Bruce Willis' daughter Tallulah has shared that she received a life-changing autism diagnosis as an adult.

Willis, 30, on Friday posted a throwback video on Instagram that showed her touching her father's head and playing with his ear as he held her at an event when she was a child. "Tell me your autistic without telling me your autistic," she wrote, adding a crying laughing emoji.

In the comments of the post, one follower asked Willis for more information, and she shared that she was only diagnosed as autistic last year. "Actually this is the first time I've ever publicly shared my diagnosis," she wrote. "Found out this summer and it's changed my life."

According to the National Institutes of Health, diagnosing autism spectrum disorder (ASD) in adults is often more difficult than in kids because certain symptoms can overlap with those of anxiety, ADHD and other disorders.

"Receiving a correct diagnosis of ASD as an adult can help a person understand past challenges, identify personal strengths, and find the right kind of help," the NIH says. "Studies are underway to determine the types of services and supports that are most helpful for improving the functioning and community integration of autistic transition-age youth and adults."

Adults who notice signs of ASD can receive an evaluation, in which an expert may ask about social interaction and communication challenges, sensory issues, repetitive behaviors and restricted interests, per the NIH.

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Willis was responding to a comment from a user who identified themselves as a psychologist and wrote, "We catch undiagnosed ASD in girls and women quite often (they have unique presentations and often turn to other ways of coping to manage the dysregulation)." The follower added, "Not sure how much of your journey you’ve shared but would love to read more. You’re brave and inspiring and this is a very sweet video. All the best!"

Tallulah Willis is the youngest of three daughters whom Bruce Willis shares with ex-wife Demi Moore. He also has two children with his current wife, Emma Heming Willis.

The "Die Hard" star retired from acting after he was diagnosed with frontotemporal dementia. In an essay for Vogue magazine published last year, Tallulah Willis reflected that she had "known that something was wrong for a long time" even before her father was diagnosed.

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In that essay, Willis said that she was diagnosed with ADHD after being admitted to a residential treatment facility to address her depression and later received a new diagnosis of borderline personality disorder. She also opened up about her four-year battle with anorexia nervosa.

"I admit that I have met Bruce's decline in recent years with a share of avoidance and denial that I’m not proud of," she wrote. "The truth is that I was too sick myself to handle it. … While I was wrapped up in my body dysmorphia, flaunting it on Instagram, my dad was quietly struggling."

If you or someone you know is struggling with body image or eating concerns, the National Eating Disorders Association's toll-free and confidential helpline is available by phone or text at 1-800-931-2237 or by click-to-chat message at nationaleatingdisorders.org/helpline. For 24/7 crisis situations, text "NEDA" to 741-741.

Contributing: Edward Segarra, USA TODAY