We present the first NODDI, qMT and g-ratio study of microstructural differences between carriers and non-carriers of the APOE-e4 gene. This gene is a risk factor for the development of Alheimer's Disease later in life. Our work shows that the more specific microstructural measures offered by the NODDI technique has revealed an increase in the non-tissue (Viso) component in the brain among APOE-e4 carriers. Importantly, the other NODDI parameters and g-ratio show no difference suggesting that although the tissue component among APOE-e4 carriers is reduced, there is no detectable difference to the underlying microstructure. This important finding has not been shown before, and supports the large body of evidence that shows young healthy APOE-e4 carriers are not disadvantaged across a number of cognitive domains and (in some tasks) out-perform their non-e4 peers.