Zerr et al show that HHV-6 reactivation post-HCT is associated with increased risk of delirium and neurocognitive decline, marked by selective impairment of executive functioning with relative sparing of memory and fine motor skills.¹  Still unresolved is the question of whether HHV-6 reactivates locally within the CNS as well as in the periphery, and whether virus reactivation within the CNS is required for viral effects on cognitive function. Professional illustration by Debra Dartez.