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Kremers, Walter K

0000-0001-5714-3473

Mayo Clinic

Mayo Clinic, Rochester, Minnesota.

Citations 181

Mayo Normative Studies: Amyloid and Neurodegeneration Negative Normative Data for the Auditory Verbal Learning Test and Sex-Specific Sensitivity to Mild Cognitive Impairment/Dementia

Journal of Alzheimer’s Disease | July 12, 2024 | Volume: 100 | Issue: 3 | Pages: 879-897

10.3233/jad-240081 | PMID 38995784

Background: Conventional normative samples include individuals with undetected Alzheimer’s disease neuropathology, lowering test sensitivity for cognitive impairment. Objective: We developed Mayo Normative Studies (MNS) norms limited to individuals without elevated amyloid or neurodegeneration (A–N–) for Rey’s Auditory Verbal Learning Test (AVLT). We compared these MNS A–N– norms in female, male, and total samples to conventional MNS norms with varying levels of demographic adjustments. Methods: The A–N– sample included 1,059 Mayo Clinic Study of Aging cognitively unimpaired (CU) participants living in Olmsted County, MN, who are predominantly non-Hispanic White. Using a regression-based approach correcting for age, sex, and education, we derived fully-adjusted T-score formulas for AVLT variables. We validated these A–N– norms in two independent samples of CU ( n = 261) and mild cognitive impairment (MCI)/dementia participants ( n = 392) > 55 years of age. Results: Variability associated with age decreased by almost half in the A–N– norm sample relative to the conventional norm sample. Fully-adjusted MNS A–N– norms showed approximately 7– 9% higher sensitivity to MCI/dementia compared to fully-adjusted MNS conventional norms for trials 1– 5 total and sum of trials. Among women, sensitivity to MCI/dementia increased with each normative data refinement. In contrast, age-adjusted conventional MNS norms showed greatest sensitivity to MCI/dementia in men. Conclusions: A–N– norms show some benefits over conventional normative approaches to MCI/dementia sensitivity, especially for women. We recommend using these MNS A–N– norms alongside MNS conventional norms. Future work is needed to determine if normative samples that are not well characterized clinically show greater benefit from biomarker-refined approaches.
Persistent changes in calcium-regulating hormones and bone turnover markers in living kidney donors more than 20 years after donation

JBMR Plus | May 13, 2024 | Volume: 8 | Issue: 7 | Pages: No page available

10.1093/jbmrpl/ziae067 | PMID 38868597

Abstract In a previous study, we observed decreased 1,25-dihydroxyvitamin D levels, secondary hyperparathyroidism, and increased bone turnover markers in living kidney donors (LKDs) at 3 months and 36 months after kidney donation. In our recent survey-based study, we found no increased risk of fractures of all types but observed significantly more vertebral fractures in LKDs compared with matched controls. To elucidate the long-term effects of kidney donation on bone health, we recruited 139 LKDs and 139 age and sex matched controls from the survey-based participants for further mechanistic analyses. Specifically, we assessed whether LKDs had persistent abnormalities in calcium- and phosphorus-regulating hormones and related factors, in bone formation and resorption markers, and in density and microstructure of bone compared with controls. We measured serum markers, bone mineral density (BMD), bone microstructure and strength (via high-resolution peripheral quantitative computed tomography and micro-finite element analysis [HRpQCT]), and advanced glycation end-products in donors and controls. LKDs had decreased 1,25-dihydroxyvitamin D concentrations (donors mean 33.89 pg/mL vs. controls 38.79 pg/mL, percent difference = -12.6%; P < .001), increases in both parathyroid hormone (when corrected for ionized calcium; donors mean 52.98 pg/mL vs. controls 46.89 pg/mL,% difference 13%; P = .03) and ionized calcium levels (donors mean 5.13 mg/dL vs. controls 5.04 mg/dL; P < .001), and increases in several bone resorption and formation markers versus controls. LKDs and controls had similar measures of BMD; however, HRpQCT suggested that LKDs have a statistically insignificant tendency toward thinner cortical bone and lower failure loads as measured by micro-finite element analysis. Our findings suggest that changes in the hormonal mileu after kidney donation and the long-term cumulative effects of these changes on bone health persist for decades after kidney donation and may explain later-life increased rates of vertebral fractures.
Reliability and Validity of Smartphone Cognitive Testing for Frontotemporal Lobar Degeneration

