Exploring the neurocognitive correlates of suicidal ideation in major depressive disorder: The role of frontoparietal and default mode networks

Suicidal ideation (SI) is a common symptom of major depressive disorder (MDD), often accompanied by cognitive alterations and emotional dysregulation. However, it is unclear whether cognitive dysfunction in patients with MDD is related to the presence or absence of SI and impaired connectivity within or between large-scale neurocognitive networks. Previous studies have shown that the frontoparietal network (FPN) and default mode network (DMN) are critical for cognitive control and emotional regulation. Participants were 51 MDD patients with suicidal ideation (MDDSI), 52 MDD patients without suicidal ideation (MDDNSI), and 55 healthy controls (HC). Using areas located within FPN and DMN networks as regions of interest (ROIs), we compared the cognitive performance of the three groups and the strength of the resting state functional connections (RSFC) within and between the FPN and DMN networks. Additionally, we examined the correlation between the strength of FC within the FPN and cognitive function in the SI group. Furthermore, network-based statistics (NBS) were used to correct for the strength of FPN and DMN functional connections. The study identified significant cognitive deficits in MDD patients. Reduced strength of FC was observed within the FPN and DMN networks in the SI group compared to the NSI group. In the SI group, the strength of FC within the FPN network was positively correlated with attention/vigilance. These insights underscore the critical roles of the FPN and DMN in the suicidal ideation, shedding light on the cognitively relevant neurobiological characteristics of MDDSI, providing new insights into the neural mechanisms of MDDSI. URL: https://www.chictr.org.cn/bin/project/edit?pid=131537. Registration number: ChiCTR2100049646.

Brain structure, amyloid, and behavioral features for predicting clinical progression in subjective cognitive decline

As a potential preclinical stage of Alzheimer's dementia, subjective cognitive decline (SCD) reveals a higher risk of future cognitive decline and conversion to dementia. However, it has not been clear whether SCD status increases the clinical progression of older adults in the context of amyloid deposition, cerebrovascular disease (CeVD), and psychiatric symptoms. We identified 99 normal controls (NC), 15 SCD individuals who developed mild cognitive impairment in the next 2 years (P-SCD), and 54 SCD individuals who did not (S-SCD) from ADNI database with both baseline and 2-year follow-up data. Total white matter hyperintensity (WMH), WMH in deep (DWMH) and periventricular (PWMH) regions, and voxel-wise grey matter volumes were compared among groups. Furthermore, using structural equation modelling method, we constructed path models to explore SCD-related brain changes longitudinally and to determine whether baseline SCD status, age, and depressive symptoms affect participants' clinical outcomes. Both SCD groups showed higher baseline amyloid PET SUVR, baseline PWMH volumes, and larger increase of PWMH volumes over time than NC. In contrast, only P-SCD had higher baseline DWMH volumes and larger increase of DWMH volumes over time than NC. No longitudinal differences in grey matter volume and amyloid was observed among NC, S-SCD, and P-SCD. Our path models demonstrated that SCD status contributed to future WMH progression. Further, baseline SCD status increases the risk of future cognitive decline, mediated by PWMH; baseline depressive symptoms directly contribute to clinical outcomes. In conclusion, both S-SCD and P-SCD exhibited more severe CeVD than NC. The CeVD burden increase was more pronounced in P-SCD. In contrast with the direct association of depressive symptoms with dementia severity progression, the effects of SCD status on future cognitive decline may manifest via CeVD pathologies. Our work highlights the importance of multi-modal longitudinal designs in understanding the SCD trajectory heterogeneity, paving the way for stratification and early intervention in the preclinical stage. PRACTITIONER POINTS: Both S-SCD and P-SCD exhibited more severe CeVD at baseline and a larger increase of CeVD burden compared to NC, while the burden was more pronounced in P-SCD. Baseline SCD status increases the risk of future PWMH and DWMH volume accumulation, mediated by baseline PWMH and DWMH volumes, respectively. Baseline SCD status increases the risk of future cognitive decline, mediated by baseline PWMH, while baseline depression status directly contributes to clinical outcome.

Mitochondrial DNA abundance in blood is associated with Alzheimer's disease- and dementia-risk

The mitochondrial cascade hypothesis of Alzheimer's disease (AD) has been portrayed through molecular, cellular, and animal studies; however large epidemiological studies are lacking. This study aimed to explore the association of mitochondrial DNA copy number (mtDNAcn), a marker representative of mtDNA abundance per cell, with risk of incident all-cause dementia, AD, and vascular dementia diagnosis within 17 years and dementia-related blood biomarkers (P-tau181, GFAP, and NfL). Additionally, sex-stratified analyses were completed. In this German population-based cohort study (ESTHER), 9940 participants aged 50-75 years were enrolled by general practitioners and followed for 17 years. Participants were included in this study if information on dementia status and blood-based mtDNAcn measured via real-time polymerase chain reaction were available. In a nested case-control approach, a subsample of participants additionally had measurements of P-tau181, GFAP, and NfL in blood samples taken at baseline. Of 4913 participants eligible for analyses, 386 were diagnosed with incident all-cause dementia, including 130 AD and 143 vascular dementia cases, while 4527 participants remained without dementia diagnosis within 17 years. Participants with low mtDNAcn (lowest 10%) experienced 45% and 65% percent increased risk of incident all-cause dementia and AD after adjusting for age and sex (all-cause dementia: HRadj, 95%CI:1.45, 1.08-1.94; AD: HRadj, 95%CI: 1.65, 1.01-2.68). MtDNAcn was not associated to vascular dementia diagnosis and was more strongly associated with all-cause dementia among women. In the nested case-control study (n = 790), mtDNAcn was not significantly associated with the dementia-related blood biomarkers (P-tau181, GFAP, and NfL) levels in blood from baseline before dementia diagnosis. This study provides novel epidemiological evidence connecting mtDNA abundance, measured via mtDNAcn, to incident dementia and AD at the population-based level. Reduced mitochondrial abundance may play a role in pathogenesis, especially among women.

Antibody-assisted selective isolation of Purkinje cell nuclei from mouse cerebellar tissue

We developed a method that utilizes fluorescent labeling of nuclear envelopes alongside cytometry sorting for the selective isolation of Purkinje cell (PC) nuclei. Beginning with SUN1 reporter mice, we GFP-tagged envelopes to confirm that PC nuclei could be accurately separated from other cell types. We then developed an antibody-based protocol to make PC nuclear isolation more robust and adaptable to cerebellar tissues of any genotypic background. Immunofluorescent labeling of the nuclear membrane protein RanBP2 enabled the isolation of PC nuclei from C57BL/6 cerebellum. By analyzing the expression of PC markers, nuclear size, and nucleoli number, we confirmed that our method delivers a pure fraction of PC nuclei. To demonstrate its applicability, we isolated PC nuclei from spinocerebellar ataxia type 7 (SCA7) mice and identified transcriptional changes in known and new disease-associated genes. Access to pure PC nuclei offers insights into PC biology and pathology, including the nature of selective neuronal vulnerability.

Patterns of atrial fibrillation, relevant cardiac structural and functional changes predict functional and cognitive outcomes in patients with ischemic stroke and atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) pattern, relevant cardiac changes are important predictors of outcomes in AF, but their impact on patients with ischemic stroke and AF remained unclear. We aimed to explore the impact of AF patterns, cardiac structural and functional markers on long-term functional and cognitive outcomes in ischemic stroke patients with AF.

METHODS

Ischemic stroke patients diagnosed with AF were enrolled in this retrospective cohort study. AF pattern was defined by both traditional and novel classification, in which patients were divided into AF diagnosed after stroke (AFDAS) and known before stroke (KAF). Left atrial (LA) diameter, left ventricular ejection fraction (LVEF), natriuretic peptide (BNP) and cardiac troponin (cTnI) were dichotomized according to the median value. Outcomes include poor functional outcome and cognitive impairment at the 1-year follow-up. Multivariable logistic regression was performed to validate the association between AF pattern, parameters of cardiac change and functional and cognitive outcome.

RESULTS

A total of 377 patients were included. Non-paroxysmal AF patients had a higher risk of poor functional outcome (OR = 3.59, P < 0.0001) and cognitive impairment (OR = 2.38, P = 0.019) than paroxysmal AF patients, while there were no differences between AFDAS and KAF. Lower LVEF (OR = 1.83, P = 0.045) and higher BNP (OR = 2.66, P = 0.001) were associated with poor functional outcome. Lower LVEF (OR = 2.86, P = 0.004), higher LA diameter (OR = 2.72, P = 0.008) and BNP (OR = 2.31, P = 0.023) were associated with cognitive impairment.

CONCLUSIONS

AF type and related cardiac markers can serve as predictors for poor functional and cognitive outcomes. Comprehensive cardiac assessment and monitoring should be strengthened after stroke.

Antineutrophil cytoplasmic antibody is an independent risk factor in rheumatoid arthritis-associated interstitial lung disease

OBJECTIVES

This study aimed to investigate the clinical relevance of antineutrophil cytoplasmic antibody (ANCA) in patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD).

