The Bio-Hermes Study: Biomarker database developed to investigate blood-based and digital biomarkers in community-based, diverse populations clinically screened for Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) trial participants are often screened for eligibility by brain amyloid positron emission tomography/cerebrospinal fluid (PET/CSF), which is inefficient as many are not amyloid positive. Use of blood-based biomarkers may reduce screen failures.

METHODS

We recruited 755 non-Hispanic White, 115 Hispanic, 112 non-Hispanic Black, and 19 other minority participants across groups of cognitively normal (n = 417), mild cognitive impairment (n = 312), or mild AD (n = 272) participants. Plasma amyloid beta (Aβ)40, Aβ42, Aβ42/Aβ40, total tau, phosphorylated tau (p-tau)181, and p-tau217 were measured; amyloid PET/CSF (n = 956) determined amyloid positivity. Clinical, blood biomarker, and ethnicity/race differences associated with amyloid status were evaluated.

RESULTS

Greater impairment, older age, and carrying an apolipoprotein E (apoE) ε4 allele were associated with greater amyloid burden. Areas under the receiver operating characteristic curve for amyloid status of plasma Aβ42/Aβ40, p-tau181, and p-tau217 with amyloid positivity were ≥ 0.7117 for all ethnoracial groups (p-tau217, ≥0.8128). Age and apoE ε4 adjustments and imputation of biomarker values outside limit of quantitation provided small improvement in predictive power.

DISCUSSION

Blood-based biomarkers are highly associated with amyloid PET/CSF results in diverse populations enrolled at clinical trial sites.

HIGHLIGHTS

Amyloid beta (Aβ)42/Aβ40, phosphorylated tau (p-tau)181, and p-tau 217 blood-based biomarkers predicted brain amyloid positivity. P-tau 217 was the strongest predictor of brain amyloid positivity. Biomarkers from diverse ethnic, racial, and clinical cohorts predicted brain amyloid positivity. Community-based populations have similar Alzheimer's disease (AD) biomarker levels as other populations. A prescreen process with blood-based assays may reduce the number of AD trial screen failures.

Recruitment methods and yield rates for a multisite clinical trial exploring risk reduction for Alzheimer's disease (rrAD)

INTRODUCTION

The risk reduction for Alzheimer's disease (rrAD) trial was a multisite clinical trial to assess exercise and intensive vascular pharmacological treatment on cognitive function in community-dwelling older adults at increased risk for Alzheimer's disease.

METHODS

Eligibility, consent, and randomization rates across different referral sources were compared. Informal interviews conducted with each site's project team were conducted upon study completion.

RESULTS

Initially, 3290 individuals were screened, of whom 28% were eligible to consent, 805 consented to participate (87.2% of those eligible), and 513 (36.3% of those consented) were randomized. Emails sent from study site listservs/databases yielded the highest amount (20.9%) of screened individuals. Professional referrals from physicians yielded the greatest percentage of consented individuals (57.1%). Referrals from non-professional contacts (ie, friends, family; 75%) and mail/phone contact from a site (73.8%) had the highest yield of randomization.

DISCUSSION

Professional referrals or email from listservs/registries were most effective for enrolling participants. The greatest yield of eligible/randomized participants came from non-professional and mail/phone contacts. Future trials should consider special efforts targeting these recruitment approaches.

Highlights

Clinical trial recruitment is commonly cited as a significant barrier to advancing our understanding of cognitive health interventions.The most cited referral source was email, followed by interviews/editorials on the radio, television, local newspapers, newsletters, or magazine articles.The referral method that brought in the largest number of contacts was email but did not result in the greatest yield of consents or eligible participants.The sources that yielded the greatest likelihood of consent were professional referrals (ie, physician), social media, and mail/phone contact from study site.The greatest yield of eligible/randomized participants came from non-professional contacts and mail/phone contact from a site.Findings suggest that sites may need to focus on more selective referral sources, such as using contact mailing and phone lists, rather than more widely viewed recruitment sources, such as social media or TV/radio advertisements.

Evaluation of noise regression techniques in resting-state fMRI studies using data of 434 older adults

Subject motion is a well-known confound in resting-state functional MRI (rs-fMRI) and the analysis of functional connectivity. Consequently, several clean-up strategies have been established to minimize the impact of subject motion. Physiological signals in response to cardiac activity and respiration are also known to alter the apparent rs-fMRI connectivity. Comprehensive comparisons of common noise regression techniques showed that the "Independent Component Analysis based strategy for Automatic Removal of Motion Artifacts" (ICA-AROMA) was a preferred pre-processing technique for teenagers and adults. However, motion and physiological noise characteristics may differ substantially for older adults. Here, we present a comprehensive comparison of noise-regression techniques for older adults from a large multi-site clinical trial of exercise and intensive pharmacological vascular risk factor reduction. The Risk Reduction for Alzheimer's Disease (rrAD) trial included hypertensive older adults (60-84 years old) at elevated risk of developing Alzheimer's Disease (AD). We compared the performance of censoring, censoring combined with global signal regression, non-aggressive and aggressive ICA-AROMA, as well as the Spatially Organized Component Klassifikator (SOCK) on the rs-fMRI baseline scans from 434 rrAD subjects. All techniques were rated based on network reproducibility, network identifiability, edge activity, spatial smoothness, and loss of temporal degrees of freedom (tDOF). We found that non-aggressive ICA-AROMA did not perform as well as the other four techniques, which performed table with marginal differences, demonstrating the validity of these techniques. Considering reproducibility as the most important factor for longitudinal studies, given low false-positive rates and a better preserved, more cohesive temporal structure, currently aggressive ICA-AROMA is likely the most suitable noise regression technique for rs-fMRI studies of older adults.

