Differential Gene Expression in Pain-Related Genes are not Affected by the Presence of Dementia

BACKGROUND

Prior work has demonstrated differences in the transcriptome between those with and without chronic musculoskeletal pain.

AIMS

The aim of this study was to explore whether pain-related gene expression is similar between individuals with and without dementia.

DESIGN

This was a descriptive study using a one-time assessment.

SETTINGS

PARTICIPANTS/SUBJECTS: A total of 20 older adults living in a continuing care retirement community, 50% of whom had dementia were inlcuded in this study. All were female and the mean age of participants was 89 (SD = 6).

METHODS

Pain was evaluated based on the PROMIS Pain Intensity Short Form 3a. Whole blood was collected by venipuncture into Tempus vacutainer tubes (3 ml) and the RNA was extracted at the Translational Genomics Laboratory at the University of Maryland Baltimore. Analyses included a differential expression analysis, a weighted gene co-expression network analysis, and a pathway enrichment analysis.

RESULTS

Eighty-three genes were differentially expressed between individuals with and without pain (p <.05). After normalizing gene counts and removing the low expressed genes, 18,028 genes were left in the final analysis. There was no clustering of the samples related to study variables of pain or dementia.

CONCLUSION

The findings from this study provided some preliminary support that pain-related gene expression is similar between individuals with and without dementia.

Genetic associations with dementia-related proteinopathy: Application of item response theory

INTRODUCTION

Although dementia-related proteinopathy has a strong negative impact on public health, and is highly heritable, understanding of the related genetic architecture is incomplete.

METHODS

We applied multidimensional generalized partial credit modeling (GPCM) to test genetic associations with dementia-related proteinopathies. Data were analyzed to identify candidate single nucleotide variants for the following proteinopathies: Aβ, tau, α-synuclein, and TDP-43.

RESULTS

Final included data comprised 966 participants with neuropathologic and WGS data. Three continuous latent outcomes were constructed, corresponding to TDP-43-, Aβ/Tau-, and α-synuclein-related neuropathology endophenotype scores. This approach helped validate known genotype/phenotype associations: for example, TMEM106B and GRN were risk alleles for TDP-43 pathology; and GBA for α-synuclein/Lewy bodies. Novel suggestive proteinopathy-linked alleles were also discovered, including several (SDHAF1, TMEM68, and ARHGEF28) with colocalization analyses and/or high degrees of biologic credibility.

DISCUSSION

A novel methodology using GPCM enabled insights into gene candidates for driving misfolded proteinopathies.

HIGHLIGHTS

Latent factor scores for proteinopathies were estimated using a generalized partial credit model. The three latent continuous scores corresponded well with proteinopathy severity. Novel genes associated with proteinopathies were identified. Several genes had high degrees of biologic credibility for dementia risk factors.

An EWAS of dementia biomarkers and their associations with age, African ancestry, and PTSD

BACKGROUND

Large-scale cohort and epidemiological studies suggest that PTSD confers risk for dementia in later life but the biological mechanisms underlying this association remain unknown. This study examined this question by assessing the influences of PTSD, APOE ε4 genotypes, DNA methylation, and other variables on the age- and dementia-associated biomarkers Aβ40, Aβ42, GFAP, NfL, and pTau-181 measured in plasma. Our primary hypothesis was that PTSD would be associated with elevated levels of these markers.

METHODS

Analyses were based on data from a PTSD-enriched cohort of 849 individuals. We began by performing factor analyses of the biomarkers, the results of which identified a two-factor solution. Drawing from the ATN research framework, we termed the first factor, defined by Aβ40 and Aβ42, "Factor A" and the second factor, defined by GFAP, NfL and pTau-181, "Factor TN." Next, we performed epigenome-wide association analyses (EWAS) of the two-factor scores. Finally, using structural equation modeling (SEM), we evaluated (a) the influence of PTSD, age, APOE ε4 genotype and other covariates on levels of the ATN factors, and (b) tested the mediating influence of the EWAS-significant DNAm loci on these associations.

RESULTS

The Factor A EWAS identified one significant locus, cg13053408, in FANCD2OS. The Factor TN analysis identified 3 EWAS-significant associations: cg26033520 near ASCC1, cg23156469 in FAM20B, and cg15356923 in FAM19A4. The SEM showed age to be related to both factors, more so with Factor TN (β = 0.581, p < 0.001) than Factor A (β = 0.330, p < 0.001). Genotype-determined African ancestry was associated with lower Factor A (β = 0.196, p < 0.001). Contrary to our primary hypothesis, we found a modest negative bivariate correlation between PTSD and the TN factor scores (r = - 0.133, p < 0.001) attributable primarily to reduced levels of GFAP (r = - 0.128, p < 0.001).

CONCLUSIONS

This study identified novel epigenetic associations with ATN biomarkers and demonstrated robust age and ancestral associations that will be essential to consider in future efforts to develop the clinical applications of these tests. The association between PTSD and reduced GFAP, which has been reported previously, warrants further investigation.

Association evaluations of oral anticoagulants with dementia risk based on genomic and real-world data

BACKGROUND

Several observational studies have suggested that oral anticoagulants (OACs) might reduce the risk of dementia in the elderly, but the evidence is inconclusive. And the consistency of this relationship across different OAC classes and dementia subtypes is still uncertain.

METHODS

To comprehensively evaluate this association, we applied Mendelian randomization (MR) combined with pharmacovigilance analysis. MR was used to assess the associations between genetic proxies for three target genes of OACs (VKORC1, F2, and F10) and dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). This genetic analysis was supplemented with real-world pharmacovigilance data, employing disproportionality analysis for more reliable causal inference.

RESULTS

Increased expression of the VKORC1 gene was strongly associated with increased risk of dementia, especially for AD (OR = 1.28, 95% CI = 1.14-1.43; p value < 0.001). Based on pharmacovigilance data, vitamin K antagonists (VKAs, inhibitors targeting VKORC1) exhibited a protective effect against dementia risk (ROR = 0.43, 95% CI = 0.28-0.67). Additional sensitivity analyses, including different MR models and cohorts, supported these results. Conversely, no strong causal associations of genetically proxied F2 and F10 target genes with dementia and its subtypes were found.

CONCLUSIONS

This study reveals that the inhibition of genetically proxied VKORC1 expression or VKAs exposure is associated with a reduced risk of Alzheimer's dementia. However, there is little evidence to support similar associations with direct oral anticoagulants (F2 inhibitors and F10 inhibitors). Further research is warranted to clinically validate our findings.

Dementia and mortality in older adults: A twin study

INTRODUCTION

Dementia predicts increased mortality. We used case-control and co-twin control models to investigate genetic and shared environmental influences on this association.

METHODS

Case-control design, including 987 twins with dementia and 2938 age- and sex-matched controls in the Swedish Twin Registry. Co-twin control design, including 90 monozygotic (MZ) and 288 dizygotic (DZ) twin pairs discordant for dementia. To test for genetic and environmental confounding, differences were examined in mortality risk between twins with dementia and their matched or co-twin controls.

RESULTS

Twins with dementia showed greater mortality risk than age- and sex-matched controls (HR = 2.02 [1.86, 2.18]). Mortality risk is significantly elevated but attenuated substantially in discordant twin pairs, for example, comparing MZ twins with dementia to their co-twin controls (HR = 1.48 [1.08, 2.04]).

DISCUSSION

Findings suggest that genetic factors partially confound the association between dementia and mortality and provide an alternative hypothesis to increased mortality due to dementia itself. Highlights We studied dementia and mortality in twin pairs discordant for dementia. People without dementia outlived people with dementia. Identical twins with dementia and their co-twin controls had similar survival time. Findings suggest genotype may explain the link between dementia and mortality.

Digestive System Diseases, Genetic Risk, and Incident Dementia: A Prospective Cohort Study

INTRODUCTION

Although digestive system disease affects gut microbiota and their metabolites associated with dementia risk, the association between digestive system diseases and incident dementia has not yet been established.

METHODS

This cohort analysis included 458,181 participants free of baseline dementia in the UK Biobank (2006-2021). The associations of 14 digestive system diseases with dementia incidence were examined in 2022 using Cox proportional hazards regression models. Analyses were performed to differentiate the associations for early-onset (age <65 years) and late-onset (age ≥65 years) dementia. Interaction and stratification analyses were performed for polygenic risk score and APOE.

RESULTS

During a median follow-up of 12.4 years, 6,415 incident dementia cases were diagnosed. Eleven digestive system diseases showed significant associations with an increased risk of dementia after controlling for covariates and multiple testing. Compared with hazard ratios for individuals without digestive system diseases, the hazard ratios of dementia increased from 1.15 (95% confidence interval=1.09, 1.23) for patients with intestinal diverticular disease to 2.31 (95% confidence interval=1.98, 2.70) for patients with cirrhosis. The associations were different between certain digestive system diseases and dementia by onset age. The associations appeared to be stronger for cirrhosis (Q=0.001), irritable bowel syndrome (Q<0.001), gastritis and duodenitis (Q=0.002), gastroesophageal reflux disease (Q<0.001), ulcerative colitis (Q=0.047), gallbladder disease (Q=0.012), and peptic ulcer (Q=0.030) with early-onset dementia. There were no interactions for polygenic risk score or APOE (p>0.05).