METHODS

Detailed clinical records of rheumatoid arthritis (RA) patients who underwent ANCA screening tests were collected. ANCA measurements were determined by indirect immunofluorescence assay (IIF) and enzyme-linked immunosorbent assay (ELISA). Clinical characteristics were compared between ANCA-positive and ANCA-negative groups, and multivariable logistic models were used to evaluate the independent association of ANCA with ILD in RA patients.

RESULTS

The prevalence of ANCA by IIF was significantly higher in RA-ILD patients compared to those with RA without ILD (31.7 % vs. 19.5 %, p < 0.001). RA-ILD patients positive for ANCA exhibited elevated levels of inflammatory markers and greater disease activity, and showed more severe impairment of lung function compared to ANCA-negative RA-ILD patients. Multivariable logistic regression analysis revealed an independent association of ANCA, especially pANCA, with RA-ILD. ANCA specificities for BPI, elastase, and cathepsin-G were found in 15.6 % of RA-ILD patients; the specificities for most others remain unknown.

CONCLUSIONS

The findings suggest a potential role for ANCA/pANCA in stratifying the risk of RA and provide supplementary information to the existing clinically available assays. This additional information may be valuable in identifying RA patients who require further investigations for RA-ILD, such as high-resolution computed tomography (HRCT). These results emphasize the potential clinical relevance of ANCA in the context of RA-ILD.

Structural characterization of Hericium coralloides polysaccharide and its neuroprotective function in Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder. Polysaccharides have been scientifically demonstrated to possess neuroprotective properties. In this study, a polysaccharide was isolated from the fruiting bodies of Hericium coralloides using hot water extraction and purified using column chromatography. This H. coralloides polysaccharide (HCP) is a galactan with a main chain of →6)-α-d-Galp-(1 → and a molecular weight of 16.06 kDa. The partial α-l-Fucp-(1 → substitution takes place at its O-2 position. The neuroprotective effects of HCP were investigated in an APP/PS1 mouse model of Alzheimer's disease. The step-down and Morris water maze tests demonstrated that HCP effectively ameliorated cognitive impairment. After 8-week treatment, HCP reduced amyloid-β plaques and phosphorylated tau protein deposition. In combination with the gut microbiota and metabolites, proteomic analysis suggested that the neuroprotective effects of HCP are associated with neuroinflammation and autophagy. Immunofluorescence and western blotting analyses confirmed that HCP facilitated the polarization of M2 microglia by augmenting autophagy flux, thereby effectively reducing levels of amyloid-β plaques and neuroinflammation. These data demonstrate that HCP effectively mitigates neuroinflammation by enhancing autophagic flux, demonstrating its potential for the treatment of AD.

Polysaccharides extracted from common buckwheat (Fagopyrum esculentum) attenuate cognitive impairment via suppressing RAGE/p38/NF-κB signaling and dysbiosis in AlCl3-treated rats

Patients may find it challenging to accept several FDA-approved drugs for Alzheimer's disease (AD) treatment due to their unaffordable prices and side effects. Despite the known antioxidant, anti-inflammatory, and microbiota-regulating effects of common buckwheat (Fagopyrum esculentum) polysaccharides (FEP), their specific role in preventing AD has not been determined. Here, this study investigated the preventive effects of FEP on AD development in AlCl3-treated rats. The physical properties of FEP were evaluated using X-ray diffraction, FTIR, TGA, DSC, monosaccharide composition, molecular weight, and scanning electron microscopy. The results demonstrated that FEP administration improved memory and learning ability in AlCl3-treated rats. Additionally, AD pathological biomarkers (APP, BACE1, Aβ1-42, and p-TauSer404), inflammatory-associated proteins (IL-1β, IL-6, TNF-α, and Iba1), and MDA and the RAGE/p38/NF-κB pathway were elevated in AlCl3-treated rats. Moreover, these effects were reversed by the upregulation of LRP1, anti-inflammatory cytokines (IL-4 and IL-10), antioxidant enzymes (SOD and catalase), and autophagy proteins (Atg5, Beclin-1, and LC3B). Furthermore, FEP treatment increased the levels of short-chain fatty acids (SCFAs) and the abundance of SCFAs-producing microbes ([Eubacterium]_xylanophilum_group, Lachnospiraceae_NK4A136_group, Lactobacillus). Overall, FEP mitigated oxidative stress, RAGE/p38/NF-κB-mediated neuroinflammation, and AD-associated proteins by upregulating autophagy and SCFA levels, which led to the amelioration of cognitive impairment through microbiota-gut-brain communication in AlCl3-treated rats.

Optimal gamma-band entrainment of visual cortex

Visual entrainment is a powerful and widely used research tool to study visual information processing in the brain. While many entrainment studies have focused on frequencies around 14-16 Hz, there is renewed interest in understanding visual entrainment at higher frequencies (e.g., gamma-band entrainment). Notably, recent groundbreaking studies have demonstrated that gamma-band visual entrainment at 40 Hz may have therapeutic effects in the context of Alzheimer's disease (AD) by stimulating specific neural ensembles, which utilize GABAergic signaling. Despite such promising findings, few studies have investigated the optimal parameters for gamma-band visual entrainment. Herein, we examined whether visual stimulation at 32, 40, or 48 Hz produces optimal visual entrainment responses using high-density magnetoencephalography (MEG). Our results indicated strong entrainment responses localizing to the primary visual cortex in each condition. Entrainment responses were stronger for 32 and 40 Hz relative to 48 Hz, indicating more robust synchronization of neural ensembles at these lower gamma-band frequencies. In addition, 32 and 40 Hz entrainment responses showed typical patterns of habituation across trials, but this effect was absent for 48 Hz. Finally, connectivity between visual cortex and parietal and prefrontal cortices tended to be strongest for 40 relative to 32 and 48 Hz entrainment. These results suggest that neural ensembles in the visual cortex may resonate at around 32 and 40 Hz and thus entrain more readily to photic stimulation at these frequencies. Emerging AD therapies, which have focused on 40 Hz entrainment to date, may be more effective at lower relative to higher gamma frequencies, although additional work in clinical populations is needed to confirm these findings. PRACTITIONER POINTS: Gamma-band visual entrainment has emerged as a therapeutic approach for eliminating amyloid in Alzheimer's disease, but its optimal parameters are unknown. We found stronger entrainment at 32 and 40 Hz compared to 48 Hz, suggesting neural ensembles prefer to resonate around these relatively lower gamma-band frequencies. These findings may inform the development and refinement of innovative AD therapies and the study of GABAergic visual cortical functions.

The protective effect of biotin supplementation and swimming training on cognitive impairment and mental symptoms in a rat model of Alzheimer's disease: A behavioral, biochemical, and histological study

Vitamin B (Vit B) plays a regulatory role in cognitive memory and learning. We examined the biochemical and behavioral effects of biotin supplementation (BS) and swimming training (ST) on Alzheimer's disease (AD), the most common type of dementia, in male rats. Sixty rats were randomly assigned to six groups: control, sham (receiving phosphate-buffered saline), AD (receiving a single injection of Aβ into the lateral ventricle), ST (for 28 days and before Aβ injection), and BS (receiving BS through oral gavage for 28 days before Aβ injection). The treatments were continued until the end of the behavioral tests. Learning and memory functions were investigated through the Morris water maze (MWM) and depression and anxiety-like behaviors were tested by elevated plus-maze (EPM) and forced swimming tests. In addition, oxidative stress biomarkers, such as total thiol groups (TTG) and malondialdehyde (MDA) in serum were assessed and histological studies were performed using brain tissues. In the AD group, Aβ increased the distance traveled and escape latency in the MWM, but co-administration of BS and ST attenuated the results of the MWM, EPM, and FST tests. Furthermore, BS decreased the litigious biochemical effects of Aβ by enhancing the levels of TTG, in addition to reducing serum MDA levels. The use of BS as a potent antioxidant improved Aβ-induced memory impairment. It attenuated oxidative stress biomarkers in the brain (number of Aβ plaques) and serum of AD rats. We provide evidence for the use of BS in neurodegenerative disorders, such as AD, to elucidate the possible mechanisms.

Combined MR quantitative susceptibility mapping and multi-shell diffusion in Parkinson's disease

BACKGROUND AND PURPOSE

Quantitative susceptibility mapping (QSM), neurite orientation dispersion and density imaging (NODDI), and the g-ratio have separately shown differences between Parkinson's disease (PD) and healthy controls. The g-ratio has, however, not been studied in PD in the substantia nigra (SN) and the putamen. A combination of these methods could also potentially be a complementary imaging biomarker for PD. This study aimed to assess the diagnostic performance of QSM, NODDI, the g-ratio, and a combined QSM-NODDI imaging marker in the SN and putamen of PD patients.

METHODS

In this prospective study, the diagnostic performance of median region of interest values was compared in a cohort of 15 participants with PD and 14 healthy controls after manual segmentation. The diagnostic performance was assessed using the area under curve (AUC) for the receiving operator characteristic.

RESULTS

Median QSM in the contralateral SN identified PD with AUC 0.77, and median isotropic volume fraction identified PD in the ipsilateral SN with AUC 0.68. A combined NODDI-QSM marker improved diagnostic performance (AUC 0.80). No significant differences were found in the g-ratio.

CONCLUSION

A combination of median QSM and median isotropic volume fraction improves the differentiation of PD from healthy controls and is a potential biomarker in the diagnostics of PD. This confirms previously reported results indicating that combining QSM and NODDI modestly improves differentiation of PD.

