Research PaperExperience-dependent reduction of soluble β-amyloid oligomers and rescue of cognitive abilities in middle-age Ts65Dn mice, a model of Down syndrome

- Aged Ts65Dn mice have increased levels of hippocampal β-amyloid oligomers.
- Aged Ts65Dn mice display increased levels of neprilysin expression in the hippocampus.
- Exposure to environmental enrichment normalizes levels of β-amyloid in Ts65Dn mice.
- Exposure to environmental enrichment normalizes neprilysin levels in Ts65Dn mice.
- Enriched Ts65Dn mice display a rescue in spatial learning and memory abilities.

Down syndrome (DS) is the most diffused genetic cause of intellectual disability and, after the age of forty, is invariantly associated with Alzheimer's disease (AD). In the last years, the prolongation of life expectancy in people with DS renders the need for intervention paradigms aimed at improving mental disability and counteracting AD pathology particularly urgent. At present, however, there are no effective therapeutic strategies for DS and concomitant AD in mid-life people. The most intensively studied mouse model of DS is the Ts65Dn line, which summarizes the main hallmarks of the DS phenotype, included severe learning and memory deficits and age-dependent AD-like pathology. Here we report for the first time that middle-age Ts65Dn mice display a marked increase in soluble Aβ oligomer levels in their hippocampus. Moreover, we found that long-term exposure to environmental enrichment (EE), a widely used paradigm that increases sensory-motor stimulation, reduces Aβ oligomers and rescues spatial memory abilities in trisomic mice. Our findings underscore the potential of EE procedures as a non-invasive paradigm for counteracting brain aging processes in DS subjects.