Genome-wide association studies identified a single nucleotide polymorphism (SNP) in the MSRB3 gene encoding Methionine Sulfoxide Reductase-B3 (MsrB3) to be associated with the risk for low hippocampal volume and late onset Alzheimer's disease (AD). Subsequently, we identified AD-associated abnormal patterns of neuronal and vascular MsrB3 expression in postmortem hippocampi. The present study investigated the relationship between the MSRB3 SNP rs61921502, G (minor/risk allele) and MRI measures of brain injury including total brain volume, hippocampal volume, and white matter hyperintensities using linear regression models; the presence of brain infarcts using logistic regression models; and the incidence of stroke, dementia, and AD using Cox proportional hazards models in 2,038 Framingham Heart Study Offspring participants with MRI administered close to examination cycle 7 (1998-2001). Participants with neurological conditions that impede evaluation of vascular pathology by MRI, i.e., brain tumors, multiple sclerosis, and major head trauma, were excluded from the study. When adjusted for age and age squared at MRI exam, sex, and presence of Apolipoproteinɛ4 allele (APOE4), individuals with MSRB3 rs61921502 minor allele had increased odds for brain infarcts on MRI compared to those with no minor allele. However, in stratified analyses, MSRB3 rs61921502 minor allele was significantly associated with increased odds for MRI brain infarcts only in the absence of APOE4.

Objective

To assess the association of early morning serum cortisol with cognitive performance and brain structural integrity in community-dwelling young and middle-aged adults without dementia.

Methods

We evaluated dementia-free Framingham Heart Study (generation 3) participants (mean age 48.5 years, 46.8% men) who underwent cognitive testing for memory, abstract reasoning, visual perception, attention, and executive function (n = 2,231) and brain MRI (n = 2018) to assess total white matter, lobar gray matter, and white matter hyperintensity volumes and fractional anisotropy (FA) measures. We used linear and logistic regression to assess the relations of cortisol (categorized in tertiles, with the middle tertile as referent) to measures of cognition, MRI volumes, presence of covert brain infarcts and cerebral microbleeds, and voxel-based microstructural white matter integrity and gray matter density, adjusting for age, sex, APOE, and vascular risk factors.

Results

Higher cortisol (highest tertile vs middle tertile) was associated with worse memory and visual perception, as well as lower total cerebral brain and occipital and frontal lobar gray matter volumes. Higher cortisol was associated with multiple areas of microstructural changes (decreased regional FA), especially in the splenium of corpus callosum and the posterior corona radiata. The association of cortisol with total cerebral brain volume varied by sex (p for interaction = 0.048); higher cortisol was inversely associated with cerebral brain volume in women (p = 0.001) but not in men (p = 0.717). There was no effect modification by the APOE4 genotype of the relations of cortisol and cognition or imaging traits.

Conclusion

Higher serum cortisol was associated with lower brain volumes and impaired memory in asymptomatic younger to middle-aged adults, with the association being evident particularly in women.

Background and Purpose- Little is known about associations between vascular growth factors and magnetic resonance imaging (MRI) markers in midlife. We investigated the association of serum VEGF (vascular endothelial growth factor), Ang2 (angiopoietin 2), sTie2 (soluble tyrosine kinase with immunoglobulin-like and EGF-like domains 2), and HGF (hepatocyte growth factor) concentrations with MRI markers of brain aging in middle-aged adults. Methods- We evaluated 1853 participants (mean age, 46±9 years; 46% men) from the Framingham Heart Study. Serum growth factor concentrations were measured using standardized immunoassays. Outcomes included total brain, cortical and subcortical gray matter, white matter, cerebrospinal fluid, and white matter hyperintensity volumes derived from MRI; as well as fractional anisotropy in white matter tracts from diffusion tensor imaging. We related VEGF, Ang2, sTie2, and HGF to MRI measures using multivariable regression models adjusting for vascular risk factors. We tested for interactions with APOE (apolipoprotein E) genotype and CRP (C-reactive protein). Results were corrected for multiple comparisons. Results- Higher sTie2 was associated with smaller total brain (estimate by SD unit±SE=-0.08±0.02, P=0.002) and larger white matter hyperintensity (0.08±0.02, P=0.002) volumes. Furthermore, higher Ang2 (0.06±0.02, P=0.049) and HGF (0.09±0.02, P=0.001) were associated with larger cerebrospinal fluid volumes. Finally, higher Ang2 was associated with decreased fractional anisotropy, in APOE-ε4 carriers only. Conclusions- Vascular growth factors are associated with early MRI markers of small vessel disease and neurodegeneration in middle-aged adults.

Objective

To determine the association between plasma insulin-like growth factor binding protein 2 (IGFBP-2) and cognitive outcomes.

Methods

We measured plasma IGFBP-2 levels in 1596 (53% women, mean age 68.7 [SD 5.7] years) dementia-free Framingham Offspring cohort participants between 1998 and 2001. Multivariable Cox proportional hazards models related plasma IGFBP-2 to subsequent risk of incident dementia and Alzheimer's disease. MRI brain measures and cognitive performance were included as secondary outcomes.

