African Americans, Hispanics, and longevity

I’ve known for a while that women live longer than men, Hispanic Americans live longer than Euro Americans, and the oldest people in the US are disproportionately black:

At 116 years old, Susannah Mushatt Jones is not only the oldest woman in the US, but also the entire world.

One theory I considered was that higher infant mortality rates in Mexico (I don’t actually know the infant mortality rates in Mexico, this is just an idea,) results in the deaths of premature infants and others with severe health problems, whereas in the US these infants survive for several years–maybe even decades–before dying. The population of Hispanic immigrants, therefore, does not include these children–they’re already gone–but the US population does. This could result in a higher life expectancy among the immigrants than among non-immigrants.

But what about women and blacks? Their infant mortality would be included in the native rates, and even if worse medical care resulted in higher infant mortality among them, this still wouldn’t explain why so many supercentenarians are black.

While researching hippocampi yesterday, I ran across an article about hippocampal volumes in the elderly: Brain Morphology in Older African Americans, Caribbean Hispanics, and Whites From Northern Manhattan

We already know that different people age at different rates, but it appears as well that different races age at different rates, with black brains aging the slowest:

“Results of the regression analysis revealed significant effects of age, sex, vascular disease history, and race/ethnicity on relative brain volume (F_5,685 = 38.290, P < .001). For each additional year in age, there was an associated 0.3% decrease in relative brain volume (β = −0.003, t = 10.34, P < .001) (Figure 2). Relative brain volume among women was 2% larger than that among men (β = 0.02, t = 5.93, P < .001). Hispanic (β = 0.03, t = 7.20, P < .001) and African American (β = 0.02, t = 4.09, P < .001) participants had 2.8% and 1.6% larger relative brain volumes than white subjects, respectively. Finally, for each additional vascular disease, there was a 0.5% associated reduction in relative brain volume (β = −0.005, t = −2.70, P < .001). When interaction terms were entered into the model, none were significant, demonstrating that the association of vascular disease history and age with relative brain volume did not differ across race/ethnicity or sex. Analysis of variance controlling for age and vascular disease history confirmed main effects of sex (F_1,685 = 34.906, P < .001) and race/ethnicity (F_2,685 = 23.528, P < .001) but no sex × race/ethnicity interaction (F_2,685 = 0.167, P =.85) (Figure 3).“

Relative brain volume across racial/ethnic groups and by sex.

relationship among chronologic age, race/ethnicity, and relative brain volume.

 

So why are white males (at least in these samples) aging so quickly?