Such numbers, experts say, reflect growing desperation in Spain, which has the highest unemployment rate in the euro zone. According to recent government figures, about 1 in 10 households now has no working adults.

Some experts say they believe that retired people, sharing their pensions and dipping into their savings, have been the silent heroes of the economic crisis, and that without them Spain would be seeing far more social unrest. In many cases, they stand between their middle-aged children and homelessness.

“Why aren’t there more people in the streets protesting, asking for food?” said Gustavo García, director of Casa Amparo, Zaragoza’s municipal nursing home. “The answer is the elderly.”

Certainly that was the case for Petri Oliver, 53, and her husband, Pedro Grande, 53, who were able to survive until recently, they said, only because they were taking care of Ms. Oliver’s 80-year-old mother at home rather than putting her in a nursing home. Ms. Oliver’s mother, already suffering from Alzheimer’s, had three strokes last year, which left her in a vegetative state.

While Ms. Oliver’s mother was alive, she lay in a hospital bed in Ms. Oliver’s stifling living room, surrounded by piles of medical supplies, including her liquid meals. Ms. Oliver’s father got 300 euros, almost $370, a month from the state to take care of his wife, money he turned over to his daughter. “If she goes to a nursing home, we don’t eat,” Ms. Oliver said earlier this month. But a week later, her mother died.

Until two years ago, Ms. Oliver’s husband worked in construction, despite a workplace accident that left him blind in one eye. These days the couple’s only income is around $1,200 a month in disability payments. But the mortgage is nearly $1,000. They cannot visit their daughter, who lives a two-hour drive away in Barcelona, because they cannot afford the gas. Their daughter has been unemployed, too.

“We don’t know what we are going to do now,” Ms. Oliver said.

In the suburbs of Barcelona, Mari Ángeles Ramiro Trenado was down to earning just 120 euros, about $150, a month and facing monthly rent of 500 euros, about $615, when she and her brother decided to take their mother out of a nursing home this year. On a recent afternoon, Ms. Ramiro, who has a mentally disabled adult child at home, too, said that taking care of her mother had left her exhausted and depressed.