JAMA Network Open | April 1, 2024 | Volume: 7 | Issue: 4 | Pages: e244266

10.1001/jamanetworkopen.2024.4266 | PMID 38558141

ImportanceFrontotemporal lobar degeneration (FTLD) is relatively rare, behavioral and motor symptoms increase travel burden, and standard neuropsychological tests are not sensitive to early-stage disease. Remote smartphone-based cognitive assessments could mitigate these barriers to trial recruitment and success, but no such tools are validated for FTLD.ObjectiveTo evaluate the reliability and validity of smartphone-based cognitive measures for remote FTLD evaluations.Design, Setting, and ParticipantsIn this cohort study conducted from January 10, 2019, to July 31, 2023, controls and participants with FTLD performed smartphone application (app)–based executive functioning tasks and an associative memory task 3 times over 2 weeks. Observational research participants were enrolled through 18 centers of a North American FTLD research consortium (ALLFTD) and were asked to complete the tests remotely using their own smartphones. Of 1163 eligible individuals (enrolled in parent studies), 360 were enrolled in the present study; 364 refused and 439 were excluded. Participants were divided into discovery (n = 258) and validation (n = 102) cohorts. Among 329 participants with data available on disease stage, 195 were asymptomatic or had preclinical FTLD (59.3%), 66 had prodromal FTLD (20.1%), and 68 had symptomatic FTLD (20.7%) with a range of clinical syndromes.ExposureParticipants completed standard in-clinic measures and remotely administered ALLFTD mobile app (app) smartphone tests.Main Outcomes and MeasuresInternal consistency, test-retest reliability, association of smartphone tests with criterion standard clinical measures, and diagnostic accuracy.ResultsIn the 360 participants (mean [SD] age, 54.0 [15.4] years; 209 [58.1%] women), smartphone tests showed moderate-to-excellent reliability (intraclass correlation coefficients, 0.77-0.95). Validity was supported by association of smartphones tests with disease severity (r range, 0.38-0.59), criterion-standard neuropsychological tests (r range, 0.40-0.66), and brain volume (standardized β range, 0.34-0.50). Smartphone tests accurately differentiated individuals with dementia from controls (area under the curve [AUC], 0.93 [95% CI, 0.90-0.96]) and were more sensitive to early symptoms (AUC, 0.82 [95% CI, 0.76-0.88]) than the Montreal Cognitive Assessment (AUC, 0.68 [95% CI, 0.59-0.78]) (z of comparison, −2.49 [95% CI, −0.19 to −0.02]; P = .01). Reliability and validity findings were highly similar in the discovery and validation cohorts. Preclinical participants who carried pathogenic variants performed significantly worse than noncarrier family controls on 3 app tasks (eg, 2-back β = −0.49 [95% CI, −0.72 to −0.25]; P < .001) but not a composite of traditional neuropsychological measures (β = −0.14 [95% CI, −0.42 to 0.14]; P = .32).Conclusions and RelevanceThe findings of this cohort study suggest that smartphones could offer a feasible, reliable, valid, and scalable solution for remote evaluations of FTLD and may improve early detection. Smartphone assessments should be considered as a complementary approach to traditional in-person trial designs. Future research should validate these results in diverse populations and evaluate the utility of these tests for longitudinal monitoring.
Fracture Risk Among Living Kidney Donors 25 Years After Donation

