AAV9 Tau ΔD421 also produced cognitive impairment in the radial arm water maze task (Fig. 8a); however, despite SSAT disruption’s ability to partially reduce specific phospho-tau epitopes (Fig. 4e–h, Fig. 5a, d, h, i) and prevent the tau-induced increases in putrescine and acetylspermidine (Fig. 7a, d), cognitive impairment induced by AAV9 Tau ΔD421 was not improved by SSAT disruption (Fig. 8a). The gene discussed is MAPT; the disease is Cognitive impairment.