The latest medical research on Alzheimers

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about alzheimers gathered by our medical AI research bot.

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Poloxamer-188 Exacerbates Brain Amyloidosis, Presynaptic Dystrophies, and Pathogenic Microglial Activation in 5XFAD Mice.

Current Alzheimer Research

Alzheimer's disease (AD) is initiated by aberrant accumulation of amyloid beta (Aβ) protein in the brain parenchyma. The microenvironment surrounding amyloid plaques is characterized by the swelling of presynaptic terminals (dystrophic neurites) associated with lysosomal dysfunction, microtubule disruption and impaired axonal transport. Aβ-induced plasma membrane damage and calcium influx could be potential mechanisms underlying dystrophic neurite formation.

We tested whether promoting membrane integrity by brain administration of a safe FDA approved surfactant molecule poloxamer-188 (P188) could attenuate AD pathology in vivo.

Three-month-old 5XFAD male mice were administered several concentrations of P188 in the brain for 42 days with mini-osmotic pumps. After 42 days, mice were euthanized and assessed for amyloid pathology, dystrophic neurites, pathogenic microglia activation, tau phosphorylation and lysosomal / vesicular trafficking markers in the brain.

P188 was lethal at the highest concentration of 10mM. Lower concentrations of P188 (1.2, 12 and 120μM) were well tolerated. P188 increased brain Aβ burden, potentially through activation of the γ-secretase pathway. Dystrophic neurite pathology was exacerbated in P188 treated mice as indicated by increased LAMP1 accumulation around Aβ deposits. Pathogenic microglial activation was increased by P188. Total tau levels were decreased by P188. Lysosomal enzyme cathepsin D and calcium-dependent vesicular trafficking regulator synaptotagmin-7 (SYT7) were dysregulated upon P188 administration.

P188 brain delivery exacerbated amyloid pathology, dystrophic neurites and pathogenic microglial activation in 5XFAD mice. These effects correlated with lysosomal dysfunction and dysregulation of plasma membrane vesicular trafficking. P188 is not a promising therapeutic strategy against AD pathogenesis.

Tele-Mindfulness for Dementia's Family Caregivers: a Randomized Trial with a Usual Care Control Group.

Current Alzheimer Research

Caring for a family member with dementia is stressful and challenging. Family caregivers, as a vulnerable marginalized population and invisible backbone of the health care system, need accessible and effective interventions that are tailored to their particular needs.

To evaluate the feasibility and effectiveness of a live online mindfulness-based cognitive therapy (tele-MBCT) intervention for family caregivers of individuals with dementia.

Family caregivers were assigned to a tele-MBCT intervention or a usual care control group. Tele-MBCT participants attended eight weekly live online training and practiced mindfulness practices at home. All participants completed surveys at baseline, post-intervention, and 4-week follow-up.

26 participants (age 60±13 years) were enrolled and randomized (14 into the intervention and 12 into the control group), and 92.3% completed the study. 88% of the participants were female, and 70% were caring for a parent for the mean of 5.12±2.88 years. 84% of the participants in the intervention group attended at least seven sessions and the average of daily practice was 23.58±45.71 minutes. All participants were satisfied with the intervention, and 88.8% were satisfied with the online delivery method. Participants in the intervention group showed Pre-Post improvement in self-compassion (t (11) = -2.49, p=0.03) and coping strategies (t (11) = 3.62, p=0.004) compared to the control group.

Tele-MBCT is a feasible intervention and may improve psychological outcomes and adaptive coping in family caregivers of individuals with dementia. A larger controlled trial is warranted.

Verbal fluency response times predict incident cognitive impairment.

Alzheimers Dementia Amsterdam

In recent decades, researchers have defined novel methods for scoring verbal fluency tasks. In this work, we evaluate novel scores based on speed of word responses.

We transcribed verbal fluency recordings from 641 cases of incident cognitive impairment (ICI) and matched controls, all participants in a large national epidemiological study. Timing measurements of utterances were used to calculate a speed score for each recording. Traditional raw and speed scores were entered into Cox proportional hazards (CPH) regression models predicting time to ICI.