The association between urinary sodium and the risk of dementia: Evidence from a population-based cohort study

BACKGROUND

Sodium intake reduction is crucial for cardiovascular health, however, its lasting impact on dementia remains unclear.

METHODS

We included 458,577 UK Biobank participants without dementia at baseline. We estimated 24-h urinary sodium (E24hUNa) using spot urinary parameters and obtained the incidence of all-cause dementia, Alzheimer's disease, and vascular dementia from multiple sources.

RESULTS

The mean E24hUNa was 3.0 g (1st-99th percentile: 1.5 g-5.1 g). Over a mean follow-up of 13.6 years, 7886 (1.7 %) participants developed all-cause dementia, including 3763 (0.8 %) Alzheimer's disease and 1851 (0.4 %) vascular dementia. In the restricted cubic spline model, we identify a potential cutoff of 3.13 g for E24hUNa, below which each 1 g decrease in E24hUNa was associated with 21 % (95 % confidence interval [CI] 1.11-1.34) higher all-cause dementia risk and 35 % (95 % CI 1.11-1.63) higher vascular dementia risk (P-value <0.001 for non-linearity). The hazard ratios were 1.15 (95 % CI, 1.07-1.24) for all-cause dementia and 1.21 (95 % CI 1.04-1.40) for vascular dementia among individuals with E24hUNa below 3.13 g compared to those with E24hUNa higher than 3.13 g.

LIMITATIONS

One of the major limitations is the estimation of 24-h urinary sodium with spot urine samples.

CONCLUSIONS

An E24hUNa level below 3.13 g, equivalent to 3.37 g daily sodium intake, is associated with increased risks of all-cause and vascular dementia. This exploratory study suggests a potential lower limit below which the risk of dementia increases with a lower sodium level. Future studies are necessary to validate our findings.

Human fibroblasts from sporadic Alzheimer's disease (AD) patients show mitochondrial alterations and lysosome dysfunction

Mitophagy is a mechanism that maintains mitochondrial integrity and homeostasis and is thought to promote longevity and reduce the risk of age-related neurodegenerative diseases, including Alzheimer's disease (AD). Here, we investigate the abundance of mitochondrial reactive oxygen species (ROS), mitochondrial function, and mitophagy in primary fibroblasts from patients with sporadic AD (sAD) and normal healthy controls. The results show increased levels of mitochondrial ROS, changes in mitochondrial morphology, altered bioenergetic properties, and defects in autophagy, mitophagy, and lysosome-mediated degradation pathways in sAD fibroblasts relative to control fibroblasts. Interestingly, lysosome abundance and the staining of lysosomal markers remained high, while the capacity of lysosome-dependent degradation was lower in sAD fibroblasts than in controls fibroblasts. Nicotinamide riboside supplementation decreased mitochondrial ROS, while capacity for lysosomal degradation remained unchanged in sAD fibroblasts relative to healthy control fibroblasts. These findings provide insight into molecular mechanisms involving the dysregulation of lysosome and autophagy/mitophagy pathways that may contribute significantly to clinical signs and pathological features of sAD.

The flavonoid fisetin reduces multiple physiological risk factors for dementia

Dementia is a growing problem around the globe as the world's population continues to age. Multiple studies have identified potentially modifiable risk factors for the development of dementia suggesting that addressing some or all of these risk factors might have a significant impact on the aging population worldwide. However, this is not always as straightforward as it seems since many of these risk factors are currently treated with drugs specific to the risk factor. Moreover, since people can have multiple risk factors, addressing each of them individually could be highly problematic as it would likely lead to negative outcomes associated with polypharmacy and, in the long term, could do significant harm. A potential alternative is to identify compounds that have shown efficacy against a number of these different risk factors. As discussed in this review, there is strong evidence that the flavonol fisetin is one such compound. In animal studies it has shown efficacy against many of the risk factors that have been associated with an increased risk of developing dementia and also exhibits direct neuroprotective effects. Thus, further human research on fisetin in the context of dementia risk factors is clearly warranted.

Natural products targeting amyloid-β oligomer neurotoxicity in Alzheimer's disease

Alzheimer's disease (AD) constitutes a major global health issue, characterized by progressive neurodegeneration and cognitive impairment, for which no curative treatment is currently available. Current therapeutic approaches are focused on symptom management, highlighting the critical need for disease-modifying therapy. The hallmark pathology of AD involves the aggregation and accumulation of amyloid-β (Aβ) peptides in the brain. Consequently, drug discovery efforts in recent decades have centered on the Aβ aggregation cascade, which includes the transition of monomeric Aβ peptides into toxic oligomers and, ultimately, mature fibrils. Historically, anti-Aβ strategies focused on the clearance of amyloid fibrils using monoclonal antibodies. However, substantial evidence has highlighted the critical role of Aβ oligomers (AβOs) in AD pathogenesis. Soluble AβOs are now recognized as more toxic than fibrils, directly contributing to synaptic impairment, neuronal damage, and the onset of AD. Targeting AβOs has emerged as a promising therapeutic approach to mitigate cognitive decline in AD. Natural products (NPs) have demonstrated promise against AβO neurotoxicity through various mechanisms, including preventing AβO formation, enhancing clearance mechanisms, or converting AβOs into non-toxic species. Understanding the mechanisms by which anti-AβO NPs operate is useful for developing disease-modifying treatments for AD. In this review, we explore the role of NPs in mitigating AβO neurotoxicity for AD drug discovery, summarizing key evidence from biophysical methods, cellular assays, and animal models. By discussing how NPs modulate AβO neurotoxicity across various experimental systems, we aim to provide valuable insights into novel therapeutic strategies targeting AβOs in AD.

An integrated approach to identifying sex-specific genes, transcription factors, and pathways relevant to Alzheimer's disease

BACKGROUND

Age represents a significant risk factor for the development of Alzheimer's disease (AD); however, recent research has documented an influencing role of sex in several features of AD. Understanding the impact of sex on specific molecular mechanisms associated with AD remains a critical challenge to creating tailored therapeutic interventions.

METHODS

The exploration of the sex-based differential impact on disease (SDID) in AD used a systematic review to first select transcriptomic studies of AD with data regarding sex in the period covering 2002 to 2021 with a focus on the primary brain regions affected by AD - the cortex (CT) and the hippocampus (HP). A differential expression analysis for each study and two tissue-specific meta-analyses were then performed. Focusing on the CT due to the presence of significant SDID-related alterations, a comprehensive functional characterization was conducted: protein-protein network interaction and over-representation analyses to explore biological processes and pathways and a VIPER analysis to estimate transcription factor activity.

RESULTS

We selected 8 CT and 5 HP studies from the Gene Expression Omnibus (GEO) repository for tissue-specific meta-analyses. We detected 389 significantly altered genes in the SDID comparison in the CT. Generally, female AD patients displayed more affected genes than males; we grouped said genes into six subsets according to their expression profile in female and male AD patients. Only subset I (repressed genes in female AD patients) displayed significant results during functional profiling. Female AD patients demonstrated more significant impairments in biological processes related to the regulation and organization of synapsis and pathways linked to neurotransmitters (glutamate and GABA) and protein folding, Aβ aggregation, and accumulation compared to male AD patients. These findings could partly explain why we observe more pronounced cognitive decline in female AD patients. Finally, we detected 23 transcription factors with different activation patterns according to sex, with some associated with AD for the first time. All results generated during this study are readily available through an open web resource Metafun-AD (https://bioinfo.cipf.es/metafun-ad/).

CONCLUSION

Our meta-analyses indicate the existence of differences in AD-related mechanisms in female and male patients. These sex-based differences will represent the basis for new hypotheses and could significantly impact precision medicine and improve diagnosis and clinical outcomes in AD patients.

New insights into the involvement of serotonin and BDNF-TrkB signalling in cannabidiol's antidepressant effect

Cannabidiol (CBD) is a phytocannabinoid devoid of psychostimulant properties and is currently under investigation as a potential antidepressant drug. However, the mechanisms underlying CBD's antidepressant effects are not yet well understood. CBD targets include a variety of receptors, enzymes, and transporters, with different binding-affinities. Neurochemical and pharmacological evidence indicates that both serotonin and BDNF-TrkB signalling in the prefrontal cortex are necessary for the antidepressant effects induced by CBD in animal models. Herein, we reviewed the current literature to dissect if these are independent mechanisms or if CBD-induced modulation of the serotonergic neurotransmission could mediate its neuroplastic effects through subsequent regulation of BDNF-TrkB signalling, thus culminating in rapid neuroplastic changes. It is hypothesized that: a) CBD interaction with serotonin receptors on neurons of the dorsal raphe nuclei and the resulting disinhibition of serotonergic neurons would promote rapid serotonin release in the PFC and hence its neuroplastic and antidepressant effects; b) CBD facilitates BDNF-TRKB signalling, especially in the PFC, which rapidly triggers neurochemical and neuroplastic effects. These hypotheses are discussed with perspectives for new drug development and clinical applications.

