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Royall DR, Palmer RF. INFLAMMATION's cognitive impact revealed by a novel "Line of Identity" approach. PLoS One 2024; 19:e0295386. [PMID: 38517924 PMCID: PMC10959355 DOI: 10.1371/journal.pone.0295386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 11/22/2023] [Indexed: 03/24/2024] Open
Abstract
IMPORTANCE Dementia is an "overdetermined" syndrome. Few individuals are demented by any single biomarker, while several may independently explain small fractions of dementia severity. It may be advantageous to identify individuals afflicted by a specific biomarker to guide individualized treatment. OBJECTIVE We aim to validate a psychometric classifier to identify persons adversely impacted by inflammation and replicate it in a second cohort. DESIGN Secondary analyses of data collected by the Texas Alzheimer's Research and Care Consortium (TARCC) (N = 3497) and the Alzheimer's Disease Neuroimaging Initiative (ADNI) (N = 1737). SETTING Two large, well-characterized multi-center convenience samples. PARTICIPANTS Volunteers with normal cognition (NC), Mild Cognitive Impairment (MCI) or clinical "Alzheimer's Disease (AD)". EXPOSURE Participants were assigned to "Afflicted" or "Resilient" classes on the basis of a psychometric classifier derived by confirmatory factor analysis. MAIN OUTCOME(S) AND MEASURE(S) The groups were contrasted on multiple assessments and biomarkers. The groups were also contrasted regarding 4-year prospective conversions to "AD" from non-demented baseline diagnoses (controls and MCI). The Afflicted groups were predicted to have adverse levels of inflammation-related blood-based biomarkers, greater dementia severity and greater risk of prospective conversion. RESULTS In ADNI /plasma, 47.1% of subjects were assigned to the Afflicted class. 44.6% of TARCC's subjects were afflicted, 49.5% of non-Hispanic Whites (NHW) and 37.2% of Mexican Americans (MA). There was greater dementia severity in the Afflicted class [by ANOVA: ADNI /F(1) = 686.99, p <0.001; TARCC /F(1) = 1544.01, p <0.001]. "INFLAMMATION" factor composite scores were significantly higher (adverse) in Afflicted subjects [by ANOVA in ADNI /plasma F(1) = 1642.64, p <0.001 and in TARCC /serum F(1) = 3059.96, p <0.001]. Afflicted cases were more likely to convert to AD in the next four years [by Cox's F, ADNI /plasma: F (252, 268) = 3.74 p < 0.001; TARCC /serum: F (160, 134) = 3.03, p < 0.001 (in TARCC's entire sample), F (110, 90) = 4.92, p <0.001 in NHW, and F(50, 44) = 2.13, p = 0.006 in MA]. The proportions converting were similar among afflicted NHW in both cohorts /biofluids but MA exhibited a lower risk (7% in TARCC /serum at 48 months). CONCLUSIONS AND RELEVANCE Our inflammation-specific psychometric classifier selects individuals with pre-specified biomarker profiles and predicts conversion to "AD" across cohorts, biofluids, and ethnicities. This algorithm might be applied to any dementia-related biomarker making the psychometric estimation of individual biomarker effects feasible without biomarker assessment. Our approach also distinguishes individuals resilient to individual biomarker effects allowing for more accurate prediction and precision intervention.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry and Behavioral Science, The University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Medicine, The University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, Texas, United States of America
- The Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Disease, The University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Raymond F. Palmer
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, Texas, United States of America
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Royall DR, Palmer RF. Statin use moderates APOE's and CRP's associations with dementia and is associated with lesser dementia severity in ε4 carriers. Alzheimers Dement 2024; 20:1627-1636. [PMID: 38055626 PMCID: PMC10984456 DOI: 10.1002/alz.13543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/21/2023] [Accepted: 10/01/2023] [Indexed: 12/08/2023]
Abstract
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.