CONCLUSIONS

These findings suggest an increased need for dementia prevention among patients with digestive system diseases.

Associations of hypertensive disorders of pregnancy with cognition, dementia, and brain structure: a Mendelian randomization study

BACKGROUND

Observational studies have found associations between hypertensive disorders of pregnancy and an increased risk of cognitive dysfunction and reduced brain volume. However, the results of observational studies may have been influenced by confounding factors. This study applied two-sample Mendelian randomization (MR) to explore the causal associations of hypertensive disorders of pregnancy with cognition, dementia, and brain structure.

METHODS

Summary data on hypertensive disorders of pregnancy and their main subtypes, cognition, dementia, and brain structure were obtained from recent European genome-wide association studies. We computed the inverse-variance weighted, MR-Egger, and weighted median MR estimates. Cochran's Q statistics and the MR-Egger intercept test were used to quantify the heterogeneity and horizontal pleiotropy of the instrumental variables.

RESULTS

Genetically predicted preeclampsia or eclampsia was inversely associated with gray matter volume [beta = -0.072; 95% confidence interval (CI) = -0.131 to -0.014; P  = 1.53 × 10 -2 ]; possibly with brain volume (beta = -0.064; 95% CI = -0.117 to -0.012; P  = 1.68 × 10 -2 ). However, the association of hypertensive pregnancy disorders or gestational hypertension with brain structure was not significant. We did not find any significant association between hypertensive disorders of pregnancy, gestational hypertension, or preeclampsia or eclampsia and cognition and dementia-related outcomes.

CONCLUSION

This study provided genetic evidence supporting an association between preeclampsia or eclampsia and reduced brain volume. This supports the view of PE as a risk factor for gray matter volume reduction.

Neuropsychiatric symptoms and ApoE genotype in older adults without dementia: a cross-sectional study

BACKGROUND

The ApoE genotype and neuropsychiatric symptoms (NPS) are known risk factors for cognitive decline in older adults. However, the interaction between these variables is still unclear. The aim of this study was to determine the association between the presence of the ApoE ε4 allele and the occurrence of NPS in older adults without dementia.

METHODS

In this cross-sectional investigation we determined the apolipoprotein E (ApoE) genotype of 74 older adults who were either cognitively normal (20.3% / Clinician Dementia Rating Scale (CDR): 0) or had mild cognitive impairment (MCI: 79.7% / CDR: 0.5). We used a comprehensive cognitive assessment protocol, and NPS were estimated by the Neuropsychiatric Inventory-Clinician Rating Scale (NPI-C), Mild Behavioural Impairment-Checklist (MBI-C), Hamilton Rating Scale for Depression (HAM-D), and Apathy Inventory.

RESULTS

ApoE ε4 carriers had higher MBI-C total scores than ApoE ε4 noncarriers. Correlations between NPS and ApoE genotype were observed for two NPI-C domains, although in opposite directions: the ApoE ε4 allele was associated with a 1.8 unit decrease in the estimated aberrant motor disturbance score and with a 1.3 unit increase in the estimated appetite/eating disorders score. All fitted models were significant, except for the one fitted for the domain delusions from the NPI-C. Among individuals with amnestic MCI, ε4 carriers presented higher depression score (HAM-D) than noncarriers; in turn, ε4 noncarriers exhibited higher aggression score (NPI-C) than ε4 carriers.

CONCLUSIONS

Our analyses showed associations between NPS and the presence of the ApoE ε4 allele in two NPI-C domains, despite the sample size. Furthermore, compared to noncarriers, the presence of the ApoE ε4 correlated positively with appetite/eating disorders and negatively with aberrant motor disturbance domain. Examination of the amnestic MCI group displayed significant, although weak, associations. Therefore, ε4 carriers exhibited higher depression scores according to the HAM-D scale compared to ε4 noncarriers. Conversely, ε4 noncarriers had higher scores in the aggression domain of the NPI-C than ε4 carriers.

Statin use moderates APOE's and CRP's associations with dementia and is associated with lesser dementia severity in ε4 carriers

INTRODUCTION

We tested the effect of statins on C-reactive protein (CRP) and apolipoprotein E (APOE)'s associations with dementia severity.

METHODS

A total of 1725 participants of the Alzheimer's Disease Neuroimaging Initiative (ADNI) were assigned from 12-month follow-up data into the following groups: (1) ε4 (-)/statin (-), (2) ε4 (-)/statin (+), (3) ε4 (+)/statin (-), and (4) ε4 (+)/statin (+). Dementia severity was assessed by a δ homolog: "dHABS." A mediation model was stratified on statin use and moderation effects tested by a chi-square difference.

RESULTS

Plasma CRP level decreased with ε4 allelic dose. Statins had no effect on the dHABS d-score in non-carriers but were associated with better scores in carriers. Treated carriers did not have more severe dementia than non-carriers. Statin use moderated the mutual adjusted effects of APOE and CRP. CRP was not a mediator of APOE's effect.

DISCUSSION

Statins may provide a protective effect on the dementia severity of ε4 carriers.

HIGHLIGHTS

δ is a dementia-specific phenotype related to general intelligence "g" and is assessed via a "d-score." Apolipoprotein E (APOE) and plasma C-reactive protein (CRP) are independently associated with δ. Plasma CRP decreases with ε4 allelic dose. Statins were associated with better (less demented) d-scores in ε4 carriers but had no effect in non-ε4 carriers. Treated ε4 carriers did not have more severe dementia than non-carriers. Statin use moderated the effects of APOE and CRP on δ. CRP was not a mediator of APOE's effect on δ.

Common infections and neuroimaging markers of dementia in three UK cohort studies

INTRODUCTION

We aimed to investigate associations between common infections and neuroimaging markers of dementia risk (brain volume, hippocampal volume, white matter lesions) across three population-based studies.

METHODS

We tested associations between serology measures (pathogen serostatus, cumulative burden, continuous antibody responses) and outcomes using linear regression, including adjustments for total intracranial volume and scanner/clinic information (basic model), age, sex, ethnicity, education, socioeconomic position, alcohol, body mass index, and smoking (fully adjusted model). Interactions between serology measures and apolipoprotein E (APOE) genotype were tested. Findings were meta-analyzed across cohorts (Nmain  = 2632; NAPOE-interaction  = 1810).

RESULTS

Seropositivity to John Cunningham virus associated with smaller brain volumes in basic models (β = -3.89 mL [-5.81, -1.97], Padjusted  < 0.05); these were largely attenuated in fully adjusted models (β = -1.59 mL [-3.55, 0.36], P = 0.11). No other relationships were robust to multiple testing corrections and sensitivity analyses, but several suggestive associations were observed.

DISCUSSION

We did not find clear evidence for relationships between common infections and markers of dementia risk. Some suggestive findings warrant testing for replication.

Functional BRI2-TREM2 interactions in microglia: implications for Alzheimer's and related dementias

ITM2B/BRI2 mutations cause Alzheimer's Disease (AD)-related dementias. We observe heightened ITM2B/BRI2 expression in microglia, a pivotal cell type in AD due to risk-increasing variants in the microglial gene TREM2. Single-cell RNA-sequencing demonstrates a Trem2/Bri2-dependent microglia cluster, underscoring their functional interaction. α-secretase cleaves TREM2 into TREM2-CTF and sTREM2. As BRI2 hinders α-secretase cleavage of the AD-related Aβ-Precursor-Protein, we probed whether BRI2 influences TREM2 processing. Our findings indicate a BRI2-TREM2 interaction that inhibits TREM2 processing in heterologous cells. Recombinant BRI2 and TREM2 proteins demonstrate a direct, cell-free BRI2-TREM2 ectodomain interaction. Constitutive and microglial-specific Itm2b-Knock-out mice, and Itm2b-Knock-out primary microglia provide evidence that Bri2 reduces Trem2 processing, boosts Trem2 mRNA expression, and influences Trem2 protein levels through α-secretase-independent pathways, revealing a multifaceted BRI2-TREM2 functional interaction. Moreover, a mutant Itm2b dementia mouse model exhibits elevated Trem2-CTF and sTrem2, mirroring sTREM2 increases in AD patients. Lastly, Bri2 deletion reduces phagocytosis similarly to a pathogenic TREM2 variant that enhances processing. Given BRI2's role in regulating Aβ-Precursor-Protein and TREM2 functions, it holds promise as a therapeutic target for AD and related dementias.

