Susan Hirsch was visiting her father in the hospital where he was recuperating after a fall and was shocked to find him — long devoted to her mother — flirting with a nurse as if he were “17 and in the Navy again,” she said.

Hirsch, a 67-year-old memory care educator from Palmyra, Pennsylvania, scolded her father. But the admonishment only enraged the 93-year-old man; she recalled him saying, “in not nice words,” to get out of his room as she scuttled away.

More than 11 million adults in the United States are caring for people diagnosed with Alzheimer’s and other forms of dementia. In addition to memory loss, most people with dementia will experience mood and behavior changes including aggression, apathy, disorientation, depression, wandering, impulsivity and delusions.

Many caregivers describe mood and personality changes as the most upsetting symptoms. While antipsychotic and sedative medications are often used to manage dementia-related mood issues, they have limited efficacy.

To get on top of — and feel less toppled by — mood changes, it’s helpful for caregivers to remember that those shifts are caused by changes in the brain, said Dr. Nathaniel Chin, a geriatrician and associate professor in the department of medicine at the University of Wisconsin-Madison.

“They’re no one’s fault,” he said, and recognizing this can help you “feel less upset at your loved one.”

That day at the hospital, for example, the nurse followed Hirsch into the hall and gently explained that her father, who had shown milder symptoms of dementia before, was not acting out on purpose. “She didn’t reprimand me, and it was very helpful,” Hirsch said; the conversation helped her cope with her dad’s mood changes until he died three months later.

Understand why mood changes happen

Personality and mood changes are often caused by deterioration in parts of the brain that control attention, learning, feelings and other faculties. For example, a person who has lost cells in the frontal lobe, which controls focus and behavior, may become more passive as the ability to plan diminishes, according to the Memory and Aging Center at the University of California, San Francisco; he or she may also lash out as impulse control wanes.

Additionally, people with dementia have less brain energy to process and adjust to sensations (such as pain or fatigue) and environmental stimuli, Chin said. Many experts also agree that people with dementia have lower stress thresholds than they once had and might tip into feeling overwhelmed more quickly. This is the point when someone with dementia might suddenly become agitated or combative or begin “screaming and yelling out,” he said.

As the disease progresses, people lose language skills and communicate more through behavior, said Fayron Epps, a nursing professor at the University of Texas Health Science Center in San Antonio. For example, a person may need to use the restroom but can’t convey that verbally, and might bang on something to express frustration, Epps explained. “As a caregiver, you really have to investigate where this mood is stemming from,” she said.

DICE up challenging behaviors

Dr. Helen Kales, a geriatric psychiatrist and chair of the department of psychiatry and behavioral sciences at the University of California, Davis, conducted research and found that caregivers who have a system for addressing behavioral symptoms experience less stress than other caregivers.

They developed a caregiver education program, known as the DICE Approach: Describe, Investigate, Create and Evaluate. The approach teaches caregivers to describe mood changes in detail (taking notes on when, where and even with whom they occur), investigate why they might be happening, create informed responses and evaluate their success.

By learning to note who’s in the room or what’s playing on TV when symptoms occur, caregivers can become adept at detecting patterns, seeing issues from their care partners’ perspective and creating plans to reduce or eliminate symptoms.

And if the person you’re caring for becomes violent, it’s important to have an exit plan, experts advised. Hirsch recommended bringing your phone with you if you need to leave the house, so you can call for help to keep yourself and your loved one safe.

Emphasize tone over truth

People with dementia may not understand exactly what you’re communicating, but they will comprehend your tone and body language, said William Haley, a professor of aging studies at the University of South Florida, who advised doing your best to speak calmly, with your face and posture relaxed.

And, he said, don’t get too hung up on the facts. Telling a person with dementia in a cranky, corrective way that it’s Wednesday, not Thursday, could rattle them more. And reminding someone of a bigger sorrow they’ve forgotten — that a spouse has already died, say — can be devastating, Haley said.

Instead, if your loved one asks about someone who’s no longer alive, just say you think that person is fine and change the subject, he suggested. “It’s not an enduring lie,” he said. “And to me, it’s more moral than confronting them with an awful truth that will just cause them grief and pain.”

Embrace light

Making sure that people with dementia get regular exposure to natural and other forms of bright light can improve their sleep and mood, Kales has found in some of her research. And getting solid nightly sleep can reduce sundowning, the meltdowns that can occur with dementia late in the day, or any time of day, if there’s enough stress and fatigue brewing.

Reduce boredom if possible

Since boredom can cause mood swings, Kales and her colleagues created a list of 96 activities that people with dementia can do alone or with their caregivers. Haley has also heard about people with dementia for whom folding towels, sweeping a long driveway and, in the case of one retired schoolteacher, “grading papers” (marking up a stack of printed emails provided by her caregiver) have become favorite pastimes that give them satisfaction and a sense of pride, he said.