This article introduces the Americas in the Great Divergence debate by measuring real wages in various North and South American cities between colonization and independence, and comparing them to Europe and Asia. We find that for much of the period, North America was the most prosperous region of the world, while Latin America was much poorer. We then discuss a series of hypotheses that can explain these results, including migration, the demography of the American Indian populations, and the various labor systems implemented in the continent.

Objectives:Previous studies have shown that high serum ceramides are associated with memory impairment and hippocampal volume loss, but have not examined dementia as an outcome. The aim of this study was to examine whether serum ceramides and sphingomyelins (SM) were associated with an increased risk of all-cause dementia and Alzheimer disease (AD).Methods: Participants included 99 women without dementia aged 70-79, with baseline serum SM and ceramides, enrolled in a longitudinal population-based study and followed for up to 6 visits over 9 years. Baseline lipids, in tertiles, were examined in relation to all-cause dementia and AD using discrete time Cox proportional survival analysis. Lipids were analyzed using electrospray ionization tandem mass spectrometry.Results: Twenty-seven (27.3%) of the 99 women developed incident dementia. Of these, 18 (66.7%) were diagnosed with probable AD. Higher baseline serum ceramides, but not SM, were associated with an increased risk of AD; these relationships were stronger than with all-cause dementia. Compared to the lowest tertile, the middle and highest tertiles of ceramide d18:1-C16:0 were associated with a 10-fold (95% confidence interval [CI] 1.2-85.1) and 7.6-fold increased risk of AD (95% CI 0.9-62.1), respectively. The highest tertiles of ceramide d18:1-C24:0 (hazard ratio [HR] ϭ 5.1, 95% CI 1.1-23.6) and lactosylceramide (HR ϭ 9.8, 95% CI 1.2-80.1) were also associated with risk of AD. Total and high-density lipoprotein cholesterol and triglycerides were not associated with dementia or AD. Conclusions:Results from this preliminary study suggest that particular species of serum ceramides are associated with incident AD and warrant continued examination in larger studies. Neurology ® 2012;79:633-641 GLOSSARY A␤ ϭ amyloid-␤; AD ϭ Alzheimer disease; amu ϭ atomic mass units; APP ϭ amyloid precursor protein; BACE-1 ϭ ␤-site APP cleaving enzyme 1; BMI ϭ body mass index; CI ϭ confidence interval; DSM-IV ϭ Diagnostic and Statistical Manual of Mental Disorders, 4th edition; ESI-MS/MS ϭ electrospray ionization tandem mass spectrometry; HDL ϭ high-density lipoprotein; HR ϭ hazard ratio; MCI ϭ mild cognitive impairment; MMSE ϭ Mini-Mental State Examination; SM ϭ sphingomyelin; WHAS II ϭ Women's Health and Aging Study II.Lipidomic, metabolomic, and targeted approaches have identified pathways and products of sphingolipid metabolism that are altered early in the course of Alzheimer disease (AD). [1][2][3][4][5] Ceramides facilitate the regulation of ␤-site APP cleaving enzyme 1 (BACE-1) and ␥-secretase activity and amyloid precursor protein (APP) processing and trafficking. Evidence also suggests that glycosphingolipids bind amyloid-␤ (A␤) at the cell surface and form domains that facilitate the oligomerization and fibril formation of A␤. 6 -10 In addition to these roles, ceramide is aFrom the Division