Hydrocephalus describes an expansion of the cerebral ventricles that is associated
with decreased cerebral volume and compromised neurological function. Although hydrocephalus
mostly occurs sporadically, it is frequently associated with diseases caused by defective
cilia function, including Bardet–Biedl syndrome (BBS). A new study reveals that
hydrocephalus in a mouse model of BBS is related to defective proliferation and apoptosis of
neural progenitor cells (NPCs) and can be rescued with lithium treatment (pages 1797–1804).