By Stephanie Stahl

PHILADELPHIA (CBS) — The power of friendship.

A group of girlfriends from Hallahan High School who’ve been together for 60 years say the friendships have helped keep them active and healthy.

They were 12 girls who graduated together six decades ago and vowed to keep their friendships alive forever. They agreed that no matter what, nothing would stop them from getting together every month.

They share a life time of memories, this sisterhood from Hallahan High School, the class of 1956.

“We just kind of got to know each other and I don’t know, it stood the test of time for whatever reason and we’ve just been there for one another,” explains Pat Kling

A storyboard of photos documents the 60 plus years they’ve been getting together every month.

Joyce McKeon says simply, “It’s fabulous.”

This anniversary celebrated at the Watermark retirement community, where Dr. Karl Benedict is the medical director.

He says, “I think it’s amazing that they’ve been able to do that for so long.”

Dr. Benedict adding that long-term friendships and social interaction helps the elderly live, longer better lives.

“It’s beneficial to heart health probably by helping with reducing levels of stress and some studies suggest that it’s even more important than exercise … I think it also helps to preserve mental function, cognitive function and there are studies that show that people who have good social ties and interaction have less dementia,” Dr. Benedict explains.

Most of the girlfriends are 78 years old now. Together they’ve celebrated all the milestones: marriages, children, grandchildren and heart break too – deaths and illnesses.

“There’s been a lot going on these years with ups and downs,” says Anne Marie Gallagher. She was the class president.

What keeps them together? Anne Marie says, “I can’t think of anything specific, we were just very compatible and had lots of fun.”

They made up a sorority name for themselves sigma delta pie and are committed to growing even older together.

In May for the actual anniversary of their high school graduation, the ladies went on a cruise together to Bermuda and they’re already busy planning their next trip.

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