Variably protease-sensitive prionopathy with methionine homozygosity at codon 129 in the prion protein gene

Variably protease-sensitive prionopathy (VPSPr) is a recently characterised rare subtype of sporadic prion disease, mainly affecting individuals with valine homozygosity at codon 129 in the prion protein gene, with only seven methionine homozygote cases reported to date. This case presents clinical, neuropathological and biochemical features of the eighth VPSPr case worldwide with methionine homozygosity at codon 129 and compares the features with the formerly presented cases.The patient, a woman in her 70s, presented with cognitive decline, impaired balance and frequent falls. Medical history and clinical presentation were suggestive of a rapidly progressive dementia disorder. MRI showed bilateral thalamic hyperintensity. Cerebrospinal fluid real-time quaking-induced conversion was negative, and the electroencephalogram was unremarkable. The diagnosis was established through post-mortem pathological examinations. VPSPr should be suspected in rapidly progressive dementia lacking typical features or paraclinical results of protein misfolding diseases.

Association of Rare NOTCH3 Variants With Prevalent and Incident Stroke and Dementia in the General Population

BACKGROUND

It is uncertain whether rare NOTCH3 variants are associated with stroke and dementia in the general population and whether they lead to alterations in cognitive function. This study aims to determine the associations of rare NOTCH3 variants with prevalent and incident stroke and dementia, as well as cognitive function changes.

METHODS AND RESULTS

In the prospective community-based Shunyi Study, a total of 1007 participants were included in the baseline analysis. For the follow-up analysis, 1007 participants were included in the stroke analysis, and 870 participants in the dementia analysis. All participants underwent baseline brain magnetic resonance imaging, carotid ultrasound, and whole exome sequencing. Rare NOTCH3 variants were defined as variants with minor allele frequency <1%. A total of 137 rare NOTCH3 carriers were enrolled in the baseline study. At baseline, rare NOTCH3 variant carriers had higher rates of stroke (8.8% versus 5.6%) and dementia (2.9% versus 0.8%) compared with noncarriers. After adjustment for associated risk factors, the epidermal growth factor-like repeats (EGFr)-involving rare NOTCH3 variants were associated with a higher risk of prevalent stroke (odds ratio [OR], 2.697 [95% CI, 1.266-5.745]; P=0.040) and dementia (OR, 8.498 [95% CI, 1.727-41.812]; P=0.032). After 5 years of follow-up, we did not find that the rare NOTCH3 variants increased the risk of incident stroke and dementia. There was no statistical difference in the change in longitudinal cognitive scale scores.

CONCLUSIONS

Rare NOTCH3 EGFr-involving variants are genetic risk factors for stroke and dementia in the general Chinese population.

Joint Exposure to Multiple Air Pollutants, Genetic Susceptibility, and Incident Dementia: A Prospective Analysis in the UK Biobank Cohort

Objectives: This study aimed to evaluate the joint effects of multiple air pollutants including PM2.5, PM10, NO2, and NOx with dementia and examined the modifying effects of genetic susceptibility. Methods: This study included 220,963 UK Biobank participants without dementia at baseline. Weighted air pollution score reflecting the joint exposure to multiple air pollutants were constructed by cross-validation analyses, and inverse-variance weighted meta-analyses were performed to create a pooled effect. The modifying effect of genetic susceptibility on air pollution score was assessed by genetic risk score and APOE ε4 genotype. Results: The HR (95% CI) of dementia for per interquartile range increase of air pollution score was 1.13 (1.07∼1.18). Compared with the lowest quartile (Q1) of air pollution score, the HR (95% CI) of Q4 was 1.26 (1.13∼1.40) (P trend = 2.17 × 10-5). Participants with high air pollution score and high genetic susceptibility had higher risk of dementia compared to those with low air pollution score and low genetic susceptibility. Conclusion: Our study provides evidence that joint exposure to multiple air pollutants substantially increases the risk of dementia, especially among individuals with high genetic susceptibility.

Stress response silencing by an E3 ligase mutated in neurodegeneration

Stress response pathways detect and alleviate adverse conditions to safeguard cell and tissue homeostasis, yet their prolonged activation induces apoptosis and disrupts organismal health1-3. How stress responses are turned off at the right time and place remains poorly understood. Here we report a ubiquitin-dependent mechanism that silences the cellular response to mitochondrial protein import stress. Crucial to this process is the silencing factor of the integrated stress response (SIFI), a large E3 ligase complex mutated in ataxia and in early-onset dementia that degrades both unimported mitochondrial precursors and stress response components. By recognizing bifunctional substrate motifs that equally encode protein localization and stability, the SIFI complex turns off a general stress response after a specific stress event has been resolved. Pharmacological stress response silencing sustains cell survival even if stress resolution failed, which underscores the importance of signal termination and provides a roadmap for treating neurodegenerative diseases caused by mitochondrial import defects.

Lack of causal association between epilepsy and dementia: A Mendelian randomization analysis

OBJECTIVE

Epidemiological studies have reported an association between epilepsy and dementia. However, the causal relationship between epilepsy and the risk of dementia is not clear. We aimed to inspect the causal effect of epilepsy on memory loss and dementia.

METHODS

We analyzed summary data of epilepsy, memory loss, and dementia from the genome-wide association study (GWAS) using the two-sample Mendelian randomization (MR) method. We used the estimated odds ratio of memory loss and dementia associated with each of the genetically defined traits to infer evidence for a causal relationship with the following exposures: all epilepsy, focal epilepsy (including focal epilepsy with hippocampal sclerosis, lesion-negative focal epilepsy, and focal epilepsy with other lesions), and genetic generalized epilepsy (including childhood absence epilepsy, generalized tonic-clonic seizures alone, Juvenile absence epilepsy, and Juvenile myoclonic epilepsy).

RESULTS

According to the result of MR using the inverse variance weighted method (IVW), we found that genetically predicted epilepsy did not causally increase the risk of memory loss and dementia (p > 0.05). Results of the MR-Egger and weighted median method were consistent with the IVW method.

CONCLUSIONS

No evidence has been found to support the notion that epilepsy can result in memory loss and dementia. The associations observed in epidemiological studies could be attributed, in part, to confounding or nongenetic determinants.

Causal relationship between psoriasis vulgaris and dementia: Insights from Mendelian randomization analysis

Many clinical studies have demonstrated a correlation between psoriasis vulgaris and dementia, yet this correlation remains controversial. Our study employed the Mendelian randomization (MR) method to investigate the causal relationship between psoriasis vulgaris and dementia. Data were obtained from the summary statistics of the genome-wide association studies from IEU-OpenGWAS project database. In univariate Mendelian randomization (UVMR) analysis, psoriasis vulgaris was used as exposure. Alzheimer disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB), Parkinson's disease with dementia (PDD) and frontotemporal dementia (FTD) served as the outcomes. In multivariate Mendelian randomization (MVMR) analysis, VaD served as the outcome. The first MVMR analysis used psoriasis vulgaris, mean platelet volume (MPV), platelet distribution width (PDW) and platelet count (PLT) as exposures. The second MVMR analysis used psoriasis vulgaris, vitamin D level and 25 hydroxyvitamin D level as exposures. The main analysis employed the inverse variance weighted method, and the outcomes were evaluated by odds ratio (OR) and 95% confidence interval (95% CI). In UVMR analysis, the results depicted that psoriasis vulgaris was associated with VaD (OR: 0.903, 95% CI: 0.818-0.996, p = 0.041). The results revealed insignificant associations between psoriasis vulgaris and other dementia types. After adjusting the effects of MPV, PDW and PLT in MVMR analysis, the association between psoriasis vulgaris and VaD was no longer significant (p = 0.164). Similarly, after adjusting the effects of vitamin D level and 25 hydroxyvitamin D level in MVMR analysis, the association between psoriasis vulgaris and VaD was also no longer significant (p = 0.533). Our study suggests that psoriasis vulgaris may potentially decrease VaD incidence. However, the causal association between psoriasis vulgaris and VaD may be impeded by platelet-related indices, vitamin D level and 25 hydroxyvitamin D level.

Habitual coffee consumption and risk of dementia in older persons: modulation by CYP1A2 polymorphism

Higher coffee consumption has been associated with reduced dementia risk, yet with inconsistencies across studies. CYP1A2 polymorphisms, which affects caffeine metabolism, may modulate the association between coffee and the risk of dementia and Alzheimer's disease (AD). We included 5964 participants of the Three-City Study (mean age 74 years-old), free of dementia at baseline when they reported their daily coffee consumption, with available genome-wide genotyping and followed for dementia over a median of 9.0 (range 0.8-18.7) years. In Cox proportional-hazards models, the relationship between coffee consumption and dementia risk was modified by CYP1A2 polymorphism at rs762551 (p for interaction = 0.034). In multivariable-adjusted models, coffee intake was linearly associated with a decreased risk of dementia among carriers of the C allele only ("slower caffeine metabolizers"; HR for 1-cup increased [95% CI] 0.90 [0.83-0.97]), while in non-carriers ("faster caffeine metabolizers"), there was no significant association but a J-shaped trend toward a decrease in dementia risk up to 3 cups/day and increased risk beyond. Thus, compared to null intake, drinking ≥ 4 cups of coffee daily was associated with a reduced dementia risk in slower but not faster metabolizers (HR [95% CI] for ≥ 4 vs. 0 cup/day = 0.45 [0.25-0.80] and 1.32 [0.89-1.96], respectively). Results were similar when studying AD and another CYP1A2 candidate polymorphism (rs2472304), but no interaction was found with CYP1A2 rs2472297 or rs2470893. In this cohort, a linear association of coffee intake to lower dementia risk was apparent only among carriers of CYP1A2 polymorphisms predisposing to slower caffeine metabolism.