JAMA Network Open | January 24, 2024 | Volume: 7 | Issue: 1 | Pages: e2353005

10.1001/jamanetworkopen.2023.53005 | PMID 38265798

Importance Living kidney donors may have an increased risk of fractures due to reductions in kidney mass, lower concentrations of serum 1,25-dihydroxyvitamin D, and secondary increases in serum parathyroid hormone. Objective To compare the overall and site-specific risk of fractures among living kidney donors with strictly matched controls from the general population who would have been eligible to donate a kidney but did not do so. Design, Setting, and Participants This survey study was conducted between December 1, 2021, and July 31, 2023. A total of 5065 living kidney donors from 3 large transplant centers in Minnesota were invited to complete a survey about their bone health and history of fractures, and 16 156 population-based nondonor controls without a history of comorbidities that would have precluded kidney donation were identified from the Rochester Epidemiology Project and completed the same survey. A total of 2132 living kidney donors and 2014 nondonor controls responded to the survey. Statistical analyses were performed from May to August 2023. Exposure Living kidney donation. Main Outcomes and Measures The rates of overall and site-specific fractures were compared between living kidney donors and controls using standardized incidence ratios (SIRs). Results At the time of survey, the 2132 living kidney donors had a mean (SD) age of 67.1 (8.9) years and included 1245 women (58.4%), and the 2014 controls had a mean (SD) age of 68.6 (7.9) years and included 1140 women (56.6%). The mean (SD) time between donation or index date and survey date was 24.2 (10.4) years for donors and 27.6 (10.7) years for controls. The overall rate of fractures among living kidney donors was significantly lower than among controls (SIR, 0.89; 95% CI, 0.81-0.97). However, there were significantly more vertebral fractures among living kidney donors than among controls (SIR, 1.42; 95% CI, 1.05-1.83). Conclusions and Relevance This survey study found a reduced rate of overall fractures but an excess of vertebral fractures among living kidney donors compared with controls after a mean follow-up of 25 years. Treatment of excess vertebral fractures with dietary supplements such as vitamin D 3 may reduce the numbers of vertebral fractures and patient morbidity.
The Effect of Implant Density on Adolescent Idiopathic Scoliosis Fusion

Journal of Bone and Joint Surgery | November 16, 2023 | Volume: 106 | Issue: 3 | Pages: 180-189

10.2106/jbjs.23.00178 | PMID 37973031

Background: Severe adolescent idiopathic scoliosis (AIS) can be treated with instrumented fusion, but the number of anchors needed for optimal correction is controversial. Methods: We conducted a multicenter, randomized study that included patients undergoing spinal fusion for single thoracic curves between 45° and 65°, the most common form of operatively treated AIS. Of the 211 patients randomized, 108 were assigned to a high-density screw pattern and 103, to a low-density screw pattern. Surgeons were instructed to use ≥1.8 implants per spinal level fused for patients in the high-implant-density group or ≤1.4 implants per spinal level fused for patients in the low-implant-density group. The primary outcome measure was the percent correction of the coronal curve at the 2-year follow-up. The power analysis for this trial required 174 patients to show equivalence, defined as a 95% confidence interval (CI) within a ±10% correction margin with a probability of 90%. Results: In the intention-to-treat analysis, the mean percent correction of the coronal curve was equivalent between the high-density and low-density groups at the 2-year follow-up (67.6% versus 65.7%; difference, −1.9% [95% CI: −6.1%, 2.2%]). In the per-protocol cohorts, the mean percent correction of the coronal curve was also equivalent between the 2 groups at the 2-year follow-up (65.0% versus 66.1%; difference, 1.1% [95% CI: −3.0%, 5.2%]). A total of 6 patients in the low-density group and 5 patients in the high-density group required reoperation (p = 1.0). Conclusions: In the setting of spinal fusion for primary thoracic AIS curves between 45° and 65°, the percent coronal curve correction obtained with use of a low-implant-density construct and that obtained with use of a high-implant-density construct were equivalent. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.
Association of Cerebrovascular Imaging Biomarkers, Depression, and Anxiety, with Mild Cognitive Impairment

Journal of Alzheimer's Disease Reports | November 3, 2023 | Volume: 7 | Issue: 1 | Pages: 1237-1246

10.3233/adr-230073 | PMID 38025797

The study included 1,738 Mayo Clinic Study of Aging participants (≥50 years old; 1,460 cognitively unimpaired and 278 with mild cognitive impairment (MCI)) and examined the cross-sectional association between cerebrovascular (CVD) imaging biomarkers (e.g., white matter hyperintensities (WMH), infarctions) and Beck Depression Inventory-II (BDI-II) and Beck Anxiety Inventory (BAI) scores, as well as their association with MCI. High (abnormal) WMH burden was significantly associated with having BDI-II>13 and BAI > 7 scores, and both (CVD imaging biomarkers and depression/anxiety) were significantly associated with MCI when included simultaneously in the model, suggesting that both were independently associated with the odds of MCI.
Eligibility for Anti-Amyloid Treatment in a Population-Based Study of Cognitive Aging

Neurology | August 16, 2023 | Volume: 101 | Issue: 19 | Pages: No page available

10.1212/wnl.0000000000207770 | PMID 37586881

Plasma‐derived biomarkers of Alzheimer's disease and neuropsychiatric symptoms: A community‐based study

Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring | July 31, 2023 | Volume: 15 | Issue: 3 | Pages: No page available

10.1002/dad2.12461 | PMID 37529120

AbstractINTRODUCTIONWe examined associations between plasma‐derived biomarkers of Alzheimer's disease (AD) and neuropsychiatric symptoms (NPS) in community‐dwelling older adults.METHODSCross‐sectional study involving 1005 persons ≥50 years of age (mean 74 years, 564 male, 118 cognitively impaired), who completed plasma‐derived biomarker (amyloid beta 42 [Aβ42]/Aβ40, phosphorylated tau 181 [p‐tau181], p‐tau217, total tau [t‐tau], neurofilament light [NfL]), and NPS assessment.RESULTSP‐tau181 (odds ratio [OR] 2.06, 95% confidence interval [CI] 1.41–3.00, p < 0.001), p‐tau217 (OR 1.70, 95% CI 1.10–2.61, p = 0.016), and t‐tau (OR 1.44, 95% CI 1.08–1.92, p = 0.012) were associated with appetite change. We also found that p‐tau181 and p‐tau217 were associated with increased symptoms of agitation (OR 1.93, 95% CI 1.20–3.11, p = 0.007 and OR 2.04, 95% CI 1.21–3.42, p = 0.007, respectively), and disinhibition (OR 2.39, 95% CI 1.45–3.93, p = 0.001 and OR 2.30, 95% CI 1.33–3.98, p = 0.003, respectively). Aβ42/Aβ40 and NfL were not associated with NPS.CONCLUSIONHigher plasma‐derived p‐tau181 and p‐tau217 levels are associated with increased symptoms of appetite change, agitation, and disinhibition. These findings may support the validity of plasma tau biomarkers for predicting behavioral symptoms that often accompany cognitive impairment.HIGHLIGHTS We studied 1005 community‐dwelling persons aged ≥ 50 years Higher plasma tau levels are associated with increased neuropsychiatric symptoms Aβ42/Aβ40 and NfL are not associated with neuropsychiatric symptoms Clinicians should treat neuropsychiatric symptoms in persons with high plasma‐derived tau
Clinicoradiologic and Neuropathologic Evaluation of Corticobasal Syndrome

Neurology | June 2, 2023 | Volume: 101 | Issue: 3 | Pages: No page available

10.1212/wnl.0000000000207397 | PMID 37268436

At-Home Use of a Pregnancy-Specific Zone-MPC Closed-Loop System for Pregnancies Complicated by Type 1 Diabetes: A Single-Arm, Observational Multicenter Study

Diabetes Care | May 17, 2023 | Volume: 46 | Issue: 7 | Pages: 1425-1431

10.2337/dc23-0173 | PMID 37196353

OBJECTIVE There are no commercially available hybrid closed-loop insulin delivery systems customized to achieve pregnancy-specific glucose targets in the U.S. This study aimed to evaluate the feasibility and performance of at-home use of a zone model predictive controller–based closed-loop insulin delivery system customized for pregnancies complicated by type 1 diabetes (CLC-P). RESEARCH DESIGN AND METHODS Pregnant women with type 1 diabetes using insulin pumps were enrolled in the second or early third trimester. After study sensor wear collecting run-in data on personal pump therapy and 2 days of supervised training, participants used CLC-P targeting 80–110 mg/dL during the day and 80–100 mg/dL overnight running on an unlocked smartphone at home. Meals and activities were unrestricted throughout the trial. The primary outcome was the continuous glucose monitoring percentage of time in the target range 63–140 mg/dL versus run-in. RESULTS Ten participants (HbA1c 5.8 ± 0.6%) used the system from mean gestational age of 23.7 ± 3.5 weeks. Mean percentage time in range increased 14.1 percentage points, equivalent to 3.4 h per day, compared with run-in (run-in 64.5 ± 16.3% versus CLC-P 78.6 ± 9.2%; P = 0.002). During CLC-P use, there was significant decrease in both time over 140 mg/dL (P = 0.033) and the hypoglycemic ranges of less than 63 mg/dL and 54 mg/dL (P = 0.037 for both). Nine participants exceeded consensus goals of above 70% time in range during CLC-P use. CONCLUSIONS The results show that the extended use of CLC-P at home until delivery is feasible. Larger, randomized studies are needed to further evaluate system efficacy and pregnancy outcomes.