Chronic deep brain stimulation in an Alzheimer's disease mouse model enhances memory and reduces pathological hallmarks.

BACKGROUND: Alzheimer's disease (AD) is a progressive degenerative disorder that currently remains extremely disabling. Recent work has shown that deep brain stimulation (DBS) has promising effects in AD patients. In parallel to the clinical trials, we investigated the impact of chronic DBS in 3xTg mice, a well-established animal model of AD.

METHODS: AD mice were assigned to control (Cont), non-stimulation (NS) and stimulation (DBS) groups, along with age matched wild type controls (WT-Cont). Bilateral electrodes were implanted in the entorhinal cortex to deliver chronic high frequency stimulation for 25 days. Animals were tested in memory behavioral tasks, with post-mortem measurements of pathological markers.

RESULTS: We found that chronic DBS in AD mice normalized their impaired performance in the Morris water maze task to that of the WT group in the probe test. In the novel object and novel place preference tasks, AD-DBS mice spent more time at the novel object and novice location compared to AD-NS mice. These cognitive improvements in AD-DBS mice were associated with DBS induced increased neurogenesis in the dentate gyrus, a significant reduction in β-amyloid plaques, a reduction in CA-1 cellular β-amyloid-42 levels, decreased cortical total-tau and phosphorylated-tau, along with decreased hippocampal total-tau.

CONCLUSION: Overall, we show that chronic DBS of the entorhinal cortex in AD mice improves both memory and AD specific pathological markers. These results support further testing of DBS as a potential treatment in AD patients.