It has now long been established that the apolipoprotein epsilon 4 allele (APOE-∊4) on chromosome 19 constitutes a genetic risk factor for the development of Alzheimer’s disease.1 Since that discovery, APOE-∊4 has also often been implicated as being harmful in acquired types of brain injury including traumatic injury2 at least in the short term. Willemse-van Son et al’s evidence (see page 10.1136/jnnp.2007.129460) is reported to suggest, however, that APOE-∊4 can be associated with better, not …