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Affiliation(s)
- Donald R. Royall
- Department of PsychiatryUniversity of Texas Health Science CenterSan AntonioTexasUSA
- Department of MedicineUniversity of Texas Health Science CenterSan AntonioTexasUSA
- Department of Family and Community MedicineUniversity of Texas Health Science CenterSan AntonioTexasUSA
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative DisordersSan AntonioUSA
| | - Raymond F. Palmer
- Department of Family and Community MedicineUniversity of Texas Health Science CenterSan AntonioTexasUSA
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Royall DR, Palmer RF. Multiple Adipokines Predict Dementia Severity as Measured by δ: Replication Across Biofluids and Cohorts. J Alzheimers Dis 2023; 92:639-652. [PMID: 36776066 DOI: 10.3233/jad-221052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
BACKGROUND We have explored dementia's blood-based protein biomarkers in the Texas Alzheimer's Research and Care Consortium (TARCC) study. Among them are adipokines, i.e., proteins secreted by adipose tissue some of which have been associated with cognitive impairment. OBJECTIVE To associate adipokines with dementia severity and replicate their association across cohorts and biofluids (serum /plasma). METHODS We used eight rationally chosen blood-based protein biomarkers as indicators of a latent variable, i.e., "Adipokines". We then associated that construct with dementia severity as measured by the latent dementia-specific phenotype "δ" in structural equation models (SEM). Significant factor loadings and Adipokines' association with δ were replicated across biofluids in the Alzheimer's Disease Neuroimaging Initiative (ADNI). RESULTS Eight adipokine proteins loaded significantly on the Adipokines construct. Adipokines measured in plasma (ADNI) or serum (TARCC) explained 24 and 70% of δ's variance, respectively. An Adipokine composite score, derived from the latent variables, rose significantly across clinical diagnoses and achieved high areas under the receiver operating characteristic curve (ROC/AUC) for discrimination of Alzheimer's disease from normal controls (NC) or cases of mild cognitive impairment (MCI) and between NC and MCI. CONCLUSION These results again suggest that SEM can be used to create latent biomarker classifiers that replicate across samples and biofluids, and that a substantial fraction of dementia's variance is attributable to peripheral blood-based protein levels via the patterns codified in those latent constructs.
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Affiliation(s)
- Donald R Royall
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, TX, USA.,Department of Medicine, the University of Texas Health Science Center, San Antonio, TX, USA.,Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA.,The Glenn Biggs Institute for Alzheimer's and Neurodegenerative Disease, the University of Texas Health ScienceCenter, San Antonio, TX, USA
| | - Raymond F Palmer
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
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Royall DR, Palmer RF. δ-Related Biomarkers Attenuate Multiple Alzheimer's Disease Conversion Risks and Offer Targets for Intervention. J Gerontol A Biol Sci Med Sci 2020; 75:2177-2183. [PMID: 31665233 DOI: 10.1093/gerona/glz253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND We tested certain serum proteins' ability to mediate the effects of demographic variables on prospective 5-year conversion to clinical "Alzheimer's disease" from non-demented states (i.e. normal control and mild cognitive impairment). The proteins were rationally selected from previously published mediators of those same variables' (plural posessive) association with the latent variable "δ," a novel omnibus dementia severity metric. METHODS Each protein's attenuation of its risk factor's independent association with conversion was performed using logistic regression, adjusted for education, ethnicity, self-reported diabetes mellitus, and hypertension, among initially non-demented Mexican American and non-Hispanic white (N = 772) participants in the Texas Alzheimer's Research and Care Consortium. RESULTS A total of 70 (9.1%) non-demented participants at baseline converted to "Alzheimer's disease", with a mean follow-up of 5.4 years. Age >80 years (odds ratio = 3.1), 30-item Geriatric Depression Scale >10/30 (odds ratio = 2.3), female gender (odds ratio = 2.2), and the presence of an apolipoprotein E ε4 allele (odds ratio = 2.4) were independently associated with prospective conversion. These effects were fully attenuated by five serum proteins: age: insulin-like growth factor-binding protein 2 and epidermal growth factor receptor 1; depression: resistin; gender: thrombopoietin; and apolipoprotein E: C-reactive protein. CONCLUSION Clinical dementia arises from the sum of independent δ-related processes. This analysis provides proof of concept for the rational selection of antidementia targets and offers a foundation for precision antidementia therapy.
