydrocephalus with and without comorbid Alzheimer's disease

OBJECTIVE

Alzheimer's disease (AD) is highly comorbid with idiopathic normal pressure hydrocephalus (iNPH) and may diminish the benefits of shunting; however, findings in this area are mixed. We examined postoperative outcomes, with emphases on cognition and utilization of novel scoring procedures to enhance sensitivity.

METHODS

Using participant data from an iNPH outcome study at Butler Hospital, a mixed effect model examined main and interaction effects of time since surgery (baseline, 3 months, 12 months, and 24-60 months) and AD comorbidity (20 iNPH and 11 iNPH+AD) on activities of daily living (ADLs) and iNPH symptoms. Regression modeling explored whether baseline variables predicted improvements 3 months postoperatively.

RESULTS

There were no group differences in gait, incontinence, and global cognition over time, and neither group showed changes in ADLs. Cognitive differences were observed postoperatively; iNPH patients showed stable improvements in working memory (p = 0.012) and response inhibition (p = 0.010), while iNPH + AD patients failed to maintain initial gains. Regarding predicting postoperative outcomes, baseline AD biomarkers did not predict shunt response at 3 months; however, older age at surgery predicted poorer cognitive outcomes (p = 0.04), and presurgical Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) (p = 0.035) and Mini-Mental Status Examination (MMSE) scores (p = 0.009) predicted improvements incontinence.

CONCLUSION

iNPH + AD may be linked with greater declines in aspects of executive functioning postoperatively relative to iNPH alone. While baseline AD pathology may not prognosticate shunt response, younger age appears linked with postsurgical cognitive improvement, and utilizing both brief and comprehensive cognitive measures may help predict improved incontinence. These results illustrate the potential benefits of surgery and inform postoperative expectations for those with iNPH + AD.

Genetic, vascular and amyloid components of cerebral blood flow in a preclinical population

Aging-related cognitive decline can be accelerated by a combination of genetic factors, cardiovascular and cerebrovascular dysfunction, and amyloid-β burden. Whereas cerebral blood flow (CBF) has been studied as a potential early biomarker of cognitive decline, its normal variability in healthy elderly is less known. In this study, we investigated the contribution of genetic, vascular, and amyloid-β components of CBF in a cognitively unimpaired (CU) population of monozygotic older twins. We included 134 participants who underwent arterial spin labeling (ASL) MRI and [18F]flutemetamol amyloid-PET imaging at baseline and after a four-year follow-up. Generalized estimating equations were used to investigate the associations of amyloid burden and white matter hyperintensities with CBF. We showed that, in CU individuals, CBF: 1) has a genetic component, as within-pair similarities in CBF values were moderate and significant (ICC > 0.40); 2) is negatively associated with cerebrovascular damage; and 3) is positively associated with the interaction between cardiovascular risk scores and early amyloid-β burden, which may reflect a vascular compensatory response of CBF to early amyloid-β accumulation. These findings encourage future studies to account for multiple interactions with CBF in disease trajectory analyses.

Striatal dopamine transporter uptake, parkinsonism and cognition in Alzheimer's disease

BACKGROUND AND PURPOSE

The correlates of motor parkinsonism in Alzheimer's disease (AD) remain controversial. The effects of nigrostriatal dopaminergic degeneration on parkinsonism and cognition in biomarker-validated patients with AD were evaluated.

METHODS

This study recruited 116 patients with AD who underwent dual-phase 18 F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane positron emission tomography, 18 F-florbetaben positron emission tomography, 3 T brain magnetic resonance imaging, and Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological tests. The mean cortical thickness in the frontal, temporal, parietal and occipital cortices, and the dopamine transporter (DAT) uptake in the caudate, anterior/posterior putamen and substantia nigra were quantified. The relationship between DAT uptake, mean lobar cortical thickness, UPDRS motor score and cognition was investigated using general linear models (GLMs) after controlling for age, sex, education, intracranial volume, and deep and periventricular white matter hyperintensities. A path analysis was performed for the UPDRS motor score with the same covariates.

RESULTS

Path analysis and multivariable GLMs for UPDRS motor score showed that lower caudate DAT uptake was directly associated with a higher UPDRS motor score, whereas caudate DAT uptake confounded the association between mean frontal/parietal thickness and UPDRS motor score. Multivariable GLMs for cognitive scores showed that lower caudate DAT uptake was associated with visuospatial/executive dysfunction independent of mean frontal or parietal thickness.

CONCLUSIONS

Nigrostriatal dopaminergic dysfunction is associated with parkinsonism and visuospatial/executive dysfunction in patients with AD.

Short-term memory conjunctive binding in Alzheimer's disease: A systematic review and meta-analysis

OBJECTIVE

Short-term memory (STM) binding tests assess the ability to temporarily hold conjunctions between surface features, such as objects and their colors (i.e., feature binding condition), relative to the ability to hold the individual features (i.e., single feature condition). Impairments in performance of these tests have been considered cognitive markers of Alzheimer's disease (AD). The objective of the present study was to conduct a meta-analysis of results from STM binding tests used in the assessment of samples mapped along the AD clinical continuum.

METHOD

We searched PubMed, Scopus, and Web of Science for articles that assessed patients with AD (from preclinical to dementia) using the STM binding tests and compared their results with those of controls. From each relevant article, we extracted the number of participants, the mean and standard deviations from single feature and of feature binding conditions. Results across studies were combined using standardized mean differences (effect sizes) to produce overall estimates of effect.

RESULTS

The feature binding condition of the STM binding showed large effects in all stages of AD. However, small sample sizes across studies, the presence of moderate to high heterogeneity and cross-sectional, case-controls designs decreased our confidence in the current evidence.

CONCLUSIONS

To be considered as a cognitive marker for AD, properly powered longitudinal designs and studies that clearly relate conjunctive memory tests with biomarkers (amyloid and tau) are still needed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Staff and Proxy Views of Multiple Family Member Involvement in Decision Making for Nursing Home Residents With Advanced Dementia

Decision making for nursing home (NH) residents with Alzheimer disease and related dementias often involves input from multiple family members and NH staff to address goals of care at the end of life. Using data from the Assessment of Disparities and Variation for Alzheimer's disease Nursing home Care at End of life research study, a secondary analysis of qualitative data was conducted involving interviews of 144 NH staff and 44 proxies in 14 NHs to examine the perspectives of NH staff and proxies for NH residents with Alzheimer disease and related dementias on the involvement of multiple family members in decision making about end-of-life care decisions. Interviews took place between 2018 and 2021. Nursing home staff and proxies had differing perspectives of the involvement of multiple family members in decision making, with NH staff primarily viewing families as a source of conflict, whereas proxies viewed families as a source of support. Nursing home staff also had differing opinions of their role with families; some attempted to ameliorate conflict, and some did not get involved. Some NH staff felt that Black families had more conflict than White families, indicating unacceptable bias and stereotyping of Black families by NH staff. These findings suggest training and education is needed for NH staff to facilitate better communication with families and to support proxies in end-of-life decision making to address goals of care for NH residents with Alzheimer disease and related dementias.