Concordance of the CPH model with speed scores was 0.599, an improvement of 3.4% over a model with only raw scores and demographics. Scores with significant effects included animals raw and speed scores, and letter F speed score.

Novel verbal fluency scores based on response times could enable use of remotely administered fluency tasks for early detection of cognitive decline.

 The current work evaluates prognostication with verbal fluency speed scores. These speed scores improve survival models predicting cognitive decline. Cases with progressive decline have some characteristics suggestive of Alzheimer's disease. The subset of acute decliners is probably pathologically heterogeneous.

Effects of age, amyloid, sex, and APOE ε4 on the CSF proteome in normal cognition.

Alzheimers Dementia Amsterdam

It is important to understand which biological processes change with aging, and how such changes are associated with increased Alzheimer's disease (AD) risk. We studied how cerebrospinal fluid (CSF) proteomics changed with age and tested if associations depended on amyloid status, sex, and apolipoprotein E Ɛ4 genotype.

We included 277 cognitively intact individuals aged 46 to 89 years from Alzheimer's Disease Neuroimaging Initiative, European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery, and Metabolic Syndrome in Men. In total, 1149 proteins were measured with liquid chromatography mass spectrometry with multiple reaction monitoring/Rules-Based Medicine, tandem mass tag mass spectrometry, and SOMAscan. We tested associations between age and protein levels in linear models and tested enrichment for Reactome pathways.

Levels of 252 proteins increased with age independently of amyloid status. These proteins were associated with immune and signaling processes. Levels of 21 proteins decreased with older age exclusively in amyloid abnormal participants and these were enriched for extracellular matrix organization.

We found amyloid-independent and -dependent CSF proteome changes with older age, perhaps representing physiological aging and early AD pathology.

Data-Driven Analyses of Longitudinal Hippocampal Imaging Trajectories: Discrimination and Biomarker Prediction of Change Classes.

Journal of Alzheimer's Disease

Hippocampal atrophy is a well-known biomarker of neurodegeneration, such as that observed in Alzheimer's disease (AD). Although distributions of hippocampal volume trajectories for asymptomatic individuals often reveal substantial heterogeneity, it is unclear whether interpretable trajectory classes can be objectively detected and used for prediction analyses.

To detect and predict hippocampal trajectory classes in a computationally competitive context using established AD-related risk factors/biomarkers.

We used biomarker/risk factor and longitudinal MRI data in asymptomatic adults from the AD Neuroimaging Initiative (n = 351; Mean = 75 years; 48.7% female). First, we applied latent class growth analyses to left (LHC) and right (RHC) hippocampal trajectory distributions to identify distinct classes. Second, using random forest analyses, we tested 38 multi-modal biomarkers/risk factors for their relative importance in discriminating the lower (potentially elevated atrophy risk) from the higher (potentially reduced risk) class.

For both LHC and RHC trajectory distribution analyses, we observed three distinct trajectory classes. Three biomarkers/risk factors predicted membership in LHC and RHC lower classes: male sex, higher education, and lower plasma Aβ1-42. Four additional factors selectively predicted membership in the lower LHC class: lower plasma tau and Aβ1-40, higher depressive symptomology, and lower body mass index.

Data-driven analyses of LHC and RHC trajectories detected three classes underlying the heterogeneous distributions. Machine learning analyses determined three common and four unique biomarkers/risk factors discriminating the higher and lower LHC/RHC classes. Our sequential analytic approach produced evidence that the dynamics of preclinical hippocampal trajectories can be predicted by AD-related biomarkers/risk factors from multiple modalities.

Aberrant Cross-Tissue Functional Connectivity in Alzheimer's Disease: Static, Dynamic, and Directional Properties.

Journal of Alzheimer's Disease

BOLD signals in the gray matter (GM) and white matter (WM) are tightly coupled. However, our understanding of the cross-tissue functional network in Alzheimer's disease (AD) is limited.