MAMs and Mitochondrial Quality Control: Overview and Their Role in Alzheimer's Disease

Alzheimer's disease (AD) represents the most widespread neurodegenerative disorder, distinguished by a gradual onset and slow progression, presenting a substantial challenge to global public health. The mitochondrial-associated membrane (MAMs) functions as a crucial center for signal transduction and material transport between mitochondria and the endoplasmic reticulum, playing a pivotal role in various pathological mechanisms of AD. The dysregulation of mitochondrial quality control systems is considered a fundamental factor in the development of AD, leading to mitochondrial dysfunction and subsequent neurodegenerative events. Recent studies have emphasized the role of MAMs in regulating mitochondrial quality control. This review will delve into the molecular mechanisms underlying the imbalance in mitochondrial quality control in AD and provide a comprehensive overview of the role of MAMs in regulating mitochondrial quality control.

The mediating role of systemic inflammation and moderating role of racialization in disparities in incident dementia

BACKGROUND

Exposure to systemic racism is linked to increased dementia burden. To assess systemic inflammation as a potential pathway linking exposure to racism and dementia disparities, we investigated the mediating role of C-reactive protein (CRP), a systemic inflammation marker, and the moderating role of the racialization process in incident dementia.

METHODS

In the US Health and Retirement Study (n = 6,908), serum CRP was measured at baseline (2006, 2008 waves). Incident dementia was classified by cognitive tests over a six-year follow-up. Self-reported racialized categories were a proxy for exposure to the racialization process. We decomposed racialized disparities in dementia incidence (non-Hispanic Black and/or Hispanic vs. non-Hispanic white) into 1) the mediated effect of CRP, 2) the moderated portion attributable to the interaction between racialized group membership and CRP, and 3) the controlled direct effect (other pathways through which racism operates).

RESULTS

The 6-year cumulative incidence of dementia is 12%. Among minoritized participants (i.e., non-Hispanic Black and/or Hispanic), high CRP levels ( ≥ 75th percentile or 4.73μg/mL) are associated with 1.26 (95%CI: 0.98, 1.62) times greater risk of incident dementia than low CRP ( < 4.73μg/mL). Decomposition analysis comparing minoritized versus non-Hispanic white participants shows that the mediating effect of CRP accounts for 3% (95% CI: 0%, 6%) of the racial disparity, while the interaction effect between minoritized group status and high CRP accounts for 14% (95% CI: 1%, 27%) of the disparity. Findings are robust to potential violations of causal mediation assumptions.

CONCLUSIONS

Minoritized group membership modifies the relationship between systemic inflammation and incident dementia.

Evaluating a model of best practice in primary care led post-diagnostic dementia care: feasibility and acceptability findings from the PriDem study

OBJECTIVES

To evaluate the feasibility and acceptability of a primary care-based intervention for improving post-diagnostic dementia care and support (PriDem), and implementation study procedures.

DESIGN

A non-randomised, mixed methods, feasibility study.

SETTING

Seven general practices from four primary care networks (PCNs) in the Northeast and Southeast of England.

PARTICIPANTS

We aimed to recruit 80 people with dementia (PWD) and 66 carers INTERVENTION: Clinical Dementia Leads delivered a 12-month intervention in participating PCNs, to develop care systems, build staff capacity and capability, and deliver tailored care and support to PWD and carers.

OUTCOMES

Recruitment and retention rates were measured. A mixed methods process evaluation evaluated feasibility and acceptability of the intervention and study procedures. Using electronic care records, researchers extracted service use data and undertook a dementia care plan audit, preintervention and postintervention, assessing feasibility of measuring the primary implementation outcome: adoption of personalised care planning by participating general practices. Participants completed quality of life, and service use measures at baseline, 4 and 9 months.

RESULTS

60 PWD (75% of recruitment target) and 51 carers (77% of recruitment target) were recruited from seven general practices across four PCNs. Retention rate at 9 months was 70.0% of PWD and 76.5% of carers. The recruitment approach showed potential for including under-represented groups within dementia. Despite implementation challenges, the intervention was feasible and acceptable, and showed early signs of sustainability. Study procedures were feasible and accessible, although researcher capacity was crucial. Participants needed time and support to engage with the study. Care plan audit procedures were feasible and acceptable.

CONCLUSIONS

The PriDem model is an acceptable and feasible intervention. A definitive study is warranted to fully inform dementia care policy and personalised dementia care planning guidance. Successful strategies to support inclusion of PWD and their carers in future research were developed.

TRIAL REGISTRATION NUMBER

ISRCTN11677384.

Optimizing the Implementation of a Lifestyle Dementia Prevention Intervention for Older Patients in an Academic Healthcare System

Background

Interventions that promote healthy lifestyles are critical for the prevention of Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD). However, knowledge of the best practices for implementing AD/ADRD prevention in healthcare settings remains limited.

Objective

We aimed to qualitatively identify barriers and facilitators to implementing a clinical trial of a novel lifestyle intervention (My Healthy Brain) in our medical center for older patients with subjective cognitive decline who are at-risk for AD/ADRD.

Methods

We conducted focus groups with 26 healthcare professionals (e.g., physicians, psychology, nursing) from 5 clinics that treat older patients (e.g., memory care, psychiatry). Our qualitative analysis integrated two implementation frameworks to systematically capture barriers and facilitators to AD/ADRD prevention (Consolidated Framework for Implementation Science Research) that impact implementation outcomes of acceptability, appropriateness, and feasibility (Proctor's framework).

Results

We found widespread support for an RCT of My Healthy Brain and AD/ADRD prevention. Participants identified barriers related to patients (stigma, technological skills), providers (dismissiveness of "worried well," doubting capacity for behavior change), clinics (limited time and resources), and the larger healthcare system (underemphasis on prevention). Implementation strategies guided by Expert Recommendations for Implementing Change (ERIC) included: developing tailored materials, training staff, obtaining buy-in from leadership, addressing stigmatized language and practices, identifying "champions," and integrating with workflows and resources.

Conclusions

The results will inform our recruitment, enrollment, and retention procedures to implement the first randomized clinical trial of My Healthy Brain. Our study provides a blueprint for addressing multi-level barriers to the implementation of AD/ADRD prevention for older patients in medical settings.

Ethnic differences in the effects of apolipoprotein E ɛ4 and vascular risk factors on accelerated brain aging

The frequency of the apolipoprotein E ɛ4 allele and vascular risk factors differs among ethnic groups. We aimed to assess the combined effects of apolipoprotein E ɛ4 and vascular risk factors on brain age in Korean and UK cognitively unimpaired populations. We also aimed to determine the differences in the combined effects between the two populations. We enrolled 2314 cognitively unimpaired individuals aged ≥45 years from Korea and 6942 cognitively unimpaired individuals from the UK, who were matched using propensity scores. Brain age was defined using the brain age index. The apolipoprotein E genotype (ɛ4 carriers, ɛ2 carriers and ɛ3/ɛ3 homozygotes) and vascular risk factors (age, hypertension and diabetes) were considered predictors. Apolipoprotein E ɛ4 carriers in the Korean (β = 0.511, P = 0.012) and UK (β = 0.302, P = 0.006) groups had higher brain age index values. The adverse effects of the apolipoprotein E genotype on brain age index values increased with age in the Korean group alone (ɛ2 carriers × age, β = 0.085, P = 0.009; ɛ4 carriers × age, β = 0.100, P < 0.001). The apolipoprotein E genotype, age and ethnicity showed a three-way interaction with the brain age index (ɛ2 carriers × age × ethnicity, β = 0.091, P = 0.022; ɛ4 carriers × age × ethnicity, β = 0.093, P = 0.003). The effects of apolipoprotein E on the brain age index values were more pronounced in individuals with hypertension in the Korean group alone (ɛ4 carriers × hypertension, β = 0.777, P = 0.038). The apolipoprotein E genotype, age and ethnicity showed a three-way interaction with the brain age index (ɛ4 carriers × hypertension × ethnicity, β=1.091, P = 0.014). We highlight the ethnic differences in the combined effects of the apolipoprotein E ɛ4 genotype and vascular risk factors on accelerated brain age. These findings emphasize the need for ethnicity-specific strategies to mitigate apolipoprotein E ɛ4-related brain aging in cognitively unimpaired individuals.

Association of triglyceride glucose-body mass index with Alzheimer's disease pathology, cognition and brain structure in non-demented people

The relationship between the triglyceride glucose-body mass index (TyG-BMI) index and Alzheimer's disease (AD) pathology, cognition, and brain structure remains unclear. This study aimed to investigate these associations, focusing on cerebrospinal fluid (CSF) biomarkers, cognitive measures, and brain imaging data. Eight hundred and fifty-five non-demented participants were included. Linear regression was used to explore associations between the TyG-BMI index and AD pathology, cognition, and brain structure. The association between the TyG-BMI index and AD risk was assessed using Kaplan-Meier and Cox proportional hazards models. Longitudinal relationships were assessed using linear mixed-effects models. Mediation analyses were conducted to examine AD pathology's potential mediating role between the TyG-BMI index and cognition as well as brain structure. In the linear regression analyses, higher TyG-BMI levels were associated with increased Aβ42 and decreased Tau, pTau, Tau/Aβ42, pTau/Aβ42, and pTau/Tau. Positive correlations were observed with mini-mental state examination (MMSE), memory (MEM), executive function (EF), and the volumes of the hippocampus, entorhinal cortex, and middle temporal regions, while negative correlations were found with Alzheimer's Disease Assessment Scale (ADAS). Longitudinally, the TyG-BMI index was inversely associated with ADAS, and positively with MMSE, MEM, EF, hippocampus, entorhinal, and middle temporal. High TyG-BMI levels were correlated with lower AD risk (HR 0.996 [0.994, 0.999]). Mediation analyses revealed AD pathology mediated the association between TyG-BMI index and cognition as well as brain structure. Additionally, the TyG-BMI index could mediate cognitive changes by influencing brain structure. The TyG-BMI index is associated with AD pathology, cognition, and brain structure.

