Journal of Alzheimer's Disease - Volume Pre-press, issue Pre-press

Authors: Parker, Daniel C. | Kraus, William E. | Whitson, Heather E. | Kraus, Virginia B. | Smith, Patrick J. | Cohen, Harvey Jay | Pieper, Carl F. | Faldowski, Richard A. | Hall, Katherine S. | Huebner, Janet L. | Ilkayeva, Olga R. | Bain, James R. | Newby, L. Kristin | Huffman, Kim M.

Article Type: Research Article

Abstract: Background: The kynurenine pathway (KP) comprises a family of tryptophan-derived metabolites that some studies have reported are associated with poorer cognitive performance and an increased risk of Alzheimer’s disease and related dementias (ADRD). Objective: The objective of this study was to determine the associations of plasma KP metabolites (kynurenine [KYN], kynurenic acid [KA], and tryptophan [TRP]) with a panel of plasma ADRD biomarkers (Aβ42 / β40 ratio, pTau-181, glial fibrillary acidic protein [GFAP], and neurofilament light [NfL]) and cognitive performance in a subset of older adults drawn from the Duke Physical Performance Across the LifeSpan (PALS) study. …Methods: The Montreal Cognitive Assessment (MoCA) was used to assess cognitive performance. We used multivariate multiple regression to evaluate associations of the KYN/TRP and KA/KYN ratios with MoCA score and plasma ADRD biomarkers at baseline and over two years (n  = 301; Age = 74.8±8.7). Results: Over two years, an increasing KYN/TRP ratio was associated with increasing plasma concentrations of plasma p-Tau181 (β= 6.151; 95% CI [0.29, 12.01]; p  = 0.040), GFAP (β= 11.12; 95% CI [1.73, 20.51 ]; p  = 0.020), and NfL (β= 11.13; 95% CI [2.745, 19.52 ]; p  = 0.009), but not MoCA score or the Aβ42 /Aβ40 ratio. There were no significant associations of KA/KYN with MoCA score or plasma ADRD biomarkers. Conclusion: Our findings provide evidence that greater concentrations of KP metabolites are associated longitudinally over two years with greater biomarker evidence of neurofibrillary tau pathology (pTau-181), neuroinflammation (GFAP), and neurodegeneration (NfL), suggesting that dysregulated KP metabolism may play a role in ADRD pathogenesis. Show more

Keywords: Alzheimer’s disease and related dementias, biomarkers, cognition, kynurenines, tryptophan

DOI: 10.3233/JAD-220906

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-10, 2022

Authors: Leng, Yue | Stone, Katie L. | Yaffe, Kristine

Article Type: Research Article

Abstract: Background: The effect of sleep medications on cognition in older adults is controversial, possibly dependent upon sleep quality, and may differ by race. Objective: To determine the longitudinal association between sleep medication use and incident dementia over 15 years, and to explore whether the association is independent of nighttime sleep disturbances and if it differs by race. Methods: We examined 3,068 community-dwelling older adults (aged 74.1±2.9 years, 41.7% Black, 51.5% female) without dementia. Sleep medication use was recorded three times by asking “Do you take sleeping pills or other medications to help you sleep?” with the …response options: “Never (0)”, “Rarely (≤1/month)”, “Sometimes (2–4/month)”, “Often (5–15/month)”, or “Almost Always (16–30/month)”. Incident dementia was defined using hospitalization records, dementia medication prescription or clinically significant decline in global cognition. Results: 138 (7.71%) of Whites and 34 (2.66%) of Blacks reported taking sleep medications “often or almost always”. Whites were almost twice as likely to take all prescription hypnotics. 617 participants developed dementia over the follow-up. After adjustment for all covariates, participants who reported taking sleep medications ≥ 5/month versus ≤1/month were significantly more likely to develop dementia, and the association was only observed among Whites (HR = 1.79,1.21–2.66) but not Blacks (HR = 0.84,0.38–1.83); p for interaction = 0.048. Further adjustment for nighttime sleep did not appreciably alter the results. The association was similar for the cumulative frequency of sleep medication use and remained after introducing a time lag of 3 years. Conclusion: Frequent sleep medication use was associated with an increased risk of dementia in White older adults. Further research is needed to determine underlying mechanisms. Show more

