Plasma EFEMP1 Is Associated with Brain Aging and Dementia: The Framingham Heart Study

BACKGROUND

Epidermal growth factor containing fibulin extracellular matrix protein-1 (EFEMP1) has been associated with increased white matter hyperintensities (WMH) burden and disorders of premature aging and may have a shared pathophysiological role in the development of WMH and dementia.

OBJECTIVE

To determine the association between plasma EFEMP1 levels and MRI markers of vascular brain injury and incident all-cause and Alzheimer's disease (AD) dementia.

METHODS

We measured plasma EFEMP1 levels in 1597 [53% women, mean age 68.7 (SD 5.7) years] dementia-free Framingham Offspring cohort participants between 1998-2001 and subsequently followed them for incident dementia. Secondary outcomes included stroke, structural MRI brain measures and neurocognitive test performance.

RESULTS

During a median 11.8 [Q1, Q3 : 7.1, 13.3] year follow-up, 131 participants developed dementia. The highest quintile of plasma EFEMP1, compared to the bottom four quintiles, was associated with an increased risk of time to incident all-cause dementia (HR 1.77, 95% CI 1.18-2.64) and AD dementia (HR 1.76, 95% CI 1.11-2.81) but not with markers of vascular brain injury (WMH, covert brain infarcts or stroke). Higher circulating EFEMP1 concentrations were also cross-sectionally associated with lower total brain (β±SE, -0.28±0.11, p = 0.01) and hippocampal volumes (-0.006±0.003, p = 0.04) and impaired abstract reasoning (Similarities test, -0.18±0.08, p = 0.018 per standard deviation increment in EFEMP1).

CONCLUSION

Elevated circulating EFEMP1 is associated with an increased risk of all-cause and AD dementia, smaller hippocampal and total brain volumes, and poorer cognitive performance. EFEMP1 may play an important biological role in the development of AD dementia. Further studies to validate these findings are warranted.

Accelerometer-Measured, Habitual Physical Activity and Circulating Brain-Derived Neurotrophic Factor: A Cross-Sectional Study

BACKGROUND

One of the mechanisms suggested to link physical activity (PA) to favorable brain health is through stimulation of neural growth factors such as brain-derived neurotrophic factor (BDNF). Acute bouts of PA stimulate circulating BDNF levels.

OBJECTIVE

In this investigation, we assessed whether habitual, accelerometer-measured PA levels were related to circulating BDNF levels in a middle-aged cohort.

METHODS

In the Framingham Heart Study Third Generation cohort, 1,769 participants provided reliable accelerometry data and were not missing BDNF measurement and platelet counts. In a cross-sectional analysis, using multivariable regression, we related PA measures to serum BDNF levels, adjusting for age, sex, smoking status, platelet count, depression status, and accelerometer wear time.

RESULTS

Our study participants (mean age 47±9 years, 50.8% women) spent an average of 22.3 mins/day moderate-to-vigorous (MV)PA. Most PA variables (steps, MVPA, light activity, and sedentary time) were not related to BDNF levels (p > 0.05). We observed a non-linear trend, where 15-50 mins/week vigorous activity was associated with lower BDNF compared to those with 0 min vigorous activity (β= -0.049±0.024, p = 0.05), but with no significant associations at lower or higher vigorous activity levels. In smokers, MVPA was also associated with lower BDNF levels (β= -0.216±0.079, p = 0.01).

CONCLUSION

Our study reveals that circulating BDNF is not chronically elevated in individuals with higher levels of habitual PA in middle-aged adults from the community and may even be chronically suppressed with higher PA in subgroups, including current smokers. These results do not contradict previous studies demonstrating that circulating BDNF rises acutely after PA.

