Recently, the Food and Drug Administration has approved a technique called repetitive transcranial magnetic stimulation (rTMS), a noninvasive method for stimulating the brain, for the treatment of Major depressive disorder (MDD). While rTMS is an important alternative for patients who cannot tolerate medications or fail to respond to standard pharmacotherapy, like any single antidepressant treatment, rTMS fails to fully alleviate symptoms in 50- 65% of patients. One of the major stumbling blocks in improving the efficacy of rTMS efficacy is our limited understanding of how rTMS works on the brain to alleviate depression. rTMS changes neural excitability, and a typical treatment course consists of 25 rTMS sessions (1 session per day). Fifteen or more sessions are generally required before symptom changes become evident, and very little information exists about the nature and extent of induced changes (i.e., neural plasticity). The current proposal will use functional magnetic resonance imaging (fMRI) to investigate changes in neural activation in MDD patients after multiple rTMS treatments to left dorsolateral prefrontal cortex (dlPFC), targeting functional networks of the dlPFC. Forty patients with MDD will be scanned while performing a working memory task, as working memory (WM) is impaired in MDD and working memory performance reliably activates left dlPFC. Patients will be randomized to receive 20 active or 20 sham rTMS sessions, followed by fMRI scans. Using arterial spin labeling (ASL) fMRI, we will quantitate cerebral blood flow (CBF) during WM performance and during rest. As patients with MDD often overactivate left dlPFC relative to healthy control subjects, left dlPFC activation is predicted to decrease in the active rTMS group compared to the sham group, reflecting improved cortical efficiency as a specific result of the rTMS treatments. Comparison to stimulation with a sham coil should establish that observed changes are not due to placebo or time effects. Networks functionally connected to left dlPFC will also be assessed for changes as a result of active rTMS. Neural activity pre-treatment and changing with treatment will be explored as biomarkers which may moderate and mediate treatment response. The study will fill an important gap by providing information about neural changes associated with rTMS therapy, improving our understanding of the mechanism of rTMS. Impact of the proposed research: MDD is one of the most common mental disorders in the United States, and current pharmacologic treatments leave at least 1/3 of patients with persistent symptoms of depression, highlighting the need to develop and refine therapy. Improved understanding of regions and networks altered by rTMS in MDD will begin the development of a biomarker for treatment response and may identify new targets, both critical steps necessary to refine rTMS methods and improve treatment efficacy.

Public Health Relevance

Repetitive transcranial magnetic stimulation (rTMS) is an FDA-approved treatment for major depressive disorder, but questions remain about its mechanism of action that limit attempts to improve efficacy. This proposal will use functional magnetic resonance imaging (fMRI) to identify changes in neural activity (biomarkers) in patients receiving rTMS for depression. The identification of networks associated with clinical improvement may provide a biomarker of treatment response, which should increase our understanding of the mechanism of rTMS as an antidepressant therapy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21MH098174-01A1
Application #
8507377
Study Section
Neural Basis of Psychopathology, Addictions and Sleep Disorders Study Section (NPAS)
Program Officer
Rumsey, Judith M
Project Start
2013-06-01
Project End
2015-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
1
Fiscal Year
2013
Total Cost
$233,250
Indirect Cost
$83,250
Name
University of Michigan Ann Arbor
Department
Psychiatry
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Taylor, Stephan F; Ho, S Shaun; Abagis, Tessa et al. (2018) Changes in brain connectivity during a sham-controlled, transcranial magnetic stimulation trial for depression. J Affect Disord 232:143-151
Weigand, Anne; Horn, Andreas; Caballero, Ruth et al. (2018) Prospective Validation That Subgenual Connectivity Predicts Antidepressant Efficacy of Transcranial Magnetic Stimulation Sites. Biol Psychiatry 84:28-37
Demeter, Elise; Mirdamadi, Jasmine L; Meehan, Sean K et al. (2016) Short theta burst stimulation to left frontal cortex prior to encoding enhances subsequent recognition memory. Cogn Affect Behav Neurosci 16:724-35
Taylor, Stephan F (2014) Using graph theory to connect the dots in obsessive-compulsive disorder. Biol Psychiatry 75:593-4