RCT of tDCS Combined With Cognitive Training in Schizophrenia

Given the superior effects of CT augmented tDCS in healthy subjects, the aim of the current study was to examine whether the effect of CT on cognition can be enhanced with concurrent anodal tDCS in schizophrenia patients. A double-blinded randomised controlled trial design was utilised and cognitive performances were examined at baseline (T0), immediately after the intervention (T1) and one month post-intervention (T2). It was hypothesized that concurrent CT with tDCS would result in greater and more sustainable cognitive improvement than CT alone because of increased susceptibility to neuroplasticity changes of the underlying activated network (Bikson et al., 2013; Orlov, O'Daly, et al., 2017). The effects of concurrent CT with tDCS were also assessed using blinded assessments of psychotic, negative symptoms, affective symptoms, psychosocial functioning, subjective quality of life (QOL) and tolerability in the two groups.

The current study is a parallel-group, double-blinded, randomised controlled trial that aimed to fill the knowledge gap in investigating the effect of five sessions of concurrent cognitive training with 'online' tDCS on specific cognitive domains in stable schizophrenia patients at two time-points, (i) immediately after the intervention (ii) at one month after intervention.

It was hypothesized that concurrent cognitive training with 'online' tDCS would result in greater incremental effective improvements in cognitive domains as compared to the cognitive training alone, and the effect would be sustainable at one-month follow-up. The effect of the concurrent cognitive training with 'online' tDCS were also assessed using blinded assessments of psychotic, negative symptoms, affective symptoms, psychosocial functioning, subjective quality of life (QOL) and tolerability in the two groups.

Participant were randomly allocated to one of the two groups using a predetermined randomisation sequence and block randomisation generator (block of 6). Group 1 received active tDCS stimulation and CT and will be referred to as the active tDCS + CT group. Group 2 received sham tDCS and CT and will be referred to as the sham tDCS + CT group. Both groups consisted of 23 participants and received five treatment sessions on five consecutive days.

Stimulation protocol with the corresponding randomisation code was set up by an independent psychiatrist.The double-blind administration panel of the SatrStim8 system of tDCS ensured effective blinding; both the principal investigator and the participants were blinded to the group allocation until the statistical analysis stage. All outcome measures were assessed at three time-points (T0, baseline; T1, end-treatment course; and T2, at one-month post-intervention).

Declaration:

The research protocol fully complies with the Declaration of Helsinki and the guidelines of ICH-GCP.

Eligibility Criteria:
Inclusion Criteria:

1. Participants aged 18-65 years old; and
2. Being right handed; and
3. Able to communicate in Cantonese; and
4. With the diagnosis of schizophrenia meeting the diagnostic criteria of the World Health Organization's 10th version of the International Statistical Classification of Disease and Related Health Problems (ICD-10). All diagnoses were ascertained at multidisciplinary team and endorsed by at least a consultant psychiatrist and a specialist in psychiatry in the clinical teams based in Tai Po Hospital.

Exclusion Criteria:

1. Significant neurologic history such as dementia, stroke, seizure, Parkinson's disease, multiple sclerosis; or
2. History of brain neurosurgery; or
3. Active abuse of alcohol or illicit substances; or
4. Concurrent use of cognitive-enhancing medications e.g. acetylcholinesterase inhibitors; or
5. Documented history of learning disability; or
6. Implanted with pacemakers, intracranial electrodes, defibrillators, metal implants in head or neck area; or
7. Pregnancy or breastfeeding; or
8. Changes in medication regime over the two weeks before or during the study period (Brunoni, Ferrucci, et al., 2011).