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Affiliation(s)
- Donald R Royall
- Department of Psychiatry, The University of Texas Health Science Center, San Antonio, Texas
- Department of Medicine, The University of Texas Health Science Center, San Antonio, Texas
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, Texas
- The Glenn Biggs Institute for Alzheimer's and Neurodegenerative Disease, The University of Texas Health Science Center, San Antonio, Texas
| | - Raymond F Palmer
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, Texas
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Briceño EM, Mehdipanah R, Gonzales XF, Langa KM, Levine DA, Garcia NM, Longoria R, Giordani BJ, Heeringa SG, Morgenstern LB. Neuropsychological assessment of mild cognitive impairment in Latinx adults: A scoping review. Neuropsychology 2020; 34:493-510. [PMID: 32281811 DOI: 10.1037/neu0000628] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Objective: Latinx populations are rapidly growing and aging in the United States. There is a critical need to accurately and efficiently detect those at risk for dementia, particularly those with mild cognitive impairment (MCI). MCI diagnosis often relies on neuropsychological assessment, although cultural, demographic, and linguistic characteristics may impact test scores. This study provides a scoping review of neuropsychological studies on MCI in Hispanic/Latinx populations to evaluate how studies report and account for these factors in diagnosis of MCI. Method: Studies were identified using Web of Science, PubMed, and Scopus, using search terms (Hispanic* OR Latin* OR "Mexican American*" OR "Puerto Ric*" OR Caribbean) and ("Mild Cognitive Impairment" OR MCI). Studies using neuropsychological tests in diagnosis of MCI for Latinx individuals in the United States were identified. Sample characterization (e.g., country of origin, literacy, language preference and proficiency), neuropsychological testing methods (e.g., test selection and translation, normative data source), and method of MCI diagnosis were reviewed. Results: Forty-four articles met inclusion criteria. There was considerable variability in reporting of demographic, cultural and linguistic factors across studies of MCI in Latinx individuals. For example, only 5% of studies reported nativity status, 52% reported information on language preference and use, and 34% reported the method and/or source of test translation and adaptation. Conclusions: Future studies of diagnosis of MCI in Latinx individuals should report cultural details and use of appropriate neuropsychological assessment tools and normative data. This is important to accurately estimate the prevalence of MCI in Latinx individuals. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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Affiliation(s)
- Emily M Briceño
- Department of Physical Medicine and Rehabilitation, University of Michigan Medical School
| | | | | | - Kenneth M Langa
- Development Service (HSR&D), Center for Clinical Management Research (CCMR), University of Michigan
| | - Deborah A Levine
- Development Service (HSR&D), Center for Clinical Management Research (CCMR), University of Michigan
| | - Nelda M Garcia
- Department of Neurology, University of Michigan Medical School
| | - Ruth Longoria
- Department of Neurology, University of Michigan Medical School
| | - Bruno J Giordani
- Departments of Psychiatry, Neurology, and Psychology and School of Nursing, University of Michigan
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Royall DR, Bishnoi RJ, Palmer RF. Blood-based protein predictors of dementia severity as measured by δ: Replication across biofluids and cohorts. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2019; 11:763-774. [PMID: 31909176 PMCID: PMC6939046 DOI: 10.1016/j.dadm.2019.