Using TMS to Increase Executive Function in Older Adults

Cognitive decline and dementia have become important public health issues in our time as
medical science has increased lifespan and our society becomes progressively older. A great
deal of the cognitive decline due to aging can be explained by decline in working memory
(WM), a mental function central to cognition in which aging deficits appear almost
universally. Attempts to use WM training to increase WM ability in older adults has had some
success, but the transfer of performance enhancements caused by this training to other
cognitive skills is controversial. Another intervention that shows much promise is
noninvasive stimulation of cerebral cortex using transcranial magnetic stimulation (TMS),
which has been shown to increase performance in many cognitive tasks. Here, the investigator
proposes to use fMRI-guided TMS enhancement paradigm to stimulate dorsolateral prefrontal
cortex (DLPFC), a region involved not only in the maintenance of items in WM, but also in
their manipulation, in order to create WM performance enhancements that will be long lasting
and that will transfer to other cognitive tasks as well. This will be achieved through three
studies. In the first the investigator will stimulate both old and young healthy adults while
they perform different WM tasks that will increasingly engage DLPFC in order to demonstrate
enhancement of WM performance that is greater in the older adults. In the second and third
studies, older adults will receive active or sham TMS over two weeks of daily sessions while
they perform the WM tasks. In the second study, the investigator hopes to demonstrate that
the cumulative effect of multiple TMS sessions, in tandem with the synergistic effects of
simultaneous TMS + WM training, create WM performance enhancements greater than those found
with WM training alone, whose effects are long-lasting, continuing a month following the
course of TMS sessions. In the third, the investigator will investigate whether the WM
enhancements generated by the two weeks of TMS sessions will generalize to other cognitive
tasks. Success of these studies will provide proof in principle for long-lasting,
transferable effects of TMS in remediating WM and more general cognitive deficits due to
aging, and point to a possible non-invasive brain stimulation therapy for cognitive decline
in healthy aging and in dementia.