Improved Accuracy of the Addenbrooke's Cognitive Examination-Revised in the Diagnosis of Mild Cognitive Impairment, Mild Dementia Due to Alzheimer's Disease and Behavioral Variant Frontotemporal Dementia Using Mokken Scale Analysis

Background

The Addenbrooke's Cognitive Examination-Revised (ACE-R) is an accessible cognitive tool that supports the early detection of mild cognitive impairment (MCI), Alzheimer's disease (AD), and behavioral variant frontotemporal dementia (bvFTD).

Objective

To investigate the diagnostic efficacy of the ACE-R in MCI, AD, and bvFTD through the identification of novel coefficients for differentiation between these diseases.

Methods

We assessed 387 individuals: 102 mild AD, 37 mild bvFTD, 87 with amnestic MCI patients, and 161 cognitively unimpaired controls. The Mokken scaling technique facilitated the extraction out of the 26 ACE-R items that exhibited a common latent trait, thereby generating the Mokken scales for the AD group and the MCI group. Subsequently, we performed logistic regression, integrating each Mokken scales with sociodemographic factors, to differentiate between AD and bvFTD, as well as between AD or MCI and control groups. Ultimately, the Receiver Operating Characteristic curve analysis was employed to assess the efficacy of the coefficient's discrimination.

Results

The AD-specific Mokken scale (AD-MokACE-R) versus bvFTD exhibited an Area Under the Curve (AUC) of 0.922 (88% sensitivity and specificity). The AD-MokACE-R versus controls achieved an AUC of 0.968 (93% sensitivity, 94% specificity). The MCI-specific scale (MCI-MokACE-R) versus controls demonstrated an AUC of 0.859 (78% sensitivity, 79% specificity).

Conclusions

The ACE-R's capacity is enhanced through statistical methods and demographic integration, allowing for accurate differentiation between AD and bvFTD, as well as between MCI and controls. This new method not only reinforces its clinical value in early diagnosis but also surpasses traditional approaches noted in prior studies.

Activation of the Neuronal Cell Cycle in Brains in Amnestic Mild Cognitive Impairment: Early Involvement in the Progression of Alzheimer's Disease

Activation of cell-cycle machinery in Alzheimer's disease (AD) brain was reported by Mark Smith and colleagues and by other researchers. Among other biochemical processes underlying this activation, the notion that AD brain, under the onslaught of oxidative and nitrosative damage leading to neuronal loss, neurons would attempt to replenish their numbers by entering the cell cycle. However, being post-mitotic, neurons entering the cell cycle would become trapped therein, ultimately leading to death of these neurons. Yang and co-workers and the Butterfield laboratory first reported that similar activation of the cell cycle was present in the brains of individuals with amnestic mild cognitive impairment (MCI), arguably the earliest clinical stage of AD, but who demonstrate normal activities of daily living and no dementia. Activation of the cell cycle in MCI brain is consonant with the concept that this process is an early aspect in the progression of AD. This brief review article discusses these findings and recognizes the contribution of Dr. Mark Smith to the investigation of cell-cycle activation in AD brain and other aspects of AD neuropathology.

Age-Related Hearing Loss, Cognitive Decline, and Social Interaction: Testing a Framework

PURPOSE

Aging increases risk for hearing loss, cognitive decline, and social isolation; however, the nature of their interconnection remains unclear. This study examined the interplay between age-related hearing loss, cognitive decline, and social isolation in adults by testing the ability to understand speech in background noise, a challenge frequently reported by many older adults.

METHOD

We analyzed data collected from 128 adults (20-79 years of age, Mage = 51 years) recruited as part of the Aging Brain Cohort at the University of South Carolina repository. The participants underwent testing for hearing, cognition, and social interaction, which included pure-tone audiometry, a words-in-noise (WIN) test, a hearing questionnaire (Speech, Spatial and Qualities of Hearing Scale [SSQ12]), a social questionnaire (Patient-Reported Outcomes Measurement Information System-57 Social), and the Montreal Cognitive Assessment. We used a single pure-tone average (PTA) threshold value and a single WIN threshold value for each participant because there were no differences on average between the left and right ears.

RESULTS

Poorer hearing was significantly associated with cognitive decline, through both PTA and WIN thresholds, with a stronger association observed for WIN threshold. Adults with poorer hearing also exhibited greater social isolation, as evidenced by their WIN threshold and SSQ12 score, although not through PTA. This connection was more pronounced with the WIN threshold than with the SSQ12 score. Cognition was not related to social isolation, suggesting that social isolation is affected more by the ability to understand words in noise than by cognition in a nondemented population.

CONCLUSIONS

Understanding speech in challenging auditory environments rather than mere threshold detection is strongly linked to social isolation and cognitive decline. Thus, inclusion of a word-recognition-in-noise test and a social isolation survey in clinical settings is warranted.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.26237060.

Myeloid ectopic viral integration site 2 accelerates the progression of Alzheimer's disease

Amyloid plaques, a major pathological hallmark of Alzheimer's disease (AD), are caused by an imbalance between the amyloidogenic and non-amyloidogenic pathways of amyloid precursor protein (APP). BACE1 cleavage of APP is the rate-limiting step for amyloid-β production and plaque formation in AD. Although the alteration of BACE1 expression in AD has been investigated, the underlying mechanisms remain unknown. In this study, we determined MEIS2 was notably elevated in AD models and AD patients. Alterations in the expression of MEIS2 can modulate the levels of BACE1. MEIS2 downregulation improved the learning and memory retention of AD mice and decreased the number of amyloid plaques. MEIS2 binds to the BACE1 promoter, positively regulates BACE1 expression, and accelerates APP amyloid degradation in vitro. Therefore, our findings suggest that MEIS2 might be a critical transcription factor in AD, since it regulates BACE1 expression and accelerates BACE1-mediated APP amyloidogenic cleavage. MEIS2 is a promising early intervention target for AD treatment.

Identifying the earliest-occurring clinically targetable precursors of late-onset Alzheimer's disease

Most cases of Alzheimer's disease (AD) are late-onset dementias (LOAD). However, research on AD is predominantly of early-onset disease (EOAD). The determinants of EOAD, gene variants of APP and presenilin proteins, are not the basic precursors of LOAD. Rather, multiple other genes and associated cellular processes underlie risk for LOAD. These determinants could be modified in individuals at risk for LOAD well before signs and symptoms appear. Studying brain cells produced from patient-derived induced-pluripotent-stem-cells (iPSC), in culture, will be instrumental in developing such interventions. This paper summarises evidence accrued from iPSC culture models identifying the earliest occurring clinically targetable determinants of LOAD. Results obtained and replicated, thus far, suggest that abnormalities of bioenergetics, lipid metabolism, digestive organelle function and inflammatory activity are primary processes underlying LOAD. The application of cell culture platforms will become increasingly important in research and also on LOAD detection, assessment, and treatment in the years ahead.

Genetic and multi-omic resources for Alzheimer disease and related dementia from the Knight Alzheimer Disease Research Center

The Knight-Alzheimer Disease Research Center (Knight-ADRC) at Washington University in St. Louis has pioneered and led worldwide seminal studies that have expanded our clinical, social, pathological, and molecular understanding of Alzheimer Disease. Over more than 40 years, research volunteers have been recruited to participate in cognitive, neuropsychologic, imaging, fluid biomarkers, genomic and multi-omic studies. Tissue and longitudinal data collected to foster, facilitate, and support research on dementia and aging. The Genetics and high throughput -omics core (GHTO) have collected of more than 26,000 biological samples from 6,625 Knight-ADRC participants. Samples available include longitudinal DNA, RNA, non-fasted plasma, cerebrospinal fluid pellets, and peripheral blood mononuclear cells. The GHTO has performed deep molecular profiling (genomic, transcriptomic, epigenomic, proteomic, and metabolomic) from large number of brain (n = 2,117), CSF (n = 2,012) and blood/plasma (n = 8,265) samples with the goal of identifying novel risk and protective variants, identify novel molecular biomarkers and causal and druggable targets. Overall, the resources available at GHTO support the increase of our understanding of Alzheimer Disease.

Specific Mode Electroacupuncture Stimulation Mediates the Delivery of NGF Across the Hippocampus Blood-Brain Barrier Through p65-VEGFA-TJs to Improve the Cognitive Function of MCAO/R Convalescent Rats

Cognitive impairment frequently presents as a prevalent consequence following stroke, imposing significant burdens on patients, families, and society. The objective of this study was to assess the effectiveness and underlying mechanism of nerve growth factor (NGF) in treating post-stroke cognitive dysfunction in rats with cerebral ischemia-reperfusion injury (MCAO/R) through delivery into the brain using specific mode electroacupuncture stimulation (SMES). From the 28th day after modeling, the rats were treated with NGF mediated by SMES, and the cognitive function of the rats was observed after treatment. Learning and memory ability were evaluated using behavioral tests. The impact of SMES on blood-brain barrier (BBB) permeability, the underlying mechanism of cognitive enhancement in rats with MCAO/R, including transmission electron microscopy, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and TUNEL staining. We reported that SMES demonstrates a safe and efficient ability to open the BBB during the cerebral ischemia repair phase, facilitating the delivery of NGF to the brain by the p65-VEGFA-TJs pathway.