Imbalance of multiple neurotransmitter pathways leading to depression-like behavior and cognitive dysfunction in the triple transgenic mouse model of Alzheimer disease

Depression is among the most frequent psychiatric comorbid conditions in Alzheimer disease (AD). However, pharmacotherapy for depressive disorders in AD is still a big challenge, and the data on the efffcacy of current antidepressants used clinically for depressive symptoms in patients with AD remain inconclusive. Here we investigated the mechanism of the interactions between depression and AD, which we believe would aid in the development of pharmacological therapeutics for the comorbidity of depression and AD. Female APP/PS1/Tau triple transgenic (3×Tg-AD) mice at 24 months of age and age- and sex-matched wild-type (WT) mice were used. The shuttle-box passive avoidance test (PAT) were implemented to assess the abilities of learning and memory, and the open field test (OFT) and the tail suspension test (TST) were used to assess depression-like behavior. High-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was used to detect the level of neurotransmitters related to depression in the hippocampus of mice. The data was identified by orthogonal projections to latent structures discriminant analysis (OPLS-DA). Most neurotransmitters exert their effects by binding to the corresponding receptor, so the expression of relative receptors in the hippocampus of mice was detected using Western blot. Compared to WT mice, 3×Tg-AD mice displayed significant cognitive impairment in the PAT and depression-like behavior in the OFT and TST. They also showed significant decreases in the levels of L-tyrosine, norepinephrine, vanillylmandelic acid, 5-hydroxytryptamine, and acetylcholine, in contrast to significant increases in 5-hydroxyindoleacetic acid, L-histidine, L-glutamine, and L-arginine in the hippocampus. Moreover, the expression of the alpha 1a adrenergic receptor (ADRA1A), serotonin 1 A receptor (5HT1A), and γ-aminobutyric acid A receptor subunit alpha-2 (GABRA2) was significantly downregulated in the hippocampus of 3×Tg-AD mice, while histamine H3 receptor (H3R) expression was significantly upregulated. In addition, the ratio of phosphorylated cAMP-response element-binding protein (pCREB) and CREB was significantly decreased in the hippocampus of 3×Tg-AD mice than WT mice. We demonstrated in the present study that aged female 3×Tg-AD mice showed depression-like behavior accompanied with cognitive dysfunction. The complex and diverse mechanism appears not only relevant to the imbalance of multiple neurotransmitter pathways, including the transmitters and receptors of the monoaminergic, GABAergic, histaminergic, and cholinergic systems, but also related to the changes in L-arginine and CREB signaling molecules.

Further evaluation of narrative description as a measure of cognitive function in Alzheimer's disease

OBJECTIVE

The narrative description (ND) test objectively measures the ability to understand and describe visual scenes. As subtle differences in speech occur early in cognitive decline, we analyzed linguistic features for their utility in detecting cognitive impairment and predicting downstream decline.

METHOD

Participants (n = 52) with normal cognition to mild dementia performed the ND test (watched twenty 30-s video clips and described the visual content). Cognitive function was followed for up to 5 years. We computed simple linguistic features such as content efficiency, speech rate, and part of speech and unique word counts. We examined (a) relationships between cognitive status and ND score and linguistic features; (b) ability to discriminate early cognitive impairment from normal cognition using ND score and linguistic features; and (c) whether ND score and linguistic features were associated with future cognitive functional decline.

RESULTS

Many of the linguistic-feature metrics were related to cognitive status. Many of the linguistic features could distinguish between the cognitively normal group and the mild cognitive impairment (MCI) and Dementia groups. The area under the curve (AUC) for ND score alone was 0.74, with a nonsignificant increase to 0.78 when adding mean word length. Among participants with subjective cognitive decline (SCD) at the first visit, a smaller number of words plus more interjections or a lower ND score at baseline were predictive of future cognitive decline.

CONCLUSIONS

While many linguistic features were associated with cognitive status, and some were able to detect early cognitive impairment or predictive of future cognitive decline, all the features we tested seem to have been captured by the ND score. Thus, adding linguistic measures to the ND test score did not add to its value in assessing current or predicting future cognitive status. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

[Coincidence of normal pressure hydrocephalus and Alzheimer`s disease: therapeutic implications and open questions]

Normal pressure hydrocephalus (NPH) is prevalent in aging patient populations. Despite its clinical relevance, many patients with NPH may not receive adequate treatment. Because of the frequency of Alzheimer`s disease in these patients, there could be overlapping pathophysiological mechanisms that are as yet incompletely understood. Cerebral comorbidities seem to have negative effects on therapeutic response to ventriculoperitoneal shunting. In order to avoid unnecessary and unsuccessful surgery in highly vulnerable elderly patients, they have to be taken into consideration in the diagnostic process.

Fatigue in Alzheimer's disease: biological basis and clinical management-a narrative review

BACKGROUND

Fatigue is a common symptom in neurodegenerative diseases and is associated with decreased cognitive performances. A full knowledge of the causes and physiopathological pathways leading to fatigue in Alzheimer's disease could help treating this symptom and obtain positive effects on cognitive functions.

OBJECTIVES

To provide an overview of the clinical conditions and the biological mechanisms leading to fatigue in Alzheimer's disease patients. To review the recent advances on fatigue management and describe the landscape of future possibilities.

METHODS

We performed a narrative review including all type of studies (e.g. cross-sectional and longitudinal analysis, reviews, clinical trials).

RESULTS

We found very few studies considering the symptom fatigue in Alzheimer's disease patients. Populations, designs, and objectives varied across studies rendering comparability across studies difficult to perform. Results from cross-sectional and longitudinal analysis suggest that the amyloid cascade may be involved in the pathogenesis of fatigue and that fatigue may be a prodromal manifestation of Alzheimer's disease. Fatigue and neurodegeneration of Alzheimer's disease could share common brain signatures (i.e. hippocampal atrophy and periventricular leukoaraiosis). Some mechanisms of aging (i.e. inflammation, mitochondrial dysfunction, telomere shortening) may be proposed to play a common underlying role in Alzheimer's disease neurodegeneration and muscle fatigability. Considering treatments, donepezil has been found to reduce cognitive fatigue in a 6-week randomized controlled study. Fatigue is frequently reported as an adverse event in patients treated by anti-amyloid agents in clinical trials.

