Former President George H.W. Bush was released Monday from a Houston hospital after seven weeks of treatment for bronchitis, a bacterial infection and a persistent cough, the Bush family spokesman said.

Hospital officials said that Bush, 88, was discharged to his Houston home and would continue treatment.

"Mr. Bush has improved to the point that he will not need any special medication when he goes home, but he will continue physical therapy," said Dr. Amy Mynderse, the physician in charge of the former president's care.

Bush was admitted to the Methodist Hospital on Nov. 29, suffering from severe bronchitis.

After initial expectations that he would be hospitalized for just a few days turned out to be wrong, his office disclosed that he was in intensive care in December because physicians were having difficulty controlling a fever that developed after the cough was mostly resolved and were concerned about balancing his medication.

Last week, sources close to the former president indicated that his condition had improved. Visitors to Bush said he was in a good mood and joking with family members and hospital staff and that he was “looking forward to heading home.”

"I am deeply grateful for the wonderful doctors and nurses at Methodist who took such good care of me," the former President said. "Let me add just how touched we were by the many get-well messages we received from our friends and fellow Americans. Your prayers and good wishes helped more than you know, and as I head home my only concern is that I will not be able to thank each of you for your kind words."

Bush and his wife, Barbara, live in Houston during the winter and spend their summers at a home in Kennebunkport, Maine. On Jan. 6, they celebrated their 68th wedding anniversary. They are the longest-married presidential couple, and Bush is the nation's oldest living president.

Bronchitis is a common condition in which the bronchial tubes in the lungs become inflamed and produce mucus, which creates the need to cough, according to the Centers for Disease Control and Prevention. It can turn serious in people with weak immune systems, including children and the elderly. Symptoms such as chest pain, weakness and coughing typically last two weeks, but can linger for as long as two months.

Bush was elected president of the United States in 1988, the capstone of a long career of public service.

He was a Texas Republican member of the House of Representatives in the 1960s and 1970s and head of the CIA in 1976-1977. The organization’s headquarters in Langley, Va., was later renamed the “George Bush Center for Intelligence.”

Bush lost his first bid for the Republican nomination for the U.S. presidency in 1980, at which time Ronald Reagan chose him to be his running mate. He went on to serve two terms as Reagan’s vice president before winning the presidency. He was defeated for re-election in 1992 by Bill Clinton.

In late 2004, Bush teamed up with Clinton to raise money for the victims of the Asian tsunami. That effort was so successful, the two former presidents did the same for Katrina victims in 2005.

Slideshow: The life and times of George H.W. Bush

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Leader of an American political dynasty, George Bush's influence was felt beyond his terms as president and vice president. Take a look back at his life and career.

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WASHINGTON - A nearly three-year-long investigation by Senate Intelligence Committee Democrats is expected to find there is little evidence the harsh "enhanced interrogation techniques" the CIA used on high-value prisoners produced counter-terrorism breakthroughs.

People familiar with the inquiry said committee investigators, who have been poring over records from the administration of President George W. Bush, believe they do not substantiate claims by some Bush supporters that the harsh interrogations led to counter-terrorism coups.

The backers of such techniques, which include "water-boarding," sleep deprivation and other practices critics call torture, maintain they have led to the disruption of major terror plots and the capture of al-Qaida leaders.

One official said investigators found "no evidence" such enhanced interrogations played "any significant role" in the years-long intelligence operations which led to the discovery and killing of Osama bin Laden last May by U.S. Navy SEALs.

'Tortured' Gitmo prisoner seeks release of secret videos

The debate over the effectiveness of enhanced interrogations, which human rights advocates condemn as torture, is resurfacing in part because of a new book by a former top CIA official.

In the book, "Hard Measures," due to be published on Monday, the former chief of CIA clandestine operations Jose Rodriguez defends the use of interrogation practices including water-boarding, which involves pouring water on a subject's face, which is covered with a cloth, to simulate drowning.

Slideshow: Life goes on in Guantanamo

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President Obama's one-year deadline to close the facility has long passed as shutting it down has proven complicated and controversial.

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"We made some al-Qaida terrorists with American blood on their hands uncomfortable for a few days," Rodriguez says in an interview with CBS News' "60 Minutes" that will air on Sunday. "I am very secure in what we did and am very confident that what we did saved American lives."

Expert: War on terror at 'critical' point as al-Qaida looks to regroup in Africa

For nearly three years, the Senate intelligence committee's majority Democrats have been conducting what is described as the first systematic investigation of the effectiveness of such extreme interrogation techniques.

