Repeated Anodal tDCS Coupled with Cognitive Training for Patients

with Severe Traumatic Brain Injury

A Pilot RCT

Marcin Leśniak, Katarzyna Polanowska and Joanna Seniów

2nd Department of Neurology, Institute of Psychiatry & Neurology, Warsaw, Poland

1 OBJECTIVES

Cognitive rehabilitation becomes a practice standard

in treatment of memory and attention impairments

which are typically the main targets of cognitive

training after severe traumatic brain injury (TBI)

(Cicerone et al., 2011). However, functional gains

from this form of therapy are still limited and

patients usually require long-lasting, and costly

rehabilitation.

Non-invasive neuromodulatory techniques,

aimed to boost neuroplastic changes in the brain, are

expected to enhance the effects of behavioural

interventions. One of these techniques - transcranial

direct current stimulation (tDCS) delivers a low

electric current that modulates the resting potential

of neurons that underlie the stimulation site. Anodal

tDCS (A-tDCS) which increases cortical excitability

has been shown to improve cognitive performance

both in healthy individuals (Chi et al., 2010) and

patients with brain damage (Jo et al., 2009).

However, efficacy of this method in alleviating

cognitive impairments post TBI has not been tested

to date.

In this pilot, randomized controlled trial (RCT)

we aimed to determine whether cumulative A-tDCS

of the left dorso-lateral prefrontal cortex (DLPFC)

could enhance rehabilitation of memory and

attention in patients with severe TBI. The target area

of stimulation was chosen based on recent data that

demonstrated DLPFC involvement during attention

and memory task performance (Blumenfeld et al,

2011).

2 METHODS

Twenty three adult patients (17 men and 6 women;

mean age: 28.7±8) with severe TBI (4-92 months

prior to enrollment) and subsequent cognitive

deficits participated in the study. They were

randomly allocated to two groups. The experimental

group (N=12) received 15 (5 times/week for 3

weeks) 10-min. A-tDCS (anode over left DLPFC;

cathode above the contralateral supraorbital area;

stimulation parameters: 1 mA, current density=

0,028mA/cm2) sessions followed by 60-min.

cognitive training. The control group (N=11)

received the same amount of cognitive

rehabilitation, but the A-tDCS was applied only

during the first 30 sec. (sham condition).

3 OUTCOME MEASURES

The effects of A-tDCS were measured using a

battery of tests of memory, and attention, assessed

both in visual and auditory modality. The battery

included tests from Cambridge Neuropsychological

Test Automated Battery (CANTAB, Cambridge

Cognition, Cambridge, United Kingdom) (Pattern

Recognition Memory, Spatial Span, Rapid Visual

Processing), Rey’s Auditory Verbal Learning Test,

and Paced Auditory Serial Addition Test. European

Brain Injury Questionnaire (EBIQ) was used to

assess subjective impact of cognitive and emotional

problems on daily functioning.

Participants were tested twice before the start of

the rehabilitation programme (to control for

spontaneous recovery), immediately after its

completion, and four months post rehabilitation

treatment completion.

4 RESULTS

Most patients tolerated the stimulation well. Some

participants experienced tingling sensations, itching,

drowsiness, headache, stinging, dizziness, and one

had a panic attack.

The effects of spontaneous recovery, and the

effects of the applied therapy on short-term efficacy,

and long-term efficacy were assessed with a mixed

model ANOVA, with time of assessment as a within-

sniak M., Polanowska K. and Seniów J..

Repeated Anodal tDCS Coupled with Cognitive Training for Patients with Severe Traumatic Brain Injury - A Pilot RCT.

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

group factor and intervention as a between-groups

factor. Effect sizes were determined with Cohen’s d

(the mean change score divided by the pooled

standard deviation).

The results of pretreatment comparison

suggested relatively stable cognitive functions in

both groups during the first (pretreatment) phase of

the experiment. The two groups exhibited similar

effect sizes.

Post-treatment comparisons generally revealed

improved cognitive performance and higher effect

sizes in both groups. In six outcome measures, the

tDCS group performed better than the sham group.

Importantly however, none of the differences

between groups were statistically significant.

At the 4-month follow-up, both groups showed

improved performance in most tests (compared to

pre-treatment), as indicated by the increases in effect

sizes. The tDCS group achieved higher effect sizes

than the sham group in five outcome measures.

However, the differences between the groups were

not sufficiently marked to reach the significance

level.

5 DISCUSSION

In this study, we hypothesized that consecutive A-

tDCSs would facilitate adaptive changes in neural

networks that were involved in attention control and

memory track formation. We assumed that these

changes would strengthen the effects of the

cognitive training.

Our results did not provide sufficiently strong

evidence to support the use of repeated A-tDCS over

the left DLPFC for neuromodulation supplementary

to cognitive rehabilitation of individuals recovering

from severe TBI. However, since the tDCS-treated

group exhibited overall larger effects sizes, some

positive response to stimulation may be possible. It

is likely that longer and/or more intense stimulation

as well as better control of EEG activity (Ulam et

al., 2014) will result in more beneficial effects in

future studies.

REFERENCES

Cicerone, K., Langenbahn, D., Braden, C., Malec, J.,

Kalmar, K., Fraas, M., Felicetti, T., Laatsch, L.,

Harley, J., Bergquist, T., Azulay, J., Cantor, J., &

Ashman, T., 2011. Evidence-based cognitive

rehabilitation: updated review of the literature from

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And Rehabilitation, 92, 4, pp. 519-530

Chi R., Fregni F., Snyder A., 2010, ‘Visual memory

improved by non-invasive brain stimulation’. Brain

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Jo, J., Kim, Y., Ko, M., Ohn, S., Joen, B., & Lee, K.,

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Blumenfeld R., Parks C., Yonelinas A., Ranganath C.,

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Ulam, F., Shelton, C., Richards, L., Davis, L., Hunter, B.,

Fregni, F., & Higgins, K., 2014. Cumulative effects of

transcranial direct current stimulation on EEG

oscillations and attention/working memory during

subacute neurorehabilitation of traumatic brain injury,

Clinical Neurophysiology: Official Journal Of The

International Federation Of Clinical Neurophysiology,

MEDLINE, EBSCOhost, viewed 18 August 2014