Meaningful benefits: a framework to assess disease-modifying therapies in preclinical and early Alzheimer's disease

BACKGROUND

The need for preventive therapies that interrupt the progression of Alzheimer's disease (AD) before the onset of symptoms or when symptoms are emerging is urgent and has spurred the ongoing development of disease-modifying therapies (DMTs) in preclinical and early AD (mild cognitive impairment [MCI] to mild dementia). Assessing the meaningfulness of what are likely small initial treatment effects in these earlier stages of the AD patho-clinical disease continuum is a major challenge and warrants further consideration. BODY: To accommodate a shift towards earlier intervention in AD, we propose meaningful benefits as a new umbrella concept that encapsulates the spectrum of potentially desirable outcomes that may be demonstrated in clinical trials and other studies across the AD continuum, with an emphasis on preclinical AD and early AD (i.e., MCI due to AD and mild AD dementia). The meaningful benefits framework applies to data collection, assessment, and communication across three dimensions: (1) multidimensional clinical outcome assessments (COAs) including not only core disease outcomes related to cognition and function but also patient- and caregiver-reported outcomes, health and economic outcomes, and neuropsychiatric symptoms; (2) complementary analyses that help contextualize and expand the understanding of COA-based assessments, such as number-needed-to-treat or time-to-event analyses; and (3) assessment of both cumulative benefit and predictive benefit, where early changes on cognitive, functional, or biomarker assessments predict longer-term clinical benefit.

CONCLUSION

The concept of meaningful benefits emphasizes the importance of multidimensional reporting of clinical trial data while, conceptually, it advances our understanding of treatment effects in preclinical AD and mild cognitive impairment due to AD. We propose that such an approach will help bridge the gap between the emergence of DMTs and their clinical use, particularly now that a DMT is available for patients diagnosed with MCI due to AD and mild AD dementia.

Current directions in tau research: Highlights from Tau 2020

Studies supporting a strong association between tau deposition and neuronal loss, neurodegeneration, and cognitive decline have heightened the allure of tau and tau-related mechanisms as therapeutic targets. In February 2020, leading tau experts from around the world convened for the first-ever Tau2020 Global Conference in Washington, DC, co-organized and cosponsored by the Rainwater Charitable Foundation, the Alzheimer's Association, and CurePSP. Representing academia, industry, government, and the philanthropic sector, presenters and attendees discussed recent advances and current directions in tau research. The meeting provided a unique opportunity to move tau research forward by fostering global partnerships among academia, industry, and other stakeholders and by providing support for new drug discovery programs, groundbreaking research, and emerging tau researchers. The meeting also provided an opportunity for experts to present critical research-advancing tools and insights that are now rapidly accelerating the pace of tau research.

Best Practices in the Clinical Management of Progressive Supranuclear Palsy and Corticobasal Syndrome: A Consensus Statement of the CurePSP Centers of Care

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS; the most common phenotype of corticobasal degeneration) are tauopathies with a relentless course, usually starting in the mid-60s and leading to death after an average of 7 years. There is as yet no specific or disease-modifying treatment. Clinical deficits in PSP are numerous, involve the entire neuraxis, and present as several discrete phenotypes. They center on rigidity, bradykinesia, postural instability, gait freezing, supranuclear ocular motor impairment, dysarthria, dysphagia, incontinence, sleep disorders, frontal cognitive dysfunction, and a variety of behavioral changes. CBS presents with prominent and usually asymmetric dystonia, apraxia, myoclonus, pyramidal signs, and cortical sensory loss. The symptoms and deficits of PSP and CBS are amenable to a variety of treatment strategies but most physicians, including many neurologists, are reluctant to care for patients with these conditions because of unfamiliarity with their multiplicity of interacting symptoms and deficits. CurePSP, the organization devoted to support, research, and education for PSP and CBS, created its CurePSP Centers of Care network in North America in 2017 to improve patient access to clinical expertise and develop collaborations. The directors of the 25 centers have created this consensus document outlining best practices in the management of PSP and CBS. They formed a writing committee for each of 12 sub-topics. A 4-member Steering Committee collated and edited the contributions. The result was returned to the entire cohort of authors for further comments, which were considered for incorporation by the Steering Committee. The authors hope that this publication will serve as a convenient guide for all clinicians caring for patients with PSP and CBS and that it will improve care for patients with these devastating but manageable disorders.