Vascular risk factors as predictors of epilepsy in older age: The Framingham Heart Study

OBJECTIVE

Stroke is the most common cause of epilepsy in older age. Subclinical cerebrovascular disease is believed to underlie some of the 30%-50% of late-onset epilepsy without a known cause (Li et al. Epilepsia. 1997;38:1216; Cleary et al. Lancet. 2004;363:1184). We studied the role of modifiable vascular risk factors in predicting subsequent epilepsy among participants ages 45 or older in the Framingham Heart Study (FHS), a longitudinal, community-based study.

METHODS

Participants of the Offspring Cohort who attended FHS exam 5 (1991-1995) were included who were at least 45-years-old at that time, had available vascular risk factor data, and epilepsy follow-up (n = 2986, mean age 58, 48% male). Adjudication of epilepsy cases included review of medical charts to exclude seizure mimics and acute symptomatic seizures. The vascular risk factors studied included hypertension, diabetes mellitus, smoking, and hyperlipidemia. The role of the Framingham Stroke Risk Profile score was also investigated. Cox proportional hazards regression models were used for the analyses.

RESULTS

Fifty-five incident epilepsy cases were identified during a mean of 19 years of follow-up. Hypertension was associated with a near 2-fold risk (hazard ratio [HR]: 1.93, 95% confidence interval [CI]: 1.10-3.37, p = .022) of developing epilepsy, even after adjustment for prevalent and interim stroke. In secondary analysis, excluding patients with normal blood pressure who were receiving anti-HTN (anti-hypertensive) treatment (n = 2613, 50 incident epilepsy cases) the association was (HR: 2.44, 95% CI: 1.36-4.35, p = .003).

SIGNIFICANCE

Our results offer further evidence that hypertension, a potentially modifiable and highly prevalent vascular risk factor in the general population, increases 2- to 2.5-fold the risk of developing late-onset epilepsy.

Cortical superficial siderosis in the general population: The Framingham Heart and Rotterdam studies

OBJECTIVE

We aimed to characterize cortical superficial siderosis, its determinants and sequel, in community-dwelling older adults.

METHODS

The sample consisted of Framingham (n = 1724; 2000-2009) and Rotterdam (n = 4325; 2005-2013) study participants who underwent brain MRI. In pooled individual-level analysis, we compared baseline characteristics in patients with cortical superficial siderosis to two reference groups: (i) persons without hemorrhagic MRI markers of cerebral amyloid angiopathy (no cortical superficial siderosis and no microbleeds) and (ii) those with presumed cerebral amyloid angiopathy based on the presence of strictly lobar microbleeds but without cortical superficial siderosis.

RESULTS

Among a total of 6049 participants, 4846 did not have any microbleeds or cortical superficial siderosis (80%), 401 had deep/mixed microbleeds (6.6%), 776 had strictly lobar microbleeds without cortical superficial siderosis (12.8%) and 26 had cortical superficial siderosis with/without microbleeds (0.43%). In comparison to participants without microbleeds or cortical superficial siderosis and to those with strictly lobar microbleeds but without cortical superficial siderosis, participants with cortical superficial siderosis were older (OR 1.09 per year, 95% CI 1.05, 1.14; p < 0.001 and 1.04, 95% CI 1.00, 1.09; p = 0.058, respectively), had overrepresentation of the APOE ɛ4 allele (5.19, 2.04, 13.25; p = 0.001 and 3.47, 1.35, 8.92; p = 0.01), and greater prevalence of intracerebral hemorrhage (72.57, 9.12, 577.49; p < 0.001 and 81.49, 3.40, >999.99; p = 0.006). During a mean follow-up of 5.6 years, 42.4% participants with cortical superficial siderosis had a stroke (five intracerebral hemorrhage, two ischemic strokes and four undetermined strokes), 19.2% had transient neurological deficits and 3.8% developed incident dementia.

CONCLUSION

Our study adds supporting evidence to the association between cortical superficial siderosis and cerebral amyloid angiopathy within the general population. Community-dwelling persons with cortical superficial siderosis may be at high risk for intracerebral hemorrhage and future neurological events.

