The present invention provides nucleic acids comprising a nucleotide sequence encoding an apolipoprotein E (apoE) splice variant, e.g., an unprocessed apoE, that retains intron 3; and vectors and host cells comprising same. The present invention further provides screening methods to identify agents that inhibit cleavage of intron-3 from the apoE splice variant. The present invention further provides methods of treating apoE-related neurological disorders, involving administering an agent that inhibits removal of intron-3 from a precursor apoE mRNA.