An electroencephalographic study comparing maximum blink rates in schizophrenic and nonschizophrenic psychiatric patients and nonpsychiatric control subjects

Background: We did a retrospective electroencephalographic (EEG) analysis of blink rates in patients with psychiatric disorders and control subjects to determine whether maximum blink rates under different conditions were higher in patients with psychiatric disorders. Methods: Maximum blink rates in those with schizophrenia (n = 23), those with nonschizophrenic psychiatric illnesses (n = 21), and nonpsychiatric control subjects (n = 35) were obtained from patientsʹ EEGs and compared with one-way analysis of variance and post hoc tests. In addition, correlation analysis was performed to determine if patientsʹ medications affected maximum blink rates. Results: Patients with schizophrenic and nonschizophrenic psychiatric disorders had twofold higher maximum resting blink rates compared to controls (p < .05 respectively). No difference was found between those with schizophrenic and nonschizophrenic psychiatric disorders. The maximum blink rate during cognitive testing was also twofold higher in those with nonschizophrenic psychiatric disorders (n = 11) compared to controls (n = 16; p < .05). Within each group, maximum blink rates during quiet rest and cognitive testing did not differ, nor were there differences between groups in the duration of highfrequency blinking (greater than 40 blinks per minute) during quiet rest. In psychiatric patients, none of the medications taken at the time of EEG recording correlated with maximum blink rates. Conclusions: High maximum blink rates recorded by EEG may suggest the presence of a psychiatric disorder.