Q. I need advice to help my beloved 74-year-old sister, who now has full-blown dementia.

Although I take time off from work to go see her a few times a year — and to give her husband a respite — I don’t know how to interact with someone who has this horrible disease. My sister is very friendly, social, artistic and musical, but she has trouble remembering words and can no longer speak in complete sentences.

She also refuses to take showers, clean her fingernails and follow other rules of basic hygiene. She has always been a gifted, talented, generous and very loving person.

by Marguerite Kelly

A. You’re not just dealing with dementia; you’re dealing with heartaches and heartbreaks, too.

(Hadley Hooper for the Washington Post)

No matter how hard you try to bring your sister into the present, she will keep slipping into the past, not because she wants to do that but because she can’t help it. She lives in the moment, and you can’t make her change her behavior or finish her sentences, either. You can, however, change your own expectations, and you really should. It’s the only way you’ll be able to enjoy her in her declining years.

You also should call local charities, churches and adult day-care centers to see what services they offer to dementia patients, because her husband is probably too tired or too overwhelmed to find out what kind of services your sister could be getting. For instance, a church in your neighborhood may have respite care for a disabled parishioner, so your brother-in-law could get an occasional break. Even a few hours a week or a month could let him shop, have lunch with a friend, or just go home and take a worry-free nap.

Because music is our earliest intelligence — and because your sister is so musical — you might also burn a CD of her favorite songs or give her one of the deeply calming Gregorian chants, such as “Ave Maria” by the Benedictine Monks of Santo Domingo de Silos or “Gregorian Chant” by the Choralschola of the Niederaltaicher, a more varied collection conducted by Konrad Ruhland.

You also might take a couple of photo albums with you when you visit your sister, so you can reminisce through the pages. But first give her 20 to 30 minutes to pull her thoughts together, and only talk about the four or five friends and relatives whom she remembers best. She won’t want to hear about too many people at once now that her memory is failing.

Take some art supplies to your sister, too, because dementia patients like to use the skills they mastered in the past. Although oils, acrylics and watercolors would be too messy for her now, she should still do well with oil pastels, crayons and colored chalk. Don’t be surprised, though, if she forgets what she is drawing before she finishes her picture.

Hygiene is, in a way, a bigger problem, and it may take ingenuity — and money — to solve it. Although your sister can’t clean her fingernails anymore, a high school counselor may know of a student you could pay to give your sister a weekly manicure, as long as you pay for the supplies, too. It will be worth it; if the colors are dark enough, they’ll hide any dirt that gets under your sister’s nails from one manicure to the next.

If you can spare considerably more money — and if there is an electric socket near her toilet — you could treat your sister to an easy-to-install bidet toilet seat, because it would send up jets of warm water to wash her bottom when someone pressed the button for her. These seats are extremely popular in other parts of the world and in many U. S. nursing homes, too, but they’re not cheap. The top-rated Brondell Swash 1000, which costs several hundred dollars, can sometimes be bought from Overstock.com for just under $400.

Your social sister may even agree to take showers more willingly if her husband promised to invite a neighbor over for a cup of tea afterward or if he simply told her that the doctor said that she had to take a shower right away. If she’s like most patients, she’ll obey her doctor better than her husband.

Send questions about parenting to advice@margueritekelly.com.

Chat Sept. 19 at noon Join Kelly for a live Q&A about parenting and other family relationships at washingtonpost.com/parenting , where you can also read past columns.