Bone Mineral Density Measurements and Association With Brain Structure and Cognitive Function: The Framingham Offspring Cohort

BACKGROUND

Bone mineral density (BMD) is a potential surrogate marker of lifetime estrogen exposure previously linked to increased risk of Alzheimer dementia among elderly women. We examine the association between BMD in the "young old" with imaging biomarkers of brain aging and cognitive performance.

METHODS

Offspring participants (N=1905, mean age 66) of a population-based cohort who had BMD, brain imaging and detailed cognitive assessment were included in the study. Sex-stratified, linear, and logistic regression models were used for analysis.

RESULTS

Higher femoral neck BMD was associated with lower white matter hyperintensity burden and better performance on Trails B-A in both sexes, even after adjustment for cerebrovascular risk factors. Among women, the positive association with Trails B-A performance was seen only in APOE4 allele carriers. Higher BMD measurements were linked to better visual reproductions test performance in men. Finally, among women, higher femoral trochanter BMD was associated with better logical memory and Hooper visual organization test performance.

CONCLUSION

Among the "young old," higher BMD is associated with less white matter hyperintensity burden and better, domain-specific, cognitive performance. This suggests that lifetime estrogen exposure may modulate the degree of cumulative vascular brain injury independent of cerebrovascular risk factors.

Mind Diet Adherence and Cognitive Performance in the Framingham Heart Study

BACKGROUND

Adherence to the Mediterranean-DASH for Neurodegenerative Delay (MIND) diet has previously been associated with cognitive decline and dementia. To our knowledge, no prior study has investigated the association between the MIND diet and measures of brain volume, silent brain infarcts (SBIs), or brain atrophy.

OBJECTIVE

We evaluated whether adherence to the MIND diet associated with superior cognitive function, larger brain volumes, fewer SBIs, and less cognitive decline in the community-based Framingham Heart Study.

METHODS

2,092 participants (mean±SD, age 61±9) completed Food Frequency Questionnaires, averaged across a maximum of 3-time points (examination cycles 5, 6, and 7), cognitive testing at examination cycle 7 (present study baseline: 1998-2001) and after a mean±SD of 6.6±1.1 years from baseline (n = 1,584). A subset of participants also completed brain magnetic resonance imaging (MRI) at examination cycle 7 (n = 1,904). In addition, participants with dementia, stroke, and other relevant neurological diseases such as significant head trauma, subdural hematoma, or multiple sclerosis were excluded from the analyses.

RESULTS

Higher MIND diet scores were associated with better global cognitive function (β±SE,+0.03SD±0.01; p = 0.004), verbal memory, visual memory, processing speed, verbal comprehension/reasoning, and with larger total brain volume (TBV) following adjustments for clinical, lifestyle and demographic covariates, but not with other brain MRI measures (i.e., hippocampal volume, lateral ventricular volume, white matter hyperintensity volume, and SBIs) or cognitive decline.

CONCLUSION

Higher MIND diet scores associated with better cognitive performance and larger TBV at baseline, but not with cognitive decline. Clinical trials are needed to ascertain whether adopting the MIND diet affects trajectories of cognitive decline.

Assessment of Incidence and Risk Factors of Intracerebral Hemorrhage Among Participants in the Framingham Heart Study Between 1948 and 2016

Importance

Intracerebral hemorrhage (ICH) has the highest mortality of all stroke types and is the most serious complication of anticoagulation. Data regarding trends in ICH incidence and location-specific risk factors on the population level are conflicting.

Objective

To assess long-term population-based trends in the incidence of ICH, examine incidence rates stratified by deep and lobar locations, and characterize location-specific risk factors.