Could Accelerated Long-Term Forgetting Be a Feature of the Higher Rate of Memory Complaints Associated with Subjective Cognitive Decline? An Exploratory Study

Background

Recently, subjective cognitive decline (SCD) was proposed as an early risk factor for future Alzheimer's disease (AD).

Objective

In this study, we investigated whether accelerated long-term forgetting (ALF), assessed with extended testing intervals than those adopted in clinical practice, might be a cognitive feature of SCD. Using an explorative MRI analysis of the SCD sample, we attempted to investigate the areas most likely involved in the ALF pattern.

Methods

We recruited 31 individuals with SCD from our memory clinic and subdivided them based on their rate of memory complaints into mild SCDs (n = 18) and severe SCDs (n = 13). A long-term forgetting procedure, involving the recall of verbal and visuo-spatial material at four testing delays (i.e., immediate, 30 min, 24 h, and 7 days post-encoding) was used to compare the two sub-groups of SCDs with a healthy control group (HC; n = 16).

Results

No significant between-group difference was found on the standard neuropsychological tests, nor in the immediate and 30 min recall of the experimental procedure. By contrast, on the verbal test severe SCDs forgot significantly more than HCs in the prolonged intervals (i.e., 24 h and 7 days), with the greatest decline between 30 min and 24 h. Finally, in the whole SCD sample, we found significant associations between functional connectivity values within some cortical networks involved in memory (default mode network, salience network, and fronto-parietal network) and verbal long-term measures.

Conclusions

Our preliminary findings suggest that long-term forgetting procedures could be a sensitive neuropsychological tool for detecting memory concerns in SCDs, contributing to early AD detection.

Synaptic Vesicle-Related Proteins and Ubiquilin 2 in Cortical Synaptosomes Mediate Cognitive Impairment in Vascular Dementia Rats

Synaptic dysfunction is considered the best neuropathological correlate of cognitive decline in vascular dementia (VaD). However, the alterations of synaptic proteins at the synaptosomal level in VaD remain unclear. In this study, a VaD model was established in male rats using bilateral common carotid artery occlusion (2VO). We performed a novel object recognition task to evaluate cognitive impairment. Immunohistochemistry was used to assess the expression of neuron-specific nuclear binding protein (NeuN). Brain synaptosomes were isolated and subjected to label-free proteomic analysis to quantify and identify the synaptic features of differentially expressed proteins (DEPs). Synaptic and hub protein expression was detected in synaptosomes using western blotting. We found that male rats with VaD presented impaired memory and decreased NeuN protein expression in the cortex. Synaptosome proteomic analysis revealed 604 DEPs, with 493 and 111 markedly downregulated and upregulated proteins, respectively. KEGG analysis and SynGO annotation revealed that the synaptic vesicle (SV) cycle may be a key signaling pathway in VaD. Hub protein analysis of the main nodes in the protein network identified UBQLN2 and SV-related proteins, including CLTC, SNAP91, AP2S1, CLTA, VAMP2, EPN1, UBQLN2, AP2B1, AP2A2, and AP2M1. Western blotting showed that the levels of SV2A, CLTC, AP2S1, and VAMP2 decreased in the synaptosomes of 2VO rats, while UBQLN2 expression significantly increased. Our results suggest that the disruption in the presynaptic SV cycle is a key event in male rats with VaD, which could be characterized by the aberrant SV2A expression. SV-related proteins and UBQLN2 may be essential in synaptopathy. Thus, targeting the specific molecular markers in synaptosomes may be critical for the development of mechanism-directed therapies against VaD.

Loneliness and Resting-State Functional Brain Connectivity Among Older Adults: A Proportional Correlation

OBJECTIVE

Loneliness reportedly increases the risk of dementia, especially Alzheimer's disease (AD). The authors' previous study demonstrated associations between loneliness and structural abnormalities observed in early-stage AD. The present study examined associations between the brain's functional characteristics and loneliness among older adults with concerns about cognitive decline.

METHODS

This single-center study included 43 participants (13 with amnestic mild cognitive impairment and 30 with normal cognition). Participants were assessed with the revised University of California Los Angeles (UCLA) Loneliness Scale and underwent resting-state functional MRI. Functional images were preprocessed with the CONN toolbox. The selected seeds were within brain regions reportedly associated with loneliness. One-sample general linear model analysis was performed to examine regressions of UCLA Loneliness Scale scores and functional connectivity between the seeds and regions of interest.

RESULTS

The revised UCLA Loneliness Scale scores were positively correlated with functional connectivity between the right hippocampus and left lateral parietal lobe and were negatively correlated with functional connectivity between the left amygdala and left frontal operculum and between the left amygdala and right supramarginal gyrus. Analyses were adjusted for age, sex, and education and scores on the Mini-Mental State Examination and Clinical Dementia Rating scale.

CONCLUSIONS

Loneliness was associated with abnormal function of the hippocampus, parts of the parietal lobe and frontal cortex, and the amygdala. These findings may suggest a possible correlation between loneliness and neurological changes associated with dementia.

Digital biomarkers for non-motor symptoms in Parkinson's disease: the state of the art

Digital biomarkers that remotely monitor symptoms have the potential to revolutionize outcome assessments in future disease-modifying trials in Parkinson's disease (PD), by allowing objective and recurrent measurement of symptoms and signs collected in the participant's own living environment. This biomarker field is developing rapidly for assessing the motor features of PD, but the non-motor domain lags behind. Here, we systematically review and assess digital biomarkers under development for measuring non-motor symptoms of PD. We also consider relevant developments outside the PD field. We focus on technological readiness level and evaluate whether the identified digital non-motor biomarkers have potential for measuring disease progression, covering the spectrum from prodromal to advanced disease stages. Furthermore, we provide perspectives for future deployment of these biomarkers in trials. We found that various wearables show high promise for measuring autonomic function, constipation and sleep characteristics, including REM sleep behavior disorder. Biomarkers for neuropsychiatric symptoms are less well-developed, but show increasing accuracy in non-PD populations. Most biomarkers have not been validated for specific use in PD, and their sensitivity to capture disease progression remains untested for prodromal PD where the need for digital progression biomarkers is greatest. External validation in real-world environments and large longitudinal cohorts remains necessary for integrating non-motor biomarkers into research, and ultimately also into daily clinical practice.

Midlife stress-related exhaustion and dementia incidence: a longitudinal study over 50 years in women

BACKGROUNDS

Cognitive problems are common symptoms among individuals with stress-related exhaustion. It is still unknown whether these individuals are at a higher risk of developing dementia later. This study aims to examine the relationship between midlife stress-related exhaustion and dementia incidence.

METHODS

A population sample of 777 women (aged 38, 46, 50 and 54 years) without dementia at baseline was followed over 50 years, from 1968 to 2019. Stress-related exhaustion was based on information from the psychiatric examination in 1968/69. Information on dementia incidence between 1968 and 2019 was obtained from neuropsychiatric examinations, key-informant interviews, and hospital registry. Dementia was diagnosed according to the DSM-III-R criteria. A subgroup of non-demented women (n = 284) was examined for cognitive functions by the Gottfries-Bråne-Steen scale 24 years after baseline.

RESULTS

Stress-related exhaustion in midlife was associated with higher risk for development of dementia before age 75 (Hazard ratio and 95% confidence interval: 2.95 and 1.35-6.44). The association remained after adjustment for age, major depression, and anxiety disorder. Mean age of dementia onset was younger for women with stress-related exhaustion than women without stress (mean ± SD, 76 ± 9 vs. 82 ± 8 . p = 0.009). Women with stress-related exhaustion in midlife still showed more cognitive impairments 24 years later compared with women without stress (Odds ratio and 95% confidence interval: 2.64 and 1.15-6.06).

CONCLUSIONS

We found that women with stress-related exhaustion in midlife were at a higher risk to develop dementia at relatively younger age. These women showed persistently lower cognitive functions over years even without dementia. Present study results need to be interpreted with caution due to small sample size and should be confirmed in future studies with larger sample size. Our study findings may imply the importance of long-term follow-up regarding cognitive function among individuals with stress-related exhaustion.

Reduced rapid eye movement sleep in late middle-aged and older apolipoprotein E ɛ4 allele carriers

STUDY OBJECTIVES

Apolipoprotein E ɛ4 (APOE4) is the strongest genetic risk factor for Alzheimer's disease (AD). In addition, APOE4 carriers may exhibit sleep disturbances, but conflicting results have been reported, such that there is no clear consensus regarding which aspects of sleep are impacted. Our objective was to compare objective sleep architecture between APOE4 carriers and non-carriers, and to investigate the modulating impact of age, sex, cognitive status, and obstructive sleep apnea (OSA).

