I don't know about any link between psychosis and difficulty reading. I guess I can say that when I was psychotic I wasn't exactly reading. I was mostly in the hospital, or at home in a manic crisis. I do not have psychosis outside of severe bipolar episodes, so am unaware how psychosis may or may not affect people who have long-term psychosis.

I have indeed had periods when I had great difficulty reading. I suspect that period was due to certain bipolar medications that affected me cognitively, perhaps some depression, anxiety and/or hypomania/mania that affected my ability to concentrate on one thing for long, and/or just my brain being affected by severe episodes. In any case, my current mix is pretty friendly in terms of cognitive impairment. I can pinpoint high doses of Lamictal and pretty much any significant dose of Lithium as impairing me cognitively. I also think that some medications that were highly sedating affected my ability to read. If I'm extremely tired/sedated, I can barely do anything. In early periods of taking Seroquel, Seroquel XR and Geodon (and maybe some others I forget) I struggled with sedation. I did, however, adjust to these medications over time. I don't regard Seroquel XR to be overly sedating anymore. Perhaps if it was even less sedating I'd be prone to hypomania or mania.

I am a believer that bad episodes hurt my brain in ways that resembled cognitive impairment. Depression definitely hurts me cognitively. But time and healing seems to clear that cloud.