Cognitive impairment in schizophrenia is one of the most difficult symptom domains to treat with pharmacotherapy and psychotherapy available at present.

Noninvasive neuromodulation techniques use either magnetic or electrical stimulation to directly target specific brain areas, alter neuronal oscillations, cause long-term neuroplasticity changes. Various neuromodulation techniques including rTMS, tDCS, tRNS, tACS etc. are found to be well tolerated. Their effect in improving cognitive impairments in schizophrenia is found to be equivocal. Evidence is limited due to majority of research having small sample size, some having contradictory findings and lack of evidence regarding long-term efficacy. (Kar and Singh, 2022) tACS is more effective at entraining the endogenous brain oscillations as compared to tDCS as it mimics the alternating nature of brain oscillations. (Elyamany et al., 2021)

According to a study by Parker et. al. (2014), considering the extensive anatomical connection between cerebellum, thalamus, prefrontal and anterior cingulate cortex, cerebellar stimulation may restore prefrontal function and improve cognition in schizophrenia. No serious adverse event was reported in any study administering tACS to cerebellum in healthy or diseased population. Singh et. al. conducted a study where single session of theta tACS was applied on cerebellar vermis in schizophrenia patients which led to changes in theta activity in frontal cortex but no significant change in performance on a core cognitive-timing task, concluding that repeated or longer duration tACS sessions may induce long-lasting or more robust changes in midfrontal oscillatory activity at lower frequency bands that may lead to significant behavioural improvement. (Singh et al., 2019)