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Dementia severity can be empirically described by the latent dementia phenotype "δ" and its various composite "homologs". We have explored δ's blood-based protein biomarkers in the Texas Alzheimer's Research and Care Consortium (TARCC) study. However, it would be convenient to replicate those associations in the Alzheimer's Disease Neuroimaging Initiative (ADNI). To this end, we recently engineered a δ homolog from observed cognitive performance measures common to both projects (i.e., "dT2A"). METHODS We used nine rationally chosen peripheral blood-based protein biomarkers as indicators of a latent variable "INFLAMMATION". We then associated that construct with dT2A in structural equation models adjusted for age, gender, depressive symptoms, and apolipoprotein E (APOE) ε4 allelic burden. Significant factor loadings and INFLAMMATION's association with dT2A were confirmed in random splits of TARCC's relatively large sample, and across biofluids in the ADNI. RESULTS Nine proteins measured in serum (TARCC) or plasma (ADNI) explained ≅10% of dT2A's variance in both samples, independently of age, APOE, education, and gender. All loaded significantly on INFLAMMATION, and positively or negatively, depending on their known roles are PRO- or ANTI-inflammatory proteins, respectively. The parameters of interest were confirmed across random 50% splits of the TARCC's sample, and replicated across biofluids in the ADNI. DISCUSSION These results suggest that SEM can be used to replicate biomarker findings across samples and biofluids, and that a substantial fraction of dementia's variance is attributable to peripheral blood-based protein levels.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX, USA
- Department of Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
- Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
- The Biggs Institute for Alzheimer's and Neurodegenerative Disease, the University of Texas Health Science Center, San Antonio, TX, USA
| | - Ram J. Bishnoi
- The Department of Psychiatry, The Medical College of Georgia, Augusta, GA, USA
| | - Raymond F. Palmer
- Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
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Royall DR, Palmer RF. Blood-based protein mediators of senility with replications across biofluids and cohorts. Brain Commun 2019; 2:fcz036. [PMID: 32954311 PMCID: PMC7425523 DOI: 10.1093/braincomms/fcz036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/25/2019] [Accepted: 10/07/2019] [Indexed: 01/08/2023] Open
Abstract
Dementia severity can be quantitatively described by the latent dementia phenotype 'δ' and its various composite 'homologues'. We have explored δ's blood-based protein biomarkers in the Texas Alzheimer's Research and Care Consortium. However, it would be convenient to replicate them in the Alzheimer's Disease Neuroimaging Initiative. To that end, we have engineered a δ homologue from the observed cognitive performance measures common to both projects [i.e. 'd:Texas Alzheimer's Research and Care Consortium to Alzheimer's Disease Neuroimaging Initiative' (dT2A)]. In this analysis, we confirm 13/22 serum proteins as partial mediators of age's effect on dementia severity as measured by dT2A in the Texas Alzheimer's Research and Care Consortium and then replicate 4/13 in the Alzheimer's Disease Neuroimaging Initiative's plasma data. The replicated mediators of age-specific effects on dementia severity are adiponectin, follicle-stimulating hormone, pancreatic polypeptide and resistin. In their aggregate, the 13 confirmed age-specific mediators suggest that 'cognitive frailty' pays a role in dementia severity as measured by δ. We provide both discriminant and concordant support for that hypothesis. Weight, calculated low-density lipoprotein and body mass index are partial mediators of age's effect in the Texas Alzheimer's Research and Care Consortium. Biomarkers related to other disease processes (e.g. cerebrospinal fluid Alzheimer's disease-specific biomarkers in the Alzheimer's Disease Neuroimaging Initiative) are not. It now appears that dementia severity is the sum of multiple independent processes impacting δ. Each may have a unique set of mediating biomarkers. Age's unique effect appears to be at least partially mediated through proteins related to frailty. Age-specific mediation effects can be replicated across cohorts and biofluids. These proteins may offer targets for the remediation of age-specific cognitive decline (aka 'senility'), help distinguish it from other determinants of dementia severity and/or provide clues to the biology of Aging Proper.
