Glenn Greenwald, a columnist with The Guardian newspaper who first reported on the intelligence leaks, told The Associated Press that disclosure of the information in the documents "would allow somebody who read them to know exactly how the NSA does what it does, which would in turn allow them to evade that surveillance or replicate it."
He said the "literally thousands of documents" taken by Snowden constitute "basically the instruction manual for how the NSA is built."
"In order to take documents with him that proved that what he was saying was true he had to take ones that included very sensitive, detailed blueprints of how the NSA does what they do," the journalist said Sunday in a Rio de Janeiro hotel room. He said the interview was taking place about four hours after his last interaction with Snowden.
Greenwald said he believes the disclosure of the information in the documents would not prove harmful to Americans or their national security, but that Snowden has insisted they not be made public.
"I think it would be harmful to the U.S. government, as they perceive their own interests, if the details of those programs were revealed," he said.
He has previously said the documents have been encrypted to help ensure their safekeeping.
Snowden emerged from weeks of hiding in a Moscow airport Friday, and said he was willing to meet President Vladimir Putin's condition that he stop leaking U.S. secrets if it means Russia would give him asylum until he can move on to Latin America.
Greenwald told The AP that he deliberately avoids talking to Snowden about issues related to where the former analyst might seek asylum in order to avoid possible legal problems for himself.
Snowden is believed to be stuck in the transit area of Moscow's main international airport, where he arrived from Hong Kong on June 23. He's had offers of asylum from Venezuela, Nicaragua and Bolivia, but because his U.S. passport has been revoked, the logistics of reaching whichever country he chooses are complicated.
Still, Greenwald said that Snowden remains "calm and tranquil," despite his predicament.
"I haven't sensed an iota of remorse or regret or anxiety over the situation that he's in," said Greenwald, who has lived in Brazil for the past eight years. "He's of course tense and focused on his security and his short-term well-being to the best extent that he can, but he's very resigned to the fact that things might go terribly wrong and he's at peace with that."
Greenwald said he worried that interest in Snowden's personal saga had detracted from the impact of his revelations, adding that Snowden deliberately turned down nearly all requests for interviews to avoid the media spotlight.
Asked whether Snowden seemed worried about his personal safety, Greenwald responded, "he's concerned."
He said the U.S. has shown it's "willing to take even the most extreme steps if they think doing so is necessary to neutralize a national security threat," Greenwald said. "He's aware of all those things, he's concerned about them but he's not going to be in any way paralyzed or constrained in what he thinks he can do as a result of that."
Asked about a so-called dead man's pact, which Greenwald has said would allow several people to access Snowden's trove of documents were anything to happen to him, Greenwald replied that "media descriptions of it have been overly simplistic.
"It's not just a matter of, if he dies, things get released, it's more nuanced than that," he said. "It's really just a way to protect himself against extremely rogue behavior on the part of the United States, by which I mean violent actions toward him, designed to end his life, and it's just a way to ensure that nobody feels incentivized to do that."
He declined to provide any more details about the pact or how it would work.
Greenwald said he himself has beefed up his own security, particularly since a laptop went missing from his Rio home.
"I don't really feel comfortable discussing the specific measures, but one would be really irrational and foolish to have thousands of top-secret documents from the most secretive agency of the world's most powerful government and not be thoughtful about added security," said the 46-year-old former constitutional and civil rights lawyer who has written three books contending the government has violated personal rights in the name of protecting national security.
Greenwald has also co-authored a series of articles in Rio de Janeiro's O Globo newspaper focusing on NSA actions in Latin America. He said he expected to continue publishing further stories based on other Snowden documents over the next four months.
Upcoming stories would likely include details on "other domestic spying programs that have yet to be revealed," but which are similar in scope to those he has been reporting on. He did not provide further details on the nature of those programs.
It was not immediately clear whether Russia would take Snowden up on his latest request for asylum, which could further test U.S.-Russia relations.
Following Friday's meeting between Snowden and human rights activists, U.S. officials criticized Russia for allowing a "propaganda platform" for the NSA leader.
White House spokesman Jay Carney said Russia should instead send Snowden back to the U.S. to face the felony charges that are pending against him.
Carney said Snowden is not a human rights activist or a dissident. "He is accused of leaking classified information, has been charged with three felony counts and should be returned to the United States," the spokesman said.
It's by far the largest study to look at this, and researchers say the conclusion makes sense. Working tends to keep people physically active, socially connected and mentally challenged - all things known to help prevent mental decline.
"For each additional year of work, the risk of getting dementia is reduced by 3.2 percent," said Carole Dufouil, a scientist at INSERM, the French government's health research agency.
She led the study and gave results Monday at the Alzheimer's Association International Conference in Boston.
About 35 million people worldwide have dementia, and Alzheimer's is the most common type. In the U.S., about 5 million have Alzheimer's - 1 in 9 people aged 65 and over. What causes the mind-robbing disease isn't known and there is no cure or any treatments that slow its progression.
France has had some of the best Alzheimer's research in the world, partly because its former president, Nicolas Sarkozy, made it a priority. The country also has detailed health records on self-employed people who pay into a Medicare-like health system.
Researchers used these records on more than 429,000 workers, most of whom were shopkeepers or craftsmen such as bakers and woodworkers. They were 74 on average and had been retired for an average of 12 years.