Design, Setting, and Participants

This longitudinal prospective community-based cohort study comprised 10 333 original participants (n = 5209; age range, 28-62 years) and offspring participants (n = 5124; age range, 5-70 years) from the Framingham Heart Study who were followed up from January 1, 1948, to December 31, 2016. Original and offspring patient cohorts were confirmed to have experienced a spontaneous ICH event through imaging or pathologic testing. A total of 129 participants were identified with a primary incident of ICH. After exclusions, the remaining 99 patients were divided into 2 nested case-control samples, which were created by stratifying the first incident of ICH by brain region (lobar ICH or deep ICH), with 55 patients included in the lobar ICH sample and 44 patients included in the deep ICH sample. Patients were matched by age and sex (1:4 ratio) with 396 individuals without any stroke event (the control group). No participant in the patient samples was excluded or approached for consent, as their initial consent to participate in the Framingham Heart Study included consent to follow-up of cardiovascular outcomes. Data were analyzed in October 2019.

Main Outcomes and Measures

The unadjusted and age-adjusted ICH incidence rates, assessed in 3 periods (period 1, from 1948-1986; period 2, from 1987-1999; and period 3, from 2000-2016) to study incidence trends. Nested case-control samples were used to examine baseline risk factors and medication exposures with the incidence of ICH events located in the lobar and deep brain regions within the 10 years before participants experienced a stroke event.

Results

Of 10 333 original and offspring participants in the Framingham Heart Study, 129 patients (72 women [55.8%]; mean [SD] age, 77 [11] years) experienced a primary ICH incident during a follow-up period of 68 years (301 282 person-years), with an incidence rate of 43 cases per 100 000 person-years. The unadjusted incidence rate increased over time, but the age-adjusted incidence rate decreased slightly between periods 2 and 3. An age-stratified analysis indicated a continued increase in ICH incidence among patients 75 years and older, reaching 176 cases per 100 000 person-years in period 3. A concurrent 3-fold increase in the use of anticoagulant medications was observed, from 4.4% in period 2 to 13.9% in period 3. The incidence rate increased substantially with age for both lobar and deep ICH. Higher systolic and diastolic blood pressure and statin medication use (odds ratio [OR], 4.07; 95% CI, 1.16-14.21; P = .03) were associated with the incidence of deep ICH. Higher systolic blood pressure and apolipoprotein E ε4 allele homozygosity (OR, 3.66; 95% CI, 1.28-10.43; P = .02) were associated with the incidence of lobar ICH.

Conclusions and Relevance

This study found that the incidence of ICH increased in the oldest patients. Hypertension is a treatable risk factor for both deep and lobar ICH, while the use of statin medications is associated with the risk of a deep ICH event.

Systemic inflammation as a moderator between sleep and incident dementia

STUDY OBJECTIVES

To determine whether C-reactive protein (CRP), a marker of systemic inflammation, moderates the association between sleep and incident dementia.

METHODS

We studied Framingham Heart Study participants who completed at baseline a serum CRP assessment and in-home polysomnography to measure sleep duration, sleep efficiency, sleep latency, wake after sleep onset (WASO), number of awakenings, arousal index, and apnea-hypopnea index. Participants were divided into groups according to their CRP level: low (<1 mg/L), average (1-3 mg/L), and high inflammation (>3 mg/L). Surveillance for outcomes (incident all-cause and Alzheimer's disease [AD] dementia) commenced at baseline and continued up to 22.5 years.

RESULTS

In 291 participants (mean age 67.5 ± 4.9 years, 51.6% men) followed for 13.4 ± 5.4 years, we observed 43 cases of all-cause dementia, 33 of which were clinically consistent with AD. Whereas no direct association between CRP or sleep exposures was observed with incident dementia, CRP levels interacted with nighttime wakefulness when predicting both incident all-cause and AD dementia. In the high CRP group, longer WASO (hazard ratio [HR], 2.89; 95% CI, 1.31-6.34) and more nighttime awakenings (HR, 4.55; 95% CI, 1.19-17.38) were associated with higher risk of incident dementia. In the low CRP group, fewer nighttime awakenings were associated with a higher risk of incident dementia (HR, 0.07; 95% CI, 0.01-0.68).

