Comparison of treatment schedules on cognitive effects of rTMS in the 3xTg-AD model of Alzheimer's disease.

Abstract

Repetitive transcranial magnetic stimulation (rTMS) is a promising non-invasive therapy for improving cognition in Alzheimer's disease (AD), but the optimal treatment parameters have yet to be elucidated. One important parameter is the treatment schedule. In this study, we used an established rodent low intensity rTMS stimulation protocol to compare cognitive and biochemical effects of an intensive treatment protocol (daily for 12 days) to a distributed protocol (twice a week for six weeks) in 12-month-old 3xTg-AD mice and B6 controls. We found that both protocols improved object place memory function, but only the distributed protocol improved working memory as measured with the Y-Maze. We did not find any effect of either rTMS protocol on BDNF or amyloid pathology, although these measures correlated well with activity and cognitive performance, suggesting rTMS improvement was independent of these mechanisms. Intensive rTMS increased choline acetyltransferase-positive neurons in the anterior bed nucleus of the stria terminalis (BNST), which may be due to the function of this region in mediating cognitive and limbic circuitry. These results indicate that while both treatment protocols can improve specific aspects of recognition memory, only distributed rTMS improves working memory function, possibly due to causing less cognitive fatigue and physiological stress. Future studies should examine region specific changes relating working memory function and stress related signaling to further understand the mechanisms behind this important rTMS treatment parameter.