When examining the presence of sIL-1R1 (the soluble form of the ligand-binding signalling receptor), it is interesting to see that its levels were significantly lower in SMC vs. NHS (706.8 ± 211.0 pg/ml vs. 925.7 ± 231.5 pg/ml, p < 0.001), but significantly higher in AD (1333.6 ± 365.6 pg/ml) as compared to all other groups, NHS (p = 0.009), SMC (706.8 ± 211.0 pg/ml, p < 0.001), and MCI (869.0 ± 388.2 pg/ml, p = 0.03) (Fig. 1, centre right). Here, IL1R1 is linked to Alzheimer disease.