Exercise Training in Amnestic Mild Cognitive Impairment: A One-Year Randomized Controlled Trial

BACKGROUND

The current evidence is inconclusive to support the benefits of aerobic exercise training (AET) for preventing neurocognitive decline in patients with amnestic mild cognitive impairment (aMCI).

OBJECTIVE

To examine the effect of a progressive, moderate-to-high intensity AET program on memory and executive function, brain volume, and cortical amyloid-β (Aβ) plaque deposition in aMCI patients.

METHODS

This is a proof-of-concept trial that randomized 70 aMCI patients to 12 months of AET or stretching and toning (SAT, active control) interventions. Primary neuropsychological outcomes were assessed by using the California Verbal Learning Test-second edition (CVLT-II) and the Delis-Kaplan Executive Function System (D-KEFS). Secondary outcomes were the global and hippocampal brain volumes and the mean cortical and precuneus Aβ deposition.

RESULTS

Baseline cognitive scores were similar between the groups. Memory and executive function performance improved over time but did not differ between the AET and SAT groups. Brain volume decreased and precuneus Aβ plaque deposition increased over time but did not differ between the groups. Cardiorespiratory fitness was significantly improved in the AET compared with SAT group. In amyloid positive patients, AET was associated with reduced hippocampal atrophy when compared with the SAT group.

CONCLUSION

The AET and SAT groups both showed evidence of slightly improved neuropsychological scores in previously sedentary aMCI patients. However, these interventions did not prevent brain atrophy or increases in cortical Aβ deposition over 12 months. In amyloid positive patients, AET reduced hippocampal atrophy when compared with the SAT group.

Baseline Prevalence of Polypharmacy in Older Hypertensive Study Subjects with Elevated Dementia Risk: Findings from the Risk Reduction for Alzheimer's Disease Study (rrAD)

BACKGROUND

Little is known about the prevalence of polypharmacy, the taking of five or more medications a day, in older adults with specific dementia risk factors.

OBJECTIVE

To examine the prevalence of polypharmacy in participants at baseline in a vascular risk reduction focused Alzheimer's disease (rrAD) trial targeting older patients with hypertension and elevated dementia risk.

METHODS

We conducted a detailed review of medications in a cross-sectional study of community-dwelling older adults with hypertension and elevated dementia risk. Medications were identified in a structured interview process with an onsite pharmacist or qualified designee. Polypharmacy was defined as use of five or more medications on a regular basis. Descriptive analyses were conducted on the sample as well as direct comparisons of subgroups of individuals with hypertension, diabetes, and hyperlipidemia.

RESULTS

The 514 rrAD participants, mean age 68.8 (standard deviation [sd] 6), reported taking different combinations of 472 unique medications at their baseline visit. The median number of medications taken by participants was eight [Range 0-21], with 79.2% exhibiting polypharmacy (n = 407). Sites differed in their prevalence of polypharmacy, χ2(3) = 56.0, p < 0.001. A nearly identical percentage of the 2,077 prescribed (51.8%) and over the counter (48.2%) medications were present in the overall medication profile. The presence of diabetes (87.5%), hyperlipidemia (88.2%), or both (97.7%) was associated with a higher prevalence of polypharmacy than participants who exhibited hypertension in the absence of either of these conditions (63.2%), χ2(3) = 35.8, p < 0.001.

CONCLUSION

Participants in a dementia risk study had high levels of polypharmacy, with the co-existence of diabetes or hyperlipidemia associated with a greater prevalence of polypharmacy as compared to having hypertension alone.

Individualized atrophy scores predict dementia onset in familial frontotemporal lobar degeneration

INTRODUCTION

Some models of therapy for neurodegenerative diseases envision starting treatment before symptoms develop. Demonstrating that such treatments are effective requires accurate knowledge of when symptoms would have started without treatment. Familial frontotemporal lobar degeneration offers a unique opportunity to develop predictors of symptom onset.

METHODS

We created dementia risk scores in 268 familial frontotemporal lobar degeneration family members by entering covariate-adjusted standardized estimates of brain atrophy into a logistic regression to classify asymptomatic versus demented participants. The score's predictive value was tested in a separate group who were followed up longitudinally (stable vs. converted to dementia) using Cox proportional regressions with dementia risk score as the predictor.

RESULTS

Cross-validated logistic regression achieved good separation of asymptomatic versus demented (accuracy = 90%, SE = 0.06). Atrophy scores predicted conversion from asymptomatic or mildly/questionably symptomatic to dementia (HR = 1.51, 95% CI: [1.16,1.98]).

DISCUSSION

Individualized quantification of baseline brain atrophy is a promising predictor of progression in asymptomatic familial frontotemporal lobar degeneration mutation carriers.