Huntington disease-like 2: insight into neurodegeneration from an African disease

Huntington disease (HD)-like 2 (HDL2) is a rare genetic disease caused by an expanded trinucleotide repeat in the JPH3 gene (encoding junctophilin 3) that shows remarkable clinical similarity to HD. To date, HDL2 has been reported only in patients with definite or probable African ancestry. A single haplotype background is shared by patients with HDL2 from different populations, supporting a common African origin for the expansion mutation. Nevertheless, outside South Africa, reports of patients with HDL2 in Africa are scarce, probably owing to limited clinical services across the continent. Systematic comparisons of HDL2 and HD have revealed closely overlapping motor, cognitive and psychiatric features and similar patterns of cerebral and striatal atrophy. The pathogenesis of HDL2 remains unclear but it is proposed to occur through several mechanisms, including loss of protein function and RNA and/or protein toxicity. This Review summarizes our current knowledge of this African-specific HD phenocopy and highlights key areas of overlap between HDL2 and HD. Given the aforementioned similarities in clinical phenotype and pathology, an improved understanding of HDL2 could provide novel insights into HD and other neurodegenerative and/or trinucleotide repeat expansion disorders.

Dem-Aging: autophagy-related pathologies and the "two faces of dementia"

Neuronal ceroid lipofuscinosis (NCL) is an umbrella term referring to the most frequent childhood-onset neurodegenerative diseases, which are also the main cause of childhood dementia. Although the molecular mechanisms underlying the NCLs remain elusive, evidence is increasingly pointing to shared disease pathways and common clinical features across the disease forms. The characterization of pathological mechanisms, disease modifiers, and biomarkers might facilitate the development of treatment strategies.The DEM-AGING project aims to define molecular signatures in NCL and expedite biomarker discovery with a view to identifying novel targets for monitoring disease status and progression and accelerating clinical trial readiness in this field. In this study, we fused multiomic assessments in established NCL models with similar data on the more common late-onset neurodegenerative conditions in order to test the hypothesis of shared molecular fingerprints critical to the underlying pathological mechanisms. Our aim, ultimately, is to combine data analysis, cell models, and omic strategies in an effort to trace new routes to therapies that might readily be applied in the most common forms of dementia.

HLA-C*07:01 and HLA-DQB1*02:01 protect against white matter hyperintensities and deterioration of cognitive function: A population-based cohort study

BACKGROUND

Neuroinflammation and aberrant immune regulation are increasingly implicated in the pathophysiology of white matter hyperintensities (WMH), an imaging marker of cerebrovascular pathologies and predictor of cognitive impairment. The role of human leukocyte antigen (HLA) genes, critical in immunoregulation and associated with susceptibility to neurodegenerative diseases, in WMH pathophysiology remains unexplored.

METHODS

We performed association analyses between classical HLA alleles and WMH volume, derived from MRI scans of 38 302 participants in the UK Biobank. To identify independent functional alleles driving these associations, we conducted conditional forward stepwise regression and lasso regression. We further investigated whether these functional alleles showed consistent associations with WMH across subgroups characterized by varying levels of clinical determinants. Additionally, we validated the clinical relevance of the identified alleles by examining their association with cognitive function (n = 147 549) and dementia (n = 460 029) in a larger cohort.

FINDINGS

Four HLA alleles (DQB1*02:01, DRB1*03:01, C*07:01, and B*08:01) showed an association with reduced WMH volume after Bonferroni correction for multiple comparisons. Among these alleles, DQB1*02:01 exhibited the most significant association (β = -0.041, 95 % CI: -0.060 to -0.023, p = 1.04 × 10-5). Forward selection and lasso regression analyses indicated that DQB1*02:01 and C*07:01 primarily drove this association. The protective effect against WMH conferred by DQB1*02:01 and C*07:01 persisted in clinically relevant subgroups, with a stronger effect observed in older participants. Carrying DQB1*02:01 and C*07:01 was associated with higher cognitive function, but no association with dementia was found.

INTERPRETATION

Our population-based findings support the involvement of immune-associated mechanisms, particularly both HLA class I and class II genes, in the pathogenesis of WMH and subsequent consequence of cognitive functions.

HLA-A23/HLA-A24 serotypes and dementia interaction in the elderly: Association with increased soluble HLA class I molecules in plasma

MHC class I molecules regulate brain development and plasticity in mice and HLA class I molecules are associated with brain disorders in humans. We investigated the relationship between plasma-derived soluble human HLA class I molecules (sHLA class I), HLA class I serotypes and dementia. A cohort of HLA class I serotyped elderly subjects with no dementia/pre-dementia (NpD, n = 28), or with dementia (D, n = 28) was studied. Multivariate analysis was used to examine the influence of dementia and HLA class I serotype on sHLA class I levels, and to compare sHLA class I within four groups according to the presence or absence of HLA-A23/A24 and dementia. HLA-A23/A24 and dementia, but not age, significantly influenced the level of sHLA class I. Importantly, the concurrent presence of HLA-A23/A24 and dementia was associated with higher levels of sHLA class I (p < 0.001). This study has shown that the simultaneous presence of HLA-A23/HLA-A24 and dementia is associated with high levels of serum sHLA class I molecules. Thus, sHLA class I could be considered a biomarker of neurodegeneration in certain HLA class I carriers.

Associations of dietary cholesterol and fat, blood lipids, and risk for dementia in older women vary by APOE genotype

INTRODUCTION

Whether apolipoprotein E's (APOE's) involvement in lipid metabolism contributes to Alzheimer's disease (AD) risk remains unknown.

METHODS

Incident probable dementia and cognitive impairment (probable dementia+mild cognitive impairment) were analyzed in relation to baseline serum lipids (total, low-density lipoprotein [LDL], high-density lipoprotein [HDL], non-HDL cholesterol, total-to-HDL, LDL-to-HDL, remnant cholesterol, and triglycerides) using Mendelian randomization in 5358 postmenopausal women from the Women's Health Initiative Memory Study. We also examined associations of baseline dietary cholesterol and fat with lipids based on APOE status.

RESULTS

After an average of 11.13 years, less favorable lipid levels related to greater dementia and cognitive impairment risk. Dementia (odds ratio [OR] = 3.13; 95% confidence interval [CI]: 2.31 to 4.24) and cognitive impairment (OR = 2.38; 95% CI: 1.85 to 3.06) risk were greatest in relation to higher remnant cholesterol levels. Greater cholesterol consumption related to poorer lipids in APOE4+ compared to APOE3 carriers.

DISCUSSION

APOE4+ carriers consuming more cholesterol had less favorable lipids, which were associated with greater dementia and cognitive impairment risk.

HIGHLIGHTS

Less favorable serum lipids were associated with higher dementia incidence. Mendelian randomization findings suggest causality between lipids and dementia. Lipid levels in older women may be clinical indicators of dementia risk. APOE4 carriers had poorest lipid profiles in relation to cholesterol consumption. APOE risk for dementia may be modifiable through lipid management.

Validation of newly derived polygenic risk scores for dementia in a prospective study of older individuals

INTRODUCTION

Recent genome-wide association studies identified new dementia-associated variants. We assessed the performance of updated polygenic risk scores (PRSs) using these variants in an independent cohort.

METHODS

We used Cox models and area under the curve (AUC) to validate new PRSs (PRS-83SNP, PRS-SBayesR, and PRS-CS) compared with an older PRS-23SNP in 12,031 initially-healthy participants ≥70 years of age. Dementia was rigorously adjudicated according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.

RESULTS

PRS-83SNP, PRS-SBayesR, and PRS-CS were associated with incident dementia, with fully adjusted (including apolipoprotein E [APOE] ε4) hazard ratios per standard deviation (SD) of 1.35 (1.23-1.47), 1.37 (1.25-1.50), and 1.42 (1.30-1.56), respectively. The AUC of a model containing conventional/non-genetic factors and APOE was 74.7%. This was improved to 75.7% (p = 0.007), 76% (p = 0.004), and 76.1% (p = 0.003) with addition of PRS-83SNP, PRS-SBayesR, and PRS-CS, respectively. The PRS-23SNP did not improve AUC (74.7%, p = 0.95).

CONCLUSION

New PRSs for dementia significantly improve risk-prediction performance, but still account for less risk than APOE genotype overall.