CONCLUSION

The literature is actually inconclusive about the main causes of fatigue in Alzheimer's disease individuals and its potential treatments. Further research is needed to disentangle the role of several components such as comorbidities, depressive symptoms, iatrogenic factors, physical decline and neurodegeneration itself. Given the clinical relevance of this symptom, it seems to be important to systematically assess fatigue by validated tools in Alzheimer's disease clinical trials.

Longitudinal decline in semantic versus letter fluency, but not their ratio, marks incident Alzheimer's disease in Latinx Spanish-speaking older individuals

OBJECTIVE

To compare longitudinal verbal fluency performance among Latinx Spanish speakers who develop Alzheimer's disease to those who do not develop dementia in absolute number of words produced on each task and their ratio to combine both scores.

METHOD

Participants included 833 Latinx Spanish-speaking older adults from a community-based prospective cohort in Manhattan. We performed growth curve modeling to investigate the trajectories of letter and semantic fluency, and their ratio (i.e., 'semantic index'), between individuals who developed Alzheimer's disease and those who did not (i.e., controls). The semantic index quantifies the proportion of words generated for semantic fluency in relation to the total verbal fluency performance.

RESULTS

Letter fluency performance did not decline in controls; we observed a linear decline in those who developed Alzheimer's disease. Semantic fluency declined in both groups and showed an increased rate of change over time in the incident Alzheimer's disease group; in comparison, the control group had a linear and slower decline. There were no group differences in the longitudinal trajectory (intercept and slope) of the semantic index.

CONCLUSION

A decline in letter fluency and a more rapid and accelerating decline over time in semantic fluency distinguished people who developed Alzheimer's disease from controls. Using the semantic index was not a superior marker of incident Alzheimer's disease compared to examining the two fluency scores individually. Results suggest the differential decline in verbal fluency tasks, when evaluated appropriately, may be useful for early identification of Alzheimer's disease in Latinx Spanish speakers, a historically understudied population.

Movement-related beta and gamma oscillations indicate parallels and disparities between Alzheimer's disease and HIV-associated neurocognitive disorder

People with HIV (PWH) often develop HIV-related neurological impairments known as HIV-associated neurocognitive disorder (HAND), but cognitive dysfunction in older PWH may also be due to age-related disorders such as Alzheimer's disease (AD). Discerning these two conditions is challenging since the specific neural characteristics are not well understood and limited studies have probed HAND and AD spectrum (ADS) directly. We examined the neural dynamics underlying motor processing during cognitive interference using magnetoencephalography (MEG) in 22 biomarker-confirmed patients on the ADS, 22 older participants diagnosed with HAND, and 30 healthy aging controls. MEG data were transformed into the time-frequency domain to examine movement-related oscillatory activity and the impact of cognitive interference on distinct stages of motor programming. Both cognitively impaired groups (ADS/HAND) performed significantly worse on the task (e.g., less accurate and slower reaction time) and exhibited reductions in frontal and cerebellar beta and parietal gamma activity relative to controls. Disease-specific aberrations were also detected such that those with HAND exhibited weaker gamma interference effects than those on the ADS in frontoparietal and motor areas. Additionally, temporally distinct beta interference effects were identified, with ADS participants exhibiting stronger beta interference activity in the temporal cortex during motor planning, along with weaker beta interference oscillations dispersed across frontoparietal and cerebellar cortices during movement execution relative to those with HAND. These results indicate both overlapping and distinct neurophysiological aberrations in those with ADS disorders or HAND in key motor and top-down cognitive processing regions during cognitive interference and provide new evidence for distinct neuropathology.

A blood biomarker test for brain amyloid impacts the clinical evaluation of cognitive impairment

OBJECTIVE

The objective of this study was to examine clinicians' patient selection and result interpretation of a clinically validated mass spectrometry test measuring amyloid beta and ApoE blood biomarkers combined with patient age (PrecivityAD® blood test) in symptomatic patients evaluated for Alzheimer's disease (AD) or other causes of cognitive decline.

METHODS

The Quality Improvement and Clinical Utility PrecivityAD Clinician Survey (QUIP I, ClinicalTrials.gov Identifier: NCT05477056) was a prospective, single-arm cohort study among 366 patients evaluated by neurologists and other cognitive specialists. Participants underwent blood biomarker testing and received an amyloid probability score (APS), indicating the likelihood of a positive result on an amyloid positron emission tomography (PET) scan. The primary study outcomes were appropriateness of patient selection as well as result interpretation associated with PrecivityAD blood testing.

RESULTS

A 95% (347/366) concordance rate was noted between clinicians' patient selection and the test's intended use criteria. In the final analysis including these 347 patients (median age 75 years, 56% women), prespecified test result categories incorporated 133 (38%) low APS, 162 (47%) high APS, and 52 (15%) intermediate APS patients. Clinicians' pretest and posttest AD diagnosis probability changed from 58% to 23% in low APS patients and 71% to 89% in high APS patients (p < 0.0001). Anti-AD drug therapy decreased by 46% in low APS patients (p < 0.0001) and increased by 57% in high APS patients (p < 0.0001).

INTERPRETATION

These findings demonstrate the clinical utility of the PrecivityAD blood test in clinical care and may have added relevance as new AD therapies are introduced.

The effect of hyperthyroidism on cognitive function, neuroinflammation, and necroptosis in APP/PS1 mice

BACKGROUND

Increasing evidence has linked the thyroid dysfunction to the pathogenesis of dementia. Evidence from clinical studies has demonstrated that hypothyroidism is related to an increased risk of dementia. But the association of hyperthyroidism with dementia is largely unknown.

METHODS

We used the adenovirus containing thyrotropin receptor (TSHR) amino acid residues 1-289 (Ad-TSHR289)-induced Graves' disease (GD) phenotype in Alzheimer's disease (AD) model mice (APP/PS1 mice) to evaluate the effect of hyperthyroidism on the cognitive function and β-amyloid (Aβ) accumulation.

RESULTS

GD mice exhibited a stable long-term hyperthyroidism and cognitive deficits. Single Cell RNA-sequencing analysis indicated that microglia function played a critical role in the pathophysiological processes in GD mice. Neuroinflammation and polarization of microglia (M1/M2 phenotype) and activated receptor-interacting serine/threonine protein kinase 3 (RIPK3)/mixed lineage kinase domain-like pseudo-kinase (MLKL)-mediated necroptosis contributed to the pathological process, including Aβ deposition and neuronal loss. RIPK3 inhibitor could inhibit GD-mediated Aβ accumulation and neuronal loss.

CONCLUSIONS

Our findings reveal that GD hyperthyroidism aggravates cognitive deficits in AD mice and induces Aβ deposition and neuronal loss by inducing neuroinflammation and RIPK3/MLKL-mediated necroptosis.

