Johansen, Michelle C.

Introduction: We recently reported that abnormal P-wave indices (PWI)—ECG markers of atrial cardiomyopathy (AC)—are associated with an increased risk of dementia, independent of atrial fibrillation (AF) and clinical ischemic stroke. The mechanisms, however, remain unclear, but may include silent ischemia. Hypothesis: Abnormal PWI are associated with higher prevalence of cortical infarcts on MRI, suggesting cardioembolism as a potential mechanism. Methods: ARIC-NCS participants (mean age, 72.2±5.3 years; 60% women; 29% black) who underwent 3T brain MRI scans in 2011-2013 were included. Abnormal PWI included P-wave terminal force in lead V1 [(PTFV1) defined as ≥4000 μV*ms] and P-wave duration [(PWD) defined as >120 ms], which were measured from standard 12-lead ECGs. Brain MRI outcomes included cortical infarcts, cerebral microbleeds (CMB), and markers of small vessel disease [white matter hyperintensities (WMH) and lacunar infarcts]. We used weighted multivariable logistic and linear regression analyses. Results: Of the 1,850 participants, 464 had abnormal PTFV1 and 415 had prolonged PWD. After multivariable adjustment including AF, abnormal PTFV1 and PWD were significantly associated with 26-44% increased odds of cortical and lacunar infarcts (Table) . Although PWD was associated with CMB in Model 1, the association was no longer significant after multivariable adjustment. Finally, abnormal PWIs were not associated with WMH after adjusting for stroke and AF (P >0.5). Conclusions: Abnormal PWI are associated with higher prevalence of cortical infarcts, suggesting cardioembolism with silent ischemia as a possible mechanism underlying the association of AC with dementia. More research is needed to evaluate other mechanisms such as cerebral small vessel disease.

Background: Cerebral microbleeds (CMBs) are associated with cognitive decline, but their importance outside of clinical cerebral amyloid angiopathy is less well understood, as are the mechanisms of their impact on cognition. In a community-based dementia-free cohort, we evaluate cross-sectional associations between CMB patterns and cerebral amyloid β (Aβ) deposition, measured by florbetapir PET. Methods: ARIC-PET recruited nondemented individuals from 3 US sites. Participants completed 3T brain MRI with T2*GRE (with CMBs read for presence, frequency, location (lobar vs subcortical), and pattern, as well as florbetapir (Aβ) PET (global cortical standardized uptake value ratio >1.2 as a positive scan). Multivariable (see Table) logistic regression models of Aβ+ scans evaluated CMB presence, frequency, location, and pattern, in separate models. Effect modification by sex, race, APOE status, and cognition (normal vs mild cognitive impairment) was evaluated. Results: Nearly 25% of the 322 individuals included had CMBs. No significant associations were found between CMBs (presence or number) and Aβ positivity, but a pattern of isolated lobar CMBs or superficial siderosis was associated with over a 4-fold higher odds of elevated Aβ vs having no CMBs, without a similar elevated risk in those with isolated subcortical CMBs or mixed subcortical + either lobar CMBs or superficial siderosis. Although no significant interactions were found, a mixed pattern was nonsignificantly protective (OR estimates 0.4-0.6) and lobar only CMBs had a (nonsignificantly) higher risk (OR up to 6.4) of Aβ for three subgroups: women (vs men); Blacks (vs whites), APOE ε4 noncarriers (vs carriers), and cognitively normal (vs MCI). Conclusions: A lobar-only pattern of CMBs is most strongly associated with brain Aβ, with no elevated risk for a mixed CMB pattern. Further study is needed to understand differences in these CMB patterns and their meaning across distinct demographic subgroups.

Background: Ischemic Stroke (IS) is associated with an increased risk of dementia, but the relative contribution of IS severity or recurrence to cognition is not known. We aimed to determine the risk of dementia after incident IS and how it varies by stroke severity and recurrence in the Atherosclerosis Risk in Communities (ARIC) study. Methods: 15,405 ARIC participants free of stroke and dementia at baseline (1987-9) were followed for IS and dementia through 2019. Incident and recurrent IS were classified by expert review of hospital records, with stroke severity by the National Institutes of Health Stroke Scale (NIHSS) classified as NIHSS≤5, 6-10, 11-15, ≥16. Dementia cases were adjudicated through expert review of in-person evaluations, informant interviews, phone assessments, hospitalization code or death certificates. Poisson regression models with robust error variance were used to estimate dementia incidence in participants with and without IS, and associations between time-dependent IS incidence (excluding dementia in the first year after stroke), frequency and severity, and dementia were studied with Cox proportional hazards models, adjusting for demographics, APOE ε4 and vascular risk factors . Results: 1151 IS (970 incident) and 2807 dementia cases were identified. NIHSS was available for 877 IS (76%). Adjusted incidence rates (95% CI) of dementia per 100 person-years were 0.45 (0.42-0.49) in participants without IS vs. 1.33 (1.15-1.55) in those with IS. Compared to no IS, risk of dementia (adjusted HR, 95% CI) increased with IS number and severity from 1.71 (1.47-1.99) for participants with one IS to 6.68 (3.58-12.46) for those with ≥3 events, and from 1.64 (1.36-1.98) for NIHSS≤5 to 4.43 (1.84-10.68) for NIHSS≥16 ( Table ). Conclusion: Risk of dementia is significantly increased after stroke, independent of vascular risk factors. These data suggest a dose-response relationship between number of stroke events and stroke severity, and risk of dementia.

