"My husband has dementia and has erectile dysfunction as a result. Am I supposed to never have sex again?"

The inability to perform sexually often (not always) accompanies dementia. The net result -- looking at years of living with a mate but not a sexual partner -- is the same as for those who decide to cease sexual relations with a partner who has advancing dementia. In other words: Now what?

"This becomes a time when people often have affairs," Robbins says -- including devoted spouses who would never have considered such a thing when their partner was healthy. "They feel free of the marital commitment because the person they're with is not the same person anymore."

Again, one is left weighing his or her individual moral and sexual appetite for an affair. People can live 5, 10, 20 years or more with dementia. In cases of early-onset Alzheimer's, for example, the caregiver is often still in his or her sexual prime. Many caregivers have hooked up with a fellow caregiver in the same situation (with or without an emotional commitment), given their parallel physical needs.