A transgenic construct containing 2.1kb of the human amyloid beta-precursor protein, APP gene, 770 isoform, with the Swedish K670N/M671L, Dutch E693Q and Iowa D694N mutations, under the control of the mouse thymus cell antigen 1, theta, Thy1, promoter was injected into fertilized C57BL/6 mouse eggs. Founder line B was subsequently established and homozygotes generated. Human amyloid beta precursor protein expression is detected in the brains of transgenic mice. Two other lines, A anc C were also generated, with line A having similar levels of transgene expression and amyloid beta accumulation to line B while line C has 2-fold higher expression of human Amyloid beta-precursor protein and shows 4-fold higher accumulations of soluble and insoluble AB peptides in the brain.