A single pre-symptomatic intraventricular injection of an AAV2 vector harboring canine TPP1 (cTPP1) cDNA into the CLN2 Dachshund model led to the reduced storage of autofluorescent material and decreased astrocytosis in the brain, and delayed onset of cognitive deficits and extended lifespan of the mutant dogs (35). This evidence concerns the gene TPP1 and Cognitive impairment.