Keywords: Dementia, epidemiology, medication, race, sleep

DOI: 10.3233/JAD-221006

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-7, 2022

Authors: Liu, Jia-Yao | Ma, Ling-Zhi | Wang, Jun | Cui, Xin-Jing | Sheng, Ze-Hu | Fu, Yan | Li, Meng | Ou, Ya-Nan | Yu, Jin-Tai | Tan, Lan | Lian, Yan

Article Type: Research Article

Abstract: Background: APOE ɛ4 genotype was correlated with exacerbation of pathology and higher risk of dementia in Parkinson’s disease (PD). Meanwhile, the differential influence of APOE ɛ4 on cognition in young and old individuals interpreted as antagonistic pleiotropy. Objective: To examine whether the effect of APOE ɛ4 on cognitive progression in de novo PD is age dependent. Methods: In this study, 613 de novo PD patients were recruited from Parkinson’s Progression Markers Initiative (PPMI). To examine the age-dependent relationship between APOE ɛ 4 and cognitive changes, we added 3-way interaction of …APOE ɛ4*baseline age*time to the linear mixed-effect (LME) models and evaluated the specific roles of APOE ɛ4 in the middle age group and elderly group separately. Cox regression was utilized to examine the progression of cognition in age-stratified PD participants. Results: Age significantly modified relationship between APOE ɛ4 and cognitive changes in most cognitive domains (pinteraction <0.05). In the elderly group, APOE ɛ4 carriers showed steeper decline in global cognition (p  = 0.001) as well as in most cognitive domains, and they had a greater risk of cognitive progression (adjusted HR 1.625, 95% CI 1.143–2.310, p  = 0.007), compared with non-carriers. However, in the middle age group, no significant relationships between APOE ɛ4 and cognitive decline can be detected. Conclusion: Our results indicated that the APOE ɛ4 allele has an age-dependent effect on cognitive decline in PD patients. The underlying mechanisms need to be investigated in the future. Show more

Keywords: Age, APOE ɛ4, cognition, Parkinson’s disease

DOI: 10.3233/JAD-220976

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-12, 2022

Authors: Posis, Alexander Ivan B. | Yarish, Natalie M. | McEvoy, Linda K. | Jain, Purva | Kroenke, Candyce H. | Saquib, Nazmus | Ikramuddin, Farha | Schnatz, Peter F. | Bellettiere, John | Rapp, Stephen R. | Espeland, Mark A. | Shadyab, Aladdin H.

Article Type: Research Article

Abstract: Background: Social support may be a modifiable risk factor for cognitive impairment. However, few long-term, large prospective studies have examined associations of various forms of social support with incident mild cognitive impairment (MCI) and dementia. Objective: To examine associations of perceived social support with incident MCI and dementia among community-dwelling older women. Methods: This prospective cohort study included 6,670 women from the Women’s Health Initiative Memory Study who were cognitively unimpaired at enrollment. We used Cox proportional hazards models to assess associations between perceived social support with incident MCI, dementia, or either MCI/dementia during an average …10.7 (SD = 6.1)-year follow-up. Modelling was repeated for emotional/information support, affection support, tangible support, and positive social interaction subscales of social support. Results: Among 6,670 women (average age = 70 years [SD = 3.8]; 97.0% non-Hispanic/Latina; 89.8% White), greater perceived social support was associated with lower risk of MCI/dementia after adjustment for age, ethnicity, race, hormone therapy, education, income, diabetes, hypertension, and body mass index (Tertile [T]3 versus T1: HR = 0.85, 95% CI 0.74–0.99; p trend  = 0.08). Associations were significant for emotional/information support (T3 versus T1: HR = 0.84, 95% CI 0.72–0.97; p trend  = 0.04) and positive social interaction (T3 versus T1: HR = 0.85, 95% CI 0.72–0.99; p trend  = 0.06) subscales. Associations were attenuated and not significant after adjustment for depressive symptom severity. Objective: Perceived social support, emotional/information support, and positive social interaction were associated with incident MCI/dementia among older women. Results were not significant after adjustment for depressive symptom severity. Improving social support may reduce risk of MCI and dementia in older women. Show more

