Sort of Exorcist references

Lizzie is supposed to be a 12-year-old girl (according to Radio Times), like Regan (though looks older than Linda Blair), and the post menarche bath scene has the girl in an identical pose to the pose pissing bath scene in The Exorcist, presumably deliberately.

Otherwise, there is a brain scan, and a sort of attempt at exorcism, though without the involvement of the Church.

And the happy ending is rather like the happy ending of The Exorcist.

A bit underplayed though I thought. I kept waiting for things to happen.