Assessment of executive function declines in presymptomatic and mildly symptomatic familial frontotemporal dementia: NIH-EXAMINER as a potential clinical trial endpoint

INTRODUCTION

Identifying clinical measures that track disease in the earliest stages of frontotemporal lobar degeneration (FTLD) is important for clinical trials. Familial FTLD provides a unique paradigm to study early FTLD. Executive dysfunction is a clinically relevant hallmark of FTLD and may be a marker of disease progression.

METHODS

Ninety-three mutation carriers with no symptoms or minimal/questionable symptoms (MAPT, n = 31; GRN, n = 28; C9orf72, n = 34; Clinical Dementia Rating scale plus NACC FTLD Module < 1) and 78 noncarriers enrolled through Advancing Research and Treatment in Frontotemporal Lobar Degeneration/Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects studies completed the Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (NIH-EXAMINER) and the UDS neuropsychological battery. Linear mixed-effects models were used to identify group differences in cognition at baseline and longitudinally. We examined associations between cognition, clinical functioning, and magnetic resonance imaging volumes.

RESULTS

NIH-EXAMINER scores detected baseline and differences in slopes between carriers and noncarriers, even in carriers with a baseline Clinical Dementia Rating scale plus NACC FTLD Module = 0. NIH-EXAMINER declines were associated with worsening clinical symptoms and brain volume loss.

DISCUSSION

The NIH-EXAMINER is sensitive to cognitive changes in presymptomatic familial FTLD and is a promising surrogate endpoint.

Ambulatory pulse pressure, brain neuronal fiber integrity, and cerebral blood flow in older adults

Ambulatory blood pressure (ABP) reflects the end-organ vascular stress in daily life; however, its influence on brain neuronal fiber integrity and cerebral blood flow (CBF) remains unclear. The objective of this study was to determine the associations among ABP, white matter (WM) neuronal fiber integrity, and CBF in older adults. We tested 144 participants via ABP monitoring and diffusion tensor imaging. The total level and pulsatile indices of CBF were measured by phase-contrast MRI and transcranial Doppler, respectively. Neuropsychological assessment was conducted in 72 participants. Among ambulatory and office BP measures, elevated 24-h pulse pressure (PP) was associated with the greatest number of WM skeleton voxels with decreased fractional anisotropy (FA) and increased mean diffusivity (MD). Furthermore, these associations remained significant after adjusting for age, antihypertensive use, aortic stiffness, WM lesion volume, and office PP. Radial diffusivity (RD) was elevated in the regions with decreased FA, while axial diffusivity was unaltered. The reduction in diastolic index explained a significant proportion of the individual variability in FA, MD, and RD. Executive function performance was correlated with WM fiber integrity. These findings suggest that elevated ambulatory PP may deteriorate brain neuronal fiber integrity via reduction in diastolic index.

Rationale and methods for a multicenter clinical trial assessing exercise and intensive vascular risk reduction in preventing dementia (rrAD Study)

Alzheimer's Disease (AD) is an age-related disease with modifiable risk factors such as hypertension, hypercholesterolemia, obesity, and physical inactivity influencing the onset and progression. There is however, no direct evidence that reducing these risk factors prevents or slows AD. The Risk Reduction for Alzheimer's Disease (rrAD) trial is designed to study the independent and combined effects of intensive pharmacological control of blood pressure and cholesterol and exercise training on neurocognitive function. Six hundred and forty cognitively normal older adults age 60 to 85 years with hypertension and increased risk for dementia will be enrolled. Participants are randomized into one of four intervention group for two years: usual care, Intensive Reduction of Vascular Risk factors (IRVR) with blood pressure and cholesterol reduction, exercise training (EX), and IRVR+EX. Neurocognitive function is measured at baseline, 6, 12, 18, and 24 months; brain MRIs are obtained at baseline and 24 months. We hypothesize that both IRVR and EX will improve global cognitive function, while IRVR+EX will provide a greater benefit than either IRVR or EX alone. We also hypothesize that IRVR and EX will slow brain atrophy, improve brain structural and functional connectivity, and improve brain perfusion. Finally, we will explore the mechanisms by which study interventions impact neurocognition and brain. If rrAD interventions are shown to be safe, practical, and successful, our study will have a significant impact on reducing the risks of AD in older adults. NCT Registration: NCT02913664.

Cardiorespiratory Fitness and White Matter Neuronal Fiber Integrity in Mild Cognitive Impairment

BACKGROUND

Mounting evidence showed the self-reported levels of physical activity are positively associated with white matter (WM) integrity and cognitive performance in normal adults and patients with mild cognitive impairment (MCI). However, the objective measure of cardiorespiratory fitness (CRF) was not used in these studies.

OBJECTIVE

To determine the associations of CRF measured by maximal oxygen uptake (VO2max) with WM fiber integrity and neurocognitive performance in older adults with MCI.

METHODS

Eighty-one participants (age = 65±7 years, 43 women), including 26 cognitively normal older adults and 55 amnestic MCI patients, underwent VO2max test to measure CRF, diffusion tensor imaging (DTI) to assess WM fiber integrity, and neurocognitive assessment focused on memory and executive function. DTI data were analyzed by the tract-based spatial statistics and region-of-interest approach.

