Reference is made to this Journal article by authors; Pazooki, K., Leibetseder, M., Renner, W., & Kapsali, E.

Appl. Psychophysiol Biofeedback, 2019; 44(1): 31-39. doi: 10.1007/s10484-018-9417-1.

Negative symptoms of schizophrenia, such as, decreased ability to express emotions, and inability to regulate self-initiated behaviors become prominent over time. With the use of neurofeedback therapy, there were obvious reduction of such symptoms enabling more social, interpersonal and improved mental processes.  The results indicate that neurofeedback therapy may be further examined since it offers positively to existing treatment.

Full text pdf: uSchizophrenia and the efficacy of qEEG-guided neurofeedback treatment: a clinical case series.
Surmeli T, Ertem A, Eralp E, and Kos IH
Clinical EEG and Neuroscience, 43, 2012, pp 133-44