Effect of Adjuvant Cerebellar Anodal Transcranial Direct Current Stimulation (tDCS) on Negative Symptoms of Schizophrenia: A Pilot Randomized Controlled Trial

Schizophrenia, a disabling mental disorder is characterized by cluster of both negative and positive symptoms. The positive symptoms are characterized by delusions, hallucinations and disorganization in thinking and behaviour. The negative symptoms refer to reduction of normal behaviour in the form of avolition, anhedonia, asociality, affective flattening and alogia. Whereas, the positive symptoms respond better to the available antipsychotic medications, the response of these medications in negative symptoms are meagre. There is also concern that negative symptoms run a chronic progressive course that leads to overall poor outcomes in the patient’s personal, social and occupational domains.

A recent study has shown that dysconnectivity between dorsolateral prefrontal cortex to cerebellum network directly corresponds to negative symptom severity. Another study involving 260 individuals with negative symptoms supported the evidence that reduced connectivity between the cerebellar-prefrontal network is associated with negative symptoms.

In recent researches, various non-invasive cerebellar stimulation at the vermis has shown to improve the negative symptoms of schizophrenia by improving the connectivity between the cerebellum and the prefrontal cortex. A systematic review further adds on to the evidence to positive outcomes of cerebellar stimulation. Amongst various NIBS techniques, most studied techniques are repeated transcranial magnetic stimulation (rTMS) and theta burst stimulation at cerebellum.

Indeed, some researchers have already used transcranial Direct Current Stimulation (tDCS) as a treatment for schizophrenia, evaluating effects over its common positive and negative symptoms. tDCS is a NIBS technique where direct current in the range of 0.5 to 2 mA is passed through the scalp by means of electrodes over designated areas of interest with an aim is to modulate the activity of specific brain region. Till date there is only 01 descriptive study including 04 patients investigating the effects of anodal tDCS over the cerebellum and primary motor cortex in schizophrenic patients suffering from tardive dyskinesia, also found that showed significant decrease in negative symptoms. Additionally, tDCS is considered one of the safe office procedures with minimal and self-limiting side-effects viz. burning sensation, redness at electrode placement area, tingling sensation, itching and headache.

Despite multiple benefits of this non-invasive treatment modality, there is a huge research gap in this field. Hence, this study proposes to study the effect of adjuvant Cerebellar anodal tDCS on Negative Symptoms of Schizophrenia