Transgenic mice overexpressing the betaAPP gene with the Swedish mutation under the control of the murine thy1 promoter show Alzheimer-like characteristics such as Abeta plaques in cerebral cortex and vessel walls. By comparison to age-matched non-transgenic controls, 2-year-old female APP23 transgenic mice crossed more segments in the open-field and had a higher number of fast ambulatory and stereotyped movements in a photocell activity chamber. In addition, APP23 mice entered more often and spent more time in the open arms of the elevated plus-maze. The acquisition of place learning in the Morris water maze was impaired in APP23 transgenic mice, but not in probe and visible platform subtasks. These results indicate that hyperactivity and impaired learning abilities characterize this mouse model of Alzheimer's disease and cerebral angiopathy.