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Affiliation(s)
- Donald R Royall
- Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
- Department of Medicine, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
- The Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Raymond F Palmer
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
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Royall DR, Palmer RF. Selection for depression-specific dementia cases with replication in two cohorts. PLoS One 2019; 14:e0216413. [PMID: 31150419 PMCID: PMC6544211 DOI: 10.1371/journal.pone.0216413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/21/2019] [Indexed: 01/01/2023] Open
Abstract
The latent variable "δ" (for "dementia") provides an etiologically "agnostic" omnibus dementia severity metric capable of recognizing the dementing potential of any condition. Depressive symptoms are independent predictors of δ and are thereby implicated as "dementing". Serum resistin levels partially mediate the association between depressive symptoms and δ. We use a novel "off-diagonal" CHI SQ algorithm to demonstrate our ability to select individuals demented solely by depression's effect in both the Texas Alzheimer's Research and Care Consortium (TARCC) (N ≌ 3,500), and the Alzheimer's Disease Neuroimaging Initiative (ADNI (N ≌ 1,750), and demonstrate the higher resistin levels of such cases in TARCC. This approach can be adapted to any δ-related dementia risk factor or biomarker and used identify individuals who might revert back to non-demented states after its successful treatment.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- South Texas Veterans’ Health System Audie L. Murphy Division Geriatric Research Education and Clinical Care Center, San Antonio, Texas, United States of America
| | - Raymond F. Palmer
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
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Royall DR, Palmer RF. A δ Homolog for Dementia Case Finding with Replication in the Alzheimer's Disease Neuroimaging Initiative. J Alzheimers Dis 2019; 67:67-79. [PMID: 30507569 DOI: 10.3233/jad-171053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dementia can be empirically described by the latent dementia phenotype "δ" and its various composite "homologs". We have explored δ's blood-based protein biomarkers in the Texas Alzheimer's Research and Care Consortium (TARCC) study. However, it would be convenient to replicate those associations in the Alzheimer's Disease Neuroimaging Initiative (ADNI). To this end, we have engineered a δ homolog from observed cognitive performance measures common to both projects. Our findings were replicated in randomly selected 50% splits of TARCC data (Group 1, N = 1,747; Group 2, N = 1,755), and then independently in ADNI (N = 1,737). The new δ homolog, i.e., "dT2A" (d-TARCC to ADNI), fit the data of both studies well, and was strongly correlated with dementia severity, as rated by the Clinical Dementia Rating Scale "sum of boxes" (TARCC: r = 0.99, p < 0.001; ADNI: r = 0.96, p < 0.001). dT2A achieved an area under the receiver operating characteristic curve of 0.981 (0.976-0.985) for the discrimination of Alzheimer's disease from normal controls in TARCC, and 0.988 (0.983-0.993) in ADNI. dT2A is the 12th δ homolog published to date, and opens the door to independent replications across these and similar studies.
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Affiliation(s)
- Donald R Royall
- Department of Psychiatry, The University of Texas Health Science Center, San Antonio, TX, USA
- Department of Medicine, The University of Texas Health Science Center, San Antonio, TX, USA
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, TX, USA
- South Texas Veterans' Health System Audie L. Murphy Division GRECC, San Antonio, TX, USA
| | - Raymond F Palmer
- Department of Family and Community Medicine, The University of Texas Health Science Center, San Antonio, TX, USA
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Royall DR, Palmer RF. δ Scores Identify Subsets of "Mild Cognitive Impairment" with Variable Conversion Risks. J Alzheimers Dis 2019; 70:199-210. [PMID: 31127788 DOI: 10.3233/jad-190266] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The latent variable "δ" (for "dementia) is a transdiagnostic measure of dementia severity. δ can be reified and applied to individuals as a composite "d-score". Like Spearman's general intelligence factor "g", δ can be constructed from almost any cognitive battery. So many are available that we must further distinguish each composite as a δ "homolog". Fourteen have been validated. All are strongly associated with dementia severity and potentially with mild cognitive impairment (MCI) conversion. OBJECTIVES To assess δ's impact on MCI conversion risk. METHODS A new δ homolog (dDx) was constructed in 1,230 Mexican-American (MA) and 2,215 non-Hispanic White (NHW) participants in the Texas Alzheimer's Research and Care Consortium (TARCC). 1,445 normal controls (NC) and 723 MCI were followed annually for up to 6 years. RESULTS Each SD decrease in the dDx score increased the risk of conversion sixteen-fold [OR = 16.39 (CI: 5.0-52.6)]. Cases below the optimal diagnostic threshold for Alzheimer's disease (AD) versus NC were labeled as having a functionally salient cognitive impairment (FSCI). Such cases were at a 73-fold increase risk of a diagnosis of AD [OR = 73.19 (95% CI: 58.3-92.0)]. However, 25.6% of MCI cases were also FSCI(+). They accounted disproportionately for prospective conversions. Age <80 years, the absence of an ɛ4 allele, <12 years of education, and MA ethnicity independently increased the risk of diagnosing FSCI as MCI. CONCLUSION A sizable minority of MCI cases may be misdiagnosed and they account disproportionately for AD conversions.
