There are plenty of what-ifs: What if Chuck had not been home alone that day? What if his mother, Ellie, who was living with him at the time, had not told him about getting her driver’s license renewed? What if he had not been so upset? What if his sister, Joanne, had moved to Maine to take care of Chuck when she first considered making the move?

These and other questions still weigh on the minds of the family of Charles M. Springer, a Belmont man, then 69, who walked away from his home on Halls Corner Road May 2, 2008, and has never been seen since. What makes Chuck’s case a precarious one is that he suffered from dementia and Alzheimer’s Disease.

It wasn’t unusual for Chuck to go for walks alone. His mind was still fairly clear, said his sister, Joanne Grigoreas, 62, of Lebanon. And whenever he did have episodes where he became disoriented, he found his way home with the help of his neighbors.

But on that fateful May day two years ago, he didn’t find his way back.

It is believed that what happened to Chuck is an example of what is known as “wandering,” when a person afflicted with dementia or Alzheimer’s wanders off — on foot or in a car — and becomes lost.

This type of wandering, according to the Alzheimer’s Association of Maine, is different from the normal sense of wandering. A person with dementia who wanders often has a goal of looking for something or of fulfilling a former obligation. This can be dangerous in many cases, said Kathryn Pears, the Alzheimer’s Association of Maine’s director of programs, public policy and communications, because the mechanisms and areas of the brain responsible for judgment and orientation have begun to deteriorate, and the person doesn’t have a sense of being in danger.

“People make the mistake of thinking that because their loved one has never wandered, they never will,” said Pears. “But there is a first time for everything, and that first time can be fatal.”

According to Pears, 60 percent of people who suffer from dementia or Alzheimer’s wander at some point. Of that number, half either die or become injured if they are not found within the first 24 hours, she said. In many cases, a person is found within a mile of their house; but sometimes, as has been the case with Chuck Springer so far, a person is not found. The worst-case scenario, according to Pears, is that a person who has wandered is not found alive.

Stress, anxiety and agitation are a few of the common triggers that cause a person suffering from dementia or Alzheimer’s to wander, according to the Alzheimer’s Association. Grigoreas said anger might have been the impetus for her brother’s wandering.

“He either did it intentionally because he was angry,” she said, “or he was just so angry that he got confused and got lost.”

He had been brooding all week, she said, because he felt it was unfair that his mother, Ellie Springer, then 88 years old, had been allowed to renew her driver’s license while he had not.

Chuck worked as a long-distance truck driver for more than 30 years. It was a job he enjoyed, said Grigoreas, because it allowed him to be on the road, to see the country, and to visit with friends and relatives. When Chuck’s license was revoked in 2006 on the recommendation of a doctor, it was a huge blow to him.

“He couldn’t understand it,” said his sister. “He felt he was okay to drive. For the most part he was, but not always. And that was the problem.”

He would experience long stretches of relative normalcy, Grigoreas said, and then little incidents would come up. Like the time he took a road trip down to Florida and on the way back to Maine became disoriented. He stopped in Virginia, thinking he was in Massachusetts, and Chuck’s brother, Everett Springer, had to pick him up.

Chuck also became increasingly quiet as the Alzheimer’s progressed, his sister said, and he began to have trouble communicating his thoughts. Despite this, Grigoreas said, he was still a relatively clear thinker.

Grigoreas and Ellie Springer, who both relocated to Lebanon — a small town in southern Maine, on the New Hampshire border — a short time after Chuck disappeared, said that their family, which includes Chuck’s other siblings, Everett Springer and Patricia Bernstein, continues to hold onto hope that he is still alive. They wonder if he was possibly picked up by someone, perhaps another trucker, and is working in some small, faraway town. They don’t like to think of the other possibility — that Chuck, who had no identification or wallet on him the day he disappeared, wandered into the Maine woods and died.

They said as time goes by, however, it becomes more difficult to remain hopeful.

“The past two years have been just awful,” said Ellie Springer. “I’m still hoping, but I sometimes wonder how I’m able to keep strong. I have to keep strong for my family’s sake. I don’t want to get sick. I want to stay well, so that if Chuck is found, I’ll be able to see him.”

Still, there are moments when she wants to break down and cry. Sometimes she feels like screaming, she said, especially when it seems as though the search is at a standstill.

The Maine State Police are still investigating the case, but with few leads, police said there is little momentum.

The family continues its own search for Chuck. They recently drove around small towns in northern Maine, putting up posters, and have even posted a YouTube video of Ellie Springer asking anyone who might have seen her son to contact them. In the video, the mother holds up a poster with Chuck’s basic information — his age, height and what he might have been wearing the day he disappeared.

And then she describes her son in a more personal manner: fit, strong, fairly capable, with a friendly, wide smile, a lover of music, dancing, old cars, the Red Sox and his family.

“I am Chuck’s 90-year-old mother,” Ellie says in the video, “and I miss him very much.”

Ellie said she visits missing persons Web sites and wonders how families have been able to get through 10, sometimes 20 years of not knowing where their loved ones are or what happened to them.

“Here we are,” she said. “It’s only been two years and it feels really bad. I never thought this would happen to me.”

Anyone with information on Chuck Springer can contact the Maine State Police at (800) 452-4664. For more information on Alzheimer’s and wandering, visit the Alzheimer’s Association of Maine’s Web site at alz.org.