PHOENIX - Rep. Gabrielle Giffords struggles to find words and put together sentences as it remains unclear five months after she was shot in the head in Tucson whether she will eventually be able to resume work in Congress, an aide said in an interview published Thursday.

The interview with chief of staff Pia Carusone published in the Arizona Republic provides the latest information about the congresswoman's condition since she was shot and injured in a rampage that killed six people and wounded a dozen others Jan. 8.

A decision on whether Giffords will return to work in Washington does not have to be made until May 2012, Carusone said, adding that if the progress Giffords has made so far were to slow down or stop, she would be unable to fulfill her legislative responsibilities.

Carusone said Giffords' limited speaking ability had led her to rely primarily on facial expressions and hand gestures to communicate.

"She is borrowing upon other ways of communicating," Carusone told the Arizona Republic. "Her words are back more and more now, but she's still using facial expressions as a way to express. Pointing. Gesturing. Add it all together and she's able to express the basics of what she wants or needs. But, when it comes to a bigger and more complex thought that requires words, that's where she's had the trouble."

Often, Giffords is clearly frustrated by her limits, Carusone said.

Giffords was shot in the left side of her head, which controls speech and communication, while meeting with constituents in Tucson. A judge has declared shooting suspect Jared Loughner mentally incapable of participating in his defense and sent him to a federal facility where doctors will try to treat his condition and make it possible to put him on trial.

Giffords' survival was considered a major feat by doctors, and the progress she has made while undergoing intensive rehabilitation at TIRR Memorial Hermann in Houston has also been described as almost miraculous. But the public has not seen Giffords since the shooting, and information on her recovery has been scant.

Carusone's comments make clear that despite doctors' optimism, Giffords is still a shadow of her former self.

"She's living. She's alive," Carusone said. "But if she were to plateau today, and this was as far as she gets, it would not be nearly the quality of life she had before. . . . All that we can hope for is that she won't plateau today and that she'll keep going and that when she does plateau, it will be at a place far away from here."

Experts say they expect Giffords to be released in the coming weeks from the inpatient setting. She will then undergo months of intensive outpatient care in Houston.