AGA and schizophrenia: Several studies, including a meta-analysis, have suggested an association between increased AGAs for native gliadins and schizophrenia.12, 20, 21, 22, 23, 25 However, the present study failed to show a significant increase in either AGA IgG levels or AGA IgA levels, although a nonsignificant increase in AGA IgA levels was observed in patients with schizophrenia (Table 4).