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Affiliation(s)
- Donald R Royall
- Departments of Psychiatry, The University of Texas Health Science Center, San Antonio, TX, USA
- Departments of Medicine, The University of Texas Health Science Center, San Antonio, TX, USA
- Departments of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
- South Texas Veterans' Health System Audie L. Murphy Division GRECC, San Antonio, TX, USA
| | - Raymond F Palmer
- Departments of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, TX, USA
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Royall DR, Al-Rubaye S, Bishnoi R, Palmer RF. Serum proteins mediate depression's association with dementia. PLoS One 2017; 12:e0175790. [PMID: 28594820 PMCID: PMC5464526 DOI: 10.1371/journal.pone.0175790] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/31/2017] [Indexed: 01/08/2023] Open
Abstract
The latent variable "δ" (for "dementia") uniquely explains dementia severity. Depressive symptoms are independent predictors of δ. We explored 115 serum proteins as potential causal mediators of the effect of depressive symptoms on δ in a large, ethnically diverse, longitudinal cohort. All models were adjusted for age, apolipoprotein E, education, ethnicity, gender, hemoglobin A1c, and homocysteine, and replicated in randomly selected 50% subsets. Alpha1-antitrypsin (A1AT), FAS, Heparin-binding EGF-like Growth Factor (HB-EGF), Insulin-like Growth Factor-1 (IGF-1), Luteinizing Hormone (LH), Macrophage Inflammatory Protein type 1 alpha (MIP-1α), Resitin, S100b, Tissue Inhibitor of Metalloproteinase type 1 (TIMP-1), and Vascular Cell Adhesion Molecule type 1 (VCAM-1) each were partial mediators of depression's association with δ. These proteins may offer targets for the treatment of depression's specific effect on dementia severity and Alzheimer's Disease (AD) conversion risk.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- South Texas Veterans’ Health System Audie L. Murphy Division Geriatric Research Education and Clinical Care Center, San Antonio, Texas, United States of America
| | - Safa Al-Rubaye
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Ram Bishnoi
- Department of Psychiatry, the Medical College of Georgia, Augusta, Georgia, United States of America
| | - Raymond F. Palmer
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
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Royall DR, Al-Rubaye S, Bishnoi R, Palmer RF. Few serum proteins mediate APOE's association with dementia. PLoS One 2017; 12:e0172268. [PMID: 28291794 PMCID: PMC5349443 DOI: 10.1371/journal.pone.0172268] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 02/02/2017] [Indexed: 02/08/2023] Open
Abstract
The latent variable "δ" (for "dementia") appears to be uniquely responsible for the dementing aspects of cognitive impairment. Age, depression, gender and the apolipoprotein E (APOE) e4 allele are independently associated with δ. In this analysis, we explore serum proteins as potential mediators of APOE's specific association with δ in a large, ethnically diverse longitudinal cohort, the Texas Alzheimer's Research and Care Consortium (TARCC). APOE was associated only with C-Reactive Protein (CRP), Adiponectin (APN) and Amphiregulin (AREG), although the latter two's associations did not survive Bonferroni correction for multiple comparisons. All three proteins were associated with δ and had weak potential mediation effects on APOE's association with that construct. Our findings suggest that APOE's association with cognitive performance is specific to δ and partially mediated by serum inflammatory proteins. The majority of APOE's significant unadjusted effect on δ is unexplained. It may instead arise from direct central nervous system effects, possibly on native intelligence. If so, then APOE may exert a life-long influence over δ and therefore all-cause dementia risk.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
