Our proposed study employs a novel approach to determine the clinical and functional imaging effects of transcranial direct current stimulation (tDCS) as an adjunctive treatment to improve insight in schizophrenia – a significant predictor of medication adherence. The positive effects of tDCS will be assessed in conjunction with neuroimaging markers to provide solid mechanistic justification for larger treatment-controlled studies to determine if tDCS is a practical approach clinically. If proven effective, this safe and easy to use intervention can be used in in-patient and ambulatory settings as an adjunctive treatment to antipsychotic medication. This approach may improve or maintain treatment adherence, improve clinical outcomes, including reduced rates of re-hospitalization, and the well-being of individuals with SCZ and their families with potential economic and social benefits.

Impaired insight into illness is a common feature of schizophrenia that is frequently associated with worse clinical and functional outcomes. Transcranial direct current stimulation (tDCS) is a method of brain stimulation that delivers a weak electric current to targeted brain regions. Recent studies support the potential value of tDCS to improve impaired insight in schizophrenia. In this pilot randomized-sham controlled study, we aimed to examine the efficacy of adjunctive tDCS to improve insight in patients with schizophrenia.

A total of 20 participants (mean age=43.8 (SD=13.6), female ratio=20%) with moderate-to-severe insight impairment in schizophrenia (>3 PANSS G12 lack of judgment & insight) were randomized to receive twice-daily bilateral PPA active (n=12) or sham (n=8) stimulation for 10 days. The anode was placed at P4 (right-parietal) and the cathode at P3 (left-parietal). Insight was assessed using the VAGUS, a 10-point self-report scale of insight into psychosis. The baseline mean VAGUS score was 6.0 out of 10 (SD=1.3). Active bilateral tDCS was associated with improved insight (t(11)=-2.46, p=0.032). No significant changes in VAGUS average and or subscale scores occurred in the sham group.

The results of this pilot study suggest tDCS improves insight in patients with schizophrenia.
Further investigation with a larger sample size is required to confirm these preliminary results. Further, identification of neuroimaging biomarkers associated with tDCS and changes in insight, such as cerebral blood flow or brain activity in response to an insight task, can help elucidate the mechanisms of tDCS and insight in schizophrenia. Data from this project was used to secure funds for a larger grant investigating the effects of tDCS on treatment adherence in schizophrenia.

Kim, J., Plitman, E., Nakajima, S., Alshehri, Y., Iwata, Y., Chung JK., et al. Modulation of brain activity with transcranial direct current stimulation: Targeting regions implicated in impaired illness awareness in schizophrenia. European Psychiatry (2019), 61(63-71). https://doi.org/10.1016/j.eurpsy.2019.06.007

Kim, J., Song, J., Kambari, Y., Plitman, E., Shah, P., Iwata, Y., et al. Cortical
thinning in relation to impaired insight into illness in patients with treatment resistant schizophrenia. Schizophrenia(2023), 9(27). https://doi.org/10.1038/s41537-023-00347-y