Exploring the possible causal effects of cardiac blood biomarkers in dementia and cognitive performance: a Mendelian randomization study

Prospective cohort studies have implied associations between blood levels of troponin T, troponin I, NT-proBNP, GDF15, dementia, and cognitive function, without providing evidence favoring possible causality. We aimed to assess the causal associations of these cardiac blood biomarkers with dementia and cognition using two-sample Mendelian randomization (MR). Independent genetic instruments (p < 5e-7) for troponin T and I, N-terminal pro B-type natriuretic peptide (NT-proBNP) and growth-differentiation factor 15 (GDF15) were obtained from previously-performed genome-wide association studies of predominantly European ancestry. Summary statistics for gene-outcome associations in European-ancestry participants, for the two-sample MR analyses, were obtained for general cognitive performance (n = 257,842) and dementia (n = 111,326 clinically diagnosed and "proxy" AD cases, and 677,663 controls). Two-sample MR analyses were performed using inverse variance-weighted (IWV) analyses. Sensitivity analyses to evaluate horizontal pleiotropy included weighted median estimator, MR-Egger, and MR using cis-SNPs only. Using IVW, we did not find evidence for possible causal associations between genetically influenced cardiac biomarkers with cognition and dementia. For example, per standard deviation (SD) higher cardiac blood biomarker, the odds ratio for risk of dementia was 1.06 (95%CI 0.90; 1.21) for troponin T, 0.98 (95%CI 0.72; 1.23) for troponin I, 0.97 (95%CI 0.90; 1.06) for NT-proBNP and 1.07 (95%CI 0.93; 1.21) for GDF15. Sensitivity analyses showed higher GDF15 was significantly associated with higher dementia risk and worse cognitive function. We did not find strong evidence that cardiac biomarkers causally influence dementia risk. Future research should aim at elucidating the biological pathways through which cardiac blood biomarkers associate with dementia.

APOE-Genotype and Insulin Modulate Estimated Effect of Dietary Macronutrients on Cognitive Performance: Panel Analyses in Nondiabetic Older Adults at Risk of Dementia

BACKGROUND

The apolipoprotein E gene (APOE ε-2/3/4, combined as 6 different genotypes: ε-22/23/24/33/34/44) and insulin status modulate dementia risk and play a role in the metabolism of macronutrients.

OBJECTIVES

We aimed to examine APOE-genotype and fasting insulin as effect modifiers of the slopes between dietary macronutrients and cognitive performance among older adults at risk of dementia.

METHODS

Panel analyses-with diet and cognition measured at baseline and follow-up at years 1 and 2-were performed in a sub-sample from the FINGER (Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability) trial (n = 676, 60-77 y, 46% females, all nondiabetics). The associations between macronutrients (3-d food records, z-scores) and global cognition (modified Neuropsychological Test Battery, z-score) were analyzed in mixed regression models adjusted for confounders selected a priori. After a gradient was implied by the point estimates in categorical APOE analyses, we investigated a continuous APOE variable [APOE-gradient, coded -1 (for ε-23), -0.5 (ε-24), 0 (ε-33), 1 (ε-34), 2 (ε-44)] as an effect-modifier.

RESULTS

At increasing levels of the APOE-gradient, a relatively more favorable slope between diet and cognition was observed for a lower carbohydrate/fat ratio [β = -0.040, 95% confidence interval (CI): -0.074, -0.006; P = 0.020 for interaction diet × APOE-gradient), and higher protein (β = 0.075, 95% CI: 0.042, 0.109; P = 9.4 × 10-6). Insulin concentration (log-linear) modulated the association between the carbohydrate/fat ratio and cognition by a quadratic interaction (β = -0.016, P = 0.039). Coherent findings for exploratory predictors (fiber, fat subtypes, composite score, metabolic biomarkers) were compatible with published hypotheses of differential dietary adaptation by APOE, with cognition among ε-33 being relatively independent of dietary parameters-implying "metabolic flexibility." Antagonistic slopes to cognition for ε-23 (positive) compared with ε-34 and ε-44 (negative) were found for a Higher-carbohydrates-fiber-Lower-fat-protein composite score, even as within-subjects effects.

CONCLUSIONS

APOE-based precision nutrition appears conceptually promising, but replications in wider samples are warranted, as well as support from trials. Both relative hyper- and hypoinsulinemia might modulate the effect of diet on cognition.

Association between BMI trajectories in late-middle age and subsequent dementia risk in older age: a 26-year population-based cohort study

BACKGROUND

The association between body mass index (BMI) and dementia risk differs depending on follow-up time and age at BMI measurement. The relationship between BMI trajectories in late-middle age (50-65 years old) and the risk of dementia in older age (> 65 years old) has not been revealed.

METHODS

In the present study, participants from the Health and Retirement Study were included. BMI trajectories were constructed by combining BMI trend and variation information. The association between BMI trajectories at the age of 50-65 years and dementia risk after the age of 65 years was investigated. Participants with European ancestry and information on polygenic scores for cognitive performance were pooled to examine whether genetic predisposition could modify the association.

RESULTS

A total of 10,847 participants were included in the main analyses. A declining BMI trend and high variation in late-middle age were associated with the highest subsequent dementia risk in older age compared with an ascending BMI trend and low variation (RR = 1.76, 95% CI = 1.45-2.13). Specifically, in stratified analyses on BMI trajectories and dementia risk based on each individual's mean BMI, the strongest association between a declining BMI trend with high variation and elevated dementia risk was observed in normal BMI group (RR = 2.66, 95% CI = 1.72-4.1). Similar associations were found when participants were stratified by their genetic performance for cognition function without interaction.

CONCLUSIONS

A declining BMI trend and high variation in late-middle age were associated with a higher risk of dementia. Early monitoring of these individuals is needed to prevent dementia in older individuals.

Brain hypometabolism in non-demented microtubule-associated protein tau H1 carriers with Parkinson's disease

BACKGROUND AND PURPOSE

The microtubule-associated protein tau (MAPT) H1 homozygosity (H1/H1 haplotype) is a genetic risk factor for neurodegenerative diseases, such as Parkinson's disease (PD). MAPT H1 homozygosity has been associated with conversion to PD; however, results are conflicting since some studies did not find a strong influence. Cortical hypometabolism is associated with cognitive impairment in PD. In this study, we aimed to evaluate the metabolic pattern in nondemented PD patients MAPT H1/H1 carriers in comparison with MAPT H1/H2 haplotype. In addition, we evaluated domain-specific cognitive differences according to MAPT haplotype.

METHODS

We compared a group of 26 H1/H1 and 20 H1/H2 carriers with late-onset PD. Participants underwent a comprehensive neuropsychological cognitive evaluation and a [18F]-Fluorodeoxyglucose PET-MR scan.

RESULTS

MAPT H1/H1 carriers showed worse performance in the digit span forward test of attention compared to MAPT H1/H2 carriers. In the [18F]-Fluorodeoxyglucose PET comparisons, MAPT H1/H1 displayed hypometabolism in the frontal cortex, parahippocampal, and cingulate gyrus, as well as in the caudate and globus pallidus.

CONCLUSION

PD patients MAPT H1/H1 carriers without dementia exhibit relative hypometabolism in several cortical areas as well as in the basal ganglia, and worse performance in attention than MAPT H1/H2 carriers. Longitudinal studies should assess if lower scores in attention and dysfunction in these areas are predictors of dementia in MAPT H1/H1 homozygotes.

Neuroepigenetics of ageing and neurodegeneration-associated dementia: An updated review

Gene expression is tremendously altered in the brain during memory acquisition, recall, and forgetfulness. However, non-genetic factors, including environmental elements, epigenetic changes, and lifestyle, have grabbed significant attention in recent years regarding the etiology of neurodegenerative diseases (NDD) and age-associated dementia. Epigenetic modifications are essential in regulating gene expression in all living organisms in a DNA sequence-independent manner. The genes implicated in ageing and NDD-related memory disorders are epigenetically regulated by processes such as DNA methylation, histone acetylation as well as messenger RNA editing machinery. The physiological and optimal state of the epigenome, especially within the CNS of humans, plays an intricate role in helping us adjust to the changing environment, and alterations in it cause many brain disorders, but the mechanisms behind it still need to be well understood. When fully understood, these epigenetic landscapes could act as vital targets for pharmacogenetic rescue strategies for treating several diseases, including neurodegeneration- and age-induced dementia. Keeping this objective in mind, this updated review summarises the epigenetic changes associated with age and neurodegeneration-associated dementia.