- South Texas Veterans’ Health System Audie L. Murphy Division Geriatric Research Education and Clinical Care Center, San Antonio, Texas, United States of America
| | - Safa Al-Rubaye
- Department of Psychiatry, the University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Ram Bishnoi
- Department of Psychiatry, the Medical College of Georgia, Augusta, Georgia, United States of America
| | - Raymond F. Palmer
- Department of Family and Community Medicine, the University of Texas Health Science Center, San Antonio, Texas, United States of America
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Royall DR, Palmer RF. δ scores predict mild cognitive impairment and Alzheimer's disease conversions from nondemented states. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2017; 6:214-221. [PMID: 28378011 PMCID: PMC5369695 DOI: 10.1016/j.dadm.2017.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION We tested the latent variable "δ" (for "dementia")'s ability to predict conversion to "mild cognitive impairment" (MCI) and Alzheimer's disease (AD). METHODS An ethnicity equivalent d homolog ("dEQ") was constructed in n = 1113 Mexican- American (MA) and n = 1958 non-Hispanic white (NHW) participants in the Texas Alzheimer's Research and Care Consortium. "Normal Controls" (NC) (n = 1276) and MCI cases (n = 611) were followed annually for up to 6 years [m = 4.7(0.6)]. RESULTS 22.0% (n = 281) of NC converted to "MCI" or "AD". 17.3%( n = 106) of MCI converted to "AD." Independently of covariates, each quintile increase in the dEQ scores of NC increased the odds of conversion by 52%. Each quintile increase in the dEQ scores of MCI cases increased the odds of conversion to AD almost three-fold. DISCUSSION Baseline δ scores predict MCI and AD conversions from nondemented states in MA and NHW.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Family and Community Medicine, University of Texas Health Science Center, San Antonio, TX, USA
- South Texas Veterans' Health System Audie L. Murphy Division GRECC, San Antonio, TX, USA
| | - Raymond F. Palmer
- Department of Family and Community Medicine, University of Texas Health Science Center, San Antonio, TX, USA
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Royall DR, Al-Rubaye S, Bishnoi R, Palmer RF. Serum protein mediators of dementia and aging proper. Aging (Albany NY) 2016; 8:3241-3254. [PMID: 27922822 PMCID: PMC5270666 DOI: 10.18632/aging.101091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/17/2016] [Indexed: 12/27/2022]
Abstract
The latent variable "δ" (for "dementia") appears to be uniquely responsible for the dementing aspects of cognitive impairment. Age, depressive symptoms, gender and the apolipoprotein E (APOE) ε4 allele are independently associated with δ. In this analysis, we explore serum proteins as potential mediators of age's specific association with δ in a large, ethnically diverse longitudinal cohort, the Texas Alzheimer's Research and Care Consortium (TARCC). 22 serum proteins were recognized as partial mediators of age's association with δ. These include Insulin-like Growth Factor-Binding Protein 2 (IGF-BP2), which we had previously associated with age-specific cognitive change, and both Pancreatic Polypeptide (PP) and von Willebrand Factor (vWF), previously associated with δ. Nine other δ-related proteins were not confirmed by this ethnicity adjusted analysis. Our findings suggest that age's association with the disabling fraction of cognitive performance is partially mediated by serum proteins, somatomedins and hormones. Those proteins may offer targets for the specific treatment of age-related effects on dementia severity and conversion risk.