The CIA gave the committee access to millions of pages of written records charting daily operations of the interrogation program, including graphic descriptions of how and when controversial techniques were employed.

Sources agreed to discuss the matter on condition of anonymity because the report has not been finalized.

The committee members' objective is to conduct a methodical assessment of whether enhanced interrogation techniques led to genuine intelligence breakthroughs or whether they produced more false leads than good ones.

Report: Bin Laden told followers to kill Obama, Petraeus

U.S. intelligence officials have acknowledged that while the harshest elements of the interrogation program, including water-boarding and other tactics which cause severe physical stress, were in use, the CIA never carried out a scientific assessment of the program's effectiveness.

The Bush Administration only used water-boarding on three captured suspects. One of them was Khalid Sheikh Mohammed, the mastermind of the September 11, 2001 attacks.

Slideshow: After the raid: Inside bin Laden's compound

Farooq Naeem / AFP - Getty Images

U.S. forces found and killed the al-Qaida leader in the affluent Pakistani town of Abbottabad, where he had been living in a large compound.

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Other coercive techniques included sleep deprivation, making people crouch or stretch in stressful positions and slamming detainees against a flexible wall.

The CIA started backing away from such techniques in 2004. Obama banned them shortly after taking office.

One source cautioned there could still be lengthy delays before any information or conclusions from the Senate committee's report are made public.

Hidden in plain sight: Inside a secret CIA prison

One reason the inquiry has taken so long is that in 2009, committee Republicans withdrew their participation, saying the panel would be unable to interview witnesses to ensure documentary material was reported in appropriate context due to ongoing criminal investigations.

Current and former U.S. officials have said one key source for information about the existence of the al-Qaida "courier" who ultimately led U.S. intelligence to bin Laden was Khalid Sheikh Mohammed.

KSM, as he was known to U.S. officials, was subjected to water-boarding 183 times, the U.S. government has acknowledged.

Officials said, however, that it was not until some time after he was water-boarded that KSM told interrogators about the courier's existence. Therefore a direct link between the physically coercive techniques and critical information is unproven, Bush administration critics say.

Supporters of the CIA program, including former Vice President Dick Cheney, have portrayed it as a necessary, if distasteful, step that may have stopped extremist plots and saved lives. 

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Rick Santorum's presidential campaign appears to have released a new video that subliminally links President Barack Obama with Iranian President Mahmoud Ahmadinejad.

M. Alex Johnson is a reporter for msnbc.com. Follow him on Twitter and Facebook.

The video, titled "Obamaville," is a 65-second-long production that presents bleak images of an America in dire economic and social straits, interspersed with scenes of international unrest. Prominent among those is a segment showing images of protests and violence in Iran, featuring pictures of Ahmadinejad. It doesn't include the mandatory "I'm Rick Santorum and I approved this message" tagline that would be necessary if it were intended to air on television.

The video was posted Friday on the Santorum campaign's YouTube page, where it was marked as "unlisted," meaning you can't access it without a special link. But you should still be able to see it on a Twitter account identified as belonging to Michael Biundo, Santorum's campaign manager.

Biundo didn't respond to a request for comment Friday night.

The ad also was published by National Review Online, which touted it as an exclusive "first look at Rick Santorum's latest ad."

At the 40-second mark, an image of Ahmadinejad is shown on a small TV screen. For less than a half-second, the picture flashes to a similarly framed picture of Obama before returning to the Iranian dictator.

At full speed, it looks like a tiny video glitch or small lightning strike, but if you slow down the video, the image of Obama is clear in individual frames:

Reached by NBC News on Friday night, Hogan Gidley, a Santorum spokesman, said it is "absurd" to think the ad is likening Obama to Ahmadinejad.

"If Ahmadinejad gets a nuclear weapon, then we're obviously going to deal with the fallout and coverage of that," Gidley said. "All we're going to be seeing is images of him and the president. We were trying to illustrate that."

And Politico reported that John Brabender, the media consultant who made the video, also denied there was an attempt to conflate Obama and Ahmadinejad. Brabender told Politico that the video is part of an eight-part web series that will run on the Santorum website in two weeks focusing on specific Obama policies.

The ad in some ways is reminiscent of one produced by the Republican National Committee for George W. Bush in 2000, in which the word "RATS" briefly appeared on the screen in a reference to Al Gore's health care proposals before resolving into the word "BUREAUCRATS" at the 25-second mark.

Here are the frames in question:

YouTube.com

That ad was pulled after Democrats complained that it was a subliminal insult about Gore, a charge that the RNC and the Bush campaign denied.

NBC News' Andrew Rafferty contributed to this report.

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