Caterina Scorsone, 30, plays neurosurgeon Amelia Shepherd on "Private Practice," but her character isn't worrying about neuroblastomas and brain tumors too much these days. Amelia (the kid sister of "Grey's Anatomy" Derek "McDreamy" Shepherd) has had her struggles with addiction in the past, but she officially fell off the wagon in recent episodes. She quit her job, wrote prescriptions for herself and threw herself into a drug-fueled affair with a handsome stranger named Ryan. On Thurs. Nov. 17, "Practice" will air a two-hour special episode focused on an intervention for Amelia. I spoke to Scorsone about her character's dramatic arc, what we can expect to come and why Amelia finally snapped.

"She's in the thick of it, isn't she?" the Canadian-born actress said with a rueful laugh. Though she's enjoying the chance to dive into her character's struggle, she says that when she first signed on for the show in season three she had no idea that one day the writers would explore the depths of Amelia's addiction. "I knew she suffered from addiction problems, and there were some scenes on 'Grey's' in which Patrick [Dempsey, who plays Derek Shepherd] talked about when she was a teenager and she OD'ed and crashed his Mustang, and how that affected their relationship. But Shonda [Rhimes, show creator] and the writers looked at what we had this season for material and realized we had this great storyline that's so universal and so relatable, and I think people are really going to respond to it. I feel honored to be able to portray this."
 
Of course, fans of the show have been watching Amelia teeter on the brink of collapse for a while now. "One of the things I think is really brilliant they made her relapse this gradual thing," Scorsone says. "She's on the edge and then flirting with going out, then going to AA meetings and really trying to be sober. She's struggling with her addiction and not having the power over herself. So it's been this very gradual decline. I think with Michele, that might have been tipped the balance."
 
Still, Michelle's death, though brutal [Michelle, a friend suffering from Huntington's disease, asks Amelia to help her die, after which they make a botched attempt and Michelle later does the deed herself], shouldn't be seen as the sole reason for Amelia's relapse, according to Scorsone. "She has a disease, and I think it's always a battle she has to fight, not one that just crops up when she's had bad news. But stress can trigger a relapse. But you have to remember that she was sober for a good ten years for medical school, and just like Charlotte (KaDee Strickland), she's relapsed and gone back several times. It's something she's always going to have to be vigilant about. But hopefully, like Charlotte, she can get back on the wagon."
 
Although [SPOILER ALERT] we know that Amelia decides to go into rehab after her friends' intervention, I wanted to know if Ryan would be sticking around for a while. "We do see more of Ryan," she says. "He came in on episode six, and he does stay around for a little while." 
 
Scorsone says the intervention episode on Thursday is one that breaks the "Private Practice" mold, and not just in tackling drug addiction. "It breaks from the regular format that we use, in that we have several storylines going on throughout the show which weave in and out throughout the show, and every single character is present at Amelia's intervention. The whole cast is there doing really interesting stuff, which was a great experience for me as an actor."
 
In portraying Amelia's fall from grace, Scorsone did do some research but also had secondhand experience to draw from as well. "It is such unimportant and sensitive topic that i wanted to make sure i was doing it justice, so I did do research," she says. "We have a great medical staff on the show, so I could ask any questions if I needed to, but i was also talking to people in the recovery industry and people in recovery themselves, so we would pick apart every scene. But my dad runs a homeless shelter in Toronto, so I've definitely seen the problem up close and there's always been a lot of discussion about it in my house. It wasn't a subject i was unfamiliar with, but I got more specific with it when the storyline went in this direction."
 
As far as what we can expect on Thursday, Amelia isn't going to rehab without a fight. "She's pretty no holds barred," Scorsone says. "She's on the run and very defensive, so she cuts into every. We often hurt the ones we care about the most, and I think Addison, Charlotte and Sheldon are the three hardest hit by her emotional attacks on them."
 
Even though those three friends will have to tolerate some button pushing and insults from Amelia, their efforts aren't what will ultimately push their friend in the right direction. "I think it's a collaborative effort, but I think Amelia is the only person who can decide that Amelia will stay sober. Everyone else can love her, but no one can save Amelia except Amelia."