GPR34 Knockdown Relieves Cognitive Deficits and Suppresses Neuroinflammation in Alzheimer's Disease via the ERK/NF-κB Signal

Alzheimer's disease (AD) is a serious neurodegenerative disease characterized by amyloid-β (Aβ) aggregation and neuroinflammation. G-protein-coupled receptor 34 (Gpr34) was found highly expressed in the hippocampus of APP/PS1 mice. However, its role in AD remains unclear. Herein, the role of Gpr34 as well as its molecular mechanism was explored. Data in GSE85162 were analyzed and the differently expressed genes in the hippocampus tissues of APP/PS1 mouse model of AD were subjected to GO, KEGG and GSEA enrichment analyses. APP/PS1 mice were used as an animal model of AD and the cognitive impairment was evaluated by a water maze test. The level of Gpr34 in hippocampus and BV-2 cells as well as the activation of ERK/NF-κB signal was determined by quantitative real-time PCR, western blot or immunofluorescence. Our results showed that, in BV-2 cells exposed to Aβ1-42, Gpr34 knockdown decreased the levels of TNF-α, IL-1β, IL-6 and iNOS and suppressed the activation of ERK/NF-κB signal. Moreover, the Gpr34-overexpression-induced activation of ERK/NF-κB signal and up-regulated levels of TNF-α, IL-1β, IL-6 and iNOS were abolished by FR180204, an ERK inhibitor. On the other hand, the in vivo study showed that Gpr34 knockdown ameliorated the cognitive impairment in APP/PS1 mice, decreased the levels of TNF-α, IL-1β and IL-6, the activation of microglia and ERK/NF-κB signal. In conclusion, Gpr34 knockdown relieved cognitive deficits in APP/PS1 mice and suppressed neuroinflammation and microglial activation, maybe via the ERK/NF-κB signal. It is indicated that the high level of Grp34 in hippocampus may contribute to the pathogenesis of AD.

Increased TSPO expression, pyroglutamate-modified amyloid beta (AβN3(pE)) accumulation and transient clustering of microglia in the thalamus of Tg-SwDI mice

Epidemiological studies showed that Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA) frequently co-occur; however, the precise mechanism is not well understood. A unique animal model (Tg-SwDI mice) was developed to investigate the early-onset and robust accumulation of both parenchymal and vascular Aβ in the brain. Tg-SwDI mice have been extensively used to study the mechanisms of cerebrovascular dysfunction, neuroinflammation, neurodegeneration, and cognitive decline observed in AD/CAA patients and to design biomarkers and therapeutic strategies. In the present study, we documented interesting new features in the thalamus of Tg-SwDI mice: 1) a sharp increase in the expression of ionized calcium-binding adapter molecule 1 (Iba-1) in microglia in 6-month-old animals; 2) microglia clustering at six months that disappeared in old animals; 3) N-truncated/modified AβN3(pE) peptide in 9-month-old female and 12-month-old male mice; 4) an age-dependent increase in translocator protein (TSPO) expression. These findings reinforce the versatility of this model for studying multiple pathological issues involved in AD and CAA.

NOTCH3 C201R variant causes cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) that can be confused with early-onset Alzheimer's disease

BACKGROUND

NOTCH3 is the causative gene for autosomal dominant cerebral arteriopathy with subcortical infarctions and leukoencephalopathy (CADASIL) which is associated with both stroke and dementia. When CADASIL presents primarily as dementia it can be difficult to distinguish from Alzheimer's disease (AD) at both the clinical and neuropathological levels.

METHODS

We performed exome sequencing of several affected individuals from a large family affected with AD. PCR amplification and direct Sanger sequencing were used to verify variants detected by exome analysis and to screen family members at-risk to carry those variants. Neuropathologic brain evaluation by immunohistochemistry and MRI were performed for the carriers of the NOTCH3 variant.

RESULTS

In a three-generation family with AD, we found a c.601 T > C p.Cys201Arg variant in the NOTCH3 gene that caused clinical and neuropathological manifestations of CADASIL. These features included earlier onset of dementia accompanied by behavioral abnormalities in the father and son and white matter abnormalities in the asymptomatic grandson. The family is one branch of a large pedigree studied by the Alzheimer's Disease Sequencing Project (ADSP). As part of the ADSP linkage analysis and whole genome sequencing endeavor, an ABCA1 variant, p.Ala937Val, was previously found associated with AD in this pedigree.

CONCLUSIONS

Our findings, together with other reported pathogenic missense variants of the C201 codon in NOTCH3, support the role of cysteine 201 as a mutation hotspot for CADASIL and highlight the genetic complexity both clinically and pathologically of AD and related dementia.

Cerebrospinal fluid amyloid beta and response of cognition to a tap test in idiopathic normal pressure hydrocephalus: a case-control study

OBJECTIVES

To examine the relationship between cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) and tap test response to elucidate the effects of comorbidity of AD in idiopathic normal-pressure hydrocephalus (iNPH).

DESIGN

Case-control study.

SETTING

Osaka University Hospital.

PARTICIPANTS

Patients with possible iNPH underwent a CSF tap test.

MEASUREMENTS

Concentrations of amyloid beta (Aβ) 1-40, 1-42, and total tau in CSF were measured. The response of tap test was judged using Timed Up and Go test (TUG), 10-m reciprocation walking test (10MWT), Mini-Mental State Examination (MMSE), and iNPH grading scale. The ratio of Aβ1-42 to Aβ1-40 (Aβ42/40 ratio) and total tau concentration was compared between tap test-negative (iNPH-nTT) and -positive (iNPH-pTT) patients.

RESULTS

We identified 27 patients as iNPH-nTT and 81 as iNPH-pTT. Aβ42/40 ratio was significantly lower (mean [SD] = 0.063 [0.026] vs. 0.083 [0.036], p = 0.008), and total tau in CSF was significantly higher (mean [SD] = 385.6 [237.2] vs. 293.6 [165.0], p = 0.028) in iNPH-nTT than in iNPH-pTT. Stepwise logistic regression analysis revealed that low Aβ42/40 ratio was significantly associated with the negativity of the tap test. The response of cognition was significantly related to Aβ42/40 ratio. The association between Aβ42/40 ratio and tap test response, especially in cognition, remained after adjusting for disease duration and severity at baseline.

CONCLUSIONS

A low CSF Aβ42/40 ratio is associated with a poorer cognitive response, but not gait and urinary response, to a tap test in iNPH. Even if CSF biomarkers suggest AD comorbidity, treatment with iNPH may be effective for gait and urinary dysfunction.

Late-onset epilepsy with cognitive symptoms: Comparison of cognitive and imaging profiles with probable Alzheimer's disease

OBJECTIVE

We aimed to (i) compare the clinical, neuropsychological, and neuroimaging characteristics of unprovoked late-onset epilepsy (LOE) patients with cognitive symptoms against probable Alzheimer's disease (AD) patients; (ii) clarify how neurodegeneration and other processes could be implicated in the cognitive symptoms of unprovoked LOE patients; and (iii) characterize the longitudinal trajectory of unprovoked LOE patients with cognitive symptoms.