CONCLUSIONS

Our findings suggest that inflammation moderates the association between sleep, particularly nighttime wakefulness, and dementia risk. The presence of inflammation may be an important determinant in evaluating how sleep disturbances relate to neurodegeneration.

Incidence of Transient Ischemic Attack and Association With Long-term Risk of Stroke

Importance

Accurate estimation of the association between transient ischemic attack (TIA) and risk of subsequent stroke can help to improve preventive efforts and limit the burden of stroke in the population.

Objective

To determine population-based incidence of TIA and the timing and long-term trends of stroke risk after TIA.

Design, Setting, and Participants

Retrospective cohort study (Framingham Heart Study) of prospectively collected data of 14 059 participants with no history of TIA or stroke at baseline, followed up from 1948-December 31, 2017. A sample of TIA-free participants was matched to participants with first incident TIA on age and sex (ratio, 5:1).

Exposures

Calendar time (TIA incidence calculation, time-trends analyses), TIA (matched longitudinal cohort).

Main Outcomes and Measures

The main outcomes were TIA incidence rates; proportion of stroke occurring after TIA in the short term (7, 30, and 90 days) vs the long term (>1-10 years); stroke after TIA vs stroke among matched control participants without TIA; and time trends of stroke risk at 90 days after TIA assessed in 3 epochs: 1954-1985, 1986-1999, and 2000-2017.

Results

Among 14 059 participants during 66 years of follow-up (366 209 person-years), 435 experienced TIA (229 women; mean age, 73.47 [SD, 11.48] years and 206 men; mean age, 70.10 [SD, 10.64] years) and were matched to 2175 control participants without TIA. The estimated incidence rate of TIA was 1.19/1000 person-years. Over a median of 8.86 years of follow-up after TIA, 130 participants (29.5%) had a stroke; 28 strokes (21.5%) occurred within 7 days, 40 (30.8%) occurred within 30 days, 51 (39.2%) occurred within 90 days, and 63 (48.5%) occurred more than 1 year after the index TIA; median time to stroke was 1.64 (interquartile range, 0.07-6.6) years. The age- and sex-adjusted cumulative 10-year hazard of incident stroke for patients with TIA (130 strokes among 435 cases) was 0.46 (95% CI, 0.39-0.55) and for matched control participants without TIA (165 strokes among 2175) was 0.09 (95% CI, 0.08-0.11); fully adjusted hazard ratio [HR], 4.37 (95% CI, 3.30-5.71; P < .001). Compared with the 90-day stroke risk after TIA in 1948-1985 (16.7%; 26 strokes among 155 patients with TIA), the risk between 1986-1999 was 11.1% (18 strokes among 162 patients) and between 2000-2017 was 5.9% (7 strokes among 118 patients). Compared with the first epoch, the HR for 90-day risk of stroke in the second epoch was 0.60 (95% CI, 0.33-1.12) and in the third epoch was 0.32 (95% CI, 0.14-0.75) (P = .005 for trend).

Conclusions and Relevance

In this population-based cohort study from 1948-2017, the estimated crude TIA incidence was 1.19/1000 person-years, the risk of stroke was significantly greater after TIA compared with matched control participants who did not have TIA, and the risk of stroke after TIA was significantly lower in the most recent epoch from 2000-2017 compared with an earlier period from 1948-1985.

Interleukin-6 Interacts with Sleep Apnea Severity when Predicting Incident Alzheimer's Disease Dementia

Because of their roles as potential risk factors, we evaluated whether obstructive sleep apnea (OSA) severity interacts with interleukin-6 (IL-6) in predicting incident dementia of the Alzheimer's type (DAT). In 269 dementia-free participants, IL-6 and the apnea-hypopnea index (AHI) were measured at baseline and incident DAT was surveilled for up to 22.8 years. Cox models revealed a significant interaction: In the lowest IL-6 quartile only, a higher AHI was associated with an elevated risk of DAT. The association between OSA severity and incident DAT might be especially apparent in the absence of inflammation or absence of potential benefits from IL-6.