Polygenic Propensity for Longevity, APOE-ε4 Status, Dementia Diagnosis, and Risk for Cause-Specific Mortality: A Large Population-Based Longitudinal Study of Older Adults

To deepen the understanding of genetic mechanisms influencing mortality risk, we investigated the impact of genetic predisposition to longevity and APOE-ε4, on all-cause mortality and specific causes of mortality. We further investigated the mediating effects of dementia on these relationships. Using data on 7 131 adults aged ≥50 years (mean = 64.7 years, standard deviation [SD] = 9.5) from the English Longitudinal Study of Aging, genetic predisposition to longevity was calculated using the polygenic score approach (PGSlongevity). APOE-ε4 status was defined according to the absence or presence of ε4 alleles. The causes of death were ascertained from the National Health Service central register, which was classified into cardiovascular diseases, cancers, respiratory illness, and all other causes of mortality. Of the entire sample, 1 234 (17.3%) died during an average 10-year follow-up. One-SD increase in PGSlongevity was associated with a reduced risk for all-cause mortality (hazard ratio [HR] = 0.93, 95% confidence interval [CI]: 0.88-0.98, p = .010) and mortalities due to other causes (HR = 0.81, 95% CI: 0.71-0.93, p = .002) in the following 10 years. In gender-stratified analyses, APOE-ε4 status was associated with a reduced risk for all-cause mortality and mortalities related to cancers in women. Mediation analyses estimated that the percent excess risk of APOE-ε4 on other causes of mortality risk explained by the dementia diagnosis was 24%, which increased to 34% when the sample was restricted to adults who were aged ≤75 years old. To reduce the mortality rate in adults who are aged ≥50 years old, it is essential to prevent dementia onset in the general population.

Chronic Pain, Analgesics, and Cognitive Status: A Comprehensive Mendelian Randomization Study

BACKGROUND

Observational studies have suggested an intricate relationship among chronic pain (CP), use of analgesics, and cognitive status, but it remains unclear whether these associations are of a causal nature.

METHODS

To investigate the causal relationship among them, summary statistics of 9 types of CP (headache, hip, neck/shoulder, stomach/abdominal, back, knee, facial, general, and multisite CP), analgesics (nonsteroidal anti-inflammatory drugs [NSAIDs], opioids, salicylic acid and derivatives, and anilides), and cognitive status (cognitive function, Alzheimer's disease [AD], vascular dementia, Lewy body dementia [LBD], and dementia) were included in this Mendelian randomization (MR) study. As both CP and analgesic use were associated with cognitive status and vice versa, we performed a bidirectional MR analysis between CP or analgesics and dementia using strong genetic instruments ( P < .001) identified from genome-wide association studies (GWAS). The inverse-variance weighted method was applied to calculate estimates. The MR estimated odds ratio (OR) was interpreted as odds of outcome per unit increase in the exposure. The Benjamini-Hochberg method was applied to adjust the P value for multiple testing, and P < .05 means statistically significant.

RESULTS

Multisite CP (MCP) was associated with worse cognitive function (OR [95% confidence interval], 0.69 [0.53-0.89], P = .043), but no significant reverse effect of cognitive status on CP was found. There were no significant associations observed between analgesics and cognitive status. Unexpectedly, patients with AD and LBD had significantly lower exposure to anilides (AD: OR = 0.97 [0.94-0.99], P = .034; LBD: OR = 0.97 [0.96-0.99], P = .012) and NSAIDs (AD: OR = 0.96 [0.93-0.98], P = .012; LBD: OR = 0.98 [0.96-0.99], P = .034).

CONCLUSIONS

Our findings indicate that an elevated number of CP sites predict future cognitive decline. Patients with dementia had lower exposure to anilides and NSAIDs, suggesting that they might not be adequately medicated for pain.

Transcriptomic Downregulation of APOE, Polymorphic Variations of APOE, Diet, Social Isolation, and Co-morbidities as Contributing Factors to Alzheimer's Disease: a Case-Control Study of Kashmiri Population

Alzheimer's disease (AD) is the most common form of dementia, generally affecting elderly people in the age group of above 60-65 years. Amyloid deposition has been found to be a possible cause and a characteristic feature of Alzheimer's disease. Mutations, variant genotypes, or downregulation that reduce amyloid clearance or accelerate amyloid accumulation can lead to Alzheimer's disease. This study involved clinically confirmed AD patients, age matched controls of similar ethnicity, and patients who had no history of cancer or any other chronic disease. DNA and RNA extractions of samples were done as per Saguna et al. [45] and TRIzol method, respectively. Frequencies of variant genotypes were observed using the RFLP technique, whereas, for expression analysis, qPCR was performed. The association between diet, smoking status, family history, and co-morbidities was calculated using statistical tools. Expression analysis showed downregulation in more than 65% of AD cases. Hypertension and diabetes also had a significant association with AD. Allelic isoforms ε2:ε2 and ε2:ε3 tend to be less frequent among AD cases compared to controls (2.85% vs 26.15% and 11.42% vs 21.43%, respectively). Among individuals (AD cases) with ε2:ε3 and ε2:ε4, 37.5% of the patients were having severe dementia and 62.5% were having mild to moderate dementia, whereas, among individuals with ε3:ε4 and ε4:ε4, 57% were having severe dementia and 43% were having mild to moderate dementia. Besides this, all early-onset Alzheimer's patients were found to have at least one ε4 allele. The percentage of individuals with family history (cases vs controls) was 34.17% vs 3.75%, without family history 64.55% vs 95%. On comparing AD cases against controls for smoking status, the results observed are the following: chain smokers, 12.65% vs 18.75%; moderate smokers, 16.45% vs 6.25%; ex-smokers, 36.70% vs 22.50%; non-smokers, 34.17% vs 52.50%. On comparing dietary habits in AD cases against controls, the results were as follows: individuals with generally fatty diet 26.58% vs 11.25%, with mixed diet 36.70% vs 78.75%, with generally vegetarian diet 34.17% vs 10.00%, data not available 2.53% among AD cases. Family history, dietary habits, genetics, and socioeconomic status are strongly associated with the development of Alzheimer disease. Although family history or genetic makeup cannot be changed, eating habits can be changed quite easily. We simply need to go from a high-fat diet to one that is lower in fat. Regarding socioeconomic status, which includes stress of both kinds, including economic stress, stress brought on by the loss of loved ones through death or separation, and co-morbidities (hypertension and diabetes), all are manageable and even modifiable through counseling, positive behavior, and physical activity like exercise, walking, cycling, and playing games.

The prevalence of dementia in humans could be the result of a functional adaptation

In this paper we propose that high copy number of the mitochondrial genome in neurons is a functional adaptation. We simulated the proliferation of deletion mutants of the human mitochondrial genome in a virtual mitochondrion and recorded the cell loss rates due to deletions overwhelming the wild-type. Our results showed that cell loss increased with mtDNA copy number. Given that neuron loss equates to cognitive dysfunction, it would seem counterintuitive that there would be a selective pressure for high copy number over low. However, for a low copy number, the onset of cognitive decline, while mild, started early in life. Whereas, for high copy number, it did not start until middle age but progressed rapidly. There could have been an advantage to high copy number in the brain if it delayed the onset of cognitive decline until after reproductive age. The prevalence of dementia in our aged population is a consequence of this functional adaptation.

Higher dietary advanced glycation products intake is associated with increased risk of dementia, independent from genetic predisposition

BACKGROUND

Dietary advanced glycation end products (AGEs) might exert adverse effects on cognition. The associations between dietary AGEs and long-term risk of dementia are yet to be assessed in large population studies. We aimed to explore whether elevated dietary AGEs intake is associated with increased risk of dementia, and whether this association might be affected by genetic risk.

METHODS

A prospective cohort study, which included a total of 93,830 participants (aged≥ 50 years) free from dementia at baseline of the UK Biobank study (2006-2010) and had at least two 24-h dietary assessments and were followed up until 2021. Dietary AGEs, including Nε-(1-Carboxyethyl)-l-lysine (CEL), Nε-(carboxymethyl) lysine (CML), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were estimated via averaged data from the multiple 24-h food assessments according to the ultra-performance LC-tandem MS based dAGEs database. Incidence of all-cause dementia was ascertained through hospital inpatient and mortality records. Multivariable Cox regression models were utilized to estimate hazards ratios (HRs) and 95% confidence interval (CI) of dementia risk associated with dietary AGEs.

RESULTS

During a median follow-up of 11.9 years, 728 participants developed dementia. In multivariable adjusted model, when comparing the highest with the lowest tertile of intake level, HRs (95% CI) of dementia were 1.43 (1.16, 1.76) for total AGEs Z score, 1.53 (1.25, 1.89) for CEL, 1.27 (1.03, 1.56) for CML and 1.24 (1.02, 1.52) for MG-H1 (all P trend<0.01). There was no significant interaction between dietary AGEs intake, genetic risk and APOE ε4 carrier status for dementia.

CONCLUSIONS

Higher intakes of dietary AGEs including CEL, CML and MG-H1 were associated with a higher risk of dementia, independent from genetic risk, highlighting the significance of dietary AGEs restriction for dementia prevention.

Molecular Mechanisms of Dementia

The various forms of dementia and the other neurodegenerative disorders that affect memory, cognition, and behavior have become a public health priority across the developed world [...].