RESULTS

Cognitively normal older adults and MCI patients were not different in global WM fiber integrity and VO2max. VO2max was associated positively with DTI metrics of fractional anisotropy in ∼54% WM fiber tracts, and negatively with mean and radial diffusivities in ∼46% and ∼56% of the WM fiber tracts. The associations of VO2max with DTI metrics remained statistically significant after adjustment of age, sex, body mass index, WM lesion burden, and MCI status. The DTI metrics obtained from the area that correlated to VO2max were associated with executive function performance in MCI patients.

CONCLUSIONS

Higher levels of CRF are associated with better WM fiber integrity, which in turn is correlated with better executive function performance in MCI patients.

Cognitive Performance Does not Limit Physical Activity Participation in the Lifestyle Interventions and Independence for Elders Pilot Study (LIFE-P)

OBJECTIVES

We examined whether multiple domains of baseline cognitive performance were associated with prospective physical activity (PA) adherence in the Lifestyle Interventions and Independence for Elders Pilot study (LIFE-P).

DESIGN, SETTING, PARTICIPANTS

The LIFE-P study was a single-blind, multicenter, randomized controlled trial of a PA intervention compared to a successful aging educational intervention in sedentary, mobility-limited older adults.

INTERVENTION

A 12-month structured, moderate-intensity, multi-modal PA program that included walking, resistance training, and flexibility exercises. For the first 2 months (adoption), 3 center-based exercise sessions (40-60 min) / week were conducted. During the next 4 months (transition), center-based sessions were conducted 2 times / week. The subsequent maintenance phase consisted of optional once-to-twice-per-week center-based sessions and home-based PA.

MEASUREMENTS

Tests of executive and global cognitive functioning, working memory and psychomotor speed were administered at baseline. Median test scores were used to dichotomize participants into low or high cognitive performance groups.

RESULTS

52 mobility-limited older adults (age: 76.9 ±5 yrs) were randomized to the PA arm of LIFE-P. Compared to participants with high cognitive performance, participants with low performance had similar PA adherence rates (all P ≥ 0.34). Furthermore, weak and non-significant univariate relationships were elicited between all measures of cognition and overall PA adherence levels (r values ranged: -0.20 to 0.12, P ≥ 0.12).

CONCLUSION

These data suggest that cognitive performance does not limit long-term PA adherence in mobility-limited older adults. Additional studies in larger cohorts are warranted to verify these findings.

Anti-tau antibody administration increases plasma tau in transgenic mice and patients with tauopathy

Tauopathies are a group of disorders in which the cytosolic protein tau aggregates and accumulates in cells within the brain, resulting in neurodegeneration. A promising treatment being explored for tauopathies is passive immunization with anti-tau antibodies. We previously found that administration of an anti-tau antibody to human tau transgenic mice increased the concentration of plasma tau. We further explored the effects of administering an anti-tau antibody on plasma tau. After peripheral administration of an anti-tau antibody to human patients with tauopathy and to mice expressing human tau in the central nervous system, there was a dose-dependent increase in plasma tau. In mouse plasma, we found that tau had a short half-life of 8 min that increased to more than 3 hours after administration of anti-tau antibody. As tau transgenic mice accumulated insoluble tau in the brain, brain soluble and interstitial fluid tau decreased. Administration of anti-tau antibody to tau transgenic mice that had decreased brain soluble tau and interstitial fluid tau resulted in an increase in plasma tau, but this increase was less than that observed in tau transgenic mice without these brain changes. Tau transgenic mice subjected to acute neuronal injury using 3-nitropropionic acid showed increased interstitial fluid tau and plasma tau. These data suggest that peripheral administration of an anti-tau antibody results in increased plasma tau, which correlates with the concentration of extracellular and soluble tau in the brain.

Amyloid burden and sleep blood pressure in amnestic mild cognitive impairment

OBJECTIVE

To determine whether cortical β-amyloid (Aβ) deposition is associated with circadian blood pressure (BP) profiles and dynamic cerebral blood flow (CBF) regulation in patients with amnestic mild cognitive impairment (aMCI).

METHODS

Forty participants with aMCI were included in this study. Cortical Aβ depositions were measured by (18)F-florbetapir PET and expressed as the standardized uptake value ratio (SUVR) relative to the cerebellum. Circadian BP profiles were measured by 24-hour ambulatory monitoring during awake and sleep periods. The dipping status of sleep BP (i.e., the percent changes from the awake BP) was calculated and dichotomized into the dipper (≥10%) and nondipper (<10%) groups. Dynamic CBF regulation was assessed by a transfer function analysis between beat-to-beat changes in BP and CBF velocity measured from the middle cerebral artery during a repeated sit-stand maneuver.

RESULTS

Age was positively correlated with a greater Aβ deposition in the posterior cingulate, precuneus, and mean cortex. Accounting for the age effect, attenuated reductions in sleep systolic BP were associated with higher levels of posterior cingulate SUVR. Consistently, the nondippers exhibited a higher SUVR in the posterior cingulate than the dippers. Transfer function gain between changes in BP and CBF velocity was diminished in the nondippers, and moreover those individuals with a lower gain exhibited a higher SUVR in the posterior cingulate.

