IGF2 and Cognitive impairment: However, as Fig. 2D shows, cognitive impairment did not significantly affect plasma concentrations of 3-NT (t56 = 1.28, p = 0.206), IGF-1 (t56 = 0.294, p = 0.770), IGF-2 (t56 = 0.070, p = 0.944) or IGFBP-3 (t53 = 0.515, p = 0.609).