Kidney function, albuminuria, and their modification by genetic factors and risk of incident dementia in UK Biobank

BACKGROUND

Associations between kidney function and dementia risk are inconclusive. Chronic kidney disease (CKD) severity is determined by levels of both estimated glomerular filtration rate (eGFR) and the urine albumin to creatinine ratio (ACR). However, whether there is a graded increase in dementia risk for worse eGFR in each ACR category is unclear. Also, whether genetic risk for dementia impacts the associations is unknown. The current study aims to investigate the associations between eGFR and albuminuria with dementia risk both individually and jointly, whether the associations vary by different follow-up periods, and whether genetic factors modified the associations.

METHODS

In 202,702 participants aged ≥ 60 years from the UK Biobank, Cox proportional-hazards models were used to examine the associations between eGFR and urine albumin creatinine ratio (ACR) with risk of incident dementia. GFR was estimated based on serum creatinine, cystatin C, or both. The models were restricted to different follow-up periods (< 5 years, 5-10 years, and ≥ 10 years) to investigate potential reverse causation.

RESULTS

Over 15 years of follow-up, 6,042 participants developed dementia. Decreased kidney function (eGFR < 60 ml/min/1.73m2) was associated with an increased risk of dementia (Hazard Ratio [HR] = 1.42, 95% Confidence Interval [CI] 1.28-1.58), compared to normal kidney function (≥ 90 ml/min/1.73m2). The strength of the association remained consistent when the models were restricted to different periods of follow-up. The HRs for incident dementia were 1.16 (95% CI 1.07-1.26) and 2.24 (95% CI 1.79-2.80) for moderate (3-30 mg/mmol) and severely increased ACR (≥ 30 mg/mmol) compared to normal ACR (< 3 mg/mmol). Dose-response associations were observed when combining eGFR and ACR, with those in the severest eGFR and ACR group having the greatest risk of dementia (HR = 4.70, 95% CI 2.34-9.43). APOE status significantly modified the association (p = 0.04), with stronger associations observed among participants with a lower genetic risk of dementia. There was no evidence of an interaction between kidney function and non-APOE polygenic risk of dementia with dementia risk (p = 0.42).

CONCLUSIONS

Kidney dysfunction and albuminuria were individually and jointly associated with higher dementia risk. The associations were greater amongst participants with a lower genetic risk of dementia based on APOE, but not non-APOE polygenic risk.

The Polyherbal Functional Ingredient Containing Ginger, Chinese Date, and Wood Ear Mushroom Protects against Dementia following Metabolic Syndrome

The anti-dementia effect following ischemic stroke with metabolic syndrome (MetS) of the polyherbal functional ingredient comprising ginger, Chinese date, and wood ear mushroom (GCJ) was hypothesized due to its neuroprotective effect against stroke. This study was performed to test this hypothesis and to explore the underlying mechanism. Male Wistar rats weighing 180-220 g were induced metabolic syndrome (MetS) with a 16-week high-carbohydrate high-fat diet (HCHF) feeding. The rats with MetS characteristics were orally administered GCJ at various doses (GCJ100, GCJ200, and GCJ300 mg kg-1 BW) 21 days pre-induction and 21 days post-induction of reperfusion injury (I/R) at the right middle cerebral artery (MCAO). Memory was evaluated every 7 days during the study period. At the end of the study, neuron density, AChE activity, and the expressions of eNOS, BDNF, and pERK/ERK in the prefrontal cortex, and hippocampus were also determined. MetS rats with GCJ treatment improved memory impairment, enhanced neuron density, and increased the expressions of eNOS, BDNF, and pERK/ERK but suppressed AChE in both areas. Therefore, the anti-dementia effect following ischemic stroke with metabolic syndrome of GCJ may involve the improvement of AChE, eNOS, BDNF, pERK/ERK, and neural plasticity. However, this required confirmation by clinical study.

Polygenic Susceptibility to Hypertension and Cognitive Performance in Middle-aged Persons Without Stroke or Dementia

BACKGROUND AND OBJECTIVES

Mounting evidence indicates that hypertension leads to a higher risk of dementia. Hypertension is a highly heritable trait, and a higher polygenic susceptibility to hypertension (PSH) is known to associate with a higher risk of dementia. We tested the hypothesis that a higher PSH leads to worse cognitive performance in middle-aged persons without dementia. Confirming this hypothesis would support follow-up research focused on using hypertension-related genomic information to risk-stratify middle-aged adults before hypertension develops.

METHODS

We conducted a nested cross-sectional genetic study within the UK Biobank (UKB). Study participants with a history of dementia or stroke were excluded. We categorized participants as having low (≤20th percentile), intermediate, or high (≥80th percentile) PSH according to results of 2 polygenic risk scores for systolic and diastolic blood pressure (BP) generated with data on 732 genetic risk variants. A general cognitive ability score was calculated as the first component of an analysis that included the results of 5 cognitive tests. Primary analyses focused on Europeans, and secondary analyses included all race/ethnic groups.

RESULTS

Of the 502,422 participants enrolled in the UKB, 48,118 (9.6%) completed the cognitive evaluation, including 42,011 (8.4%) of European ancestry. Multivariable regression models using systolic BP-related genetic variants indicated that compared with study participants with a low PSH, those with intermediate and high PSH had reductions of 3.9% (β -0.039, SE 0.012) and 6.6% (β -0.066, SE 0.014), respectively, in their general cognitive ability score (p < 0.001). Secondary analyses including all race/ethnic groups and using diastolic BP-related genetic variants yielded similar results (p < 0.05 for all tests). Analyses evaluating each cognitive test separately indicated that reaction time, numeric memory, and fluid intelligence drove the association between PSH and general cognitive ability score (all individual tests, p < 0.05).

DISCUSSION

Among nondemented, community-dwelling, middle-aged Britons, a higher PSH is associated with worse cognitive performance. These findings suggest that genetic predisposition to hypertension influences brain health in persons who have not yet developed dementia. Because information on genetic risk variants for elevated BP is available long before the development of hypertension, these results lay the foundation for further research focused on using genomic data for the early identification of high-risk middle-aged adults.

Late-onset hereditary ataxias with dementia

PURPOSE OF REVIEW

Late-onset genetic cerebellar ataxias are clinically heterogenous with variable phenotypes. Several of these conditions are commonly associated with dementia. Recognition of the relationship between ataxia and dementia can guide clinical genetic evaluation.

RECENT FINDINGS

Spinocerebellar ataxias often present with variable phenotypes that may include dementia. Genomic studies have begun to identify links between incomplete penetrance and such variable phenotypes in certain hereditary ataxias. Recent studies evaluating the interaction of TBP repeat expansions and STUB1 sequence variants provide a framework to understand how genetic interactions influence disease penetrance and dementia risk in spinocerebellar ataxia types 17 and 48. Further advances in next generation sequencing methods will continue to improve diagnosis and create new insights into the expressivity of existing disorders.

SUMMARY

The late-onset hereditary ataxias are a clinically heterogenous group of disorders with complex presentations that can include cognitive impairment and/or dementia. Genetic evaluation of late-onset ataxia patients with dementia follows a systemic testing approach that often utilizes repeat expansion testing followed by next-generation sequencing. Advances in bioinformatics and genomics is improving both diagnostic evaluation and establishing a basis for phenotypic variability. Whole genome sequencing will likely replace exome sequencing as a more comprehensive means of routine testing.

Weight Loss Is a Strong Predictor of Memory Disorder Independent of Genetic Influences

BACKGROUND

Past studies identified a link between weight loss and dementia, but lacked consistent conclusions. We sought to establish this link by examining the weight change profiles before and after dementia diagnosis.

METHODS

Using data from the Health and Retirement Study (1996-2020), we examined 13,123 participants. We conducted a nested case-control analysis to assess differences in biennial weight change profile while controlling for BMI, longevity polygenic risk scores, and APOE gene variants.

RESULTS

Participants with a memory disorder lost weight (-0.63%) biennially, whereas those without a diagnosis did not (+0.013%, p-value < 0.0001). Our case-control study shows a significant difference (p-value < 0.01) in pre-dementia % weight changes between the cases (-0.29%) and controls (0.19%), but not in post-dementia weight changes. The weight loss group have the highest risk (OR = 2.01; p-value < 0.0001) of developing a memory disorder compared to the stable weight and weight gain groups. The observations hold true after adjusting for BMI, longevity polygenic risk scores, and APOE variant in a multivariable model.

CONCLUSIONS

We observe that weight loss in dementia is a physiological process independent of genetic factors associated with BMI and longevity. Pre-dementia weight loss may be an important prognostic criterion to assess a person's risk of developing a memory disorder.

