In storyteller Garrison Keillor's corner of Minnesota, all the children may be "above average." But a study of older Minnesotans in the county surrounding the famed Mayo Clinic suggests that the ones who stay "above average" mentally are more likely to be female, to have completed more education, and to have been married at some point.
The study, published in Neurology, aims to refine what we know about age-related cognitive decline. Starting in 2004, it tracked 4,398 Minnesotans aged 70 to 89 to see how that population's mental state weathered advancing age and to determine who was most likely to develop a condition called mild cognitive impairment—a greater-than-average decline in mental performance that often progresses to dementia, including the dementia of Alzheimer's Disease.
All told, 16% of the population studied was diagnosed by standard neurocognitive tests as having mild cognitive impairment. Roughly two-thirds of those with MCI primarily had memory problems, while the remaining third had broader problems of thinking and reasoning. As a group, women were less likely at every age to be diagnosed with mild cognitive impairment than were men of the same age. Men and women who had been married at some point in their lives and those who had completed more schooling also had a lower likelihood of MCI at every age.
Alzheimer's disease is thought to affect men and women roughly equally or to be slightly higher in women, suggesting that at some point, women catch up with men. But the authors of the study suggested gender may play a role in how the disease starts and progresses. They suggested, for instance, that men who will go on to develop Alzheimer's may begin their mental decline earlier and experience a gradual decline in memory, while women who will go on to develop Alzheimer's may experience a more dramatic transition from normal cognition to dementia, all at a later age than men typically do.
The study follows one appearing in the same journal last week that found that for those whose engagement in mentally challenging activities was intensive, the transition from normal cognition to dementia, when it came, was very rapid.