METHODS

A total of 198 dementia-free participants aged >55 years old (mean age: 68.7 ± 8.08 years old, 40.91% women, 41 APOE4 carriers) were recruited in this cross-sectional study. They underwent polysomnography, APOE4 genotyping, and a neuropsychological evaluation. ANCOVAs assessed the effect of APOE4 status on sleep architecture, controlling for age, sex, cognitive status, and the apnea-hypopnea index. Interaction terms were added between APOE4 status and covariates.

RESULTS

Rapid eye movement (REM) sleep percentage (F = 9.95, p = .002, ηp2 = 0.049) and duration (F = 9.23, p = .003, ηp2 = 0.047) were lower in APOE4 carriers. The results were replicated in a subsample of 112 participants without moderate-to-severe OSA. There were no significant interactions between APOE4 status and age, sex, cognitive status, and OSA in the whole sample.

CONCLUSIONS

Our results show that APOE4 carriers exhibit lower REM sleep duration, including in cognitively unimpaired individuals, possibly resulting from early neurodegenerative processes in regions involved in REM sleep generation and maintenance.

Adjunctive clozapine with bright light mitigates cognitive deficits by synaptic plasticity and neurogenesis in sub-chronic MK-801 treated mice

Schizophrenia impacts about 1 % of the global population, with clozapine (CLZ) being a critical treatment for refractory cases despite its limitations in effectiveness and adverse effects. Therefore, the search for more effective treatments remains urgent. Light treatment (LT) recognized for enhancing cognition and mood, presents a promising complementary approach. This study investigated the effects of CLZ and LT on cognitive impairments in a sub-chronic MK-801 induced schizophrenia mouse model. Results showed that both CLZ and CLZ + LT treatment elevate cognitive performance of sub-chronic MK-801 treated mice in serial behavioral tests over two months. Histological analysis revealed increased dendritic spine density and branching, and synaptic repair in the hippocampus with CLZ and CLZ + LT interventions. Furthermore, both treatments increased brain-derived neurotrophic factor (BDNF) expression in the hippocampus, likely contributing to cognitive amelioration in MK-801 treated mice. Additionally, BrdU labeling revealed that CLZ + LT further enhances neurogenesis in the dentate gyrus (DG) and lateral ventricle (LV) of sub-chronic MK-801 treated mice. These findings may have implications for the development of noninvasive and adjunctive treatment strategies aimed at alleviating cognitive impairments and improving functional outcomes in individuals with schizophrenia.

The processing of verbal memories after traumatic brain injury

Objective: Memory dysfunction is a persistent cognitive symptom following traumatic brain injury (TBI), negatively impacting capacity for independent living and productivity. Traditional scoring of neuropsychological memory tests does not allow for differentiation of specific impairments of encoding, consolidation and/or retrieval, or the potential impact of strategy deficits. Method: The current study examined performance of 142 moderate-to-severe TBI participants and 68 demographically matched healthy controls on the Rey Auditory Verbal Learning Test (RAVLT) using Item Specific Data Analysis (ISDA) and strategy use analyses. Results: Results revealed significantly greater impairments in encoding, consolidation, and retrieval in TBI participants, compared to controls. Encoding deficits significantly explained the most variance in the long-delayed recall of TBI participants, followed by consolidation, and then retrieval. Participants with TBI showed a reduced ability to spontaneously apply strategies during learning, evident in decreased subjective clusters and increased word omissions, compared to controls. No difference was found between groups in passive learning strategy application, shown through serial clustering. Spontaneous strategy measures both uniquely accounted for variance in the encoding ability of TBI participants. Conclusions: These findings highlight the potential value in using ISDA and strategy use measures to assess RAVLT results to better characterize individual memory profiles and inform rehabilitative interventions.

Effect of imipramine on memory, adult neurogenesis, neuroinflammation, and mitochondrial biogenesis in a rat model of alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline and memory loss. Imipramine, a tricyclic antidepressant, has potent anti-inflammatory and antioxidant properties in the central nervous system. The aim of this study was to investigate the neuroprotective effects of imipramine on streptozotocin (STZ)-induced memory impairment. Male Wistar rats received an intracerebroventricular injection of STZ (3 mg/kg, 3 μl/ventricle) using the stereotaxic apparatus. The Morris water maze and passive avoidance tests were used to evaluate cognitive functions. 24 h after the STZ injection, imipramine was administered intraperitoneally at doses of 10 or 20 mg/kg for 14 consecutive days. The mRNA and protein levels of neurotrophic factors (BDNF and GDNF) and pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) were measured in the hippocampus using real-time PCR and ELISA techniques, respectively. In addition, real-time PCR was used to evaluate the mRNA levels of markers associated with neurogenesis (Nestin, DCX, and Ki67) and mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM). The results showed that imipramine, especially at a dose of 20 mg/kg, effectively improved STZ-induced memory impairment. This improvement was associated with an increase in neurogenesis and neurotrophic factors and a decrease in neuroinflammation and mitochondrial biogenesis dysfunction. Based on these results, imipramine appears to be a promising therapeutic option for improving cognitive functions in neurodegenerative diseases such as AD.

Disentangling the causal effects of education and participation bias on Alzheimer's disease using Mendelian Randomization

Introduction

People with university degrees have a lower incidence of Alzheimer's Disease (AD). However, the relationship between education and AD could be due to selection, collider, and ascertainment biases, such as lower familiarity with cognitive testing or the fact that those with degrees are more likely to participate in research. Here, we use two-sample Mendelian randomization (MR) to investigate the causal relationships between education, participation, and AD.

Method

We used genome-wide association study (GWAS) summary statistics for educational attainment, three different measures of participation, AD (clinically diagnosed AD), and AD/ADRD (clinical diagnosis and family history of AD and related dementias). Independent genome-wide significant single nucleotide polymorphisms (SNPs) were extracted from the exposure summary statistics and harmonized with the outcome SNPs. Fixed-effects inverse variance weighted meta-analysis was the primary MR method; Cochran's Q statistic and MR Egger intercept were used to test for heterogeneity and pleiotropy, and Radial-MR was used to identify outliers. Sensitivity analyses included MR Egger, Weighted Median, and Weighted mode. Bidirectional analyses were used to test if AD pathology affects participation and multivariable MR (MVMR) assessed independent exposure-outcome effects.

Results

Educational attainment reduced the risk of AD (OR IVW 95% CI= 0.70 [0.63, 0.79], p = 8e-10), and the results were robust based on sensitivity analyses. However, education increased the risk of AD/ADRD, though the results were not robust to sensitivity analyses (OR IVW 95% CI= 1.09 [1.02, 1.15], p = 0.006). Participation in MHQ reduced the odds of AD (OR IVW 95% CI= 0.325 [0.128, 0.326], p = 0.01). When adjusting for participation in MVMR, education remained associated with a reduced risk of AD (OR IVW 95% CI= 0.76 [0.62, 0.92], p = 0.006).

Conclusion

Univariate MR analyses indicated that education and participation reduced the risk of AD. However, MR also suggested that education increased the risk of AD/ADRD, highlighting the inconsistencies between clinical and proxy diagnoses of AD, as proxy-AD may be affected by selection, collider, or ascertainment bias. MVMR indicated that participation is unlikely to explain the effect of education on AD identified in MR, and the protective effect of educational attainment may be due to other biological mechanisms, such as cognitive reserve.

Gene-environment interactions within a precision environmental health framework

Understanding the complex interplay of genetic and environmental factors in disease etiology and the role of gene-environment interactions (GEIs) across human development stages is important. We review the state of GEI research, including challenges in measuring environmental factors and advantages of GEI analysis in understanding disease mechanisms. We discuss the evolution of GEI studies from candidate gene-environment studies to genome-wide interaction studies (GWISs) and the role of multi-omics in mediating GEI effects. We review advancements in GEI analysis methods and the importance of large-scale datasets. We also address the translation of GEI findings into precision environmental health (PEH), showcasing real-world applications in healthcare and disease prevention. Additionally, we highlight societal considerations in GEI research, including environmental justice, the return of results to participants, and data privacy. Overall, we underscore the significance of GEI for disease prediction and prevention and advocate for integrating the exposome into PEH omics studies.

Inconsistent Music-Based Intervention Reporting in Dementia Studies: A Systematic Mapping Review

Background

Recent research has shown beneficial results for music-based interventions (MBIs) for persons living with Alzheimer's disease and related dementias (AD/ADRD), but reports often lack sufficient detail about the MBI methodology, which reduces replicability. A detailed checklist for best practices in how to report MBIs was created in 2011 by Robb and colleagues to remedy the lack of detail in MBI descriptions. The implementation of the checklist specifically in AD/ADRD research has not been established. Given the complexity of music and the variety of uses for research and health, specific MBI descriptions are necessary for rigorous replication and validation of study results.

Objective

This systematic mapping review utilized the "Checklist for Reporting Music-Based Interventions" to evaluate the current state of MBI descriptive specificity in AD/ADRD research.

Methods

Research articles testing MBIs and reviews of MBI efficacy published between January 2015 and August 2023 were scored using the checklist and the results were summarized.

Results

Forty-eight studies were screened, and reporting was inconsistent across the 11 checklist criteria. Ten out of 48 studies fully reported more than 5 of the 11 criteria. Only one of the 11 scoring criteria was at least partially reported across 47 of 48 studies.

