To identify whether the elevation of Smad7 in neurons in the hippocampal CA1 region after unilateral nephrectomy contributed to cognitive impairment, a serotype 2/9 adeno-associated virus encoding shRNA of Smad7 (shRNA–Smad7) was constructed and injected into the bilateral hippocampus to inhibit Smad7 expression. The gene discussed is SMAD7; the disease is Cognitive impairment.