METHODS

Twenty-six unprovoked LOE patients with cognitive symptoms and 26 probable AD were retrospectively recruited from epilepsy and memory clinics at a single tertiary referral center. The patients underwent comprehensive clinical, neuropsychological, and 18Fluorodeoxyglucose PET-CT assessments. All LOE patients had clinical follow-up and a subset of 17 patients had repeat neuropsychological assessments.

RESULTS

At baseline, 18% of LOE patients with cognitive symptoms had dementia-range cognitive impairment and one received a diagnosis of probable AD. Compared with the probable AD group, the LOE group did not perform significantly better in global measures of cognition (total ACE-III), neuropsychological tests for fluency, working memory, language, attention, or executive function, but performed better in naming, memory, and visuospatial ability. The commonest patterns of cognitive impairment in the LOE group were frontal and left temporal, whereas all AD patients exhibited parietotemporal patterns. The AD group had more 18Fluorodeoxyglucose PET-CT hypometabolism in the parietal and occipital, but not the temporal and frontal lobes. During the 3.0 ± 3.2 years follow-up, improved seizure frequency in the LOE group covaried with improved total ACE-III score, there was no further conversion to probable AD and no group-level cognitive decline.

CONCLUSION

Unprovoked LOE patients with cognitive symptoms had varying severities of cognitive impairment, and different patterns of cognitive and imaging abnormalities compared with AD patients. They were rarely diagnosed with probable AD at presentation or follow-up. Cognitive outcome in LOE may be related to seizure control. Cerebral small vessel disease may play a role in LOE-associated cognitive impairment.

Time-dependent impact of type 2 diabetes mellitus on incident prodromal Alzheimer disease: A longitudinal study in 1395 participants

BACKGROUND AND PURPOSE

This study was undertaken to investigate the longitudinal impact of type 2 diabetes mellitus (T2DM) on the prodromal and dementia stages of Alzheimer disease (AD), focusing on diabetes duration and other comorbidities.

METHODS

A total of 1395 dementia-free individuals aged 55-90 years with maximum 15-year follow-up data were enrolled from the Alzheimer's Disease Neuroimaging Initiative database. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) of the incidence of prodromal or dementia stages of AD.

RESULTS

Longer T2DM duration (≥5 years; multiadjusted HR = 2.19, 95% confidence interval [CI] = 1.05-4.58), but not shorter T2DM duration (<5 years), was associated with a significantly increased risk of incident prodromal AD over a mean follow-up of 4.8 years. APOE ε4 allele (HR = 3.32, 95% CI = 1.41-7.79) and comorbid coronary artery disease (CAD; HR = 3.20, 95% CI = 1.29-7.95) further increased the risk of incident prodromal AD in patients with T2DM. No significant association was observed between T2DM and the risk of progression from prodromal AD to AD dementia.

CONCLUSIONS

T2DM, which is characterized by a longer duration, increases the incidence risk of prodromal AD but not AD dementia. APOE ε4 allele and comorbid CAD strengthen the relationship between T2DM and prodromal AD. These findings highlight T2DM characteristics and its comorbidities as predictors for accurate prediction of AD and screening of at-risk populations.

Safety, tolerability, and preliminary efficacy of SYN120, a dual 5-HT6/5-HT2A antagonist, for the treatment of Parkinson disease dementia: A randomized, controlled, proof-of-concept trial

BACKGROUND

SYN120 is a dual serotonin receptor (5-HT6/5-HT2A) antagonist hypothesized to improve cognition and psychiatric symptoms.

OBJECTIVES

We evaluated the safety, tolerability, and efficacy of SYN120 in patients with Parkinson disease dementia (PDD).

METHODS

In a multicenter, double-blind, parallel-group, 16-week phase 2a proof-of-concept trial in PDD with concomitant cholinesterase inhibitor use, eligible patients were randomized to oral SYN120 (100 mg/day) or placebo. Adverse events (AEs), Unified Parkinson's Disease Rating Scale (UPDRS) scores, and discontinuations assessed safety and tolerability. The primary and key secondary efficacy measures were the Cognitive Drug Research (CDR) computerized assessment system Continuity of Attention and Quality of Episodic Memory scores. Other efficacy measures were: Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Alzheimer's Disease Cooperative Study-Clinician's Global Impression of Change (ADCS-CGIC), Brief Penn Parkinson's Daily Activity Questionnaire-15 (PDAQ-15), Scales for Outcomes in Parkinson's Disease-Sleep Scale (SCOPA-Sleep), and Neuropsychiatric Inventory (NPI).

RESULTS

Eighty-two patients were randomized to SYN120 (N = 38) or placebo (N = 44), AEs occurred in 74% and 77% of patients, and treatment discontinuation in both groups was 16%. Nausea and vomiting were more frequent, and motor symptoms (UPDRS) worsened in the SYN120 group. At week 16, the SYN120 and placebo groups did not differ significantly for any cognitive assessment. Cognitive activities of daily living (PDAQ-15) and the NPI-Apathy/Indifference scores improved nominally in the SYN120 group compared with placebo (unadjusted p = 0.029 and 0.028).

CONCLUSIONS

SYN120 was adequately tolerated, mild worsening of motor symptoms was noted and it did not improve cognition in PDD patients. Its potential benefits for cognitive activities of daily living and apathy warrant further study.

REGISTRATION

Clinicaltrials.gov as NCT02258152.

Brain linear measurements for differentiating normal pressure hydrocephalus from Alzheimer's disease: an exploratory study

BACKGROUND AND PURPOSE

Easy and reliable tools for the differential diagnosis between idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) are needed.

MATERIALS AND METHODS

In this cross-sectional study iNPH and AD patients referred to the Neurology Unit of the University of Catania from 1 January 2020 to 1 December 2022 were enrolled. The following brain linear measurements (BLMs) were calculated: Evan's index (EI), the parieto-occipital ratio (POR) and the temporal ratio (TR). For each index, sensitivity, specificity and the area under the curve (AUC) were calculated. Moreover, a cumulative index, the BLM index, was also considered.

RESULTS

Fifty patients (25 iNPH and 25 AD) were enrolled. In differentiating iNPH from AD, EI had the highest AUC (0.956), POR had the highest specificity (100%) whilst TR had the highest sensitivity (92%). The BLM index differentiated iNPH and AD with a sensitivity of 96%, a specificity of 92% and an AUC of 0.963 with an optimal cut-off value of 0.303.

CONCLUSION

Evan's index, POR and TR may be useful in the differential diagnosis between iNPH and AD. At an individual level, the BLM index represents a valid and reliable tool to achieve an accurate differentiation between these two conditions.