We investigated the changes of cross-tissue functional connectivity (FC) metrics for the GM regions susceptible to AD damage.

For each GM region in the default mode (DMN) and limbic networks, we obtained its low-order static FC with any WM region, and the high-order static FC between any two WM regions based on their FC pattern similarity with multiple GM regions. The dynamic and directional properties of cross-tissue FC were then acquired, specifically for the regional pairs whose low- or high-order static FCs showed significant differences between AD and normal control (NC). Moreover, these cross-tissue FC metrics were correlated with voxel-based GM volumes and MMSE in all participants.

Compared to NC, AD patients showed decreased low-order static FCs between the intra-hemispheric GM-WM pairs (right ITG-right fornix; left MoFG-left posterior corona radiata), and increased low-order static, dynamic, and directional FCs between the inter-hemispheric GM-WM pairs (right MTG-left superior/posterior corona radiata). The high-order static and directional FCs between the left cingulate bundle-left tapetum were increased in AD, based on their FCs with the GMs of DMN. Those decreased and increased cross-tissue FC metrics in AD had opposite correlations with memory-related GM volumes and MMSE (positive for the decreased and negative for the increased).

Cross-tissue FC metrics showed opposite changes in AD, possibly as useful neuroimaging biomarkers to reflect neurodegenerative and compensatory mechanisms.

Nocturnal Hypoxia and Sleep Fragmentation May Drive Neurodegenerative Processes: The Compared Effects of Obstructive Sleep Apnea Syndrome and Periodic Limb Movement Disorder on Alzheimer's Disease Biomarkers.

Journal of Alzheimer's Disease

Sleep disorders may cause dysregulation of cerebral glucose metabolism and synaptic functions, as well as alterations in cerebrospinal fluid (CSF) biomarker levels.

This study aimed at measuring sleep, CSF Alzheimer's disease (AD) biomarkers, and cerebral glucose consumption in patients with obstructive sleep apnea syndrome (OSAS) and patients with periodic limb movement disorder (PLMD), compared to controls.

OSAS and PLMD patients underwent 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET), polysomnographic monitoring, and lumbar puncture to quantify CSF levels of amyloid-β42 (Aβ42), total tau, and phosphorylated tau. All patients were compared to controls, who were not affected by sleep or neurodegenerative disorders.

Twenty OSAS patients, 12 PLMD patients, and 15 controls were included. Sleep quality and sleep structure were altered in both OSAS and PLMD patients when compared to controls. OSAS and PLMD patients showed lower CSF Aβ42 levels than controls. OSAS patients showed a significant increase in glucose uptake in a wide cluster of temporal-frontal areas and cerebellum, as well as a reduced glucose consumption in temporal-parietal regions compared to controls. PLMD patients showed increased brain glucose consumption in the left parahippocampal gyrus and left caudate than controls.

Sleep dysregulation and nocturnal hypoxia present in OSAS patients, more than sleep fragmentation in PLMD patients, were associated with the alteration in CSF and 18F-FDG PET AD biomarkers, namely reduction of CSF Aβ42 levels and cerebral glucose metabolism dysregulation mainly in temporal areas, thus highlighting the possible role of sleep disorders in driving neurodegenerative processes typical of AD pathology.

Cattle Encephalon Glycoside and Ignotin Ameliorate Palmitoylation of PSD-95 and Enhance Expression of Synaptic Proteins in the Frontal Cortex of a APPswe/PS1dE9 Mouse Model of Alzheimer's Disease.

Journal of Alzheimer's Disease

Synaptic abnormalities in synaptic proteins are the initial hallmarks of Alzheimer's disease (AD). The higher level of palmitoylation of synaptic proteins was closely associated with amyloid-β (Aβ) in AD. Cattle encephalon glycoside and ignotin (CEGI) have been shown to act as multitarget neurotrophic agents in APPswe/PS1dE9 (APP/PS1) transgenic AD mice. However, it is not clear whether CEGI can influence Aβ deposition or whether it does so by the regulation of protein palmitoylation and expression of synaptic proteins in transgenic AD mice.

