Some interviews just stick with you.

Some years ago, I was welcomed into the home of a middle-aged couple. Let's call them Sarah and Alex. The pair had met a little later in life and shared a passion for travel. Sarah, in her forties, had no children and Alex, in his early fifties, had grown children from his first marriage.

They devoted their lives to working hard and indulging their love of travel and there were always friends coming over for dinner. "Life was good," recalls Sarah. But very, very slowly, little things began to happen that hinted at the nightmare that was beginning to unfold in their lives.

It began innocuously enough with the mislaying of keys or forgetting the odd word; things that can be put down to everyday stress. Then one day Alex, a driver of many years' experience, got inexplicably lost on a routine journey and couldn't figure out how to get home. He was naturally alarmed by the incident, as was Sarah.

Dark thoughts began to surface. Could this be a brain tumour? Was he suffering a mental breakdown? After finally acknowledging that something was amiss, the couple embarked upon a long, long battle for a diagnosis. It came as anything but a relief to be finally told that Alex was suffering from early onset Alzheimer's disease.

On the day I visited, several years after the initial diagnosis, only Sarah was home. For a couple of hours every week Alex was taken for respite care to allow Sarah to do various errands and chores alone.

Their happy life, which was portrayed in smiling photographs framed all around the lounge, had all but disappeared.

Alex had rapidly become unable to do his job and Sarah had had to give up her career in order to look after him around the clock as the illness robbed him of more and more of his faculties. Money was tight.

Unable to drive or leave the house unaccompanied, Alex was virtually housebound, as, therefore, was Sarah. She explained that when the illness strikes young, it tends to be more brutal and Alex was often crippled by frustration and mood swings, sometimes violent ones.

Even simple pleasures such as watching the television together had gone. Alex's attention span had been affected and he preferred to ask questions, often the same question over and over again.

She spoke of the terrible loneliness that descends when your loved one needs your care and attention every moment of the day, but the personality that might once have winked at you or flashed a smile when the going got tough, has gone. You are essentially on your own as you face what is likely to be the hardest battle of your life.

"You really find out who your friends are," explained Sarah sadly. Previously, they had been part of a dinner party set but, gradually, the couple had found themselves abandoned. Friends had not known how to cope with Alex's increasingly erratic behaviour and stayed away.

Fortunately for them, they had found some comfort by meeting other families in similar situations. After initial reservations Alex enjoyed attending a social group where he regularly met up with a group of other men with the same diagnosis and the wives and partners formed an informal support network for each other.

As I walked back to my car, I remember glancing back to see Sarah standing at the front door, stoic but sad. She had spent most of her precious respite talking to me.

Given the progressive nature of the illness, I often thought of them in the years afterwards. My lasting impression was that, while coping with the day-to-day challenges was extremely hard, it was the social stigma and isolation surrounding the condition in younger people that really left Sarah feeling hopeless.

Julianne Moore, whose portrayal of a sufferer of early onset Alzheimer's has earned her an Oscar, has proved a compassionate and eloquent spokeswoman to give voice to the suffering of families like Alex and Sarah. Hopefully, the light she has shone on this heart-wrenching condition will help inform where there is ignorance and encourage compassion where there is fear.