IDO1 and Cognitive impairment: More importantly, pharmacological, or genetic inhibition of IDO activity prevents induction of depressive-like behaviors, anxiety-like behaviors and/or cognitive impairments by systemic immune challenges, without impacting sickness behavior (Henry et al., 2009; O'Connor et al., 2009a,b,c; Salazar et al., 2012; Barichello et al., 2013; Xie et al., 2014).