The woman described the sensation as a delicate flicker, like a moth trapped in a small gauze bag. She ran her slender fingers repeatedly over the spot in her slightly distended abdomen and said, “Doctor, right here.”

Sometimes, she told me, the flicker gave way to a more forceful kick that rippled beneath her hand and then spread like a warm tide over her body. She felt contented and soothed as she imagined the baby growing inside.

I was tempted to smile, but I kept still. An actual pregnancy would have been international news: the woman was 83 years old, recovering from a hip fracture and pneumonia. But her delusion was not unique. Indeed, our nursing home was having something of a baby boom.

Just the day before, another woman who had recently suffered a stroke insisted that she had given birth to twin boys, who were now crying in the adjacent nursery. I reminded her that she was 90, but my words were no match for the force of her belief. She looked at me blankly and called again for her babies.

Her husband, distraught, begged me to consider some pharmacologic remedy. But I was struck not by any mental suffering on the woman’s part, but by the opposite.

In the face of terrible losses and confusion, her mind had found refuge in imaginary children. Their coos and cries brought comfort and hope.

Pseudocyesis, as delusional pregnancy is called, is neither common late in life nor a normal response to aging or illness. It is a form of psychosis, and it can lead to severe anxiety or disruptive behavior that must be treated.

But it is too easy to see pathology in what may actually be a protective mechanism in the aging brain. What a psychiatrist might call a symptom held deep meaning for each woman, and prompted them to focus on recovering from severe illness.

In each case, I had to act in the opposite direction of my instinct as a doctor. Medication might have only sedated them and even taken away a protective cocoon. Instead I let time do its work: the delusions faded, and physical and mental recovery took hold.

Such examples are relatively rare and, one might argue, easily romanticized. But they hold a larger lesson about the aging brain.

What we perceive as a brain in flight or decline, disengaging from the world or tumbling into a netherworld of oldness, might actually be a more selective, creative and wiser brain.

The paradox is that even as the normal aging brain loses capacity across numerous discrete skills — memory-processing speed, verbal reasoning and visuospatial ability, to name a few — it is simultaneously growing in knowledge, emotional maturity, adaptability to change and even levels of well-being and happiness.

I witnessed this common phenomenon in a couple I know well. The woman is a sharp and active 82-year-old who only recently retired as a social worker. Her new husband, now 92, was a World War II bomber pilot and retired marketing genius who always prided himself on his mental discipline and physical stamina.

Recently he began to complain bitterly of creeping short-term memory impairment and a general slowing of his motor functions. Both factors can bring him great unhappiness. During a recent meeting, however, I pressed him on his complaints, asking, “Is that all there is to growing old — decline, slowing and loss?”

His bride interrupted and told how their relationship was unique because of old age, in many ways deeper and more intimate than either had experienced as younger people.

Even as his memory declined, she said, his emotional maturity and wisdom had increased, opening perspectives and relationships he had never had before. Here was old age — and an aging brain — acting as a force that added even as it took away.

In telling this tale as a relatively young doctor who works primarily with older individuals, I could easily be accused of painting an overly rosy picture of what I want growing old to be.

If so, I plead guilty. But I do so in the spirit of the gerontologist Thomas Cole, who suggests that the ways in which we look at old age begin to constitute its reality.

We will all grow old, and despite the inevitable changes we do have choices. Indeed, growing evidence suggests that the aging brain retains and even increases the potential for resilience, growth and well-being.

I have seen this lesson lived in my friends, loved ones and older patients, whether free of illness or fettered by it. I saw it in the two older women whose imagined pregnancies brought needed hope at a time of threatened despair. Their fervent wishes, though unattainable, allowed them to achieve something better.

Similarly, we can all hope for a vital and meaningful old age — for our elders, ourselves and our children. In the end, we may actually get what we wish for.