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Affiliation(s)
- Donald R. Royall
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Department of Family and Community Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- South Texas Veterans’ Health System Audie L. Murphy Division GRECC, San Antonio, TX 78229, USA
| | - Safa Al-Rubaye
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Ram Bishnoi
- Department of Psychiatry, The Medical College of Georgia, Augusta, GA 30912, USA
| | - Raymond F. Palmer
- Department of Family and Community Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Peh CX, Abdin E, Vaingankar JA, Verma S, Chua BY, Sagayadevan V, Seow E, Zhang Y, Shahwan S, Ng LL, Prince M, Chong SA, Subramaniam M. Validation of a Latent Construct for Dementia in a Population-Wide Dataset from Singapore. J Alzheimers Dis 2016; 55:823-833. [PMID: 27802230 DOI: 10.3233/jad-160575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The latent variable δ has been proposed as a proxy for dementia. Previous validation studies have been conducted using convenience samples. It is currently unknown how δ performs in population-wide data. OBJECTIVE To validate δ in Singapore using population-wide epidemiological study data on persons aged 60 and above. METHODS δ was constructed using items from the Community Screening Instrument for Dementia (CSI'D) and World Health Organization Disability Assessment Schedule (WHODAS II). Confirmatory factor analysis (CFA) was conducted to examine δ model fit. Convergent validity was examined with the Clinical Dementia Rating scale (CDR) and GMS-AGECAT dementia. Divergent validity was examined with GMS-AGECAT depression. RESULTS The δ model demonstrated fit to the data, χ2(df) = 249.71(55), p < 0.001, CFI = 0.990, TLI = 0.997, RMSEA = 0.037. Latent variable δ was significantly associated with CDR and GMS-AGECAT dementia (range: β= 0.32 to 0.63), and was not associated with GMS-AGECAT depression. Compared to unadjusted models, δ model fit was poor when adjusted for age, gender, ethnicity, and education. CONCLUSION The study found some support for δ as a proxy for dementia in Singapore based on population data. Both convergent and divergent validity were established. In addition, the δ model structure appeared to be influenced by age, gender, ethnicity, and education covariates.
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Affiliation(s)
- Chao Xu Peh
- Research Division, Institute of Mental Health, Singapore, Singapore
| | - Edimansyah Abdin
- Research Division, Institute of Mental Health, Singapore, Singapore
| | | | - Swapna Verma
- Early Psychosis Intervention Programme, Institute of Mental Health, Singapore, Singapore
| | - Boon Yiang Chua
- Research Division, Institute of Mental Health, Singapore, Singapore
| | | | - Esmond Seow
- Research Division, Institute of Mental Health, Singapore, Singapore
| | - YunJue Zhang
- Research Division, Institute of Mental Health, Singapore, Singapore
| | - Shazana Shahwan
- Research Division, Institute of Mental Health, Singapore, Singapore
| | - Li Ling Ng
- Department of Psychological Medicine, Changi General Hospital, Singapore, Singapore
| | - Martin Prince
- Health Service and Population Research Department, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom
| | - Siow Ann Chong
- Research Division, Institute of Mental Health, Singapore, Singapore
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DADM: The first 2 years of the Alzheimer Association's open access journal to support the research and development of novel biomarkers and diagnostic approaches. Alzheimers Dement 2016; 12:755-7. [PMID: 27370207 DOI: 10.1016/j.jalz.2016.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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O'Bryant SE. Introduction to special issue on Advances in blood-based biomarkers of Alzheimer's disease. ALZHEIMER'S & DEMENTIA: DIAGNOSIS, ASSESSMENT & DISEASE MONITORING 2016; 3:110-2. [PMID: 27453933 PMCID: PMC4949589 DOI: 10.1016/j.dadm.2016.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Sid E O'Bryant
- Institute for Healthy Aging & Department of Family Medicine, University of North Texas Health Science Center, Fort Worth, TX, USA
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