From the abstract:

> Analysis of the TriNetX electronic health record database with data on 285 million patients revealed that the prevalence of chronic HCV was 3.6 and 3.9 percent in the SCZ and BPD populations respectively. The prevalence of chronic HCV in these populations was almost double that observed for MDD (1.8%) and approximately 7-fold higher than the control population (0.5%).

The association is real, but it’s not clear that HCV is a causal factor from this study. The only mechanistic bit that suggests a causal relation was that HCV indeed appeared in the brain (well, the choroid plexus) and may have triggered a local immune response. But the leap from that to “hepC causes schizophrenia and bipolar disorder” is pretty large.

Interestingly, the new drug used to cure hep c can throw you into a manic episode. It's something that's still being looked into because they aren't sure if the medicine can cause it directly, or if it's just the sudden life change, or if it's a response to your body suddenly not having to fight a chronic infection so you have more energy that you aren't used to handling.