One could argue that the researchers got it backwards. People who suffered less cognitive impairment remained more socially engaged, so which came first here, the chicken or the egg?
Other researchers have found that as people decline mentally, they also tend to withdraw, so it's hard here to pin down the cause and the effect. Perhaps some are socially inactive because of mental decay, and perhaps some suffer from mental decay partly because they are socially inactive.
And Ybarra notes that such things as declining health and loss of income among the elderly can cause both social withdrawal and mental decline, making it more difficult to assess the contributions of social interaction.
Participants in the study who were judged to be physically attractive were found to be more socially active, and that's probably because a lot of folks would rather talk with a hunk or beauty queen than a wallflower. The beautiful people also fared better in terms of mental decline, and the researchers think that's attributable at least partly to all that socializing with people who were trying desperately to impress them.
Although the study didn't address this directly, Ybarra suspects that who you are talking to may also make a difference. The mental workout can be more intense, he suggests, if the other person really matters to you.
"Some interactions are going to provide more of a workout than others," he says. "I would think that just greeting the person who delivers the mail may not be as intensive as chatting with a good friend, or actually dealing with a hostile employer."
One problem addressed only indirectly in the study deals with older persons who feel they are no longer taken seriously. That's a common complaint from elders who have to deal with grown children who have decided they can no longer do anything for themselves. Their opinions are rarely sought, and all too often, when they speak, no one listens.
That can lead to one serious result.
"If you don't think you're being taken seriously, you're probably going to withdraw socially," Ybarra says, thus robbing the elderly of the social interaction that might help keep their brains alert.
The system works best, he says, when the conversation matters to both parties.
"That's what provides the framework," Ybarra says, "trying to understand other people's minds."
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.