Spontaneous development of memory deficits in hypertensive rats. Systolic blood pressure (BP) was significantly higher in SHR at 12 weeks of age and gradually increased thereafter (A). Escape latencies in the Morris water maze (MWM) did not differ between both strains (B). Representative swims paths of SHR and WKY illustrate comparable learning effects over time (B). By contrast, SHR exhibited a significantly impaired discrimination capability in the novel object recognition test (C). Data are mean ± SD. *p < 0.05 versus WKY and #p < 0.05 versus week 12 by two-way RM ANOVA (A-B) or t-test (C) for n = 9-10 animals/group.