My cat attacks her reflection

I have an 8-year-old two-tone Harlequin tabby named Layla. During the past week, she has discovered her reflection in the mirror and it is freaking her out. This was amusing the first couple of times, but now my wife and I are a bit concerned. It's as if she's tormented: wherever she sees her reflection (mirror, glass door, stove door), she screams, hisses and tries to fight with the "other" cat.
This is a brand-new development and, as I said, she is 8. I'm really hoping this is just a passing phase. Anyone have any insight on this?

Bernie

I would try to distract her with healthy play when this happens and make the mirrors as inaccessible as possible. It is only stressing her out. She's a little young to have the kind of neurological problems that sometimes affect old cats. Are there strays in the neighbourhood? Maybe she thinks they are suddenly invading her space? Behavioural changes always mean something.

I'd also buy some Rescue Remedy and when she starts freaking out, put a dropperful straight into her mouth, or a quick blast if it is in spray format. RR works pretty well in these situations.