A delivery vehicle which comprises a nucleic acid construct, wherein the nucleic acid construct comprises (i) an enhancer which specifically drives gene expression in cells of the entorhinal cortex (ii) a promoter; and (iii) a therapeutic gene, wherein said enhancer, promoter and therapeutic gene are operatively linked, said enhancer and therapeutic gene are heterologous, and said delivery vehicle is suitable for delivery of the nucleic acid construct to the brain of a mammal.