According to the World Health Organization, 35.6 million people have dementia worldwide and that number is projected to double every twenty years. A large proportion of those people with dementia will die in a residential aged care facility. While the elderly are free to do what they like in their own homes, once in facilities, their sex life is regulated by staff. Far from all of them are as sympathetic as the nursing home that Emma described.

The study in the Australian Journal of Dementia Care found that staff were anxious about addressing sex among their residents. They were chiefly concerned about the reactions of a resident's family, as well as the legalities of the arrangements.

Dementia can be caused by a range of pathology -- most commonly Alzheimer's, as well as small blood clots in the brain, and abnormal proteins called Lewy Bodies, among others. In some cases the frontal lobe, which is responsible for sexual drive and interest as well as inhibition, may be affected. As Carmelle Peisah, New South Wales branch chair of the faculty of psychiatry and old age at the Royal Australian and New Zealand College of Psychiatrists, told me, it can affect "the part of the brain that stops people from acting on their sexual urges in public, such as masturbating. People have thoughts that they wouldn't act on without dementia, but with dementia they might act on it because of this lack of impulse control."

In instances where residents might express their sexuality inappropriately -- say, by masturbating in public spaces of a nursing home, Peisah says that it is crucial for staff not to chastise the person. Instead they should be redirected to a private space, or be provided with an appropriate outlet for the expression of their needs and behavior -- or both.

Other aspects of sexuality, such as emotional feelings like intimacy and warmth, are driven by the limbic system of the brain. "The needs and importance for social and physical relationships and in particular intimacy continue well into the moderate to severe stages of dementia," Peisah said.

Then there is memory loss -- the most infamous and obvious symptom of dementia, eventually including the diminished ability to recognize people. Residents may not know who the object of their erotic interest is. "Sometimes people can't tell the difference between their spouse, the care worker, or a fellow nursing home resident," Peisah said.

In Alice Munro's 1999 short story "The Bear Came Over The Mountain," which was subsequently made into the critically acclaimed film Away From Her, the protagonist has to cope with his Alzheimer's-stricken wife entering a nursing home and falling for another resident, forgetting about her husband. The scenario is not uncommon in real life.

Last year, my own grandmother entered a residential aged care facility with vascular dementia. When I visited, she had little interest in talking to me. Instead, she held hands with Eric, a cheerful fellow resident with a room across her corridor. He introduced my grandmother as his wife. In Russian (she spoke no English), she told me that he was a neighbor from Belgorod, our hometown. I hope for their sake that whatever they had -- if they wanted it to -- extended beyond handholding, because within six months both of them had died. Neither Eric nor my grandmother had living spouses, and situations like Munro's story can be very distressing for living partners who feel they have been replaced. Still, considering the importance of the happiness and well-being of your loved one in their current, new reality, can be reassuring.

Simon Blackley/Flickr Simon Blackley/Flickr

Peisah warns, too, that certain residents with dementia could be vulnerable to sexual or financial exploitation. These situations could be flagged by a power imbalance between a resident with dementia and their "partner" either due to a substantial difference in age or intellectual function, such as sex between a person with dementia and someone who doesn't have dementia, such as a carer.