In this study, we investigated the roles of CEGI in modulating postsynaptic density protein 95 (PSD-95) palmitoylation, Aβ pathologies, and expression of synaptic-associated proteins in APP/PS1 mice.

Five-month-old APP/PS1 mice were treated intraperitoneally with 6.6 mL/kg of CEGI for 6 weeks. At the end of the treatment period, APP/PS1 mice were subjected to Morris water maze to test their cognitive functions. Acyl-biotinyl exchange (ABE) for PSD-95 palmitoylation, immunofluorescent staining for expression of PSD-95, N-methyl-D-aspartic acid receptor subunit 2B (NR2B), and synaptotagmin 1 (SYT1) were assessed in mouse brain sections.

CEGI treatment in APP/PS1 mice significantly reduced Aβ deposition, relieved memory deficits, and decreased PSD-95 palmitoylation while markedly increasing the expression of PSD-95, NR2B, and SYT1 in the frontal cortex. There was a significant correlation between Aβ expression and PSD-95 palmitoylation in APP/PS1 mice.

Our findings demonstrate that CEGI improved AD-like neuropathology, possibly by inhibiting PSD-95 palmitoylation, improving learning memory, and enhancing expression of synaptic-associated proteins, representing a potential therapy for AD treatment.

Gut Microbiota and Subjective Memory Complaints in Older Women.

Journal of Alzheimer's Disease

Epidemiological studies that investigate alterations in gut microbial composition associated with cognitive dysfunction are limited.

To examine the association between the gut microbiota and subjective memory complaints (SMCs), a self-reported, validated indicator of cognitive dysfunction.

In this cross-sectional study of 95 older women selected from the New York University Women's Health Study (NYUWHS), we characterized the gut microbial composition using 16S rRNA gene sequencing. We estimated odds ratio (OR) from beta regression which approximates the ratio of mean relative abundances of individual bacterial taxon from phylum to genus levels by binary (2+ versus < 2) and continuous SMCs.

Women reporting 2 or more SMCs had higher relative abundances of genus Holdemania and family Desulfovibrionaceae compared with those reporting one or no complaint. Compared with women with < 2 SMCs, the relative abundances of Holdemania and family Desulfovibrionaceae were 2.09 times (OR: 2.09, 95% confidence interval [CI]: 1.38-3.17) and 2.10 times (OR: 2.10, 95% CI: 1.43-3.09) higher in women with 2+ SMCs, respectively (false discovery rate (FDR)-adjusted p = 0.038 and 0.010, respectively). A dose-response association was observed for genus Sutterella and family Desulfovibrionaceae. Every one-unit increase in SMCs was associated with 25% and 27% higher relative abundances of Sutterella (OR: 1.25; 95% CI: 1.11-1.40) and Desulfovibrionaceae (OR: 1.27; 95% CI: 1.13-1.42), respectively (FDR-adjusted p = 0.018 and 0.006, respectively).

Our findings support an association between alterations in the gut bacterial composition and cognitive dysfunction.

Migraine, Cognitive Decline, and Dementia in Older Adults: A Population-Based Study.

Journal of Alzheimer's Disease

The potential impact of migraine on cognitive aging among older adults remains controversial.

To examine the relationship of migraine and subtypes with cognitive decline and dementia in an older Swedish population.

This population-based study included 3069 participants (age≥60) from the Swedish National study on Aging and Care in Kungsholmen, Stockholm. Baseline examination was conducted in 2001-2004, and participants were followed every 3 or 6 years until 2013-2016. Data were collected through face-to-face interviews, clinical examinations, laboratory tests, and linkage with registers. Global cognitive function was measured with the Mini-Mental State Examination (MMSE). Dementia was diagnosed according to the DSM-IV criteria. Migraine and subtypes were defined following the international classification system. Data were analyzed using logistic regression, Cox regression, and linear mixed-effects models.

