If it's AQA A, then you must not have looked at the book properly.
There's abnormality at AS, and you can choose from schizophrenia, depression, phobic disorders and OCD at A2.
But you must bear in mind that there is more to Psychology than mental health conditions. It's the study of the mind, which includes an abundance of things, which the specification accommodates. It's an interesting subject that is predominantly taught very poorly though. I'm doing both AS and A2 this year because the teachers are absolutely atrocious, as is the case in other schools. From my experience, I'd not have chosen it as an A Level if I could go back to year 12 to be honest.
But read through the text book, see if you like it. If you're good at memorising masses of information and regurgitating that in the exam, you'll be fine. Essay-writing skills are key at A2.