APOE ε4 influences within and between network functional connectivity in posterior cortical atrophy and logopenic progressive aphasia

INTRODUCTION

Presence of apolipoprotein E (APOE) ε4 has shown greater predisposition to medial temporal involvement in posterior cortical atrophy (PCA) and logopenic progressive aphasia (LPA). Little is known about its influence on memory network connectivity, a network comprised of medial temporal structures.

METHODS

Fifty-eight PCA and 82 LPA patients underwent structural and resting state functional magnetic resonance imaging (MRI). Bayesian hierarchical linear models assessed the influence of APOE ε4 on within and between-network connectivity for five networks.

RESULTS

APOE ε4 carriers showed reduced memory and language within-network connectivity in LPA and increased salience within-network connectivity in PCA compared to non-carriers. Between-network analysis showed evidence of reduced DMN connectivity in APOE ε4 carriers, with reduced DMN-to-salience and DMN-to-language network connectivity in PCA, and reduced DMN-to-visual network connectivity in LPA.

DISCUSSION

The APOE genotype influences brain connectivity, both within and between-networks, in atypical Alzheimer's disease. However, there was evidence that the modulatory effects of APOE differ across phenotype.

HIGHLIGHTS

APOE genotype is associated with reductions in within-network connectivity for the memory and language networks in LPA APOE genotype is associated with reductions in language-to-visual connectivity in LPA and PCA APOE genotype has no effect on the memory network in PCA.

APOE genotypes modify the obesity paradox in dementia

BACKGROUND

While obesity in midlife is a risk factor for dementia, several studies suggested that obesity also protected against dementia, hence so-called obesity paradox. The current study aims to address the relationship between apolipoprotein E (APOE) genotype and obesity in dementia.

METHODS

Clinical and neuropathological records of the National Alzheimer's Coordinating Center (NACC) in the USA, which longitudinally followed approximately 20 000 subjects with different cognitive statues, APOE genotype and obesity states, were reviewed.

RESULTS

Obesity was associated with cognitive decline in early elderly cognitively normal individuals without APOE4, especially those with APOE2. Neuropathological analyses adjusted for dementia status showed that APOE2 carriers tended to have more microinfarcts and haemorrhages due to obesity. On the other hand, obesity was associated with a lower frequency of dementia and less cognitive impairment in individuals with mild cognitive impairment or dementia. Such trends were particularly strong in APOE4 carriers. Obesity was associated with fewer Alzheimer's pathologies in individuals with dementia.

CONCLUSIONS

Obesity may accelerate cognitive decline in middle to early elderly cognitive normal individuals without APOE4 likely by provoking vascular impairments. On the other hand, obesity may ease cognitive impairment in both individuals with dementia and individuals at the predementia stage, especially those with APOE4, through protecting against Alzheimer's pathologies. These results support that APOE genotype modifies the obesity paradox in dementia.

Cholecystokinin Signaling can Rescue Cognition and Synaptic Plasticity in the APP/PS1 Mouse Model of Alzheimer's Disease

Synaptic impairment and loss are an important pathological feature of Alzheimer's disease (AD). Memory is stored in neural networks through changes in synaptic activity, and synaptic dysfunction can cause cognitive dysfunction and memory loss. Cholecystokinin (CCK) is one of the major neuropeptides in the brain, and plays a role as a neurotransmitter and growth factor. The level of CCK in the cerebrospinal fluid is decreased in AD patients. In this study, a novel CCK analogue was synthesized on the basis of preserving the minimum bioactive fragment of endogenous CCK to investigate whether the novel CCK analogue could improve synaptic plasticity in the hippocampus of the APP/PS1 transgenic mouse model of AD and its possible molecular biological mechanism. Our study found that the CCK analogue could effectively improve spatial learning and memory, enhance synaptic plasticity in the hippocampus, normalize synapse numbers and morphology and the levels of key synaptic proteins, up-regulate the PI3K/Akt signaling pathway and normalize PKA, CREB, BDNF and TrkB receptor levels in APP/PS1 mice. The amyloid plaque load in the brain was reduced by CCK, too. The use of a CCKB receptor antagonist and targeted knockdown of the CCKB receptor (CCKBR) attenuated the neuroprotective effect of the CCK analogue. These results demonstrate that the neuroprotective effect of CCK analogue is achieved by activating the PI3K/Akt as well as the PKA/CREB-BDNF/TrkB signaling pathway that leads to protection of synapses and cognition.

Cognitive Aspects of COVID-19

PURPOSE OF REVIEW

Since the beginning of the coronavirus disease 2019 pandemic, many lasting neurological sequelae including cognitive impairment have been recognized as part of the so-called long COVID syndrome. This narrative review summarizes the cognitive aspects of COVID-19.

RECENT FINDINGS

Studies have consistently identified attention, memory, and executive functions as the cognitive domains most often affected by COVID-19 infection. Many studies have also reported neuroimaging, biofluid, and neurophysiological abnormalities that could potentially reflect the pathophysiological aspects of post-COVID cognitive impairment. While patients suffering from dementia have an elevated risk of COVID-19 infection, increasing evidence has also indicated that COVID-19 infection may increase the risks of Alzheimer's disease, suggesting bidirectional relationships. Post-COVID cognitive dysfunction is a pervasive and multifaceted problem and we are surely in our infancy of understanding. Future elucidation into the long-term effects, mechanisms, and therapies will depend on a concerted effort from clinicians, researchers, patients, and policy-makers alike.

A review of accelerated long-term forgetting in Alzheimer's disease: Current situation and prospects

OBJECTIVE

Advances in our understanding of the Alzheimer's disease (AD) continuum through in vivo biomarkers have highlighted the need to develop neuropsychological tests that are more sensitive to subtle cognitive changes in the preclinical stages of the disease. Recent data suggest that the assessment of memory retention over extended delays, to detect so-called accelerated long-term forgetting (ALF), may be a reliable way to discriminate between presymptomatic AD and healthy aging. This review aims to present the scientific evidence published to date on this particular aspect of memory.

METHOD

A comprehensive review of all published articles on ALF in AD to the present day.

RESULTS

We present findings relating to ALF in neurological disease, discuss theoretical aspects related to the integration of the concept of ALF in the framework of memory models, explain mechanisms that may be involved in its genesis and present supportive work from research in animal models. We focus particularly on aspects relevant to the assessment of ALF in clinical practice.

CONCLUSIONS

Despite many advances, further research will be needed to define more precisely what ALF is, what neural structures and mechanisms are involved in its occurrence, whether there are distinct patterns of forgetting according to etiology, and when and how to detect ALF most reliably. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

[Driving: What is the relevance and usability of the Reisberg scale in 2023?]

