This analysis included over 3000 people.
"meta-analysis showed that total antioxidant status and docosahexaenoic acid levels were significantly lower in FEP patients than in controls, whereas levels of homocysteine, interleukin-6 and tumor necrosis factor alpha were significantly higher in FEP patients than in controls. "
Docosahexaenoic acid is an omega 3 fatty acid. This may be why taking DHA was helpful to people in first episode psychosis or clinical high risk.
NAC is also known to decrease levels of homocysteine, so that may be why NAC is useful. It also has anti inflammatory properties.