Growing up with a movie-star mom has its perks, but for Lord of the Rings actor Sean Astin (currently on the hit series 24), being the son of Oscar-winner Patty Duke wasn’t always glamorous. From as early as Sean can remember, his mom had episodes of high-energy recklessness and periods of extreme lows. Her behavior included suicide attempts, drug dependency, impulsive romances and tantrums. Sean wasn’t privy to all of his mom’s episodes, but what he did see had a huge impact. “It was terrifying. And you could tell it was terrifying for her, which made it more scary for me,” Sean tells OK!. “We knew something was off, but we didn’t know what, and there was nothing we could do about it.” It wasn’t until 1982 (Sean was 11 years old), about 12 years after Patty exhibited symptoms, that she was diagnosed with manic depression. This chemical imbalance in the brain is also called bipolar disorder because a person with the illness alternates between the two poles of mania and depression, with mood swings that can last hours, weeks or months. “Before her diagnosis, I didn’t understand that my mom’s behavior was out of her control, and I would get very angry at her even though I loved her. I thought her suicide attempts and erratic spending were just indulgences. And when she was in a depressed part of her cycle, sleeping for days, I just felt horrible for her,” says Sean. Since her diagnosis, Patty’s (and her family’s) world has changed. She has gotten treatment, is living a happy life, and has written books about her illness and recovery in order to destigmatize the condition. But most people still don’t know what bipolar disorder is, and as a result, they don’t get treatment. The average delay between symptom onset and diagnosis is 13 years. So now Sean has taken up the cause of educating people about the disease so that other families don’t have to live with bipolar disorder without an accurate diagnosis or effective treatment. Read on to find out what he want you to know.