Here's a quad screen study:
It says, "There was a relatively low, but often significant, risk of having an adverse pregnancy complication if a patient had a single abnormal marker. However, the risk of having an adverse outcome increased significantly if a patient had 2 or more abnormal markers."
So yes, that study found a link between elevated markers and pregnancy complications, presumably including both PE and accreta.
It seems to me that accreta and PE are both defects in the process of placental invasion, but that no one's quite sure yet how things go wrong in either case.
The study Fiona has linked to says this: "Neither hypertension in pregnancy nor pre-eclampsia were mutually exclusive of placenta accreta: hypertensive disorders of pregnancy and placenta accreta occurred independently of each other."
So that looks like it says that they can both happen at once, but they're not likely to be causally related -- accreta probably doesn't cause PE, but can accompany it.
That said, there aren't a lot of studies on this issue -- I would imagine that it is extremely rare to see both complications simultaneously!