Nearly 3 percent had developed dementia but the risk of this was lower for each year of age at retirement. Someone who retired at 65 had about a 15 percent lower risk of developing dementia compared to someone retiring at 60, after other factors that affect those odds were taken into account, Dufouil said.
To rule out the possibility that mental decline may have led people to retire earlier, researchers did analyses that eliminated people who developed dementia within 5 years of retirement, and within 10 years of it.
"The trend is exactly the same," suggesting that work was having an effect on cognition, not the other way around, Dufouil said.
France mandates retirement in various jobs - civil servants must retire by 65, she said. The new study suggests "people should work as long as they want" because it may have health benefits, she said.
June Springer, who just turned 90, thinks it does. She was hired as a full-time receptionist at Caffi Plumbing & Heating in Alexandria, Va., eight years ago.
"I'd like to give credit to the company for hiring me at that age," she said. "It's a joy to work, being with people and keeping up with current events. I love doing what I do. As long as God grants me the brain to use I'll take it every day."
Heather Snyder, director of medical and scientific operations for the Alzheimer's Association, said the study results don't mean everyone needs to delay retirement.
"It's more staying cognitively active, staying socially active, continue to be engaged in whatever it is that's enjoyable to you" that's important, she said.
"My parents are retired but they're busier than ever. They're taking classes at their local university, they're continuing to attend lectures and they're continuing to stay cognitively engaged and socially engaged in their lives."
-- AP Medical Writer Lindsey Tanner in Chicago contributed to this report.
Alzheimer's info: HTTP://WWW.ALZHEIMERS.GOV
Alzheimer's Association: HTTP://WWW.ALZ.ORG
CHICAGO (AP) -- Yadier Molina hit a three-run homer in St. Louis' four-run ninth inning, and the Cardinals beat the Chicago Cubs 10-6 on Sunday night in the majors' final game before the All-Star break.
Allen Craig lined a tiebreaking RBI single into left field before Molina drove an 0-2 pitch from Kevin Gregg (2-2) over the wall in left for his seventh homer. Craig and Molina tuned up for Tuesday's game in New York with four hits apiece, helping St. Louis to a season-high 21 hits overall.
Chicago went up 4-3 on Darwin Barney's three-run homer in the sixth and pinch hitter Cody Ransom had a tying two-run double in the eighth, but the Cubs' bullpen was unable to hold off the NL's highest-scoring team.
Pete Kozma had two RBI singles as the Cardinals won for the seventh time in nine games to salvage a split of the four-game series. Edward Mujica (2-1) had his second blown save opportunity in 28 chances, but managed to get the win on the same day he was chosen to replace teammate Adam Wainwright on the NL All-Star team.
Despite injuries to key pitchers Chris Carpenter, Jaime Garcia and Jason Motte, St. Louis heads to the All-Star break with baseball's best record at 57-36. It leads the NL Central by one game over surprising Pittsburgh, which lost 4-2 to the New York Mets earlier in the day.
Barney also had a run-scoring single for the Cubs, who went 6-4 on a 10-game stretch in Chicago that included a makeup game at the crosstown White Sox last Monday. The four RBIs for Barney matched a career high set in a 14-4 victory against Pittsburgh on July 30, 2012.
After a slow start, the Cubs (42-51) are a respectable 24-21 in their last 45 games. It's good enough for a four-game improvement compared to last year at this point, when the North Siders were 38-55 on their way to their first 100-loss season since 1966.
The Cardinals carried a 3-1 lead into the sixth, but Wainwright got into trouble after Alfonso Soriano began the inning with a fly ball to the warning track in right. Dioner Navarro and Brian Bogusevic then hit consecutive singles to put runners on first and second.
Wainwright bounced back to strike out Dave Sappelt, but his first pitch to Barney was up and over the plate, and he drove it into the basket in left field for his sixth homer.
That proved to be just a minor little speed bump for the Cardinals, who used four hits to regain the lead during a two-run seventh. Kozma singled in Molina to tie it at 4 and eventually came around on Matt Carpenter's bouncer into center field.
Adams tacked on an RBI double in eighth, setting the stage for the wild finish.
Travis Wood, who will represent the Cubs at the All-Star festivities, allowed three runs and a season-high 10 hits in 5 2-3 innings. It matched the shortest outing of the year for the consistent lefty, who pitched at least six innings in 17 of his first 18 starts.
Molina was out of the starting lineup for St. Louis' 6-4 loss on Saturday night and began the night in a 1-for-19 rut covering his previous seven games. But he singled in each of his first two at-bats and forced Bogusevic to make a leaping catch against the wall in center in the eighth.
NOTES: Cardinals OF Matt Holliday (right hamstring tightness) missed his third consecutive game. "We need to be real careful so we can continue to progress, make sure we are aiming for that first day after the break," manager Mike Matheny said. ... OF Cole Gillespie joined the Cubs, and reliever Henry Rodriguez was designated for assignment to make room on the roster. Gillespie was claimed off waivers from San Francisco on Saturday. He had a pinch-hit single in the eighth. ... Cubs RHP Scott Baker allowed four runs and six hits in three innings in his first rehab start with Class A Kane County. Baker missed last season with Minnesota after undergoing elbow-ligament replacement surgery. "Today was a big hump, to pitch against hitters and getting in a real game and the whole atmosphere and everything," Cubs manager Dale Sveum said, "and then hopefully we just start seeing gradual pickup in the velocities and all that."