Keywords: Cognitive aging, epidemiology, psychosocial, women’s health

DOI: 10.3233/JAD-220967

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-13, 2022

Authors: Eruysal, Emily | Ravdin, Lisa | Zhang, Cenai | Kamel, Hooman | Iadecola, Costantino | Ishii, Makoto

Article Type: Research Article

Abstract: Background: Plasminogen activator inhibitor-1 (PAI-1), an inhibitor of fibrinolysis that is associated with adiposity, has been implicated in Alzheimer’s disease (AD) pathogenesis. However, whether circulating PAI-1 levels are altered during preclinical AD remains unclear. Objective: To measure plasma PAI-1 levels in cognitively normal cerebrospinal fluid (CSF) AD biomarker positive and biomarker negative participants and to examine the association of plasma PAI-1 levels with CSF AD biomarkers and Mini-Mental State Examination (MMSE) scores. Methods: In this cross-sectional study, plasma PAI-1 levels were measured in 155 cognitively normal (Clinical Dementia Rating, CDR 0) non-obese older adults. 29 men …and 26 women were classified as preclinical AD by previously established CSF tau/Aβ42 criteria. All analyses were sex stratified due to reported sex differences in PAI-1 expression. Results: Plasma PAI-1 levels were associated with body mass index (BMI) but not age in men and women. In men, plasma PAI-1 levels and BMI were lower in preclinical AD compared to control. Plasma PAI-1 levels were positively associated with CSF amyloid-β42 (Aβ42) and CSF Aβ42/Aβ40 and negatively associated with CSF tau/Aβ42, while BMI was positively associated with CSF Aβ42 and negatively associated with CSF p-tau181 and CSF tau/Aβ42. In women, plasma PAI-1 levels and BMI were similar between preclinical AD and control and were not associated with CSF AD biomarkers. For men and women, plasma PAI-1 levels and BMI were not associated with MMSE scores. Conclusion: These findings suggest that there are significant sex differences in the systemic metabolic changes seen in the preclinical stage of AD. Show more

Keywords: Adipokines, Alzheimer’s disease, amyloid beta-peptides, body weight, body mass index, biomarker, immunoassay, PAI-1, sexual dimorphism, tau proteins

DOI: 10.3233/JAD-220686

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-11, 2022

Authors: Chen, Yuzhao | Zhang, Yilin | Chen, Qiuxuan | Liu, Yuxiang | Wei, Xuemin | Wu, Meijian | Zhang, Keke | Liu, Yinghua | Wei, Wei

