Although it is unknown how ocularly administered plasmids reach the brain, Lambiase (2007) [32] and Di Fausto (2007) [33] have discussed different routes in order to explain the beneficial effects of the ocular administration of some compounds (e.g., BDNF) capable of reducing the neurodegenerative damage produced in Alzheimer disease (AD) models, which may also account for our results. This evidence concerns the gene BDNF and early-onset autosomal dominant Alzheimer disease.