The publication of the decree on the care of people with neurocognitive disorders brought to the fore the Reisberg's Global Deterioration Scale, a scale that only few clinicians use in memory centers or in geriatric. This scale has a number of limitations, not least of which is that it is obsolete, since it does not take into account disease advances in scientific knowledge with biomarkers. Consequently, the stages evoked no longer correspond to current descriptions. Moreover, it only concerns Alzheimer's disease, whereas in our practice we encounter other neurodegenerative pathologies. Even if we decide to use another global assessment scale, such as the Clinical Dementia Rating or the Functional Assessment Staging, they cannot replace a personalized assessment. Indeed, it is important to stress that this decree does not take into account the relevance of personalized assessments using, for example, neuropsychological tests to estimate driving ability. A personalized assessment accompanied by a real-life driving test would be preferable than a score on a global scale. This article therefore presents the Global Deterioration Scale, highlighting its unsuitability for assessing whether or not to continue driving.

Antibodies Associated With Autoimmune Encephalitis in Patients With Presumed Neurodegenerative Dementia

BACKGROUND & OBJECTIVES

Autoimmune encephalitis (AIE) may present with prominent cognitive disturbances without overt inflammatory changes in MRI and CSF. Identification of these neurodegenerative dementia diagnosis mimics is important because patients generally respond to immunotherapy. The objective of this study was to determine the frequency of neuronal antibodies in patients with presumed neurodegenerative dementia and describe the clinical characteristics of the patients with neuronal antibodies.

METHODS

In this retrospective cohort study, 920 patients were included with neurodegenerative dementia diagnosis from established cohorts at 2 large Dutch academic memory clinics. In total, 1,398 samples were tested (both CSF and serum in 478 patients) using immunohistochemistry (IHC), cell-based assays (CBA), and live hippocampal cell cultures (LN). To ascertain specificity and prevent false positive results, samples had to test positive by at least 2 different research techniques. Clinical data were retrieved from patient files.

RESULTS

Neuronal antibodies were detected in 7 patients (0.8%), including anti-IgLON5 (n = 3), anti-LGI1 (n = 2), anti-DPPX, and anti-NMDAR. Clinical symptoms atypical for neurodegenerative diseases were identified in all 7 and included subacute deterioration (n = 3), myoclonus (n = 2), a history of autoimmune disease (n = 2), a fluctuating disease course (n = 1), and epileptic seizures (n = 1). In this cohort, no patients with antibodies fulfilled the criteria for rapidly progressive dementia (RPD), yet a subacute deterioration was reported in 3 patients later in the disease course. Brain MRI of none of the patients demonstrated abnormalities suggestive for AIE. CSF pleocytosis was found in 1 patient, considered as an atypical sign for neurodegenerative diseases. Compared with patients without neuronal antibodies (4 per antibody-positive patient), atypical clinical signs for neurodegenerative diseases were seen more frequently among the patients with antibodies (100% vs 21%, p = 0.0003), especially a subacute deterioration or fluctuating course (57% vs 7%, p = 0.009).

DISCUSSION

A small, but clinically relevant proportion of patients suspected to have neurodegenerative dementias have neuronal antibodies indicative of AIE and might benefit from immunotherapy. In patients with atypical signs for neurodegenerative diseases, clinicians should consider neuronal antibody testing. Physicians should keep in mind the clinical phenotype and confirmation of positive test results to avoid false positive results and administration of potential harmful therapy for the wrong indication.

The diagnostic usefulness of experimental memory tasks for detecting subjective cognitive decline: Preliminary results in an Italian sample

OBJECTIVE

Subjective cognitive decline (SCD) was recently proposed as an early risk factor for future mild cognitive impairment and Alzheimer's disease (AD). In this study, we investigated the sensitivity of novel neuropsychological testing paradigms (which have been proposed as potentially challenging tools for the identification of preclinical AD) in capturing the subtle cognitive changes leading to SCD but not objectively detected by traditional tests.

METHOD

The performances of 18 patients with SCD and 15 healthy individuals with no worries of cognitive decline (healthy controls [HC]) was compared on demanding tasks that investigated, respectively, associative memory, memory binding, spatial pattern separation processes and semantic memory. The diagnostic utility of these tests in capturing the subtle cognitive changes associated with SCD and possible relationships with SCD-related worries were investigated.

RESULTS

No significance between-group difference was found on the standard neuropsychological tests. Conversely, the performance of patients with SCD and HC differed significantly on specific indexes derived from experimental tasks assessing face-name associative memory and spatial pattern separation. Moreover, these measures correctly classified group membership with good overall accuracy (between 79% and 82%) and were significantly associated with self-perceived memory functioning.

CONCLUSIONS

Our preliminary findings suggest that specific measures derived from demanding cognitive paradigms could be sensitive neuropsychological indexes for detecting the subtle cognitive impairment associated with SCD. These observations could be useful for further refining cognitive assessment aimed at early detection of AD. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Association between periodontitis and cognitive impairment in adults

DESIGN

To summarize the data on association between periodontal diseases and cognitive impairment in adults this systematic review scrutinized various observational studies till September 2021. This review was carried out in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2020) guidelines. The authors used PECO framework question,: population-Adults (18 years or older), exposure-adults suffering from periodontitis, comparator-adult group without periodontitis, outcome-adults at high risk for cognitive impairment.

CASE/CONTROL SELECTION

Search for the literature was conducted on PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Search was limited to human studies with no limitation to year of publication prior to September 2021. Search terms used were related to gingiva, oral bacteria like Porphyromonas gingivalis, gum inflammation, periodontitis, dementia, neuroinflammation, cognitive impairment, Alzheimer's disease, Parkinson disease. Following research, all the studies providing association between periodontal diseases and neurodegenerative diseases with quantitative measures were included in the study. Non-human studies, studies on patients below 18 year old, studies related to influence of treatment and in subjects already suffering from neurological disease were excluded. After removing duplicates, eligible studies were identified and data extracted by two reviewers to make ensure inter examiner reliability and to prevent data entry errors. Data from the studies were tabulated as study design, sample characteristics, diagnosis, exposure biomarkers/measures, outcomes and results.

DATA ANALYSIS

Methodological quality of studies was assessed by adapted Newcastle-Ottawa scale. Selection of study groups, comparability and exposure/outcome were used as parameters. Case-control and cohort studies were considered as high-quality studies if six or more stars were awarded out of nine maximum stars and four or more stars for cross-sectional studies out of six stars. Comparability among the groups was studied by taking into account primary factors for Alzheimer's disease such as age and sex and secondary factors like hypertension, osteoarthritis, depression, diabetes mellitus, and cerebrovascular disease. For cohort studies, 10 year follow up and dropout of <10% was considered to be successful.

