Interestingly, a negative correlation between low TGF-β1 concentrations and high TNF-α plasma concentrations was observed exclusively in the group of young adult individuals with DS (19–35 years) (Figure 5A, Spearman r= -0.5576, p < 0.01), while no such correlation was found neither in older adult individuals with DS without AD-related cognitive decline (Figure 5B, Spearman r 0.1598, p = 0.59) nor in older adult DS-AD (35–50 years) (Spearman r = 0.57, p = 0.10). This evidence concerns the gene TGFB1 and Alzheimer disease.