Cerebral Blood Flow Changes After Transcranial Direct Current Stimulation for a Patient With Schizophrenia: a Case Report

“Mr. R,” a 26-year-old man with schizophrenia for the last 10 years, presented with delusional thoughts, visual hallucination, problems with motivation, social withdrawal, and diminished affective responsiveness. Despite previous use of antipsychotic drugs such as haloperidol (2003–2005; higher dose of 15 mg/day), risperidone (2005–2007; maximum dose of 6 mg/day) and olanzapine (2007–2009; maximum dose of 20 mg/day), the patient had no improvement in clinical presentation. In 2009, considering the severity of symptoms and refractoriness to standard treatments, clozapine was initiated with maximum dose of 600 mg/day without success. In 2012, the medical team, decided for a tDCS treatment protocol because the patient’s family did not agree with electroconvulsive therapy. After a written informed consent was signed by a family member (patient’s mother), the patient underwent 20 sessions of tDCS for 10 days. A baseline SPECT was made to be further compared with outcome imaging. The examination showed a heterogeneous pattern of radiotracer concentration particularly in the temporal lobes, pronouncedly in the left. Thus, the cathode was positioned in the right temporoparietal transition and anode in the left temporoparietal transition. We used a direct current of 2 mA for 20 minutes. Electrodes of 35cm² were wrapped in cotton material moistened with saline to reduce the impedance. During follow-up, a new SPECT was performed (after 30 days of final stimulation), showing overall improvement of cerebral perfusion in relation to previous SPECT, especially in the left temporal lobe (Figure 1). Patient did not show clinical improvement as assessed by rating scales [Positive and Negative Syndrome Scale (PANSS)] at follow-up.

In the present case, we demonstrate cerebral blood flow changes after a tDCS protocol for a patient with schizophrenia. During follow-up (after 30 days of final stimulation), there was overall improvement of cerebral perfusion mainly in the left temporal lobe in relation to previous neuroimaging assessment. SPECT was able to assess tDCS biological effects for a patient with schizophrenia.

Studies combining tDCS with brain imaging methods, such as SPECT, promise to provide invaluable insights on the correlation between modification of behavior and its underlying neurophysiologic underpinnings.¹⁰ The results of clinical research accessing neuroimaging findings for tDCS protocols have predominately focused on motor cortical stimulation instead of stimulation of brain areas relevant to the treatment of specific mental disorders, and there has been some inconsistency within the findings. For example, Lang et al using PET found that both anodal and cathodal stimulation increased underlying regional blood flow, whereas an earlier fMRI study reported a decrease in activity with cathodal tDCS and no change with anodal stimulation.¹¹

To date, only one trial assessed tDCS in the treatment of schizophrenia. Thirty patients with schizophrenia with persistent auditory hallucinations were randomized to receive either active stimulation or sham. The cathode was placed on the left temporo-parietal region and the anode on the left dorsolateral prefrontal cortex. The rationale of this position was at the same time perform an inhibitory stimulation over the area related to positive symptoms (auditory hallucinations) and an excitatory stimulation over the area correlated with negative symptoms. tDCS was applied twice daily for 5 days, and the authors showed an improvement of hallucinatory symptoms (primary endpoint) after the end of stimulation, with sustained clinical response after 1 and 3 months of treatment.¹²

In the current case study, SPECT was a valuable tool to provide data regarding neurobiological changes induced by tDCS intervention for the treatment of a mental disorder as shown by improvement in perfusion of compromised brain areas.