Diane Keaton Says Her Brother Randy Has Dementia: 'I Don't Know If He Knows Who I Am'

The actress tells PEOPLE about her brother's hard life and her regular visits

Diane Keaton hasn’t lived a traditional life (an Oscar-winning actress, she never wanted to be a wife, she says), but family remains the center of her world. And family includes her younger brother, Randy Hall, who she says suffers from dementia.

“I’ve spent a lot of time in senior living facilities [recently] with my brother, Randy, who has dementia,” the 73-year-old actress—who’s now starring in her 58th film, Poms–tells PEOPLE in a wide-ranging interview for this week’s issue. “I’m writing a book about him. He always had mental issues. Nobody could figure it out, really.”

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Keaton explains that Hall, 71, “has had a hard life, you know? He’s a very interesting person. Very sensitive, a writer and poet. But also a big drinker, and completely solitary. It’s so complicated.” Before developing dementia, he was diagnosed with Parkinson’s disease. Never able to support himself, he was supported by their parents and, since their deaths, by Keaton. (They also have two sisters, Robin and Dorrie.)

These days, he is unable to walk or talk. “I don’t know if he knows who I am,” Keaton says.

Keaton, right, with brother Randy and sister Robin. Diane Keaton/Instagram

Despite her sadness over her brother’s condition, Keaton is amazed at the support he receives at the senior living facility where he lives, and where she visits him every Sunday — and she loves the personalities of the other inhabitants.

During one visit, she noticed two patients who had previously seemed lost in their own worlds holding hands while they went on a walk. “It was the most adorable thing,” Keaton says.

For more from the Diane Keaton interview, pick up the latest issue of PEOPLE, on stands Friday.

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The loving vibes continued for her brother’s birthday party, which included a “huge cake.” Keaton was worried no one would come, but all of his friends eventually turned up.

“There are fabulous characters on the dementia ward,” she says. “When you’re there with all of them, it’s not like, ‘They’re really weird.’ They’re people.”