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Using Transcranial Direct Current Stimulation for the Treatment of Mood Disorders

Jake Thompson
November 22, 2013

Using Transcranial Direct Current Stimulation for the Treatment of Mood Disorders

Talk given the the Hoglund Brain Imaging Center Journal Club

Jake Thompson

November 22, 2013
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  1. Using Transcranial Direct
    Current Stimulation for the
    Treatment of Mood Disorders
    Jake Thompson

    Dr. Evangelia Chrysikou

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  2. ‣ A noninvasive technique that
    involves the application of
    small currents (typically 1-2
    mA) to the scalp for a few
    minutes through two surface
    electrodes, which can
    modulate cortical excitability.
    (Chrysikou & Hamilton, 2011, Restorative Neurology &
    Neuroscience; Hamilton, Chrysikou, & Coslett, 2011)
    Transcranial Direct Current
    Stimulation (tDCS)

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  3. Transcranial Direct Current
    Stimulation (tDCS)
    ‣ Anodal tDCS: increases
    cortical excitability at the
    stimulation site through
    subthreshold neuron soma
    depolarization.

    ‣ Cathodal tDCS: decreases
    cortical excitability at the
    stimulation site due to neuron
    soma hyperpolarization.
    (Nitsche et al., 2008; Stagg & Nitsche, 2011)

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  4. Transcranial Direct Current
    Stimulation (tDCS)
    ! !
    (Chrysikou, Hamilton, Coslett, Datta, Bikson, &
    Thompson-Schill, 2013, Cognitive Neuroscience)

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  5. Electrical Field Modeling
    0 0.41 V/m
    Electric field/Current density
    33% 66% -0.41 V/m +0.41 V/m
    Electric field/Current density
    0
    LEFT SIDE VIEW
    RIGHT SIDE VIEW
    TOP VIEW
    !

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  6. Method Overview

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  7. Intra-Scanner tDCS

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  8. Intra-Scanner tDCS

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  9. intra-scanner tDCS

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  10. a few examples

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  11. tDCS had significant behavioral and regionally specific
    neural facilitation effects. Furthermore, faster naming
    responses correlated with decreased BOLD signal in
    Broca’s area. The data support the importance of Broca’s
    area within the normal naming network and as such
    indicate that Broca’s area may be a suitable candidate
    site for tDCS in neurorehabilitation of anomic patients,
    whose brain damage spares this region

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  12. The effects of a-tDCS on
    EPI data from a tDCS
    and fMRI control study
    illustrating the null effect
    of the anode electrode on
    the quality of the EPI
    images during each
    functional run.

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  13. Improved word-retrieval during
    atDCS was paralleled by selectively
    reduced task-related activation in the
    left ventral IFG, an area specifically

    implicated in semantic retrieval
    processes. Under atDCS, resting-
    state fMRI revealed increased
    connectivity of the left IFG and

    additional major hubs overlapping
    with the language network.
    Meinzer et al. (2012)

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  14. @ 1.0mA intensity: no artifacts, no excitatory or inhibitory effects
    (MEPs and BOLD signal may probe different physiological processes)

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  15. Uni- and bilateral tDCS over SM1
    resulted in functional connectivity
    changes in widespread brain areas
    compared with sham stimulation both
    during and after stimulation. Whereas
    bilateral tDCS predominantly
    modulated changes in primary and
    secondary motor as well as prefrontal
    regions, unilateral tDCS affected
    prefrontal, parietal, and cerebellar
    areas. No direct effect was seen under
    the stimulating electrode in the
    unilateral condition. The time course of
    changes in functional connectivity in the
    respective brain areas was nonlinear
    and temporally dispersed.

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  16. tDCS and Depression
    !
    Transcranial Direct Current Stimulation in the

    Treatment of Major Depression: A Meta-Analysis

    !
    !
    U. G. Kalu, C. E. Sexton, C. K. Loo, and K. P. Ebmeier

    Department of Psychiatry, University of Oxford

    !

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  17. The Dorsolateral Prefrontal Cortex
    Depression has been
    associated with a
    hypoactive left DLPFC.

    Unbalanced activity
    between left and right
    PFC.

    Can anodal tDCS increase
    left DLPFC activity,
    restoring balance?

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  18. Behavioral Studies
    The meta-analysis found that active tDCS
    was associated with a reduction in
    symptoms of about 30%.!
    This reduction persisted at follow-ups in
    studies where follow-ups were reported.!
    Significant heterogeneity limits the
    interpretability and generalizability of the
    findings.

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  19. Functional Neuromodulation of PFC
    Activity with tDCS in Unipolar Depression
    Unipolar depression is associated with negative affect,
    rumination, decreased motivation, and limited
    productivity.!
    Due to its massive individual and societal costs, much
    effort has been focused on the development of
    pharmacological and psychological interventions to
    alleviate the symptoms of depression. !
    Although these treatments are effective for some
    patients, others fail to respond to such interventions
    alone.

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  20. A limited but growing number of studies suggest
    that tDCS—particularly over prefrontal cortex—
    holds promise for the treatment of depression and
    has useful characteristics such as low cost, ease of
    use, and reliable sham methodology ( Dell’Oso et
    al., 2010; Drevets, 2000; Ferrucci et al., 2009).!
    The optimal use of tDCS for reliable clinical
    benefits in depression has not been fully
    explored. !
    We are combining tDCS and fMRI to investigate
    the effects of neurostimulation on frontal cortical
    excitability during a negative thought regulation
    task in depressed and healthy control subjects.
    Functional Neuromodulation of PFC
    Activity with tDCS in Unipolar Depression

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  21. Cognitive Reappraisal of
    Negative Stimuli
    Controls showed increased
    activity of the frontal pole
    (a), and patients showed
    increased activity in the
    right precuneous (b)
    Controls showed increased
    activity of the left frontal
    pole (a), and patients
    showed increased activity
    in the left orbitofrontal
    cortex (b & c)
    Pre-tDCS > Concurrent tDCS Concurrent tDCS > Pre-tDCS

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  22. Cognitive Reappraisal of
    Negative Stimuli
    During concurrent tDCS over the DLPFC patients
    increased activation of the left inferior frontal gyrus
    Patients > Controls

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  23. Effect of tDCS in Depressed
    Patients
    Even during ‘look only’ trails, patients showed increased
    activation of the left orbitofrontal cortex during anodal stimulation
    Concurrent tDCS > Pre-tDCS

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  24. What does it all mean?
    Findings suggest that anodal stimulation does
    alter cortical excitability in a manner that can be
    captured with fMRI.!
    Anodal stimulation is related to different
    activation patterns in depressed patients and
    controls.!
    Protocol Considerations:!
    Larger groups may help clean up behavioral comparisons.

    Increase current from 1.5mA?

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  25. Next Steps
    Large scale studies to determine optimal
    protocol.!
    Larger samples to investigate tDCS using
    fMRI.!
    Examine interactions between tDCS and other
    depression treatments (psychopharmacology)!
    Longitudinal studies to examine lasting
    effects, relapse rates, etc.

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