Results

During a median follow-up of 11.8 (Q1, Q3: 7.1, 13.3) years, 131 participants developed incident dementia, of whom 98 were diagnosed with Alzheimer's disease. The highest tertile of IGFBP-2, compared to the lowest tertile, was associated with an increased risk of incident all-cause dementia (hazard ratio [HR] 2.89, 95% CI 1.63-5.13) and Alzheimer's disease (HR 3.63, 95% CI 1.76-7.50) in multivariable analysis. Higher circulating IGFBP2 levels were also cross-sectionally associated with poorer performance on tests of abstract reasoning but not with MRI-based outcomes. After adding plasma IGFBP-2 levels to a conventional dementia prediction model, 32% of individuals with dementia were correctly assigned a higher predicted risk, while 8% of individuals without dementia were correctly assigned a lower predicted risk (overall net reclassification improvement index, 0.40, 95% CI 0.22-0.59).

Interpretation

Elevated circulating IGFBP-2 levels were associated with an increased risk of both all-cause dementia and Alzheimer's disease. Addition of IGFBP2 plasma levels to a model of traditional risk factors significantly improved dementia risk classification. Manipulation of insulin-like growth factor signaling via IGFBP-2 may be a promising therapeutic target for dementia.

Background GDF15 (growth differentiation factor 15) and NT-proBNP (N-terminal pro-B-type natriuretic peptide) may offer promise as biomarkers for cognitive outcomes, including dementia. We determined the association of these biomarkers with cognitive outcomes in a community-based cohort. Methods and Results Plasma GDF15 (n=1603) and NT-proBNP levels (n=1590) (53% women; mean age, 68.7 years) were measured in dementia-free Framingham Offspring cohort participants at examination 7 (1998-2001). Participants were followed up for incident dementia. Secondary outcomes included Alzheimer disease dementia, magnetic resonance imaging structural brain measures, and neurocognitive performance. During a median 11.8-year follow-up, 131 participants developed dementia. On multivariable Cox proportional-hazards analysis, higher circulating GDF15 was associated with an increased risk of incident all-cause and Alzheimer disease dementia (hazard ratio [HR] per SD increment in natural log-transformed biomarker value, 1.54 [95% CI, 1.22-1.95] and 1.37 [95% CI, 1.03-1.81], respectively), whereas higher plasma NT-proBNP was also associated with an increased risk of all-cause dementia (HR, 1.32; 95% CI, 1.05-1.65). Elevated GDF15 was associated with lower total brain and hippocampal volumes, greater white matter hyperintensity volume, and poorer cognitive performance. Elevated NT-proBNP was associated with greater white matter hyperintensity volume and poorer cognitive performance. Addition of both biomarkers to a conventional risk factor model improved dementia risk classification (net reclassification improvement index, 0.25; 95% CI, 0.05-0.45). Conclusions Elevated plasma GDF15 and NT-proBNP were associated with vascular brain injury on magnetic resonance imaging, poorer neurocognitive performance, and increased risk of incident dementia in individuals aged >60 years. Both biomarkers improved dementia risk classification beyond that of traditional clinical risk factors, indicating their potential value in predicting incident dementia.

Background

Insulin-like growth factor 1 (IGF-1) signaling has been implicated in Alzheimer's disease pathogenesis, and further evidence suggests inflammation can be a moderator of this association. However, most research to date has been conducted on older adults.

Objective

To investigate the association of serum IGF-1 and IGF binding protein 3 (IGFBP-3) concentrations with MRI markers of Alzheimer's disease in predominantly middle-aged adults, and further assess moderation by chronic inflammation.

Methods

We included participants from the Framingham Heart Study (n = 1,852, mean age 46±8, 46% men) and the Study of Health in Pomerania (n = 674, mean age 50±13, 42% men) with available serum IGF-1, IFGBP-3, as well as brain MRI. IGF-1 and IFGBP-3 were related to MRI outcomes (i.e., total brain, cortical gray matter, white matter, white matter hyperintensities (WMH), and hippocampal volumes) using multivariable regression models adjusting for potential confounders. Subgroup analyses by C-reactive protein (CRP) concentrations were also performed. Cohort-specific summary statistics were meta-analyzed using random-effects models and corrected for multiple comparisons.

Results

Meta-analysis results revealed that higher IGF-1 concentrations were associated with lower WMH (estimate [β] [95% CI], -0.05 [-0.09, -0.02], p = 0.006) and larger hippocampal volumes (0.07 [0.02, 0.12], p = 0.01), independent of vascular risk factors. These associations occurred predominantly in individuals with CRP concentrations < 75th percentile. We did not observe associations between IGFBP-3 and MRI outcomes.

Conclusion

Our findings suggest that IGF-1-related signaling may be implicated in brain health as early as midlife.