Telomere length and brain imaging phenotypes in UK Biobank

Telomeres form protective caps at the ends of chromosomes, and their attrition is a marker of biological aging. Short telomeres are associated with an increased risk of neurological and psychiatric disorders including dementia. The mechanism underlying this risk is unclear, and may involve brain structure and function. However, the relationship between telomere length and neuroimaging markers is poorly characterized. Here we show that leucocyte telomere length (LTL) is associated with multi-modal MRI phenotypes in 31,661 UK Biobank participants. Longer LTL is associated with: i) larger global and subcortical grey matter volumes including the hippocampus, ii) lower T1-weighted grey-white tissue contrast in sensory cortices, iii) white-matter microstructure measures in corpus callosum and association fibres, iv) lower volume of white matter hyperintensities, and v) lower basal ganglia iron. Longer LTL was protective against certain related clinical manifestations, namely all-cause dementia (HR 0.93, 95% CI: 0.91-0.96), but not stroke or Parkinson's disease. LTL is associated with multiple MRI endophenotypes of neurodegenerative disease, suggesting a pathway by which longer LTL may confer protective against dementia.

African ancestry GWAS of dementia in a large military cohort identifies significant risk loci

While genome wide association studies (GWASs) of Alzheimer's Disease (AD) in European (EUR) ancestry cohorts have identified approximately 83 potentially independent AD risk loci, progress in non-European populations has lagged. In this study, data from the Million Veteran Program (MVP), a biobank which includes genetic data from more than 650,000 US Veteran participants, was used to examine dementia genetics in an African descent (AFR) cohort. A GWAS of Alzheimer's disease and related dementias (ADRD), an expanded AD phenotype including dementias such as vascular and non-specific dementia that included 4012 cases and 18,435 controls age 60+ in AFR MVP participants was performed. A proxy dementia GWAS based on survey-reported parental AD or dementia (n = 4385 maternal cases, 2256 paternal cases, and 45,970 controls) was also performed. These two GWASs were meta-analyzed, and then subsequently compared and meta-analyzed with the results from a previous AFR AD GWAS from the Alzheimer's Disease Genetics Consortium (ADGC). A meta-analysis of common variants across the MVP ADRD and proxy GWASs yielded GWAS significant associations in the region of APOE (p = 2.48 × 10-101), in ROBO1 (rs11919682, p = 1.63 × 10-8), and RNA RP11-340A13.2 (rs148433063, p = 8.56 × 10-9). The MVP/ADGC meta-analysis yielded additional significant SNPs near known AD risk genes TREM2 (rs73427293, p = 2.95 × 10-9), CD2AP (rs7738720, p = 1.14 × 10-9), and ABCA7 (rs73505251, p = 3.26 × 10-10), although the peak variants observed in these genes differed from those previously reported in EUR and AFR cohorts. Of the genes in or near suggestive or genome-wide significant associated variants, nine (CDA, SH2D5, DCBLD1, EML6, GOPC, ABCA7, ROS1, TMCO4, and TREM2) were differentially expressed in the brains of AD cases and controls. This represents the largest AFR GWAS of AD and dementia, finding non-APOE GWAS-significant common SNPs associated with dementia. Increasing representation of AFR participants is an important priority in genetic studies and may lead to increased insight into AD pathophysiology and reduce health disparities.

Well-Being and Cognitive Resilience to Dementia-Related Neuropathology

Not all older adults with dementia-related neuropathology in their brains experience cognitive decline or impairment. Instead, some people maintain relatively normal cognitive functioning despite neuropathologic burden, a phenomenon called cognitive resilience. Using a longitudinal, epidemiological, clinical-pathologic cohort study of older adults in the United States (N = 348), the present research investigated associations between well-being and cognitive resilience. Consistent with preregistered hypotheses, results showed that higher eudaimonic well-being (measured via the Ryff Psychological Well-Being Scale) and higher hedonic well-being (measured via the Satisfaction with Life Scale) were associated with better-than-expected cognitive functioning relative to one's neuropathological burden (i.e., beta-amyloid, neurofibrillary tangles, Lewy bodies, vascular pathologies, hippocampal sclerosis, and TDP-43). The association of eudaimonic well-being in particular was present above and beyond known cognitive resilience factors (i.e., socioeconomic status, education, cognitive activity, low neuroticism, low depression) and dementia risk factors (i.e., apolipoprotein E [ApoE] genotype, medical comorbidities). This research highlights the importance of considering eudaimonic well-being in efforts to prevent dementia.

Deep phenotyping and genomic data from a nationally representative study on dementia in India

The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) is a nationally representative in-depth study of cognitive aging and dementia. We present a publicly available dataset of harmonized cognitive measures of 4,096 adults 60 years of age and older in India, collected across 18 states and union territories. Blood samples were obtained to carry out whole blood and serum-based assays. Results are included in a venous blood specimen datafile that can be linked to the Harmonized LASI-DAD dataset. A global screening array of 960 LASI-DAD respondents is also publicly available for download, in addition to neuroimaging data on 137 LASI-DAD participants. Altogether, these datasets provide comprehensive information on older adults in India that allow researchers to further understand risk factors associated with cognitive impairment and dementia.

Meta-Analysis of Variations in Association between APOE ɛ4 and Alzheimer's Disease and Related Dementias Across Hispanic Regions of Origin

BACKGROUND

Emerging research has shown racial and ethnic variations in the magnitude of association between the apolipoprotein ɛ4 (APOE ɛ4) allele and the risk of developing Alzheimer's disease and related dementias (ADRD). Studies researching this association among Hispanic groups within and outside of the United States have produced inconsistent results.

OBJECTIVE

To examine the association between the APOE ɛ4 allele and the risk of developing ADRD in global Hispanic populations from different ethnic regions of origin.

METHODS

PubMed, Embase, Scopus, and PsycInfo were searched for studies relating to Hispanic/Latin American origin, APOE ɛ4, and ADRD. Odds ratios (OR) of ADRD risk for individuals with APOE ɛ4 versus those without APOE ɛ4 were extracted and calculated using random effects analysis.

RESULTS

20 eligible studies represented Caribbean Hispanic, Mexican, South American, Spanish, and Cuban groups. Overall, APOE ɛ4 was significantly associated with increased risk of ADRD (Odds Ratio [OR] 3.80, 95% CI: 2.38-6.07). The association was only significant in the South American (OR: 4.61, 95% CI: 2.74-7.75) subgroup.

CONCLUSION

There was an association between APOE ɛ4 and increased ADRD risk for the South American subgroup. The strength of this association varied across Hispanic subgroups. Data is limited with more studies especially needed for adjusted analysis on Spanish, Central American, Cuban Hispanic, and Caribbean Hispanic groups. Results suggest additional environmental or genetic risk factors are associated with ethnic variations.

Mendelian randomization study on the causal effect of chickenpox on dementia

Some viruses, such as varicella zoster virus, are associated with severe dementia. The present study aims to identify the causal link between chickenpox and dementia. To date, the largest publicly available genome-wide association study (GWAS) for chickenpox (710 cases and 211 856 controls from European individuals) and for dementia (5933 cases and 212 859 controls from European individuals) were used to performed this two-sample Mendelian randomization (MR) study. We found no significant pleiotropy or heterogeneity in all seven selected chickenpox genetic instrumental variants in dementia GWAS. Of seven chickenpox genetic variants, two are located in the intergenic region and five are located in intron. We found that as chickenpox genetically increased, dementia risk increased based on an inverse-variance weighted analysis (β = 0.070, 95% confidence interval [CI] for β: 0.014-0.126; odds ratio [OR] = 1.073, 95% CI for OR: 1.015-1.134; p = 0.014) and weighted median (β = 0.071, 95% CI for β: 0.002-0.141; OR = 1.074, 95% CI for OR: 1.002-1.152; p = 0.045). Reverse MR analysis showed no causal effect of dementia on chickenpox. Our analysis suggests a causal effect of genetically increased chickenpox on dementia risk. Thus, chickenpox may be a potential risk factor for dementia.

Family History of Dementia in Old-Age Participants with Subjective Memory Complaints Predicts Own Risk for Dementia in a Longitudinal Multi-Center Cohort Study

BACKGROUND

Subjective memory complaints and family history of dementia are possibly intertwined risk factors for the own subsequent dementia risk and Alzheimer's disease. However, their interaction has rarely been studied.

OBJECTIVE

To study the association between subjective memory complaints and family history of dementia with regard to the own subsequent risk of dementia.

METHODS

Cross-sectional and longitudinal analyses over a follow-up period of up to 13 years were conducted in a population sample of participants without dementia at baseline (n = 3,256, mean age = 79.62 years), using group comparisons and Cox proportional hazards models.

RESULTS

Cross-sectionally, participants with subjective memory complaints were significantly more likely to report family history of dementia. Longitudinally, family history of dementia (FH) was significantly associated with subsequent dementia in the subjective memory complaints (SMC) group, but not in those without SMC. A relative excess risk due to interaction analysis confirmed a significant FHxSMC-interaction.

CONCLUSIONS

Family history of dementia was a predictor of incident dementia in those with SMC, which can serve as an additional, clinically relevant criterion to gauge the risk of dementia in older-aged subjects with SMC with and without objective cognitive impairment.