RESULTS

A total of 3693 studies were identified by two independent reviewers and finally 11 studies were included in the final analysis. Six cohort studies, three cross-sectional and two case-control studies were included after excluding remaining studies. Bias in studies was assessed by adapted Newcastle-Ottawa Scale. All included studies were of high methodological quality. Association between periodontitis and cognitive impairment was determined by using different criteria like International classification of disease, clinical measurement of periodontitis subjects, inflammatory biomarkers, microbes and antibodies. It was suggested that subjects with chronic periodontitis since 8 years or more, are at a higher risk of having dementia. Clinical measures of periodontal disease like probing depth, clinical attachment loss, alveolar bone loss were found to be positively associated with cognitive impairment. Inflammatory biomarkers and pre-existing elevated levels of serum IgG specific to periodontopathogens was reported to be associated with cognitive impairment. Within the limitations of the study, the authors concluded that though the patients with long-standing periodontitis are at greater risk for developing cognitive impairment by neurodegenerative diseases, the mechanism by which periodontitis can lead to cognitive impairment is still vague.

CONCLUSIONS

Evidence suggests a strong association between periodontitis and cognitive impairment. Still further studies should be done to explore the mechanism involved.

Ancestry-related differences in chromatin accessibility and gene expression of APOE ε4 are associated with Alzheimer's disease risk

INTRODUCTION

European local ancestry (ELA) surrounding apolipoprotein E (APOE) ε4 confers higher risk for Alzheimer's disease (AD) compared to African local ancestry (ALA). We demonstrated significantly higher APOE ε4  expression in ELA versus ALA in AD brains from APOE ε4/ε4 carriers. Chromatin accessibility differences could contribute to these expression changes.

METHODS

We performed single nuclei assays for transposase accessible chromatin sequencing from the frontal cortex of six ALA and six ELA AD brains, homozygous for local ancestry and APOE ε4.

RESULTS

Our results showed an increased chromatin accessibility at the APOE ε4  promoter area in ELA versus ALA astrocytes. This increased accessibility in ELA astrocytes extended genome wide. Genes with increased accessibility in ELA in astrocytes were enriched for synapsis, cholesterol processing, and astrocyte reactivity.

DISCUSSION

Our results suggest that increased chromatin accessibility of APOE ε4  in ELA astrocytes contributes to the observed elevated APOE ε4  expression, corresponding to the increased AD risk in ELA versus ALA APOE ε4/ε4 carriers.

Genetic propensity for cerebral amyloidosis and risk of mild cognitive impairment and Alzheimer's disease within a cognitive reserve framework

INTRODUCTION

We constructed a polygenic risk score (PRS) for β-amyloid (PRSAβ42) to proxy AD pathology and investigated its association with incident Alzheimer's disease (AD)/amnestic mild cognitive impairment (aMCI) and the influence of cognitive reserve (CR), proxied by educational years, on the relationship between PRSAβ42 and AD/aMCI risk.

METHODS

A total of 618 cognitive-normal participants were followed-up for 2.92 years. The association of PRSAβ42 and CR with AD/aMCI incidence was examined with COX models. Then we examined the additive interaction between PRSAβ42 and CR and the CR effect across participants with different PRSAβ42 levels.

RESULTS

Higher PRSAβ42 and CR were associated with a 33.9% higher risk and 8.3% less risk for AD/aMCI, respectively. An additive interaction between PRSAβ42 and CR was observed. High CR was associated with 62.6% less risk of AD/aMCI incidence only in the high-PRSAβ42 group.

DISCUSSION

A super-additive effect of PRSAβ42 and CR on AD/aMCI risk was observed. CR influence was evident in participants with high PRSAβ42.

Families of patients with Alzheimer's disease dementia notice progression from symptoms of disorientation and visual memory disturbance

BACKGROUND

Alzheimer's disease dementia (ADD) is the most common cognitive disease, but patients' families may notice some symptoms yet not recognise that they indicate ADD. This study investigated the symptoms that families notice as ADD as the disease progresses.

METHODS

New outpatients diagnosed with ADD (n = 315) at five memory clinics completed two cognitive assessments, the Revised Hasegawa Dementia Scale (HDS-R) and Mini-Mental State Examination (MMSE). During an interview, family members completed the Functional Assessment Staging Test (FAST), an observational assessment tool that classifies ADD progression into seven stages. We then examined the relationship of the family-assessed FAST score with clinician-assessed HDS-R and MMSE domain scores by comparing between patients with FAST 1-3 and FAST 4-7. Next, we divided the FAST 4-7 group into the FAST 4-5 and FAST 6-7 subgroups and divided the FAST 1-3 group into the FAST 1-2 and FAST 3 subgroups.

RESULTS

Surprisingly, half of the families did not recognise that the symptoms indicated ADD. Scores for orientation of time and place on the HDS-R and MMSE and for visual memory on the HDS-R were significantly related to family-assessed FAST score. Moreover, the orientation of time and place score on both scales and visual memory on the HDS-R were significantly worse in the FAST 4-7 group than in FAST 1-3 group. In the FAST 4-7 group, scores for age on the HDS-R and for reading and drawing on the MMSE were significantly worse in the FAST 6-7 subgroup. In the analysis of the FAST 1-3 group, there was no significant difference among the HDS-R and MMSE domains between the FAST 1-2 and FAST 3 subgroups.

CONCLUSIONS

Family members of patients with ADD tend to notice the progression of ADD from the symptoms of disorientation and visual memory.

25-hydroxyvitamin D concentrations and risk of incident dementia, mild cognitive impairment, and delirium in 443,427 UK Biobank participants

This study aimed to investigate the association between serum 25-hydroxyvitamin D (25(OH)D) levels and dementia, mild cognitive impairment (MCI), and delirium. Participants from the United Kingdom (UK) Biobank with complete information on serum 25(OH)D concentrations were enrolled. Dementia, MCI and delirium were defined using the UK Biobank algorithm. 443,427 participants with a mean (standard deviation) age of 56.8 (8.0) years were included in this study. Based on Cox regression models, serum 25(OH)D concentrations were inversely associated with the risk of dementia, MCI, and delirium in a dose-dependent manner after adjusting for demographics (P-trend <0.001). In comparison with 25(OH)D levels less than 32.4 nmol/L, participants with the highest 25(OH)D levels (i.e., >64.4 nmol/L) had the lowest risk of dementia (hazards ratio [HR]: 0.58, 95% confidence interval [CI] 0.49-0.69, P<0.001), MCI (HR: 0.55, 95% CI 0.37-0.84, P=0.005), and delirium (HR: 0.63, 95% CI 0.51-0.79, P<0.001). These results were consistent with the sensitivity analysis, in which participants with events occurring within the first two years of follow-up were excluded. This study found that a lower serum 25(OH)D concentration was significantly associated with a higher risk of dementia (including Alzheimer's disease and vascular dementia), MCI, and delirium.