TGFB1 and Alzheimer disease: With regard to cytokines, it has been shown that AD patients have higher levels of interleukin-6, 12, and 18, tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β), in blood, and higher levels of TGF-β in CSF, compared to healthy controls (Figure 3; Swardfager et al., 2010).