The 29-year-old was recently diagnosed with OCD and she fears the condition is getting worse as she has noticed changes in her mannerisms.
"It's very weird. It's only happened in the past year. I've started getting very superstitious and fixating on things. I'd get these obsessive moments, it's becoming an issue.
I'm in the middle of the street and my dog is peeing on a tree and I'm touching it," she said. Asked why the condition is worsening, Blunt said, "I don't know. I think I'm just worrying lately about my friends and family.
I'm lying awake, and getting older and realising how precious everything is; losing that slightly cavalier quality you have as a teenager when you say and do silly things."
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