I think you are correct. I have experience with a relative with schizophrenia, however the appearance in the photo is that of a meth-head, again experience, but with a neighbor who physically went to ‘H’ using meth.
Perhaps the schizophrenia started her on her trek into oblivion, and there she met up with drugs such as meth.
If she smiled we could put an end to the Meth speculation.
She looked pretty thin and younger when she disappeared.