CONCLUSIONS

Attenuated reductions in sleep BP are associated with a greater Aβ burden in the posterior cingulate and altered dynamic CBF regulation in patients with aMCI.

Central artery stiffness, baroreflex sensitivity, and brain white matter neuronal fiber integrity in older adults

Cerebral hypoperfusion elevates the risk of brain white matter (WM) lesions and cognitive impairment. Central artery stiffness impairs baroreflex, which controls systemic arterial perfusion, and may deteriorate neuronal fiber integrity of brain WM. The purpose of this study was to examine the associations among brain WM neuronal fiber integrity, baroreflex sensitivity (BRS), and central artery stiffness in older adults. Fifty-four adults (65 ± 6 years) with normal cognitive function or mild cognitive impairment (MCI) were tested. The neuronal fiber integrity of brain WM was assessed from diffusion metrics acquired by diffusion tensor imaging. BRS was measured in response to acute changes in blood pressure induced by bolus injections of vasoactive drugs. Central artery stiffness was measured by carotid-femoral pulse wave velocity (cfPWV). The WM diffusion metrics including fractional anisotropy (FA) and radial (RD) and axial (AD) diffusivities, BRS, and cfPWV were not different between the control and MCI groups. Thus, the data from both groups were combined for subsequent analyses. Across WM, fiber tracts with decreased FA and increased RD were associated with lower BRS and higher cfPWV, with many of the areas presenting spatial overlap. In particular, the BRS assessed during hypotension was strongly correlated with FA and RD when compared with hypertension. Executive function performance was associated with FA and RD in the areas that correlated with cfPWV and BRS. These findings suggest that baroreflex-mediated control of systemic arterial perfusion, especially during hypotension, may play a crucial role in maintaining neuronal fiber integrity of brain WM in older adults.

The LIFE Cognition Study: design and baseline characteristics

Observational studies have shown beneficial relationships between exercise and cognitive function. Some clinical trials have also demonstrated improvements in cognitive function in response to moderate-high intensity aerobic exercise; however, these have been limited by relatively small sample sizes and short durations. The Lifestyle Interventions and Independence for Elders (LIFE) Study is the largest and longest randomized controlled clinical trial of physical activity with cognitive outcomes, in older sedentary adults at increased risk for incident mobility disability. One LIFE Study objective is to evaluate the effects of a structured physical activity program on changes in cognitive function and incident all-cause mild cognitive impairment or dementia. Here, we present the design and baseline cognitive data. At baseline, participants completed the modified Mini Mental Status Examination, Hopkins Verbal Learning Test, Digit Symbol Coding, Modified Rey-Osterrieth Complex Figure, and a computerized battery, selected to be sensitive to changes in speed of processing and executive functioning. During follow up, participants completed the same battery, along with the Category Fluency for Animals, Boston Naming, and Trail Making tests. The description of the mild cognitive impairment/dementia adjudication process is presented here. Participants with worse baseline Short Physical Performance Battery scores (prespecified at ≤ 7) had significantly lower median cognitive test scores compared with those having scores of 8 or 9 with modified Mini Mental Status Examination score of 91 versus (vs) 93, Hopkins Verbal Learning Test delayed recall score of 7.4 vs 7.9, and Digit Symbol Coding score of 45 vs 48, respectively (all P<0.001). The LIFE Study will contribute important information on the effects of a structured physical activity program on cognitive outcomes in sedentary older adults at particular risk for mobility impairment. In addition to its importance in the area of prevention of cognitive decline, the LIFE Study will also likely serve as a model for exercise and other behavioral intervention trials in older adults.

Performance of a computer-based assessment of cognitive function measures in two cohorts of seniors

BACKGROUND

Computer-administered assessment of cognitive function is being increasingly incorporated in clinical trials; however, its performance in these settings has not been systematically evaluated.

DESIGN

The Seniors Health and Activity Research Program pilot trial (N = 73) developed a computer-based tool for assessing memory performance and executive functioning. The Lifestyle Interventions and Independence for Elders investigators incorporated this battery in a full-scale multicenter clinical trial (N = 1635). We describe relationships that test scores have with those from interviewer-administered cognitive function tests and risk factors for cognitive deficits and describe performance measures (completeness, intraclass correlations [ICC]).

RESULTS

Computer-based assessments of cognitive function had consistent relationships across the pilot and full-scale trial cohorts with interviewer-administered assessments of cognitive function, age, and a measure of physical function. In the Lifestyle Interventions and Independence for Elders cohort, their external validity was further demonstrated by associations with other risk factors for cognitive dysfunction: education, hypertension, diabetes, and physical function. Acceptable levels of data completeness (>83%) were achieved on all computer-based measures; however, rates of missing data were higher among older participants (odds ratio = 1.06 for each additional year; p < 0.001) and those who reported no current computer use (odds ratio = 2.71; p < 0.001). ICCs among clinics were at least as low (ICC < 0.013) as for interviewer measures (ICC < 0.023), reflecting good standardization. All cognitive measures loaded onto the first principal component (global cognitive function), which accounted for 40% of the overall variance.