Slow-Wave Sleep and MRI Markers of Brain Aging in a Community-Based Sample

OBJECTIVE

To test the hypothesis that reduced slow-wave sleep, or N3 sleep, which is thought to underlie the restorative functions of sleep, is associated with MRI markers of brain aging, we evaluated this relationship in the community-based Framingham Heart Study Offspring cohort using polysomnography and brain MRI.

METHODS

We studied 492 participants (age 58.8 ± 8.8 years, 49.4% male) free of neurological diseases who completed a brain MRI scan and in-home overnight polysomnography to assess slow-wave sleep (absolute duration and percentage of total sleep). Volumes of total brain, total cortical, frontal cortical, subcortical gray matter, hippocampus, and white matter hyperintensities were investigated as a percentage of intracranial volume, and the presence of covert brain infarcts was evaluated. Linear and logistic regression models were adjusted for age, age squared, sex, time interval between polysomnography and MRI (3.3 ± 1.0 years), APOE ε4 carrier status, stroke risk factors, sleeping pill use, body mass index, and depression.

RESULTS

Less slow-wave sleep was associated with lower cortical brain volume (absolute duration, β [standard error] = 0.20 [0.08], p = 0.015; percentage, 0.16 [0.08], p = 0.044), lower subcortical brain volume (percentage, 0.03 [0.02], p = 0.034), and higher white matter hyperintensities volume (absolute duration, -0.12 [0.05], p = 0.010; percentage, -0.10 [0.04], p = 0.033). Slow-wave sleep duration was not associated with hippocampal volume or the presence of covert brain infarcts.

CONCLUSION

Loss of slow-wave sleep might facilitate accelerated brain aging, as evidence by its association with MRI markers suggestive of brain atrophy and injury. Alternatively, subtle injuries and accelerated aging might reduce the ability of the brain to produce slow-wave sleep.

Association of common genetic variants with brain microbleeds: A genome-wide association study

OBJECTIVE

To identify common genetic variants associated with the presence of brain microbleeds (BMBs).

METHODS

We performed genome-wide association studies in 11 population-based cohort studies and 3 case-control or case-only stroke cohorts. Genotypes were imputed to the Haplotype Reference Consortium or 1000 Genomes reference panel. BMBs were rated on susceptibility-weighted or T2*-weighted gradient echo MRI sequences, and further classified as lobar or mixed (including strictly deep and infratentorial, possibly with lobar BMB). In a subset, we assessed the effects of APOE ε2 and ε4 alleles on BMB counts. We also related previously identified cerebral small vessel disease variants to BMBs.

RESULTS

BMBs were detected in 3,556 of the 25,862 participants, of which 2,179 were strictly lobar and 1,293 mixed. One locus in the APOE region reached genome-wide significance for its association with BMB (lead single nucleotide polymorphism rs769449; odds ratio [OR]any BMB [95% confidence interval (CI)] 1.33 [1.21-1.45]; p = 2.5 × 10-10). APOE ε4 alleles were associated with strictly lobar (OR [95% CI] 1.34 [1.19-1.50]; p = 1.0 × 10-6) but not with mixed BMB counts (OR [95% CI] 1.04 [0.86-1.25]; p = 0.68). APOE ε2 alleles did not show associations with BMB counts. Variants previously related to deep intracerebral hemorrhage and lacunar stroke, and a risk score of cerebral white matter hyperintensity variants, were associated with BMB.

CONCLUSIONS

Genetic variants in the APOE region are associated with the presence of BMB, most likely due to the APOE ε4 allele count related to a higher number of strictly lobar BMBs. Genetic predisposition to small vessel disease confers risk of BMB, indicating genetic overlap with other cerebral small vessel disease markers.