Conclusions

Thorough reporting of intervention detail for MBIs remains limited in AD/ADRD MBI research. This impedes study validation, replication, and slows the progress of research and potential application of music in practice. Greater implementation of the reporting guidelines provided by Robb and colleagues would move the field of MBI research for AD/ADRD forward more quickly and efficiently.

Subjective cognitive decline in healthy older adults is associated with altered processing of negative versus positive feedback in a probabilistic learning task

Older adults who worry about their own cognitive capabilities declining, but who do not show evidence of actual cognitive decline in neuropsychological tests, are at an increased risk of being diagnosed with dementia at a later time. Since neural markers may be more sensitive to early stages of cognitive decline, in the present study we examined whether event-related potential responses of feedback processing, elicited in a probabilistic learning task, differ between healthy older adults recruited from the community, who either did (subjective cognitive decline/SCD-group) or did not report (No-SCD group) worry about their own cognition declining beyond the normal age-related development. In the absence of group differences in learning from emotionally charged feedback in the probabilistic learning task, the amplitude of the feedback-related negativity (FRN) varied with feedback valence differently in the two groups: In the No-SCD group, the FRN was larger for positive than negative feedback, while in the SCD group, FRN amplitude did not differ between positive and negative feedback. The P3b was enhanced for negative feedback in both groups, and group differences in P3b amplitude were not significant. Altered sensitivity in neural processing of negative versus positive feedback may be a marker of SCD.

Psilocybin for the treatment of Alzheimer's disease

Alzheimer's disease (AD) stands as a formidable neurodegenerative ailment and a prominent contributor to dementia. The scarcity of available therapies for AD accentuates the exigency for innovative treatment modalities. Psilocybin, a psychoactive alkaloid intrinsic to hallucinogenic mushrooms, has garnered attention within the neuropsychiatric realm due to its established safety and efficacy in treating depression. Nonetheless, its potential as a therapeutic avenue for AD remains largely uncharted. This comprehensive review endeavors to encapsulate the pharmacological effects of psilocybin while elucidating the existing evidence concerning its potential mechanisms contributing to a positive impact on AD. Specifically, the active metabolite of psilocybin, psilocin, elicits its effects through the modulation of the 5-hydroxytryptamine 2A receptor (5-HT2A receptor). This modulation causes heightened neural plasticity, diminished inflammation, and improvements in cognitive functions such as creativity, cognitive flexibility, and emotional facial recognition. Noteworthy is psilocybin's promising role in mitigating anxiety and depression symptoms in AD patients. Acknowledging the attendant adverse reactions, we proffer strategies aimed at tempering or mitigating its hallucinogenic effects. Moreover, we broach the ethical and legal dimensions inherent in psilocybin's exploration for AD treatment. By traversing these avenues, We propose therapeutic potential of psilocybin in the nuanced management of Alzheimer's disease.

Multiplex cerebrospinal fluid proteomics identifies biomarkers for diagnosis and prediction of Alzheimer's disease

Recent expansion of proteomic coverage opens unparalleled avenues to unveil new biomarkers of Alzheimer's disease (AD). Among 6,361 cerebrospinal fluid (CSF) proteins analysed from the ADNI database, YWHAG performed best in diagnosing both biologically (AUC = 0.969) and clinically (AUC = 0.857) defined AD. Four- (YWHAG, SMOC1, PIGR and TMOD2) and five- (ACHE, YWHAG, PCSK1, MMP10 and IRF1) protein panels greatly improved the accuracy to 0.987 and 0.975, respectively. Their superior performance was validated in an independent external cohort and in discriminating autopsy-confirmed AD versus non-AD, rivalling even canonical CSF ATN biomarkers. Moreover, they effectively predicted the clinical progression to AD dementia and were strongly associated with AD core biomarkers and cognitive decline. Synaptic, neurogenic and infectious pathways were enriched in distinct AD stages. Mendelian randomization did not support the significant genetic link between CSF proteins and AD. Our findings revealed promising high-performance biomarkers for AD diagnosis and prediction, with implications for clinical trials targeting different pathomechanisms.

Continuous β-Amyloid CSF/PET Imbalance Model to Capture Alzheimer Disease Heterogeneity

BACKGROUND AND OBJECTIVES

Discordance between CSF and PET biomarkers of β-amyloid (Aβ) might reflect an imbalance between soluble and aggregated species, possibly reflecting disease heterogeneity. Previous studies generally used binary cutoffs to assess discrepancies in CSF/PET biomarkers, resulting in a loss of information on the extent of discordance. In this study, we (1) jointly modeled Aβ-CSF/PET data to derive a continuous measure of the imbalance between soluble and fibrillar pools of Aβ, (2) investigated factors contributing to this imbalance, and (3) examined associations with cognitive trajectories.

METHODS

Across 822 cognitively unimpaired (n = 261) and cognitively impaired (n = 561) Alzheimer's Disease Neuroimaging Initiative individuals (384 [46.7%] females, mean age 73.0 ± 7.4 years), we fitted baseline CSF-Aβ42 and global Aβ-PET to a hyperbolic regression model, deriving a participant-specific Aβ-aggregation score (standardized residuals); negative values represent more soluble relative to aggregated Aβ and positive values more aggregated relative to soluble Aβ. Using linear models, we investigated whether methodological factors, demographics, CSF biomarkers, and vascular burden contributed to Aβ-aggregation scores. With linear mixed models, we assessed whether Aβ-aggregation scores were predictive of cognitive functioning. Analyses were repeated in an early independent validation cohort of 383 Amyloid Imaging to Prevent Alzheimer's Disease Prognostic and Natural History Study individuals (224 [58.5%] females, mean age 65.2 ± 6.9 years).

RESULTS

The imbalance model could be fit (pseudo-R2 = 0.94) in both cohorts, across CSF kits and PET tracers. Although no associations were observed with the main methodological factors, lower Aβ-aggregation scores were associated with larger ventricular volume (β = 0.13, p < 0.001), male sex (β = -0.18, p = 0.019), and homozygous APOE-ε4 carriership (β = -0.56, p < 0.001), whereas higher scores were associated with increased uncorrected CSF p-tau (β = 0.17, p < 0.001) and t-tau (β = 0.16, p < 0.001), better baseline executive functioning (β = 0.12, p < 0.001), and slower global cognitive decline (β = 0.14, p = 0.006). In the validation cohort, we replicated the associations with APOE-ε4, CSF t-tau, and, although modestly, with cognition.

DISCUSSION

We propose a novel continuous model of Aβ CSF/PET biomarker imbalance, accurately describing heterogeneity in soluble vs aggregated Aβ pools in 2 independent cohorts across the full Aβ continuum. Aβ-aggregation scores were consistently associated with genetic and AD-associated CSF biomarkers, possibly reflecting disease heterogeneity beyond methodological influences.

Prevalence and Impact of Bypassing or Overriding Phase 2 Trials in Neurologic Drug Development

BACKGROUND AND OBJECTIVES

Pivotal trials for neurologic drugs in clinical development are often initiated without a phase 2 trial ("bypass") or despite a negative phase 2 efficacy result ("override"). Such practices may degrade the risk/benefit ratio of phase 3 trials. The aim of this study is to estimate the proportion of phase 3 trials for 10 neurologic diseases started without a positive phase 2 trial, to identify factors associated with this practice, and to investigate any association with unfavorable phase 3 trial outcomes.

METHODS

We searched ClinicalTrials.gov for phase 3 trials completed during 2011-2021, with at least 1 research site in the United States, Canada, the European Union, the United Kingdom, or Australia, and investigating drugs or biologics for treatment of 10 neurologic conditions. Our primary objective was to assess the prevalence of phase 2 bypass/override by searching for preceding phase 2 trials. We used Fisher exact tests to determine whether phase 3 trial characteristics and trial results were associated with phase 2 bypass/override.

RESULTS

Of the 1,188 phase 3 trials captured in our search, 113 met eligibility for inclusion. Of these, 46% were not preceded by a phase 2 trial that was positive on an efficacy endpoint (31% bypassed and 15% overrode phase 2 trial). Phase 2 bypass/override was not associated with industry funding (77% vs 89%, 95% CI 0.75-7.55, p = 0.13) or testing already approved interventions (23% vs 15%, 95% CI 0.60-5.14, p = 0.33). Overall, phase 3 trials based on phase 2 bypassed/override were statistically significantly less likely to be positive on their primary outcome (31% vs 57%, respectively, 95% CI 1.21-6.92, p = 0.01). This effect disappeared when indications characterized by nearly universal positive or negative results were excluded. Trials that bypassed/overrode phase 2 trials were not statistically significantly more likely to be terminated early because of safety or futility (29% vs 15%, respectively, 95% CI 0.15-1.18, p = 0.11) and did not show increased risk of adverse events in experimental arms (RR = 1.46, 95% CI 1.19-1.79, vs RR = 1.36, 95% CI 1.10-1.69, respectively, p = 0.65).

DISCUSSION

Almost half of the neurologic disease phase 3 trials were initiated without the support of a positive phase 2 trial. Although our analysis does not establish harm with bypass/override, its prevalence and the scientific rationale for phase 2 trial testing favor development of criteria defining when phase 2 bypass/override is justified.