Background Atrial fibrillation (AF) is a risk factor for cognitive decline, possibly from silent brain infarction. Left atrial changes in structure or function (atrial cardiopathy) can lead to AF but may impact cognition independently. It is unknown if AF or atrial cardiopathy also acts on Alzheimer disease–specific mechanisms, such as deposition of β‐amyloid. Methods and Results A total of 316 dementia‐free participants from the ARIC (Atherosclerosis Risk in Communities) study underwent florbetapir positron emission tomography, electrocardiography, and 2‐dimensional echocardiography. Atrial cardiopathy was defined as ≥1: (1) left atrial volume index >34 mL/m 2 ; (2) P‐wave terminal force >5000 µV×ms; and (3) serum NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) >250 pg/mL. Cross‐sectional associations between global cortical β‐amyloid (>1.2 standardized uptake value ratio) and adjudicated history of AF and atrial cardiopathy, each, were evaluated using multivariable logistic regression. Participants (mean age, 76 years) were 56% women and 42% Black individuals. Odds of elevated florbetapir standardized uptake value ratio were significantly increased among those with atrial cardiopathy (odds ratio, 1.81; 95% CI, 1.02–3.22) and doubled for those with enlarged left atrial volume index after adjustment for demographics/risk factors (95% CI, 1.04–4.61). There was no association between P‐wave terminal force or NT‐proBNP and elevated florbetapir standardized uptake value ratio, nor between AF and elevated standardized uptake value ratio. Conclusions Among healthy, nondemented community‐dwelling older individuals, we report an association between atrial cardiopathy, left atrial volume index, and elevated brain amyloid, by positron emission tomography, without a similar association in individuals with AF. Potential limitations include reverse causation and survival bias. Ongoing work will help determine if changes in cardiac structure and function precede or occur simultaneously with amyloid deposition.

Background: Atrial fibrillation (AF) is a risk factor for cognitive decline, perhaps due to silent cerebral infarction, but it is unknown if it also acts on Alzheimer’s Disease (AD)-specific mechanisms, such as deposition of β-amyloid (Aβ). Left atrial changes in structure or function, or atrial cardiopathy, can lead to AF but may cause infarcts independently, and thus might also impact cognition. We hypothesize that Aβ is associated with AF and atrial cardiopathy, independent of AF, when defined similarly to an ongoing clinical trial (ARCADIA). Methods: 321 participants without dementia from the Atherosclerosis Risk in Communities study underwent florbetapir (FBP) PET, electrocardiogram and 2D echocardiography. Atrial cardiopathy was defined as ≥1 of: 1) left atrial volume index (LAVI) >34 ml/m2; 2) P-wave terminal force >5000 uV x ms and 3) serum NT proBNP>250 pg/mL. Cross-sectional associations between global cortical Aβ (>1.2 standardized uptake value ratio (SUVR)) and adjudicated history of atrial fibrillation and atrial cardiopathy, each, were evaluated using multivariable logistic regression. Results: Participants, with mean age 76 y, were 56% female and 42% black. Odds of elevated FBP SUVR was increased for those with atrial cardiopathy (Model 3) and nearly doubled among those with enlarged LAVI that remained significant after sequential adjustment, including AF (Table). There was no significant association between either P-wave terminal force or NT proBNP and elevated FBP SUVR (Table), nor between elevated SUVR and AF. Conclusions: In this cross-sectional analysis of a cohort of healthy, nondemented community-dwelling older individuals, we report a significant association between atrial cardiopathy as well as LAVI and elevated amyloid, by PET, without a similar association in individuals with AF. Potential limitations include reverse causation and survival bias. Ongoing work will help determine if changes in cardiac structure and function precede, or occur simultaneously with amyloid deposition.

Background and Purpose— Cardiovascular disease is a known risk factor for cognitive decline, although the mechanisms remain unclear. We hypothesize that Aβ (β-amyloid), a core pathology of Alzheimer's disease, will be associated with subclinical cardiac structure and function echocardiogram indices. Methods— Three hundred six nondemented participants from the ARIC study (Atherosclerosis Risk in Communities Study) underwent florbetapir positron emission tomography and 2D echocardiography (echo). Cross-sectional associations between echo markers of left ventricular structure and function and global cortical Aβ (≥1.2 standardized uptake value ratio were evaluated using multivariable logistic regression with interaction terms when appropriate. Results— Participants ranged in age from 67 to 88 years, were 57% female and 42% black. Per 1 cm increase in end-diastolic left ventricular diameter, the odds of elevated florbetapir standardized uptake value ratio doubled (odds ratio, 2.04 [95% CI, 1.10–3.77]), with similar findings when excluding mild cognitive impairment (odds ratio, 2.61 [95% CI, 1.22–5.59]). Conclusions— We have demonstrated a significant association between a marker of left ventricular structure and elevated florbetapir standardized uptake value ratio, identified using positron emission tomography. Ongoing prospective work will help determine if changes in cardiac structure and function either precede, or occur simultaneously with deposition of amyloid.