At baseline, 305 participants were defined with non-migraine headache and 352 with migraine. The cross-sectional analysis showed that the multivariable-adjusted odds ratio (95% confidence interval) of prevalent dementia was 0.49 (0.20-1.21) for migraine and 0.66 (0.26-1.66) for migraine without aura. The longitudinal analysis showed that the multivariable-adjusted hazard ratios of incident dementia associated with migraine and subtypes ranged 0.68-0.89 (p > 0.05). Furthermore, migraine and subtypes were not significantly associated with either baseline MMSE score or MMSE changes during follow-ups (p > 0.05). The nonsignificant associations did not vary substantially by age, APOEɛ4 allele, cerebrovascular disease, and antimigraine treatment (p for interactions > 0.05).

This study shows no evidence supporting the associations of migraine and its subtypes with cognitive decline and dementia among older adults.

DNA Damage Increases Secreted Aβ40 and Aβ42 in Neuronal Progenitor Cells: Relevance to Alzheimer's Disease.

Journal of Alzheimer's Disease

Recent studies suggest a strong association between neuronal DNA damage, elevated levels of amyloid-β (Aβ), and regions of the brain that degenerate in Alzheimer's disease (AD).

To investigate the nature of this association, we tested the hypothesis that extensive DNA damage leads to an increase in Aβ40 and Aβ42 generation.

We utilized an immortalized human neuronal progenitor cell line (NPCs), ReN VM GA2. NPCs or 20 day differentiated neurons were treated with hydrogen peroxide or etoposide and allowed to recover for designated times. Sandwich ELISA was used to assess secreted Aβ40 and Aβ42. Western blotting, immunostaining, and neutral comet assay were used to evaluate the DNA damage response and processes indicative of AD pathology.

We determined that global hydrogen peroxide damage results in increased cellular Aβ40 and Aβ42 secretion 24 h after treatment in ReN GA2 NPCs. Similarly, DNA double strand break (DSB)-specific etoposide damage leads to increased Aβ40 and Aβ42 secretion 2 h and 4 h after treatment in ReN GA2 NPCs. In contrast, etoposide damage does not increase Aβ40 and Aβ42 secretion in post-mitotic ReN GA2 neurons.

These findings provide evidence that in our model, DNA damage is associated with an increase in Aβ secretion in neuronal progenitors, which may contribute to the early stages of neuronal pathology in AD.

Ethnic-Specific Type 2 Diabetes Risk Factor PAX4 R192H Is Associated with Attention-Specific Cognitive Impairment in Chinese with Type 2 Diabetes.

Journal of Alzheimer's Disease

Type 2 diabetes mellitus (T2DM) has been shown to increase the risks of cognitive decline and dementia. Paired box gene 4 (PAX4), a transcription factor for beta cell development and function, has recently been implicated in pathways intersecting Alzheimer's disease and T2DM.

In this report, we evaluated the association of the ethnic-specific PAX4 R192H variant, a T2DM risk factor for East Asians which contributes to earlier diabetes onset, and cognitive function of Chinese T2DM patients.

590 Chinese patients aged 45-86 from the SMART2D study were genotyped for PAX4 R192H variation using Illumina OmniExpress-24 Array. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) which had been validated in the Singapore population was administered to assess five cognitive domains: immediate memory, visuospatial/constructional, language, attention, and delayed memory. Multiple linear regression was used to assess the association of the R192H risk allele and cognitive domains.

Patients with two PAX4 R192H risk alleles showed significantly lower attention index score (β= -8.46, 95% CI [-13.71, -3.21], p = 0.002) than patients with wild-type alleles after adjusting for age, gender, diabetes onset age, HbA1c, body-mass index, renal function, lipid profiles, systolic blood pressure, metformin usage, smoking history, education level, Geriatric Depression Scale score, and presence of APOEɛ4 allele.

Ethnic-specific R192H variation in PAX4 is associated with attention-specific cognitive impairment in Chinese with T2DM. Pending further validation studies, determining PAX4 R192H genotype may be helpful for early risk assessment of early-onset T2DM and cognitive impairment to improve diabetes care.