APOE and Cognitive impairment: In addition and importantly, conditionally deleting apoE4 in GABAergic interneurons was sufficient to have similar effect and completely prevented the apoE4-induced deficits (Knoferle et al., 2014), suggesting that the apoE4 sourced from GABAergic interneurons is responsible for the deleterious effect of apoE4 on neuronal loss and cognitive deficit.