Supplementary Material for: The Relationship between Cytokines and Verbal Memory in Individuals with Schizophrenia and Their Unaffected Siblings

Background: Verbal memory impairment may be considered an endophenotype in schizophrenia (SZ), also affecting the siblings of SZ subjects. Furthermore, the immune-inflammatory system response has an important modulatory effect on brain processes, especially on memory circuits. Objective: Investigating the relationship between TNF-α and IL-6 and memory performance in patients with SZ, their unaffected siblings (SB) and healthy controls (HC). Methods: 35 subjects with SZ, 36 SB, and 47 HC underwent a neurocognitive assessment for verbal memory by means of the revised Hopkins Verbal Learning Test (HVLT-R) in addition to serum cytokines analyses. Results: SZ patients performed worse in HVLT-R than SB and HC, but SB and HC were not different. Regarding the biomarker levels, we found significant results of TNF-α for both groups. However, we did not find differences between groups after multiple-comparisons analysis. There were no significant correlations between episodic verbal memory, TNF-α, and IL-6. Conclusion: The results are compatible with the hypothesis that deficits in verbal memory of individuals with SZ could be secondary to inadequate functioning of cognitive processing areas, such as proactive cognitive control.