DISTINGUISHING PSYCHIATRIC SUBTYPES: BLINK RATE, SENSORY GATING, AND SYMPTOM DIFFERENCES

Similar symptoms between schizophrenia (Scz) and bipolar disorder (BPI) result in difficulty distinguishing between these mental illnesses. Sensory gating and eye blink rate are potential objective measures that could aid in differential diagnosis. In Scz and sometimes BP, sensory gating is impaired. Normal sensory gating, measured using a paired-click paradigm, occurs when the peak amplitude of a positive evoked brain potential at about 50ms (P50), derived from the electroencephalogram (EEG), is reduced (“gated” or inhibited) to the second click compared to the first. Furthermore, blink rate can be elevated in psychiatric groups. Past studies provide evidence that blink rate and sensory gating may be linked to dopamine levels and brain inhibitory function, which can be impaired in Scz and BPI, possibly leading to insightful pathophysiology knowledge. The purpose of this study was to (i) analyze differences in sensory gating measures and eye blink rates (blinks/minute) of control, SczP (paranoid Scz), SczA(schizoaffective) , and BPI patient groups; (ii) correlate these measures to clinical and behavioral symptoms and symptom severity; (iii) correlate blink rate and sensory gating. A paired-click paradigm was administered. ANOVA, correlations, and post-hoc analysis was used. Significance levels were set at p ≤ 0.05. Significant differences were found in P50 gating and blink rate among subgroups. The SczA groups showed the worst scores across gating measures. SczA and BPIPsy (BPI with psychosis) demonstrated similar gating patterns. SczP gating was not significantly different from controls. BPINoPsy (BPI without psychosis) and controls had similar gating measurements. SczA was the only psychosis without a relatively high blink rate; both the SczP and BPIPsy groups had significantly higher blink rates than the SczA and BPINoPsy groups. The correlation between blink rate and sensory gating was not significant. Patterns of blink, sensory gating and symptom correlations differed across the patient subgroups.