Article Type: Research Article

Abstract: Background: The metabotropic glutamate receptor 5 (mGluR5) is widely expressed in postsynaptic neurons and plays a vital role in the synaptic plasticity of the central nervous system. mGluR5 is a coreceptor for amyloid-β (Aβ) oligomer, and downregulation or pharmacological blockade of mGluR5 presents the therapeutic potential of Alzheimer’s disease (AD). However, the abnormality of mGluR5 in the pathogenesis of AD and its mechanism of pathology is not clear. Objective: In this study, we would like to investigate the expression of mGluR5 in the process of AD and explore the effects and the underlying mechanisms of antagonizing mGluR5 on …cognitive function, synaptic structure, and inflammation in 5xFAD mice. Methods: mGluR5 expression and interactions with PrPc in 5XFAD mice were detected using western blot and co-immunoprecipitation. The selective mGluR5 antagonist MPEP was infused into 4-month-old 5XFAD mice for 60 consecutive days. Then, cognitive function, AD-like pathology and synaptic structure were measured. Further observations were made in mGluR5 knockdown 5XFAD mice. Results: mGluR5 expression was increased with Aβ levels at 6 months in 5XFAD mice. mGluR5 antagonist rescued cognitive disorders, promoted synaptic recovery, and alleviated both the Aβ plaque load and abnormal hyperphosphorylation in 6-month-old 5XFAD mice. Meanwhile, the results were validated in mGluR5 knockdown mice. Blockade of mGluR5 efficiently alleviates AD-like pathologies by inhibiting the PI3K/AKT/mTOR pathway and activates autophagy in 5XFAD mice. Furthermore, antagonism of mGluR5 attenuated neuroinflammation by inactivating the IKK/NF-κ B pathway. Conclusion: These findings suggest that mGluR5 may be an effective drug target for AD treatment, and inhibition of the mGluR5/PI3K-AKT pathway alleviates AD-like pathology by activating autophagy and anti-neuroinflammation in 5XFAD mice. Show more

Keywords: Alzheimer’s disease, autophagy, mGluR5, MPEP, neuroinflammation

DOI: 10.3233/JAD-221058

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-18, 2022

Authors: Chai, Yuek Ling | Liang, Nathan Hao Ping | Chong, Joyce R. | Venketasubramanian, Narayanaswamy | Tan, Boon Yeow | Hilal, Saima | Chen, Christopher P. | Lai, Mitchell K. P.

Article Type: Research Article

Abstract: Background: The lysosomal protease cathepsin D (catD) has been reported to be upregulated in postmortem Alzheimer’s disease (AD) cortex, where it colocalized with neurofibrillary tangles and correlated with levels of phosphorylated tau, suggesting pathophysiological links between catD and neurodegeneration. In contrast, studies of serum catD in AD have yielded conflicting results, and potential associations between baseline serum catD and functional outcomes of patients are at present unknown. Objective: We aimed to examine the status of serum catD in a Singapore-based longitudinal study of dementia and investigate catD associations with functional and cognitive decline. Methods: 35 subjects …with no cognitive impairment, 40 patients with cognitive impairment no dementia and 34 with AD dementia underwent annual neuropsychological assessments (mean follow-up=4.3 years), as well as collection of baseline serum for catD measurements by ELISA. Results: Higher serum catD at baseline was associated with AD clinical diagnosis (odds ratios [OR]: 10.0; 95% confidence interval [CI]: 1.02–97.95) as well as with cortical atrophy. Furthermore, higher catD was associated with global cognitive and functional decline (OR: 9.94; 95% CI: 1.02–97.34). Conclusion: The associations of serum catD with AD dementia as well as atrophy provide further support for the proposed links between catD and neurodegeneration, as well as for the assessment of serum catD as a prognostic biomarker predicting global cognitive and functional decline in larger studies. Show more

Keywords: Alzheimer’s disease, brain atrophy, cathepsin D, cognitive decline, lysosomal protease, neurodegeneration

DOI: 10.3233/JAD-220852

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-10, 2022

Authors: Huang, Wenhao | Xia, Qing | Zheng, Feifei | Zhao, Xue | Ge, Fangliang | Xiao, Jiaying | Liu, Zijie | Shen, Yingying | Ye, Ke | Wang, Dayong | Li, Yanze