CONCLUSION

Our results support the use of computer-based tools for assessing cognitive function in multicenter clinical trials of older individuals.

Practical diagnosis and management of dementia due to Alzheimer's disease in the primary care setting: an evidence-based approach

OBJECTIVE

To review evidence-based guidance on the primary care of Alzheimer's disease and clinical research on models of primary care for Alzheimer's disease to present a practical summary for the primary care physician regarding the assessment and management of the disease.

DATA SOURCES

References were obtained via search using keywords Alzheimer's disease AND primary care OR collaborative care OR case finding OR caregivers OR guidelines. Articles were limited to English language from January 1, 1990, to January 1, 2013.

STUDY SELECTION

Articles were reviewed and selected on the basis of study quality and pertinence to this topic, covering a broad range of data and opinion across geographical regions and systems of care. The most recent published guidelines from major organizations were included.

RESULTS

Practice guidelines contained numerous points of consensus, with most advocating a central role for the primary care physician in the detection, diagnosis, and treatment of Alzheimer's disease. Review of the literature indicated that optimal medical and psychosocial care for people with Alzheimer's disease and their caregivers may be best facilitated through collaborative models of care involving the primary care physician working within a wider interdisciplinary team.

CONCLUSIONS

Evidence-based guidelines assign the primary care physician a critical role in the care of people with Alzheimer's disease. Research on models of care suggests the need for an appropriate medical/nonmedical support network to fulfill this role. Given the diversity and breadth of services required and the necessity for close coordination, nationwide implementation of team-based, collaborative care programs may represent the best option for improving care standards for patients with Alzheimer's disease.

The art of sharing the diagnosis and management of Alzheimer's disease with patients and caregivers: recommendations of an expert consensus panel

OBJECTIVE

To develop a set of recommendations for primary care physicians (PCPs) suggesting how best to communicate with patients, caregivers, and other family members regarding the diagnosis and management of Alzheimer's disease (AD).

PARTICIPANTS

A national roundtable of 6 leading professionals involved in treating or advocating for patients with AD was convened on March 14, 2008. This roundtable included 4 leading academic physicians with diverse backgrounds (a geriatric psychiatrist, a neuropsychiatrist, a neurologist, and a geriatrician) from geographically diverse regions of the United States, who were invited on the basis of their national reputation in the field and experience working with minority populations with dementia; the executive director of a national AD advocacy organization; the executive director of a national advocacy organization for caregivers; and a medical correspondent with expertise in interviewing and small group leadership.

EVIDENCE

Expert opinion supported by academic literature (search limited to PubMed, English language, 1996-2008, search terms: Alzheimer's disease, primary care, diagnosis, management, caregiver, family, patient-physician relationship).

CONSENSUS PROCESS

Moderated dialogue aimed at generating consensus opinion; only statements endorsed by all authors were included in the final article.

CONCLUSIONS

Diagnosis and management of AD by PCPs, utilizing specialist consultation as needed, may contribute to earlier diagnosis and treatment, improved doctor-patient and doctor-caregiver communication, increased attention to caregiver needs, and better clinical and quality-of-life outcomes for patients and caregivers. A set of expert panel recommendations describing practical strategies for achieving these goals was successfully developed.

The cross-sectional relationship between body mass index, waist-hip ratio, and cognitive performance in postmenopausal women enrolled in the Women's Health Initiative

OBJECTIVES

To determine whether body mass index (BMI) is independently associated with cognitive function in postmenopausal women and the relationship between body fat distribution as estimated by waist-hip ratio (WHR).

DESIGN

Cross-sectional data analysis.

SETTING

Baseline data from the Women's Health Initiative (WHI) hormone trials.

PARTICIPANTS

Eight thousand seven hundred forty-five postmenopausal women aged 65 to 79 free of clinical evidence of dementia who completed the baseline evaluation in the WHI hormone trials.

MEASUREMENTS

Participants completed a Modified Mini-Mental State Examination (3MSE), health and lifestyle questionnaires, and standardized measurements of height, weight, body circumference, and blood pressure. Statistical analysis was performed of associations between 3MSE score, BMI, and WHR after controlling for known confounders.

RESULTS

With the exception of smoking and exercise, vascular disease risk factors, including hypertension, waist measurement, heart disease, and diabetes mellitus, were significantly associated with 3MSE score and were included as covariables in subsequent analyses. BMI was inversely related to 3MSE score; for every 1-unit increase in BMI, 3MSE score decreased 0.988 points (P<.001) after adjusting for age, education, and vascular disease risk factors. BMI had the most pronounced association with poorer cognitive functioning scores in women with smaller waist measurements. In women with the highest WHR, cognitive scores increased with BMI.

