Clinical and Electrophysiological Outcomes of tDCS in Patients With Treatment Resistant OCD

The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is a 10-item scale designed to measure the severity and type of symptoms in people with obsessive-compulsive disorder (OCD) over the past seven days. The symptoms assessed are obsessions and compulsions. Total Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms. Scores on the obsession and compulsion subscales range from 0 to 20, but only the total Y-BOCS score is interpreted.

The participants use the self-reporting OCD Visual Analog Scale (OCD-VAS) to rate on a 10-point scale the current obsessive and compulsive symptoms (0 = Feel Worst Ever to 10 = Feel Best Ever).

The Clinical Global Impression - Improvement scale (CGI-I) is a 7 point scale that requires the clinician to assess how much the patient's illness has improved or worsened relative to a baseline state at the beginning of the intervention. Clinicians ask: "Compared to the patient's condition at baseline, this patient's average condition is rated as from 1 (Very much improved) to 7 (Very much worse).

The HAMD is designed to be administered by a trained clinician, and it contains 17 items rated on either a 3- or 5-point scale, with the sum of all items making up the total score. Low scores indicate less depression severity and greater function.

The total score of HAMA ranges from 0-56, with each of the 14 items being scored on a severity scale of 0 to 4. Low scores indicate less anxiety severity and greater function.

The Taiwanese version of World Health Organization Quality of Life-BREF is a self-report 28 items (2 generic, 7 Physical, 6 Psychological, 4 Social, and 9 Environment items) questionnaire. Item scores range from 1 (the worst condition) to 5 (the best condition), except for 3 items (Ph1, Ph2, and Ps6), which are reverse coded. A higher score indicates better quality of Life.

A neuropsychological test that examines the performance of prefrontal-mediated task

The CTT, a culture-neutral version of the Trail Making Test, was selected to measure sustained visual attention. The CTT consists of two parts (CTT-1 and CTT-2). The CTT-1 requires participants to connect a series of numbered circles that are randomly printed on a sheet of paper. In the CTT-2, numbered circles of 1 to 25 are shown twice (printed in pink and in yellow) randomly on a sheet of paper. Participants are asked to connect the numbers from 1 to 25 alternating between the two colors.

Stroop Color Word Test (SCWT), Chinese version; was administered to measure selective attention and cognitive flexibility. SCWT is composed of three parts, each lasting for 45 seconds.

A neuropsychological test for the assessment of executive functioning specifically to detect deficits in planning, which may occur due to a variety of medical and neuropsychiatric conditions.

DSST is a performance based test of cognitive performance tapping into processing speed, executive function, and attention, with 90 s test period and possible score range 0 133 (See detail in the DSST manual attached).

HRV indices represent autonomic functioning. ECG electrodes were placed on bilateral arms just below the elbows, with a ground electrode placed just above the right wrist bone. Lead I electrocardiogram of each patient was taken for 5 min after sitting and having a rest for 20 min in a soundproof, dim-lighted room with thermostatic control. At baseline and the end of intervention, HRV will be collected during rest. The ECG signals were acquired, stored, pre-processed according to the recommended procedures and processed by an HRV analyser (LR8Z11, Yangyin Corp., Taipei, Taiwan). The time domain of HRV is obtained: Standard deviation of NN intervals (SDNN). Power spectrum of HRV is quantified into the standard frequency-domain measurements including low-frequency power (LF, 0.04-0.15 Hz), high-frequency power (HF, 0.15- 0.40 Hz).

In a recliner in a dimly lit, electrically shielded room, patients' EEGs were recorded at baseline and the end of intervention by using the Neuro Prax® TMS/tDCS full-band DC-EEG system with 32 EEG Ag/AgCl electrodes in the standard 10-20 International placement. EEG will be collected during resting eye-opened (5min) and eye-closed (5min) conditions. Signals will be amplified in the dynamic input range of ± 140 mV at a resolution of 0.5 μV by using EEG amplifiers and stored for offline analyses. Eye or muscle artifacts were automatically detected and removed using NeuroPrax's built-in software.