Article Type: Review Article

Abstract: The neurovascular unit (NVU) is involved in the pathological changes in Alzheimer’s disease (AD). The NVU is a structural and functional complex that maintains microenvironmental homeostasis and metabolic balance in the central nervous system. As one of the most important components of the NVU, microglia not only induce blood-brain barrier breakdown by promoting neuroinflammation, the infiltration of peripheral white blood cells and oxidative stress but also mediate neurovascular uncoupling by inducing mitochondrial dysfunction in neurons, abnormal contraction of cerebral vessels, and pericyte loss in AD. In addition, microglia-mediated dysfunction of cellular components in the NVU, such as astrocytes and pericytes, …can destroy the integrity of the NVU and lead to NVU impairment. Therefore, we review the mechanisms of microglia-mediated NVU dysfunction in AD. Furthermore, existing therapeutic advancements aimed at restoring the function of microglia and the NVU in AD are discussed. Finally, we predict the role of pericytes in microglia-mediated NVU dysfunction in AD is the hotspot in the future. Show more

Keywords: Alzheimer’s disease, blood-brain barrier, microglia, neurovascular uncoupling, neurovascular unit, pericyte

DOI: 10.3233/JAD-221064

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-20, 2023

Authors: Guo, Xiaodi | Zhang, Guoxin | Peng, Qinyu | Huang, Liqin | Zhang, Zhaohui | Zhang, Zhentao

Article Type: Review Article

Abstract: Meningeal lymphatic vessels (mLVs), the functional lymphatic system present in the meninges, are the key drainage route responsible for the clearance of molecules, immune cells, and cellular debris from the cerebrospinal fluid and interstitial fluid into deep cervical lymph nodes. Aging and ApoE4, the two most important risk factors for Alzheimer’s disease (AD), induce mLV dysfunction, decrease cerebrospinal fluid influx and outflux, and exacerbate amyloid pathology and cognitive dysfunction. Dysfunction of mLVs results in the deposition of metabolic products, accelerates neuroinflammation, and promotes the release of pro-inflammatory cytokines in the brain. Thus, mLVs represent a novel therapeutic target for treating …neurodegenerative and neuroinflammatory diseases. This review aims to summarize the structure and function of mLVs and to discuss the potential effect of aging and ApoE4 on mLV dysfunction, as well as their roles in the pathogenesis of AD. Show more

Keywords: Alzheimer’s disease, amyloid-β, Apolipoprotein E4, meningeal lymphatic vessels, tau

DOI: 10.3233/JAD-221016

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-12, 2022

Authors: Daly, Timothy | Henry, Vincent | Bourdenx, Mathieu

Article Type: Review Article

Abstract: Background: Many putative causes and risk factors have been associated with outcomes in Alzheimer’s disease (AD) but all attempts at disease-modifying treatment have failed to be clinically significant. Efforts to address this “association—intervention” mismatch have tended to focus on the novel design of interventions. Objective: Here, we instead deal with the notion of association in depth. We introduce the concept of disease-associated process (DAP) as a flexible concept that can unite different areas of study of AD from genetics to epidemiology to identify disease-modifying targets. Methods: We sort DAPs using three properties: specificity for AD, frequency …in patients, and pathogenic intensity for dementia before using a literature review to apply these properties in three ways. Firstly, we describe and visualize known DAPs. Secondly, we exemplify qualitative specificity analysis with the DAPs of tau protein pathology and autophagy to reveal their differential implication in AD. Finally, we use DAP properties to define the terms “risk factor,” “cause,” and “biomarker.” Results: We show how DAPs fit into our collaborative disease ontology, the Alzheimer’s Disease-Associated Processes and Targets (ADAPT) ontology. We argue that our theoretical system can serve as a democratic research forum, offering a more biologically adequate view of dementia than reductionist models. Conclusion: The ADAPT ontology is a tool that could help to ground debates around priority setting using objective criteria for the identifying of targets in AD. Further efforts are needed to address issues of how biomedical research into AD is prioritized and funded. Show more

Keywords: Alzheimer’s disease, association, autophagy, biomarker, cause, disease ontology, intervention, risk factors, specificity, tau

DOI: 10.3233/JAD-221004

Citation: Journal of Alzheimer's Disease, vol. Pre-press, no. Pre-press, pp. 1-10, 2022