CONCLUSION

Higher BMI was associated with poorer cognitive function in women with smaller WHR. Higher WHR, estimating central fat mass, was associated with higher cognitive function in this cross-sectional study. Further research is needed to clarify the mechanism for this association.

Prevalence and significance of unrecognized lower extremity peripheral arterial disease in general medicine practice*

OBJECTIVE

To determine the prevalence of unrecognized lower extremity peripheral arterial disease (PAD) among men and women aged 55 years and older in a general internal medicine (GIM) practice and to identify characteristics and functional performance associated with unrecognized PAD.

DESIGN

Cross-sectional.

SETTING

Academic medical center.

PARTICIPANTS

We identified 143 patients with known PAD from the noninvasive vascular laboratory, and 239 men and women aged 55 and older with no prior PAD history from a GIM practice. Group 1 consisted of patients with PAD consecutively identified from the noninvasive vascular laboratory (n = 143). Group 2 included GIM practice patients found to have an ankle brachial index less than 0.90, consistent with PAD (n = 34). Group 3 consisted of GIM practice patients without PAD (n = 205).

MEASUREMENTS AND MAIN RESULTS

Leg functioning was assessed with the 6-minute walk, 4-meter walking velocity, and Walking Impairment Questionnaire (WIQ). Of GIM practice patients, 14% had unrecognized PAD. Only 44% of patients in Group 2 had exertional leg symptoms. Distances achieved in the 6-minute walk were 1,130, 1,362, and 1,539 feet for Groups 1, 2, and 3, respectively, adjusting for age, gender, and race (P <.001). The degree of difficulty walking due to leg symptoms as reported on the WIQ was comparable between Groups 2 and 3 and significantly greater in Group 1 than Group 2. In multiple logistic regression analysis including Groups 2 and 3, current cigarette smoking was associated independently with unrecognized PAD (odds ratio [OR], 6.82; 95% confidence interval [95% CI], 1.55 to 29.93). Aspirin therapy was nearly independently associated with absence of PAD (OR, 0.37; 95% CI, 0.12 to 1.12).

CONCLUSION

Unrecognized PAD is common among men and women aged 55 years and older in GIM practice and is associated with impaired lower extremity functioning. Ankle brachial index screening may be necessary to diagnose unrecognized PAD in a GIM practice.

Race and sex influence clearance of nifedipine: results of a population study

OBJECTIVE

To estimate oral clearance of nifedipine and to determine demographic and clinical covariates that affect nifedipine clearance in a clinical population.

METHODS

Apparent oral clearance of nifedipine and protein binding were measured in 226 patients receiving sustained-release nifedipine formulations for hypertension and coronary artery disease (black men, n = 111; black women, n = 27; white men, n = 64; white women, n = 24). Mean age +/- SD was 71 +/- 11 years, and mean weight was 86 +/- 17 kg. Nifedipine concentrations were analyzed by HPLC, protein binding was measured by equilibrium dialysis, clearance and covariate effects were estimated by a nonlinear mixed effects population model, and statistical analyses were performed by a nonlinear mixed-effects model (clearance) and ANOVA (protein binding).

RESULTS

Clearance was significantly slower in black subjects (8.9 +/- 0.7 mL/min/kg; mean +/- SE) compared with white subjects (11.6 +/- 0.8 mL/min/kg; P = .00004) and in men compared with women (9.3 +/- 0.6 versus 12.1 +/- 1.5 mL/min/kg; P = .0021). Reported alcohol use (alcohol, 8.6 +/- 1.1 versus no alcohol, 10.8 +/- 0.6 mL/min/kg; P = .0002) and smoking status (smoker, 8.8 +/- 2.0 versus nonsmoker, 10.2 +/- 0.6 mL/min/kg; P = .0362) also affected nifedipine clearance. Race and sex had no effect on protein binding of nifedipine (P = .29 and P = .44, respectively). No effects of age, stable coronary artery disease, or reported intake of beta-blockers on nifedipine clearance were detected in this primarily elderly population with hypertension.

CONCLUSIONS

The data suggest that race, sex, and environmental factors are identifiable sources of interindividual variation in the oral clearance of nifedipine, a CYP3A substrate. Our experience also suggests that data from clinical populations may be biased with regard to age, sex, and formulation selection, and covariates may not be independently distributed, which can limit analyses.

Member characteristics, participation, and interests: Public Health Nutrition Practice Group

A survey was developed to assess the level of participation and the membership interests of the Public Health Nutrition Practice Group (PHNPG). Forty-six percent (500 members) returned a completed survey. More than 80% of members believe PHNPG to be their main professional practice area "home" within the Council on Practice structure. Members overwhelmingly viewed practice group contributions as a responsibility, with personal career benefits being of secondary importance. Reading the practice group's newsletter and voting in elections were major areas of involvement. However, willingness to contribute time was a positive finding. Areas of interest and issues of greatest concern were identified. Results of the survey can be used to prepare long-range plans for PHNPG. Membership involvement in practice group activities is the key to an increase in re-enrollments and in new memberships.