Rumer Willis is confronting a frightening question about her own future as her father, Bruce Willis, continues his heartbreaking battle with frontotemporal dementia.

The 38-year-old daughter of Bruce Willis and Demi Moore has watched up close as the beloved action star’s health has declined. Now a mother herself, Rumer says her father’s diagnosis has pushed her to investigate whether she could also face an increased risk of dementia later in life.

Rumer, who shares 3-year-old daughter Louetta with ex Derek Richard Thomas, recently revealed that she underwent genetic testing after becoming concerned about her family history.

“I really miss my dad,” Rumer wrote in an emotional Instagram post. “I miss a different version of who he was.”

She said some days are incredibly difficult, but she is trying to focus on appreciating the father she still has.

“There are some days that are just so hard,” she wrote. “I try to prioritize being present with where he’s at now.”

Rumer added that dealing with her father’s condition has forced her to accept two painful realities at once — grieving the man he once was while still cherishing the time they have together.

Her concern eventually led her to take an APOE genetic test, which can help assess a person’s risk of developing Alzheimer’s disease.

“I wanted to check it out because of my family history,” Rumer explained.

Fortunately, she said her results fell within an average range.

“There is some risk, but it’s not crazy,” she said.

Longevity expert Dr. Gabe Mirkin, who has not treated Rumer, told RadarOnline.com that APOE testing can provide information about dementia risk based on genes inherited from a person’s parents.

He explained that inheriting certain genetic variants from both parents can potentially carry a higher risk than inheriting one copy.

Bruce’s condition, however, is different from Alzheimer’s disease.

The Die Hard star stepped away from Hollywood as his health problems became increasingly serious. His family later revealed that he had been diagnosed with frontotemporal dementia, commonly known as FTD.

Unlike Alzheimer’s, which is often associated primarily with memory loss, FTD commonly affects personality, behavior, language and communication.

Bruce’s illness has devastated his close-knit family, who have continued sharing occasional updates while rallying around the 71-year-old actor.

Rumer’s health concerns also come during another difficult chapter in her personal life.

Her former partner, musician Derek Richard Thomas, recently filed court documents accusing her of violating a custody agreement involving their daughter.

Thomas claimed Rumer has made it difficult for him to maintain his relationship with Louetta and asked a Los Angeles judge to enforce the existing custody order.

“[Rumer] has continued to frustrate my ability to maintain my relationship with our daughter, with whom I have had a very close and loving relationship,” Thomas alleged in court filings.

Between her father’s devastating dementia battle, concerns about her own future health and an escalating custody dispute, Rumer is facing an intensely emotional period while raising her young daughter.