Confused about the link with poverty and stress. A linked article states: "Several teams presented evidence that poverty, disadvantage and stressful life events are strongly associated with cognitive problems in middle age and dementia later in life among African-Americans.

The findings could help explain why African-Americans are twice as likely as white Americans to develop dementia. And the research suggests genetic factors are not a major contributor."

Since there are more poor whites than African Americans, I don't understand why being poor explains African Americans being twice as likely to develop dementia?