Midlife Smaller and Larger Infarctions, White Matter Hyperintensities, and 20-Year Cognitive Decline: A Cohort Study.

Background: Smaller (<3-mm) infarctions are associated with stroke and stroke mortality, but relationships with cognitive decline are unknown. Objective: To characterize the relationships of smaller, larger, and both smaller and larger infarctions in middle age with 20-year cognitive decline. Design: Longitudinal cohort study. Setting: Two ARIC (Atherosclerosis Risk in Communities) study sites with magnetic resonance imaging data (1993 to 1995) and up to 5 cognitive assessments over 20 years. Participants: Stroke-free participants aged 50 years or older. Measurements: Infarctions were categorized as none, smaller only, larger only (3 to 20 mm), or both smaller and larger. Global cognitive Z scores were derived from 3 cognitive tests administered up to 5 times. Mixed-effects models estimated adjusted associations between infarctions and cognitive decline. Results are the average difference in standardized cognitive decline associated with infarctions versus no infarctions. Results: Among 1884 participants (mean age, 62 years; 60% women; 50% black), 1611 (86%) had no infarctions, 50 (3%) had smaller infarctions only, 185 (10%) had larger infarctions only, and 35 (2%) had both. Participants with both smaller and larger infarctions had steeper cognitive decline by more than half an SD (difference, -0.57 SD [95% CI, -0.89 to -0.26 SD]) compared with those who had no infarctions. Amounts of cognitive decline associated with only smaller infarctions and only larger infarctions were similar and were not statistically different from that associated with no infarctions. Limitation: Few participants had only smaller infarctions or both smaller and larger infarctions, and the data lacked counts of smaller infarctions and volumes of white matter hyperintensities. Conclusion: The substantial cognitive decline from middle age associated with having both smaller and larger infarctions, but not larger infarctions alone, suggests that the combination of smaller and larger infarctions may escalate risk for cognitive decline later in life in stroke-free persons. Primary Funding Source: National Institutes of Health.

Hummingbirds have a greatly enlarged hippocampal formation.

Both field and laboratory studies demonstrate that hummingbirds (Apodiformes, Trochilidae) have exceptional spatial memory. The complexity of spatial-temporal information that hummingbirds must retain and use daily is probably subserved by the hippocampal formation (HF), and therefore, hummingbirds should have a greatly expanded HF. Here, we compare the relative size of the HF in several hummingbird species with that of other birds. Our analyses reveal that the HF in hummingbirds is significantly larger, relative to telencephalic volume, than any bird examined to date. When expressed as a percentage of telencephalic volume, the hummingbird HF is two to five times larger than that of caching and non-caching songbirds, seabirds and woodpeckers. This HF expansion in hummingbirds probably underlies their ability to remember the location, distribution and nectar content of flowers, but more detailed analyses are required to determine the extent to which this arises from an expansion of HF or a decrease in size of other brain regions.

Associations Between Inflammation and Physical Function in African Americans and European Americans with Prevalent Cardiovascular Risk Factors.

OBJECTIVES: To examine associations between inflammation and physical function and potential mediation by white matter hyperintensities (WMHs) in African Americans (AAs) and European Americans (EAs). DESIGN: Cross-sectional analysis using linear and logistic models with generalized estimating equations to account for family clustering, reporting results as regression coefficients (ß) and odds ratios (ORs) adjusted for education, alcohol, exercise, body mass index, hypertension, diabetes mellitus, heart disease, cognition, ankle-brachial index, race (site), and supported interactions. SETTING: Genetic Epidemiology Network of Arteriopathy-Genetics of Microangiopathic Brain Injury Study cohort. PARTICIPANTS: AA and EA sibships with two or more siblings with hypertension before age 60 (N = 1,960; 65% female, 51% AA, aged 26-91, 50% obese, 72% hypertensive). MEASUREMENTS: Inflammation (C-reactive protein (CRP), interleukin-6 (IL6), soluble tumor necrosis factor receptors (sTNFRs) 1 and 2, WMH volume (cm(3) ) according to magnetic resonance imaging), walking speed (cm/s) over 25 feet, and mobility difficulty (any self-reported difficulty walking half a mile). RESULTS: In separate models, inflammatory markers were associated with walking speed (sTNFR1: ß = -2.74, P < .001; sTNFR2: ß = -1.23, P = .03; CRP: ß = -1.95, P = .001; IL6: ß = -1.24, P = .03) and mobility difficulty (sTNFR1: OR = 1.36, P = .001; sTNFR2: OR = 1.25, P = .005; CRP: OR = 1.22, P = .005; IL6: OR = 1.18, P = .02); the association between WMH volume and sTNFR1 in AA (ß = 0.07, P = .06) did not reach typical statistical thresholds. WMH volume was associated with walking speed in AA (ß = -3.17, P = .02) but not with mobility difficulty (OR = 1.10, P = .54). Adjusting for WMH did not change associations. CONCLUSION: In young, middle-aged, and older adults with prevalent cardiovascular risk factors, multiple inflammatory biomarkers were associated with slower walking speed independent of microvascular disease in the brain. There was little evidence of mediation by brain WMH volume. Inflammation may contribute to physical function impairments through pathways other than brain microvascular disease, particularly in AAs.